LCOV - code coverage report
Current view: top level - src/backend/storage/lmgr - lock.c (source / functions) Hit Total Coverage
Test: PostgreSQL 17devel Lines: 1085 1235 87.9 %
Date: 2024-03-28 10:11:15 Functions: 54 57 94.7 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * lock.c
       4             :  *    POSTGRES primary lock mechanism
       5             :  *
       6             :  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
       7             :  * Portions Copyright (c) 1994, Regents of the University of California
       8             :  *
       9             :  *
      10             :  * IDENTIFICATION
      11             :  *    src/backend/storage/lmgr/lock.c
      12             :  *
      13             :  * NOTES
      14             :  *    A lock table is a shared memory hash table.  When
      15             :  *    a process tries to acquire a lock of a type that conflicts
      16             :  *    with existing locks, it is put to sleep using the routines
      17             :  *    in storage/lmgr/proc.c.
      18             :  *
      19             :  *    For the most part, this code should be invoked via lmgr.c
      20             :  *    or another lock-management module, not directly.
      21             :  *
      22             :  *  Interface:
      23             :  *
      24             :  *  InitLocks(), GetLocksMethodTable(), GetLockTagsMethodTable(),
      25             :  *  LockAcquire(), LockRelease(), LockReleaseAll(),
      26             :  *  LockCheckConflicts(), GrantLock()
      27             :  *
      28             :  *-------------------------------------------------------------------------
      29             :  */
      30             : #include "postgres.h"
      31             : 
      32             : #include <signal.h>
      33             : #include <unistd.h>
      34             : 
      35             : #include "access/transam.h"
      36             : #include "access/twophase.h"
      37             : #include "access/twophase_rmgr.h"
      38             : #include "access/xlog.h"
      39             : #include "access/xlogutils.h"
      40             : #include "miscadmin.h"
      41             : #include "pg_trace.h"
      42             : #include "storage/proc.h"
      43             : #include "storage/procarray.h"
      44             : #include "storage/sinvaladt.h"
      45             : #include "storage/spin.h"
      46             : #include "storage/standby.h"
      47             : #include "utils/memutils.h"
      48             : #include "utils/ps_status.h"
      49             : #include "utils/resowner.h"
      50             : 
      51             : 
      52             : /* This configuration variable is used to set the lock table size */
      53             : int         max_locks_per_xact; /* set by guc.c */
      54             : 
      55             : #define NLOCKENTS() \
      56             :     mul_size(max_locks_per_xact, add_size(MaxBackends, max_prepared_xacts))
      57             : 
      58             : 
      59             : /*
      60             :  * Data structures defining the semantics of the standard lock methods.
      61             :  *
      62             :  * The conflict table defines the semantics of the various lock modes.
      63             :  */
      64             : static const LOCKMASK LockConflicts[] = {
      65             :     0,
      66             : 
      67             :     /* AccessShareLock */
      68             :     LOCKBIT_ON(AccessExclusiveLock),
      69             : 
      70             :     /* RowShareLock */
      71             :     LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock),
      72             : 
      73             :     /* RowExclusiveLock */
      74             :     LOCKBIT_ON(ShareLock) | LOCKBIT_ON(ShareRowExclusiveLock) |
      75             :     LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock),
      76             : 
      77             :     /* ShareUpdateExclusiveLock */
      78             :     LOCKBIT_ON(ShareUpdateExclusiveLock) |
      79             :     LOCKBIT_ON(ShareLock) | LOCKBIT_ON(ShareRowExclusiveLock) |
      80             :     LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock),
      81             : 
      82             :     /* ShareLock */
      83             :     LOCKBIT_ON(RowExclusiveLock) | LOCKBIT_ON(ShareUpdateExclusiveLock) |
      84             :     LOCKBIT_ON(ShareRowExclusiveLock) |
      85             :     LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock),
      86             : 
      87             :     /* ShareRowExclusiveLock */
      88             :     LOCKBIT_ON(RowExclusiveLock) | LOCKBIT_ON(ShareUpdateExclusiveLock) |
      89             :     LOCKBIT_ON(ShareLock) | LOCKBIT_ON(ShareRowExclusiveLock) |
      90             :     LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock),
      91             : 
      92             :     /* ExclusiveLock */
      93             :     LOCKBIT_ON(RowShareLock) |
      94             :     LOCKBIT_ON(RowExclusiveLock) | LOCKBIT_ON(ShareUpdateExclusiveLock) |
      95             :     LOCKBIT_ON(ShareLock) | LOCKBIT_ON(ShareRowExclusiveLock) |
      96             :     LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock),
      97             : 
      98             :     /* AccessExclusiveLock */
      99             :     LOCKBIT_ON(AccessShareLock) | LOCKBIT_ON(RowShareLock) |
     100             :     LOCKBIT_ON(RowExclusiveLock) | LOCKBIT_ON(ShareUpdateExclusiveLock) |
     101             :     LOCKBIT_ON(ShareLock) | LOCKBIT_ON(ShareRowExclusiveLock) |
     102             :     LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock)
     103             : 
     104             : };
     105             : 
     106             : /* Names of lock modes, for debug printouts */
     107             : static const char *const lock_mode_names[] =
     108             : {
     109             :     "INVALID",
     110             :     "AccessShareLock",
     111             :     "RowShareLock",
     112             :     "RowExclusiveLock",
     113             :     "ShareUpdateExclusiveLock",
     114             :     "ShareLock",
     115             :     "ShareRowExclusiveLock",
     116             :     "ExclusiveLock",
     117             :     "AccessExclusiveLock"
     118             : };
     119             : 
     120             : #ifndef LOCK_DEBUG
     121             : static bool Dummy_trace = false;
     122             : #endif
     123             : 
     124             : static const LockMethodData default_lockmethod = {
     125             :     MaxLockMode,
     126             :     LockConflicts,
     127             :     lock_mode_names,
     128             : #ifdef LOCK_DEBUG
     129             :     &Trace_locks
     130             : #else
     131             :     &Dummy_trace
     132             : #endif
     133             : };
     134             : 
     135             : static const LockMethodData user_lockmethod = {
     136             :     MaxLockMode,
     137             :     LockConflicts,
     138             :     lock_mode_names,
     139             : #ifdef LOCK_DEBUG
     140             :     &Trace_userlocks
     141             : #else
     142             :     &Dummy_trace
     143             : #endif
     144             : };
     145             : 
     146             : /*
     147             :  * map from lock method id to the lock table data structures
     148             :  */
     149             : static const LockMethod LockMethods[] = {
     150             :     NULL,
     151             :     &default_lockmethod,
     152             :     &user_lockmethod
     153             : };
     154             : 
     155             : 
     156             : /* Record that's written to 2PC state file when a lock is persisted */
     157             : typedef struct TwoPhaseLockRecord
     158             : {
     159             :     LOCKTAG     locktag;
     160             :     LOCKMODE    lockmode;
     161             : } TwoPhaseLockRecord;
     162             : 
     163             : 
     164             : /*
     165             :  * Count of the number of fast path lock slots we believe to be used.  This
     166             :  * might be higher than the real number if another backend has transferred
     167             :  * our locks to the primary lock table, but it can never be lower than the
     168             :  * real value, since only we can acquire locks on our own behalf.
     169             :  */
     170             : static int  FastPathLocalUseCount = 0;
     171             : 
     172             : /*
     173             :  * Flag to indicate if the relation extension lock is held by this backend.
     174             :  * This flag is used to ensure that while holding the relation extension lock
     175             :  * we don't try to acquire a heavyweight lock on any other object.  This
     176             :  * restriction implies that the relation extension lock won't ever participate
     177             :  * in the deadlock cycle because we can never wait for any other heavyweight
     178             :  * lock after acquiring this lock.
     179             :  *
     180             :  * Such a restriction is okay for relation extension locks as unlike other
     181             :  * heavyweight locks these are not held till the transaction end.  These are
     182             :  * taken for a short duration to extend a particular relation and then
     183             :  * released.
     184             :  */
     185             : static bool IsRelationExtensionLockHeld PG_USED_FOR_ASSERTS_ONLY = false;
     186             : 
     187             : /* Macros for manipulating proc->fpLockBits */
     188             : #define FAST_PATH_BITS_PER_SLOT         3
     189             : #define FAST_PATH_LOCKNUMBER_OFFSET     1
     190             : #define FAST_PATH_MASK                  ((1 << FAST_PATH_BITS_PER_SLOT) - 1)
     191             : #define FAST_PATH_GET_BITS(proc, n) \
     192             :     (((proc)->fpLockBits >> (FAST_PATH_BITS_PER_SLOT * n)) & FAST_PATH_MASK)
     193             : #define FAST_PATH_BIT_POSITION(n, l) \
     194             :     (AssertMacro((l) >= FAST_PATH_LOCKNUMBER_OFFSET), \
     195             :      AssertMacro((l) < FAST_PATH_BITS_PER_SLOT+FAST_PATH_LOCKNUMBER_OFFSET), \
     196             :      AssertMacro((n) < FP_LOCK_SLOTS_PER_BACKEND), \
     197             :      ((l) - FAST_PATH_LOCKNUMBER_OFFSET + FAST_PATH_BITS_PER_SLOT * (n)))
     198             : #define FAST_PATH_SET_LOCKMODE(proc, n, l) \
     199             :      (proc)->fpLockBits |= UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l)
     200             : #define FAST_PATH_CLEAR_LOCKMODE(proc, n, l) \
     201             :      (proc)->fpLockBits &= ~(UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l))
     202             : #define FAST_PATH_CHECK_LOCKMODE(proc, n, l) \
     203             :      ((proc)->fpLockBits & (UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l)))
     204             : 
     205             : /*
     206             :  * The fast-path lock mechanism is concerned only with relation locks on
     207             :  * unshared relations by backends bound to a database.  The fast-path
     208             :  * mechanism exists mostly to accelerate acquisition and release of locks
     209             :  * that rarely conflict.  Because ShareUpdateExclusiveLock is
     210             :  * self-conflicting, it can't use the fast-path mechanism; but it also does
     211             :  * not conflict with any of the locks that do, so we can ignore it completely.
     212             :  */
     213             : #define EligibleForRelationFastPath(locktag, mode) \
     214             :     ((locktag)->locktag_lockmethodid == DEFAULT_LOCKMETHOD && \
     215             :     (locktag)->locktag_type == LOCKTAG_RELATION && \
     216             :     (locktag)->locktag_field1 == MyDatabaseId && \
     217             :     MyDatabaseId != InvalidOid && \
     218             :     (mode) < ShareUpdateExclusiveLock)
     219             : #define ConflictsWithRelationFastPath(locktag, mode) \
     220             :     ((locktag)->locktag_lockmethodid == DEFAULT_LOCKMETHOD && \
     221             :     (locktag)->locktag_type == LOCKTAG_RELATION && \
     222             :     (locktag)->locktag_field1 != InvalidOid && \
     223             :     (mode) > ShareUpdateExclusiveLock)
     224             : 
     225             : static bool FastPathGrantRelationLock(Oid relid, LOCKMODE lockmode);
     226             : static bool FastPathUnGrantRelationLock(Oid relid, LOCKMODE lockmode);
     227             : static bool FastPathTransferRelationLocks(LockMethod lockMethodTable,
     228             :                                           const LOCKTAG *locktag, uint32 hashcode);
     229             : static PROCLOCK *FastPathGetRelationLockEntry(LOCALLOCK *locallock);
     230             : 
     231             : /*
     232             :  * To make the fast-path lock mechanism work, we must have some way of
     233             :  * preventing the use of the fast-path when a conflicting lock might be present.
     234             :  * We partition* the locktag space into FAST_PATH_STRONG_LOCK_HASH_PARTITIONS,
     235             :  * and maintain an integer count of the number of "strong" lockers
     236             :  * in each partition.  When any "strong" lockers are present (which is
     237             :  * hopefully not very often), the fast-path mechanism can't be used, and we
     238             :  * must fall back to the slower method of pushing matching locks directly
     239             :  * into the main lock tables.
     240             :  *
     241             :  * The deadlock detector does not know anything about the fast path mechanism,
     242             :  * so any locks that might be involved in a deadlock must be transferred from
     243             :  * the fast-path queues to the main lock table.
     244             :  */
     245             : 
     246             : #define FAST_PATH_STRONG_LOCK_HASH_BITS         10
     247             : #define FAST_PATH_STRONG_LOCK_HASH_PARTITIONS \
     248             :     (1 << FAST_PATH_STRONG_LOCK_HASH_BITS)
     249             : #define FastPathStrongLockHashPartition(hashcode) \
     250             :     ((hashcode) % FAST_PATH_STRONG_LOCK_HASH_PARTITIONS)
     251             : 
     252             : typedef struct
     253             : {
     254             :     slock_t     mutex;
     255             :     uint32      count[FAST_PATH_STRONG_LOCK_HASH_PARTITIONS];
     256             : } FastPathStrongRelationLockData;
     257             : 
     258             : static volatile FastPathStrongRelationLockData *FastPathStrongRelationLocks;
     259             : 
     260             : 
     261             : /*
     262             :  * Pointers to hash tables containing lock state
     263             :  *
     264             :  * The LockMethodLockHash and LockMethodProcLockHash hash tables are in
     265             :  * shared memory; LockMethodLocalHash is local to each backend.
     266             :  */
     267             : static HTAB *LockMethodLockHash;
     268             : static HTAB *LockMethodProcLockHash;
     269             : static HTAB *LockMethodLocalHash;
     270             : 
     271             : 
     272             : /* private state for error cleanup */
     273             : static LOCALLOCK *StrongLockInProgress;
     274             : static LOCALLOCK *awaitedLock;
     275             : static ResourceOwner awaitedOwner;
     276             : 
     277             : 
     278             : #ifdef LOCK_DEBUG
     279             : 
     280             : /*------
     281             :  * The following configuration options are available for lock debugging:
     282             :  *
     283             :  *     TRACE_LOCKS      -- give a bunch of output what's going on in this file
     284             :  *     TRACE_USERLOCKS  -- same but for user locks
     285             :  *     TRACE_LOCK_OIDMIN-- do not trace locks for tables below this oid
     286             :  *                         (use to avoid output on system tables)
     287             :  *     TRACE_LOCK_TABLE -- trace locks on this table (oid) unconditionally
     288             :  *     DEBUG_DEADLOCKS  -- currently dumps locks at untimely occasions ;)
     289             :  *
     290             :  * Furthermore, but in storage/lmgr/lwlock.c:
     291             :  *     TRACE_LWLOCKS    -- trace lightweight locks (pretty useless)
     292             :  *
     293             :  * Define LOCK_DEBUG at compile time to get all these enabled.
     294             :  * --------
     295             :  */
     296             : 
     297             : int         Trace_lock_oidmin = FirstNormalObjectId;
     298             : bool        Trace_locks = false;
     299             : bool        Trace_userlocks = false;
     300             : int         Trace_lock_table = 0;
     301             : bool        Debug_deadlocks = false;
     302             : 
     303             : 
     304             : inline static bool
     305             : LOCK_DEBUG_ENABLED(const LOCKTAG *tag)
     306             : {
     307             :     return
     308             :         (*(LockMethods[tag->locktag_lockmethodid]->trace_flag) &&
     309             :          ((Oid) tag->locktag_field2 >= (Oid) Trace_lock_oidmin))
     310             :         || (Trace_lock_table &&
     311             :             (tag->locktag_field2 == Trace_lock_table));
     312             : }
     313             : 
     314             : 
     315             : inline static void
     316             : LOCK_PRINT(const char *where, const LOCK *lock, LOCKMODE type)
     317             : {
     318             :     if (LOCK_DEBUG_ENABLED(&lock->tag))
     319             :         elog(LOG,
     320             :              "%s: lock(%p) id(%u,%u,%u,%u,%u,%u) grantMask(%x) "
     321             :              "req(%d,%d,%d,%d,%d,%d,%d)=%d "
     322             :              "grant(%d,%d,%d,%d,%d,%d,%d)=%d wait(%d) type(%s)",
     323             :              where, lock,
     324             :              lock->tag.locktag_field1, lock->tag.locktag_field2,
     325             :              lock->tag.locktag_field3, lock->tag.locktag_field4,
     326             :              lock->tag.locktag_type, lock->tag.locktag_lockmethodid,
     327             :              lock->grantMask,
     328             :              lock->requested[1], lock->requested[2], lock->requested[3],
     329             :              lock->requested[4], lock->requested[5], lock->requested[6],
     330             :              lock->requested[7], lock->nRequested,
     331             :              lock->granted[1], lock->granted[2], lock->granted[3],
     332             :              lock->granted[4], lock->granted[5], lock->granted[6],
     333             :              lock->granted[7], lock->nGranted,
     334             :              dclist_count(&lock->waitProcs),
     335             :              LockMethods[LOCK_LOCKMETHOD(*lock)]->lockModeNames[type]);
     336             : }
     337             : 
     338             : 
     339             : inline static void
     340             : PROCLOCK_PRINT(const char *where, const PROCLOCK *proclockP)
     341             : {
     342             :     if (LOCK_DEBUG_ENABLED(&proclockP->tag.myLock->tag))
     343             :         elog(LOG,
     344             :              "%s: proclock(%p) lock(%p) method(%u) proc(%p) hold(%x)",
     345             :              where, proclockP, proclockP->tag.myLock,
     346             :              PROCLOCK_LOCKMETHOD(*(proclockP)),
     347             :              proclockP->tag.myProc, (int) proclockP->holdMask);
     348             : }
     349             : #else                           /* not LOCK_DEBUG */
     350             : 
     351             : #define LOCK_PRINT(where, lock, type)  ((void) 0)
     352             : #define PROCLOCK_PRINT(where, proclockP)  ((void) 0)
     353             : #endif                          /* not LOCK_DEBUG */
     354             : 
     355             : 
     356             : static uint32 proclock_hash(const void *key, Size keysize);
     357             : static void RemoveLocalLock(LOCALLOCK *locallock);
     358             : static PROCLOCK *SetupLockInTable(LockMethod lockMethodTable, PGPROC *proc,
     359             :                                   const LOCKTAG *locktag, uint32 hashcode, LOCKMODE lockmode);
     360             : static void GrantLockLocal(LOCALLOCK *locallock, ResourceOwner owner);
     361             : static void BeginStrongLockAcquire(LOCALLOCK *locallock, uint32 fasthashcode);
     362             : static void FinishStrongLockAcquire(void);
     363             : static void WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner,
     364             :                        bool dontWait);
     365             : static void ReleaseLockIfHeld(LOCALLOCK *locallock, bool sessionLock);
     366             : static void LockReassignOwner(LOCALLOCK *locallock, ResourceOwner parent);
     367             : static bool UnGrantLock(LOCK *lock, LOCKMODE lockmode,
     368             :                         PROCLOCK *proclock, LockMethod lockMethodTable);
     369             : static void CleanUpLock(LOCK *lock, PROCLOCK *proclock,
     370             :                         LockMethod lockMethodTable, uint32 hashcode,
     371             :                         bool wakeupNeeded);
     372             : static void LockRefindAndRelease(LockMethod lockMethodTable, PGPROC *proc,
     373             :                                  LOCKTAG *locktag, LOCKMODE lockmode,
     374             :                                  bool decrement_strong_lock_count);
     375             : static void GetSingleProcBlockerStatusData(PGPROC *blocked_proc,
     376             :                                            BlockedProcsData *data);
     377             : 
     378             : 
     379             : /*
     380             :  * InitLocks -- Initialize the lock manager's data structures.
     381             :  *
     382             :  * This is called from CreateSharedMemoryAndSemaphores(), which see for
     383             :  * more comments.  In the normal postmaster case, the shared hash tables
     384             :  * are created here, as well as a locallock hash table that will remain
     385             :  * unused and empty in the postmaster itself.  Backends inherit the pointers
     386             :  * to the shared tables via fork(), and also inherit an image of the locallock
     387             :  * hash table, which they proceed to use.  In the EXEC_BACKEND case, each
     388             :  * backend re-executes this code to obtain pointers to the already existing
     389             :  * shared hash tables and to create its locallock hash table.
     390             :  */
     391             : void
     392        1768 : InitLocks(void)
     393             : {
     394             :     HASHCTL     info;
     395             :     long        init_table_size,
     396             :                 max_table_size;
     397             :     bool        found;
     398             : 
     399             :     /*
     400             :      * Compute init/max size to request for lock hashtables.  Note these
     401             :      * calculations must agree with LockShmemSize!
     402             :      */
     403        1768 :     max_table_size = NLOCKENTS();
     404        1768 :     init_table_size = max_table_size / 2;
     405             : 
     406             :     /*
     407             :      * Allocate hash table for LOCK structs.  This stores per-locked-object
     408             :      * information.
     409             :      */
     410        1768 :     info.keysize = sizeof(LOCKTAG);
     411        1768 :     info.entrysize = sizeof(LOCK);
     412        1768 :     info.num_partitions = NUM_LOCK_PARTITIONS;
     413             : 
     414        1768 :     LockMethodLockHash = ShmemInitHash("LOCK hash",
     415             :                                        init_table_size,
     416             :                                        max_table_size,
     417             :                                        &info,
     418             :                                        HASH_ELEM | HASH_BLOBS | HASH_PARTITION);
     419             : 
     420             :     /* Assume an average of 2 holders per lock */
     421        1768 :     max_table_size *= 2;
     422        1768 :     init_table_size *= 2;
     423             : 
     424             :     /*
     425             :      * Allocate hash table for PROCLOCK structs.  This stores
     426             :      * per-lock-per-holder information.
     427             :      */
     428        1768 :     info.keysize = sizeof(PROCLOCKTAG);
     429        1768 :     info.entrysize = sizeof(PROCLOCK);
     430        1768 :     info.hash = proclock_hash;
     431        1768 :     info.num_partitions = NUM_LOCK_PARTITIONS;
     432             : 
     433        1768 :     LockMethodProcLockHash = ShmemInitHash("PROCLOCK hash",
     434             :                                            init_table_size,
     435             :                                            max_table_size,
     436             :                                            &info,
     437             :                                            HASH_ELEM | HASH_FUNCTION | HASH_PARTITION);
     438             : 
     439             :     /*
     440             :      * Allocate fast-path structures.
     441             :      */
     442        1768 :     FastPathStrongRelationLocks =
     443        1768 :         ShmemInitStruct("Fast Path Strong Relation Lock Data",
     444             :                         sizeof(FastPathStrongRelationLockData), &found);
     445        1768 :     if (!found)
     446        1768 :         SpinLockInit(&FastPathStrongRelationLocks->mutex);
     447             : 
     448             :     /*
     449             :      * Allocate non-shared hash table for LOCALLOCK structs.  This stores lock
     450             :      * counts and resource owner information.
     451             :      *
     452             :      * The non-shared table could already exist in this process (this occurs
     453             :      * when the postmaster is recreating shared memory after a backend crash).
     454             :      * If so, delete and recreate it.  (We could simply leave it, since it
     455             :      * ought to be empty in the postmaster, but for safety let's zap it.)
     456             :      */
     457        1768 :     if (LockMethodLocalHash)
     458           8 :         hash_destroy(LockMethodLocalHash);
     459             : 
     460        1768 :     info.keysize = sizeof(LOCALLOCKTAG);
     461        1768 :     info.entrysize = sizeof(LOCALLOCK);
     462             : 
     463        1768 :     LockMethodLocalHash = hash_create("LOCALLOCK hash",
     464             :                                       16,
     465             :                                       &info,
     466             :                                       HASH_ELEM | HASH_BLOBS);
     467        1768 : }
     468             : 
     469             : 
     470             : /*
     471             :  * Fetch the lock method table associated with a given lock
     472             :  */
     473             : LockMethod
     474         176 : GetLocksMethodTable(const LOCK *lock)
     475             : {
     476         176 :     LOCKMETHODID lockmethodid = LOCK_LOCKMETHOD(*lock);
     477             : 
     478             :     Assert(0 < lockmethodid && lockmethodid < lengthof(LockMethods));
     479         176 :     return LockMethods[lockmethodid];
     480             : }
     481             : 
     482             : /*
     483             :  * Fetch the lock method table associated with a given locktag
     484             :  */
     485             : LockMethod
     486        2198 : GetLockTagsMethodTable(const LOCKTAG *locktag)
     487             : {
     488        2198 :     LOCKMETHODID lockmethodid = (LOCKMETHODID) locktag->locktag_lockmethodid;
     489             : 
     490             :     Assert(0 < lockmethodid && lockmethodid < lengthof(LockMethods));
     491        2198 :     return LockMethods[lockmethodid];
     492             : }
     493             : 
     494             : 
     495             : /*
     496             :  * Compute the hash code associated with a LOCKTAG.
     497             :  *
     498             :  * To avoid unnecessary recomputations of the hash code, we try to do this
     499             :  * just once per function, and then pass it around as needed.  Aside from
     500             :  * passing the hashcode to hash_search_with_hash_value(), we can extract
     501             :  * the lock partition number from the hashcode.
     502             :  */
     503             : uint32
     504    27229442 : LockTagHashCode(const LOCKTAG *locktag)
     505             : {
     506    27229442 :     return get_hash_value(LockMethodLockHash, (const void *) locktag);
     507             : }
     508             : 
     509             : /*
     510             :  * Compute the hash code associated with a PROCLOCKTAG.
     511             :  *
     512             :  * Because we want to use just one set of partition locks for both the
     513             :  * LOCK and PROCLOCK hash tables, we have to make sure that PROCLOCKs
     514             :  * fall into the same partition number as their associated LOCKs.
     515             :  * dynahash.c expects the partition number to be the low-order bits of
     516             :  * the hash code, and therefore a PROCLOCKTAG's hash code must have the
     517             :  * same low-order bits as the associated LOCKTAG's hash code.  We achieve
     518             :  * this with this specialized hash function.
     519             :  */
     520             : static uint32
     521        1660 : proclock_hash(const void *key, Size keysize)
     522             : {
     523        1660 :     const PROCLOCKTAG *proclocktag = (const PROCLOCKTAG *) key;
     524             :     uint32      lockhash;
     525             :     Datum       procptr;
     526             : 
     527             :     Assert(keysize == sizeof(PROCLOCKTAG));
     528             : 
     529             :     /* Look into the associated LOCK object, and compute its hash code */
     530        1660 :     lockhash = LockTagHashCode(&proclocktag->myLock->tag);
     531             : 
     532             :     /*
     533             :      * To make the hash code also depend on the PGPROC, we xor the proc
     534             :      * struct's address into the hash code, left-shifted so that the
     535             :      * partition-number bits don't change.  Since this is only a hash, we
     536             :      * don't care if we lose high-order bits of the address; use an
     537             :      * intermediate variable to suppress cast-pointer-to-int warnings.
     538             :      */
     539        1660 :     procptr = PointerGetDatum(proclocktag->myProc);
     540        1660 :     lockhash ^= ((uint32) procptr) << LOG2_NUM_LOCK_PARTITIONS;
     541             : 
     542        1660 :     return lockhash;
     543             : }
     544             : 
     545             : /*
     546             :  * Compute the hash code associated with a PROCLOCKTAG, given the hashcode
     547             :  * for its underlying LOCK.
     548             :  *
     549             :  * We use this just to avoid redundant calls of LockTagHashCode().
     550             :  */
     551             : static inline uint32
     552     6509226 : ProcLockHashCode(const PROCLOCKTAG *proclocktag, uint32 hashcode)
     553             : {
     554     6509226 :     uint32      lockhash = hashcode;
     555             :     Datum       procptr;
     556             : 
     557             :     /*
     558             :      * This must match proclock_hash()!
     559             :      */
     560     6509226 :     procptr = PointerGetDatum(proclocktag->myProc);
     561     6509226 :     lockhash ^= ((uint32) procptr) << LOG2_NUM_LOCK_PARTITIONS;
     562             : 
     563     6509226 :     return lockhash;
     564             : }
     565             : 
     566             : /*
     567             :  * Given two lock modes, return whether they would conflict.
     568             :  */
     569             : bool
     570         464 : DoLockModesConflict(LOCKMODE mode1, LOCKMODE mode2)
     571             : {
     572         464 :     LockMethod  lockMethodTable = LockMethods[DEFAULT_LOCKMETHOD];
     573             : 
     574         464 :     if (lockMethodTable->conflictTab[mode1] & LOCKBIT_ON(mode2))
     575         272 :         return true;
     576             : 
     577         192 :     return false;
     578             : }
     579             : 
     580             : /*
     581             :  * LockHeldByMe -- test whether lock 'locktag' is held with mode 'lockmode'
     582             :  *      by the current transaction
     583             :  */
     584             : bool
     585           0 : LockHeldByMe(const LOCKTAG *locktag, LOCKMODE lockmode)
     586             : {
     587             :     LOCALLOCKTAG localtag;
     588             :     LOCALLOCK  *locallock;
     589             : 
     590             :     /*
     591             :      * See if there is a LOCALLOCK entry for this lock and lockmode
     592             :      */
     593           0 :     MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
     594           0 :     localtag.lock = *locktag;
     595           0 :     localtag.mode = lockmode;
     596             : 
     597           0 :     locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
     598             :                                           &localtag,
     599             :                                           HASH_FIND, NULL);
     600             : 
     601           0 :     return (locallock && locallock->nLocks > 0);
     602             : }
     603             : 
     604             : #ifdef USE_ASSERT_CHECKING
     605             : /*
     606             :  * GetLockMethodLocalHash -- return the hash of local locks, for modules that
     607             :  *      evaluate assertions based on all locks held.
     608             :  */
     609             : HTAB *
     610             : GetLockMethodLocalHash(void)
     611             : {
     612             :     return LockMethodLocalHash;
     613             : }
     614             : #endif
     615             : 
     616             : /*
     617             :  * LockHasWaiters -- look up 'locktag' and check if releasing this
     618             :  *      lock would wake up other processes waiting for it.
     619             :  */
     620             : bool
     621           0 : LockHasWaiters(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
     622             : {
     623           0 :     LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
     624             :     LockMethod  lockMethodTable;
     625             :     LOCALLOCKTAG localtag;
     626             :     LOCALLOCK  *locallock;
     627             :     LOCK       *lock;
     628             :     PROCLOCK   *proclock;
     629             :     LWLock     *partitionLock;
     630           0 :     bool        hasWaiters = false;
     631             : 
     632           0 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
     633           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
     634           0 :     lockMethodTable = LockMethods[lockmethodid];
     635           0 :     if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
     636           0 :         elog(ERROR, "unrecognized lock mode: %d", lockmode);
     637             : 
     638             : #ifdef LOCK_DEBUG
     639             :     if (LOCK_DEBUG_ENABLED(locktag))
     640             :         elog(LOG, "LockHasWaiters: lock [%u,%u] %s",
     641             :              locktag->locktag_field1, locktag->locktag_field2,
     642             :              lockMethodTable->lockModeNames[lockmode]);
     643             : #endif
     644             : 
     645             :     /*
     646             :      * Find the LOCALLOCK entry for this lock and lockmode
     647             :      */
     648           0 :     MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
     649           0 :     localtag.lock = *locktag;
     650           0 :     localtag.mode = lockmode;
     651             : 
     652           0 :     locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
     653             :                                           &localtag,
     654             :                                           HASH_FIND, NULL);
     655             : 
     656             :     /*
     657             :      * let the caller print its own error message, too. Do not ereport(ERROR).
     658             :      */
     659           0 :     if (!locallock || locallock->nLocks <= 0)
     660             :     {
     661           0 :         elog(WARNING, "you don't own a lock of type %s",
     662             :              lockMethodTable->lockModeNames[lockmode]);
     663           0 :         return false;
     664             :     }
     665             : 
     666             :     /*
     667             :      * Check the shared lock table.
     668             :      */
     669           0 :     partitionLock = LockHashPartitionLock(locallock->hashcode);
     670             : 
     671           0 :     LWLockAcquire(partitionLock, LW_SHARED);
     672             : 
     673             :     /*
     674             :      * We don't need to re-find the lock or proclock, since we kept their
     675             :      * addresses in the locallock table, and they couldn't have been removed
     676             :      * while we were holding a lock on them.
     677             :      */
     678           0 :     lock = locallock->lock;
     679             :     LOCK_PRINT("LockHasWaiters: found", lock, lockmode);
     680           0 :     proclock = locallock->proclock;
     681             :     PROCLOCK_PRINT("LockHasWaiters: found", proclock);
     682             : 
     683             :     /*
     684             :      * Double-check that we are actually holding a lock of the type we want to
     685             :      * release.
     686             :      */
     687           0 :     if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
     688             :     {
     689             :         PROCLOCK_PRINT("LockHasWaiters: WRONGTYPE", proclock);
     690           0 :         LWLockRelease(partitionLock);
     691           0 :         elog(WARNING, "you don't own a lock of type %s",
     692             :              lockMethodTable->lockModeNames[lockmode]);
     693           0 :         RemoveLocalLock(locallock);
     694           0 :         return false;
     695             :     }
     696             : 
     697             :     /*
     698             :      * Do the checking.
     699             :      */
     700           0 :     if ((lockMethodTable->conflictTab[lockmode] & lock->waitMask) != 0)
     701           0 :         hasWaiters = true;
     702             : 
     703           0 :     LWLockRelease(partitionLock);
     704             : 
     705           0 :     return hasWaiters;
     706             : }
     707             : 
     708             : /*
     709             :  * LockAcquire -- Check for lock conflicts, sleep if conflict found,
     710             :  *      set lock if/when no conflicts.
     711             :  *
     712             :  * Inputs:
     713             :  *  locktag: unique identifier for the lockable object
     714             :  *  lockmode: lock mode to acquire
     715             :  *  sessionLock: if true, acquire lock for session not current transaction
     716             :  *  dontWait: if true, don't wait to acquire lock
     717             :  *
     718             :  * Returns one of:
     719             :  *      LOCKACQUIRE_NOT_AVAIL       lock not available, and dontWait=true
     720             :  *      LOCKACQUIRE_OK              lock successfully acquired
     721             :  *      LOCKACQUIRE_ALREADY_HELD    incremented count for lock already held
     722             :  *      LOCKACQUIRE_ALREADY_CLEAR   incremented count for lock already clear
     723             :  *
     724             :  * In the normal case where dontWait=false and the caller doesn't need to
     725             :  * distinguish a freshly acquired lock from one already taken earlier in
     726             :  * this same transaction, there is no need to examine the return value.
     727             :  *
     728             :  * Side Effects: The lock is acquired and recorded in lock tables.
     729             :  *
     730             :  * NOTE: if we wait for the lock, there is no way to abort the wait
     731             :  * short of aborting the transaction.
     732             :  */
     733             : LockAcquireResult
     734      926830 : LockAcquire(const LOCKTAG *locktag,
     735             :             LOCKMODE lockmode,
     736             :             bool sessionLock,
     737             :             bool dontWait)
     738             : {
     739      926830 :     return LockAcquireExtended(locktag, lockmode, sessionLock, dontWait,
     740             :                                true, NULL);
     741             : }
     742             : 
     743             : /*
     744             :  * LockAcquireExtended - allows us to specify additional options
     745             :  *
     746             :  * reportMemoryError specifies whether a lock request that fills the lock
     747             :  * table should generate an ERROR or not.  Passing "false" allows the caller
     748             :  * to attempt to recover from lock-table-full situations, perhaps by forcibly
     749             :  * canceling other lock holders and then retrying.  Note, however, that the
     750             :  * return code for that is LOCKACQUIRE_NOT_AVAIL, so that it's unsafe to use
     751             :  * in combination with dontWait = true, as the cause of failure couldn't be
     752             :  * distinguished.
     753             :  *
     754             :  * If locallockp isn't NULL, *locallockp receives a pointer to the LOCALLOCK
     755             :  * table entry if a lock is successfully acquired, or NULL if not.
     756             :  */
     757             : LockAcquireResult
     758    29348418 : LockAcquireExtended(const LOCKTAG *locktag,
     759             :                     LOCKMODE lockmode,
     760             :                     bool sessionLock,
     761             :                     bool dontWait,
     762             :                     bool reportMemoryError,
     763             :                     LOCALLOCK **locallockp)
     764             : {
     765    29348418 :     LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
     766             :     LockMethod  lockMethodTable;
     767             :     LOCALLOCKTAG localtag;
     768             :     LOCALLOCK  *locallock;
     769             :     LOCK       *lock;
     770             :     PROCLOCK   *proclock;
     771             :     bool        found;
     772             :     ResourceOwner owner;
     773             :     uint32      hashcode;
     774             :     LWLock     *partitionLock;
     775             :     bool        found_conflict;
     776    29348418 :     bool        log_lock = false;
     777             : 
     778    29348418 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
     779           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
     780    29348418 :     lockMethodTable = LockMethods[lockmethodid];
     781    29348418 :     if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
     782           0 :         elog(ERROR, "unrecognized lock mode: %d", lockmode);
     783             : 
     784    29348418 :     if (RecoveryInProgress() && !InRecovery &&
     785      428574 :         (locktag->locktag_type == LOCKTAG_OBJECT ||
     786      428574 :          locktag->locktag_type == LOCKTAG_RELATION) &&
     787             :         lockmode > RowExclusiveLock)
     788           0 :         ereport(ERROR,
     789             :                 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
     790             :                  errmsg("cannot acquire lock mode %s on database objects while recovery is in progress",
     791             :                         lockMethodTable->lockModeNames[lockmode]),
     792             :                  errhint("Only RowExclusiveLock or less can be acquired on database objects during recovery.")));
     793             : 
     794             : #ifdef LOCK_DEBUG
     795             :     if (LOCK_DEBUG_ENABLED(locktag))
     796             :         elog(LOG, "LockAcquire: lock [%u,%u] %s",
     797             :              locktag->locktag_field1, locktag->locktag_field2,
     798             :              lockMethodTable->lockModeNames[lockmode]);
     799             : #endif
     800             : 
     801             :     /* Identify owner for lock */
     802    29348418 :     if (sessionLock)
     803       64804 :         owner = NULL;
     804             :     else
     805    29283614 :         owner = CurrentResourceOwner;
     806             : 
     807             :     /*
     808             :      * Find or create a LOCALLOCK entry for this lock and lockmode
     809             :      */
     810    29348418 :     MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
     811    29348418 :     localtag.lock = *locktag;
     812    29348418 :     localtag.mode = lockmode;
     813             : 
     814    29348418 :     locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
     815             :                                           &localtag,
     816             :                                           HASH_ENTER, &found);
     817             : 
     818             :     /*
     819             :      * if it's a new locallock object, initialize it
     820             :      */
     821    29348418 :     if (!found)
     822             :     {
     823    26280576 :         locallock->lock = NULL;
     824    26280576 :         locallock->proclock = NULL;
     825    26280576 :         locallock->hashcode = LockTagHashCode(&(localtag.lock));
     826    26280576 :         locallock->nLocks = 0;
     827    26280576 :         locallock->holdsStrongLockCount = false;
     828    26280576 :         locallock->lockCleared = false;
     829    26280576 :         locallock->numLockOwners = 0;
     830    26280576 :         locallock->maxLockOwners = 8;
     831    26280576 :         locallock->lockOwners = NULL;    /* in case next line fails */
     832    26280576 :         locallock->lockOwners = (LOCALLOCKOWNER *)
     833    26280576 :             MemoryContextAlloc(TopMemoryContext,
     834    26280576 :                                locallock->maxLockOwners * sizeof(LOCALLOCKOWNER));
     835             :     }
     836             :     else
     837             :     {
     838             :         /* Make sure there will be room to remember the lock */
     839     3067842 :         if (locallock->numLockOwners >= locallock->maxLockOwners)
     840             :         {
     841          38 :             int         newsize = locallock->maxLockOwners * 2;
     842             : 
     843          38 :             locallock->lockOwners = (LOCALLOCKOWNER *)
     844          38 :                 repalloc(locallock->lockOwners,
     845             :                          newsize * sizeof(LOCALLOCKOWNER));
     846          38 :             locallock->maxLockOwners = newsize;
     847             :         }
     848             :     }
     849    29348418 :     hashcode = locallock->hashcode;
     850             : 
     851    29348418 :     if (locallockp)
     852    28421588 :         *locallockp = locallock;
     853             : 
     854             :     /*
     855             :      * If we already hold the lock, we can just increase the count locally.
     856             :      *
     857             :      * If lockCleared is already set, caller need not worry about absorbing
     858             :      * sinval messages related to the lock's object.
     859             :      */
     860    29348418 :     if (locallock->nLocks > 0)
     861             :     {
     862     3067842 :         GrantLockLocal(locallock, owner);
     863     3067842 :         if (locallock->lockCleared)
     864     2938200 :             return LOCKACQUIRE_ALREADY_CLEAR;
     865             :         else
     866      129642 :             return LOCKACQUIRE_ALREADY_HELD;
     867             :     }
     868             : 
     869             :     /*
     870             :      * We don't acquire any other heavyweight lock while holding the relation
     871             :      * extension lock.  We do allow to acquire the same relation extension
     872             :      * lock more than once but that case won't reach here.
     873             :      */
     874             :     Assert(!IsRelationExtensionLockHeld);
     875             : 
     876             :     /*
     877             :      * Prepare to emit a WAL record if acquisition of this lock needs to be
     878             :      * replayed in a standby server.
     879             :      *
     880             :      * Here we prepare to log; after lock is acquired we'll issue log record.
     881             :      * This arrangement simplifies error recovery in case the preparation step
     882             :      * fails.
     883             :      *
     884             :      * Only AccessExclusiveLocks can conflict with lock types that read-only
     885             :      * transactions can acquire in a standby server. Make sure this definition
     886             :      * matches the one in GetRunningTransactionLocks().
     887             :      */
     888    26280576 :     if (lockmode >= AccessExclusiveLock &&
     889      379390 :         locktag->locktag_type == LOCKTAG_RELATION &&
     890      254972 :         !RecoveryInProgress() &&
     891      213728 :         XLogStandbyInfoActive())
     892             :     {
     893      159438 :         LogAccessExclusiveLockPrepare();
     894      159438 :         log_lock = true;
     895             :     }
     896             : 
     897             :     /*
     898             :      * Attempt to take lock via fast path, if eligible.  But if we remember
     899             :      * having filled up the fast path array, we don't attempt to make any
     900             :      * further use of it until we release some locks.  It's possible that some
     901             :      * other backend has transferred some of those locks to the shared hash
     902             :      * table, leaving space free, but it's not worth acquiring the LWLock just
     903             :      * to check.  It's also possible that we're acquiring a second or third
     904             :      * lock type on a relation we have already locked using the fast-path, but
     905             :      * for now we don't worry about that case either.
     906             :      */
     907    26280576 :     if (EligibleForRelationFastPath(locktag, lockmode) &&
     908    23750270 :         FastPathLocalUseCount < FP_LOCK_SLOTS_PER_BACKEND)
     909             :     {
     910    23221794 :         uint32      fasthashcode = FastPathStrongLockHashPartition(hashcode);
     911             :         bool        acquired;
     912             : 
     913             :         /*
     914             :          * LWLockAcquire acts as a memory sequencing point, so it's safe to
     915             :          * assume that any strong locker whose increment to
     916             :          * FastPathStrongRelationLocks->counts becomes visible after we test
     917             :          * it has yet to begin to transfer fast-path locks.
     918             :          */
     919    23221794 :         LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
     920    23221794 :         if (FastPathStrongRelationLocks->count[fasthashcode] != 0)
     921      349918 :             acquired = false;
     922             :         else
     923    22871876 :             acquired = FastPathGrantRelationLock(locktag->locktag_field2,
     924             :                                                  lockmode);
     925    23221794 :         LWLockRelease(&MyProc->fpInfoLock);
     926    23221794 :         if (acquired)
     927             :         {
     928             :             /*
     929             :              * The locallock might contain stale pointers to some old shared
     930             :              * objects; we MUST reset these to null before considering the
     931             :              * lock to be acquired via fast-path.
     932             :              */
     933    22871876 :             locallock->lock = NULL;
     934    22871876 :             locallock->proclock = NULL;
     935    22871876 :             GrantLockLocal(locallock, owner);
     936    22871876 :             return LOCKACQUIRE_OK;
     937             :         }
     938             :     }
     939             : 
     940             :     /*
     941             :      * If this lock could potentially have been taken via the fast-path by
     942             :      * some other backend, we must (temporarily) disable further use of the
     943             :      * fast-path for this lock tag, and migrate any locks already taken via
     944             :      * this method to the main lock table.
     945             :      */
     946     3408700 :     if (ConflictsWithRelationFastPath(locktag, lockmode))
     947             :     {
     948      307402 :         uint32      fasthashcode = FastPathStrongLockHashPartition(hashcode);
     949             : 
     950      307402 :         BeginStrongLockAcquire(locallock, fasthashcode);
     951      307402 :         if (!FastPathTransferRelationLocks(lockMethodTable, locktag,
     952             :                                            hashcode))
     953             :         {
     954           0 :             AbortStrongLockAcquire();
     955           0 :             if (locallock->nLocks == 0)
     956           0 :                 RemoveLocalLock(locallock);
     957           0 :             if (locallockp)
     958           0 :                 *locallockp = NULL;
     959           0 :             if (reportMemoryError)
     960           0 :                 ereport(ERROR,
     961             :                         (errcode(ERRCODE_OUT_OF_MEMORY),
     962             :                          errmsg("out of shared memory"),
     963             :                          errhint("You might need to increase %s.", "max_locks_per_transaction")));
     964             :             else
     965           0 :                 return LOCKACQUIRE_NOT_AVAIL;
     966             :         }
     967             :     }
     968             : 
     969             :     /*
     970             :      * We didn't find the lock in our LOCALLOCK table, and we didn't manage to
     971             :      * take it via the fast-path, either, so we've got to mess with the shared
     972             :      * lock table.
     973             :      */
     974     3408700 :     partitionLock = LockHashPartitionLock(hashcode);
     975             : 
     976     3408700 :     LWLockAcquire(partitionLock, LW_EXCLUSIVE);
     977             : 
     978             :     /*
     979             :      * Find or create lock and proclock entries with this tag
     980             :      *
     981             :      * Note: if the locallock object already existed, it might have a pointer
     982             :      * to the lock already ... but we should not assume that that pointer is
     983             :      * valid, since a lock object with zero hold and request counts can go
     984             :      * away anytime.  So we have to use SetupLockInTable() to recompute the
     985             :      * lock and proclock pointers, even if they're already set.
     986             :      */
     987     3408700 :     proclock = SetupLockInTable(lockMethodTable, MyProc, locktag,
     988             :                                 hashcode, lockmode);
     989     3408700 :     if (!proclock)
     990             :     {
     991           0 :         AbortStrongLockAcquire();
     992           0 :         LWLockRelease(partitionLock);
     993           0 :         if (locallock->nLocks == 0)
     994           0 :             RemoveLocalLock(locallock);
     995           0 :         if (locallockp)
     996           0 :             *locallockp = NULL;
     997           0 :         if (reportMemoryError)
     998           0 :             ereport(ERROR,
     999             :                     (errcode(ERRCODE_OUT_OF_MEMORY),
    1000             :                      errmsg("out of shared memory"),
    1001             :                      errhint("You might need to increase %s.", "max_locks_per_transaction")));
    1002             :         else
    1003           0 :             return LOCKACQUIRE_NOT_AVAIL;
    1004             :     }
    1005     3408700 :     locallock->proclock = proclock;
    1006     3408700 :     lock = proclock->tag.myLock;
    1007     3408700 :     locallock->lock = lock;
    1008             : 
    1009             :     /*
    1010             :      * If lock requested conflicts with locks requested by waiters, must join
    1011             :      * wait queue.  Otherwise, check for conflict with already-held locks.
    1012             :      * (That's last because most complex check.)
    1013             :      */
    1014     3408700 :     if (lockMethodTable->conflictTab[lockmode] & lock->waitMask)
    1015          72 :         found_conflict = true;
    1016             :     else
    1017     3408628 :         found_conflict = LockCheckConflicts(lockMethodTable, lockmode,
    1018             :                                             lock, proclock);
    1019             : 
    1020     3408700 :     if (!found_conflict)
    1021             :     {
    1022             :         /* No conflict with held or previously requested locks */
    1023     3405248 :         GrantLock(lock, proclock, lockmode);
    1024     3405248 :         GrantLockLocal(locallock, owner);
    1025             :     }
    1026             :     else
    1027             :     {
    1028             :         /*
    1029             :          * Set bitmask of locks this process already holds on this object.
    1030             :          */
    1031        3452 :         MyProc->heldLocks = proclock->holdMask;
    1032             : 
    1033             :         /*
    1034             :          * Sleep till someone wakes me up. We do this even in the dontWait
    1035             :          * case, beause while trying to go to sleep, we may discover that we
    1036             :          * can acquire the lock immediately after all.
    1037             :          */
    1038             : 
    1039             :         TRACE_POSTGRESQL_LOCK_WAIT_START(locktag->locktag_field1,
    1040             :                                          locktag->locktag_field2,
    1041             :                                          locktag->locktag_field3,
    1042             :                                          locktag->locktag_field4,
    1043             :                                          locktag->locktag_type,
    1044             :                                          lockmode);
    1045             : 
    1046        3452 :         WaitOnLock(locallock, owner, dontWait);
    1047             : 
    1048             :         TRACE_POSTGRESQL_LOCK_WAIT_DONE(locktag->locktag_field1,
    1049             :                                         locktag->locktag_field2,
    1050             :                                         locktag->locktag_field3,
    1051             :                                         locktag->locktag_field4,
    1052             :                                         locktag->locktag_type,
    1053             :                                         lockmode);
    1054             : 
    1055             :         /*
    1056             :          * NOTE: do not do any material change of state between here and
    1057             :          * return.  All required changes in locktable state must have been
    1058             :          * done when the lock was granted to us --- see notes in WaitOnLock.
    1059             :          */
    1060             : 
    1061             :         /*
    1062             :          * Check the proclock entry status. If dontWait = true, this is an
    1063             :          * expected case; otherwise, it will open happen if something in the
    1064             :          * ipc communication doesn't work correctly.
    1065             :          */
    1066        3362 :         if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
    1067             :         {
    1068        1290 :             AbortStrongLockAcquire();
    1069             : 
    1070        1290 :             if (dontWait)
    1071             :             {
    1072             :                 /*
    1073             :                  * We can't acquire the lock immediately.  If caller specified
    1074             :                  * no blocking, remove useless table entries and return
    1075             :                  * LOCKACQUIRE_NOT_AVAIL without waiting.
    1076             :                  */
    1077        1290 :                 if (proclock->holdMask == 0)
    1078             :                 {
    1079             :                     uint32      proclock_hashcode;
    1080             : 
    1081         886 :                     proclock_hashcode = ProcLockHashCode(&proclock->tag,
    1082             :                                                          hashcode);
    1083         886 :                     dlist_delete(&proclock->lockLink);
    1084         886 :                     dlist_delete(&proclock->procLink);
    1085         886 :                     if (!hash_search_with_hash_value(LockMethodProcLockHash,
    1086         886 :                                                      &(proclock->tag),
    1087             :                                                      proclock_hashcode,
    1088             :                                                      HASH_REMOVE,
    1089             :                                                      NULL))
    1090           0 :                         elog(PANIC, "proclock table corrupted");
    1091             :                 }
    1092             :                 else
    1093             :                     PROCLOCK_PRINT("LockAcquire: NOWAIT", proclock);
    1094        1290 :                 lock->nRequested--;
    1095        1290 :                 lock->requested[lockmode]--;
    1096             :                 LOCK_PRINT("LockAcquire: conditional lock failed",
    1097             :                            lock, lockmode);
    1098             :                 Assert((lock->nRequested > 0) &&
    1099             :                        (lock->requested[lockmode] >= 0));
    1100             :                 Assert(lock->nGranted <= lock->nRequested);
    1101        1290 :                 LWLockRelease(partitionLock);
    1102        1290 :                 if (locallock->nLocks == 0)
    1103        1290 :                     RemoveLocalLock(locallock);
    1104        1290 :                 if (locallockp)
    1105         440 :                     *locallockp = NULL;
    1106        1290 :                 return LOCKACQUIRE_NOT_AVAIL;
    1107             :             }
    1108             :             else
    1109             :             {
    1110             :                 /*
    1111             :                  * We should have gotten the lock, but somehow that didn't
    1112             :                  * happen. If we get here, it's a bug.
    1113             :                  */
    1114             :                 PROCLOCK_PRINT("LockAcquire: INCONSISTENT", proclock);
    1115             :                 LOCK_PRINT("LockAcquire: INCONSISTENT", lock, lockmode);
    1116           0 :                 LWLockRelease(partitionLock);
    1117           0 :                 elog(ERROR, "LockAcquire failed");
    1118             :             }
    1119             :         }
    1120             :         PROCLOCK_PRINT("LockAcquire: granted", proclock);
    1121             :         LOCK_PRINT("LockAcquire: granted", lock, lockmode);
    1122             :     }
    1123             : 
    1124             :     /*
    1125             :      * Lock state is fully up-to-date now; if we error out after this, no
    1126             :      * special error cleanup is required.
    1127             :      */
    1128     3407320 :     FinishStrongLockAcquire();
    1129             : 
    1130     3407320 :     LWLockRelease(partitionLock);
    1131             : 
    1132             :     /*
    1133             :      * Emit a WAL record if acquisition of this lock needs to be replayed in a
    1134             :      * standby server.
    1135             :      */
    1136     3407320 :     if (log_lock)
    1137             :     {
    1138             :         /*
    1139             :          * Decode the locktag back to the original values, to avoid sending
    1140             :          * lots of empty bytes with every message.  See lock.h to check how a
    1141             :          * locktag is defined for LOCKTAG_RELATION
    1142             :          */
    1143      159014 :         LogAccessExclusiveLock(locktag->locktag_field1,
    1144             :                                locktag->locktag_field2);
    1145             :     }
    1146             : 
    1147     3407320 :     return LOCKACQUIRE_OK;
    1148             : }
    1149             : 
    1150             : /*
    1151             :  * Find or create LOCK and PROCLOCK objects as needed for a new lock
    1152             :  * request.
    1153             :  *
    1154             :  * Returns the PROCLOCK object, or NULL if we failed to create the objects
    1155             :  * for lack of shared memory.
    1156             :  *
    1157             :  * The appropriate partition lock must be held at entry, and will be
    1158             :  * held at exit.
    1159             :  */
    1160             : static PROCLOCK *
    1161     3412028 : SetupLockInTable(LockMethod lockMethodTable, PGPROC *proc,
    1162             :                  const LOCKTAG *locktag, uint32 hashcode, LOCKMODE lockmode)
    1163             : {
    1164             :     LOCK       *lock;
    1165             :     PROCLOCK   *proclock;
    1166             :     PROCLOCKTAG proclocktag;
    1167             :     uint32      proclock_hashcode;
    1168             :     bool        found;
    1169             : 
    1170             :     /*
    1171             :      * Find or create a lock with this tag.
    1172             :      */
    1173     3412028 :     lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
    1174             :                                                 locktag,
    1175             :                                                 hashcode,
    1176             :                                                 HASH_ENTER_NULL,
    1177             :                                                 &found);
    1178     3412028 :     if (!lock)
    1179           0 :         return NULL;
    1180             : 
    1181             :     /*
    1182             :      * if it's a new lock object, initialize it
    1183             :      */
    1184     3412028 :     if (!found)
    1185             :     {
    1186     3071436 :         lock->grantMask = 0;
    1187     3071436 :         lock->waitMask = 0;
    1188     3071436 :         dlist_init(&lock->procLocks);
    1189     3071436 :         dclist_init(&lock->waitProcs);
    1190     3071436 :         lock->nRequested = 0;
    1191     3071436 :         lock->nGranted = 0;
    1192    18428616 :         MemSet(lock->requested, 0, sizeof(int) * MAX_LOCKMODES);
    1193     3071436 :         MemSet(lock->granted, 0, sizeof(int) * MAX_LOCKMODES);
    1194             :         LOCK_PRINT("LockAcquire: new", lock, lockmode);
    1195             :     }
    1196             :     else
    1197             :     {
    1198             :         LOCK_PRINT("LockAcquire: found", lock, lockmode);
    1199             :         Assert((lock->nRequested >= 0) && (lock->requested[lockmode] >= 0));
    1200             :         Assert((lock->nGranted >= 0) && (lock->granted[lockmode] >= 0));
    1201             :         Assert(lock->nGranted <= lock->nRequested);
    1202             :     }
    1203             : 
    1204             :     /*
    1205             :      * Create the hash key for the proclock table.
    1206             :      */
    1207     3412028 :     proclocktag.myLock = lock;
    1208     3412028 :     proclocktag.myProc = proc;
    1209             : 
    1210     3412028 :     proclock_hashcode = ProcLockHashCode(&proclocktag, hashcode);
    1211             : 
    1212             :     /*
    1213             :      * Find or create a proclock entry with this tag
    1214             :      */
    1215     3412028 :     proclock = (PROCLOCK *) hash_search_with_hash_value(LockMethodProcLockHash,
    1216             :                                                         &proclocktag,
    1217             :                                                         proclock_hashcode,
    1218             :                                                         HASH_ENTER_NULL,
    1219             :                                                         &found);
    1220     3412028 :     if (!proclock)
    1221             :     {
    1222             :         /* Oops, not enough shmem for the proclock */
    1223           0 :         if (lock->nRequested == 0)
    1224             :         {
    1225             :             /*
    1226             :              * There are no other requestors of this lock, so garbage-collect
    1227             :              * the lock object.  We *must* do this to avoid a permanent leak
    1228             :              * of shared memory, because there won't be anything to cause
    1229             :              * anyone to release the lock object later.
    1230             :              */
    1231             :             Assert(dlist_is_empty(&(lock->procLocks)));
    1232           0 :             if (!hash_search_with_hash_value(LockMethodLockHash,
    1233           0 :                                              &(lock->tag),
    1234             :                                              hashcode,
    1235             :                                              HASH_REMOVE,
    1236             :                                              NULL))
    1237           0 :                 elog(PANIC, "lock table corrupted");
    1238             :         }
    1239           0 :         return NULL;
    1240             :     }
    1241             : 
    1242             :     /*
    1243             :      * If new, initialize the new entry
    1244             :      */
    1245     3412028 :     if (!found)
    1246             :     {
    1247     3092714 :         uint32      partition = LockHashPartition(hashcode);
    1248             : 
    1249             :         /*
    1250             :          * It might seem unsafe to access proclock->groupLeader without a
    1251             :          * lock, but it's not really.  Either we are initializing a proclock
    1252             :          * on our own behalf, in which case our group leader isn't changing
    1253             :          * because the group leader for a process can only ever be changed by
    1254             :          * the process itself; or else we are transferring a fast-path lock to
    1255             :          * the main lock table, in which case that process can't change it's
    1256             :          * lock group leader without first releasing all of its locks (and in
    1257             :          * particular the one we are currently transferring).
    1258             :          */
    1259     6185428 :         proclock->groupLeader = proc->lockGroupLeader != NULL ?
    1260     3092714 :             proc->lockGroupLeader : proc;
    1261     3092714 :         proclock->holdMask = 0;
    1262     3092714 :         proclock->releaseMask = 0;
    1263             :         /* Add proclock to appropriate lists */
    1264     3092714 :         dlist_push_tail(&lock->procLocks, &proclock->lockLink);
    1265     3092714 :         dlist_push_tail(&proc->myProcLocks[partition], &proclock->procLink);
    1266             :         PROCLOCK_PRINT("LockAcquire: new", proclock);
    1267             :     }
    1268             :     else
    1269             :     {
    1270             :         PROCLOCK_PRINT("LockAcquire: found", proclock);
    1271             :         Assert((proclock->holdMask & ~lock->grantMask) == 0);
    1272             : 
    1273             : #ifdef CHECK_DEADLOCK_RISK
    1274             : 
    1275             :         /*
    1276             :          * Issue warning if we already hold a lower-level lock on this object
    1277             :          * and do not hold a lock of the requested level or higher. This
    1278             :          * indicates a deadlock-prone coding practice (eg, we'd have a
    1279             :          * deadlock if another backend were following the same code path at
    1280             :          * about the same time).
    1281             :          *
    1282             :          * This is not enabled by default, because it may generate log entries
    1283             :          * about user-level coding practices that are in fact safe in context.
    1284             :          * It can be enabled to help find system-level problems.
    1285             :          *
    1286             :          * XXX Doing numeric comparison on the lockmodes is a hack; it'd be
    1287             :          * better to use a table.  For now, though, this works.
    1288             :          */
    1289             :         {
    1290             :             int         i;
    1291             : 
    1292             :             for (i = lockMethodTable->numLockModes; i > 0; i--)
    1293             :             {
    1294             :                 if (proclock->holdMask & LOCKBIT_ON(i))
    1295             :                 {
    1296             :                     if (i >= (int) lockmode)
    1297             :                         break;  /* safe: we have a lock >= req level */
    1298             :                     elog(LOG, "deadlock risk: raising lock level"
    1299             :                          " from %s to %s on object %u/%u/%u",
    1300             :                          lockMethodTable->lockModeNames[i],
    1301             :                          lockMethodTable->lockModeNames[lockmode],
    1302             :                          lock->tag.locktag_field1, lock->tag.locktag_field2,
    1303             :                          lock->tag.locktag_field3);
    1304             :                     break;
    1305             :                 }
    1306             :             }
    1307             :         }
    1308             : #endif                          /* CHECK_DEADLOCK_RISK */
    1309             :     }
    1310             : 
    1311             :     /*
    1312             :      * lock->nRequested and lock->requested[] count the total number of
    1313             :      * requests, whether granted or waiting, so increment those immediately.
    1314             :      * The other counts don't increment till we get the lock.
    1315             :      */
    1316     3412028 :     lock->nRequested++;
    1317     3412028 :     lock->requested[lockmode]++;
    1318             :     Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
    1319             : 
    1320             :     /*
    1321             :      * We shouldn't already hold the desired lock; else locallock table is
    1322             :      * broken.
    1323             :      */
    1324     3412028 :     if (proclock->holdMask & LOCKBIT_ON(lockmode))
    1325           0 :         elog(ERROR, "lock %s on object %u/%u/%u is already held",
    1326             :              lockMethodTable->lockModeNames[lockmode],
    1327             :              lock->tag.locktag_field1, lock->tag.locktag_field2,
    1328             :              lock->tag.locktag_field3);
    1329             : 
    1330     3412028 :     return proclock;
    1331             : }
    1332             : 
    1333             : /*
    1334             :  * Check and set/reset the flag that we hold the relation extension lock.
    1335             :  *
    1336             :  * It is callers responsibility that this function is called after
    1337             :  * acquiring/releasing the relation extension lock.
    1338             :  *
    1339             :  * Pass acquired as true if lock is acquired, false otherwise.
    1340             :  */
    1341             : static inline void
    1342    53286606 : CheckAndSetLockHeld(LOCALLOCK *locallock, bool acquired)
    1343             : {
    1344             : #ifdef USE_ASSERT_CHECKING
    1345             :     if (LOCALLOCK_LOCKTAG(*locallock) == LOCKTAG_RELATION_EXTEND)
    1346             :         IsRelationExtensionLockHeld = acquired;
    1347             : #endif
    1348    53286606 : }
    1349             : 
    1350             : /*
    1351             :  * Subroutine to free a locallock entry
    1352             :  */
    1353             : static void
    1354    26280576 : RemoveLocalLock(LOCALLOCK *locallock)
    1355             : {
    1356             :     int         i;
    1357             : 
    1358    26417318 :     for (i = locallock->numLockOwners - 1; i >= 0; i--)
    1359             :     {
    1360      136742 :         if (locallock->lockOwners[i].owner != NULL)
    1361      136668 :             ResourceOwnerForgetLock(locallock->lockOwners[i].owner, locallock);
    1362             :     }
    1363    26280576 :     locallock->numLockOwners = 0;
    1364    26280576 :     if (locallock->lockOwners != NULL)
    1365    26280576 :         pfree(locallock->lockOwners);
    1366    26280576 :     locallock->lockOwners = NULL;
    1367             : 
    1368    26280576 :     if (locallock->holdsStrongLockCount)
    1369             :     {
    1370             :         uint32      fasthashcode;
    1371             : 
    1372      306846 :         fasthashcode = FastPathStrongLockHashPartition(locallock->hashcode);
    1373             : 
    1374      306846 :         SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
    1375             :         Assert(FastPathStrongRelationLocks->count[fasthashcode] > 0);
    1376      306846 :         FastPathStrongRelationLocks->count[fasthashcode]--;
    1377      306846 :         locallock->holdsStrongLockCount = false;
    1378      306846 :         SpinLockRelease(&FastPathStrongRelationLocks->mutex);
    1379             :     }
    1380             : 
    1381    26280576 :     if (!hash_search(LockMethodLocalHash,
    1382    26280576 :                      &(locallock->tag),
    1383             :                      HASH_REMOVE, NULL))
    1384           0 :         elog(WARNING, "locallock table corrupted");
    1385             : 
    1386             :     /*
    1387             :      * Indicate that the lock is released for certain types of locks
    1388             :      */
    1389    26280576 :     CheckAndSetLockHeld(locallock, false);
    1390    26280576 : }
    1391             : 
    1392             : /*
    1393             :  * LockCheckConflicts -- test whether requested lock conflicts
    1394             :  *      with those already granted
    1395             :  *
    1396             :  * Returns true if conflict, false if no conflict.
    1397             :  *
    1398             :  * NOTES:
    1399             :  *      Here's what makes this complicated: one process's locks don't
    1400             :  * conflict with one another, no matter what purpose they are held for
    1401             :  * (eg, session and transaction locks do not conflict).  Nor do the locks
    1402             :  * of one process in a lock group conflict with those of another process in
    1403             :  * the same group.  So, we must subtract off these locks when determining
    1404             :  * whether the requested new lock conflicts with those already held.
    1405             :  */
    1406             : bool
    1407     3410792 : LockCheckConflicts(LockMethod lockMethodTable,
    1408             :                    LOCKMODE lockmode,
    1409             :                    LOCK *lock,
    1410             :                    PROCLOCK *proclock)
    1411             : {
    1412     3410792 :     int         numLockModes = lockMethodTable->numLockModes;
    1413             :     LOCKMASK    myLocks;
    1414     3410792 :     int         conflictMask = lockMethodTable->conflictTab[lockmode];
    1415             :     int         conflictsRemaining[MAX_LOCKMODES];
    1416     3410792 :     int         totalConflictsRemaining = 0;
    1417             :     dlist_iter  proclock_iter;
    1418             :     int         i;
    1419             : 
    1420             :     /*
    1421             :      * first check for global conflicts: If no locks conflict with my request,
    1422             :      * then I get the lock.
    1423             :      *
    1424             :      * Checking for conflict: lock->grantMask represents the types of
    1425             :      * currently held locks.  conflictTable[lockmode] has a bit set for each
    1426             :      * type of lock that conflicts with request.   Bitwise compare tells if
    1427             :      * there is a conflict.
    1428             :      */
    1429     3410792 :     if (!(conflictMask & lock->grantMask))
    1430             :     {
    1431             :         PROCLOCK_PRINT("LockCheckConflicts: no conflict", proclock);
    1432     3290406 :         return false;
    1433             :     }
    1434             : 
    1435             :     /*
    1436             :      * Rats.  Something conflicts.  But it could still be my own lock, or a
    1437             :      * lock held by another member of my locking group.  First, figure out how
    1438             :      * many conflicts remain after subtracting out any locks I hold myself.
    1439             :      */
    1440      120386 :     myLocks = proclock->holdMask;
    1441     1083474 :     for (i = 1; i <= numLockModes; i++)
    1442             :     {
    1443      963088 :         if ((conflictMask & LOCKBIT_ON(i)) == 0)
    1444             :         {
    1445      484748 :             conflictsRemaining[i] = 0;
    1446      484748 :             continue;
    1447             :         }
    1448      478340 :         conflictsRemaining[i] = lock->granted[i];
    1449      478340 :         if (myLocks & LOCKBIT_ON(i))
    1450      124586 :             --conflictsRemaining[i];
    1451      478340 :         totalConflictsRemaining += conflictsRemaining[i];
    1452             :     }
    1453             : 
    1454             :     /* If no conflicts remain, we get the lock. */
    1455      120386 :     if (totalConflictsRemaining == 0)
    1456             :     {
    1457             :         PROCLOCK_PRINT("LockCheckConflicts: resolved (simple)", proclock);
    1458      116034 :         return false;
    1459             :     }
    1460             : 
    1461             :     /* If no group locking, it's definitely a conflict. */
    1462        4352 :     if (proclock->groupLeader == MyProc && MyProc->lockGroupLeader == NULL)
    1463             :     {
    1464             :         Assert(proclock->tag.myProc == MyProc);
    1465             :         PROCLOCK_PRINT("LockCheckConflicts: conflicting (simple)",
    1466             :                        proclock);
    1467        3374 :         return true;
    1468             :     }
    1469             : 
    1470             :     /*
    1471             :      * The relation extension lock conflict even between the group members.
    1472             :      */
    1473         978 :     if (LOCK_LOCKTAG(*lock) == LOCKTAG_RELATION_EXTEND)
    1474             :     {
    1475             :         PROCLOCK_PRINT("LockCheckConflicts: conflicting (group)",
    1476             :                        proclock);
    1477          32 :         return true;
    1478             :     }
    1479             : 
    1480             :     /*
    1481             :      * Locks held in conflicting modes by members of our own lock group are
    1482             :      * not real conflicts; we can subtract those out and see if we still have
    1483             :      * a conflict.  This is O(N) in the number of processes holding or
    1484             :      * awaiting locks on this object.  We could improve that by making the
    1485             :      * shared memory state more complex (and larger) but it doesn't seem worth
    1486             :      * it.
    1487             :      */
    1488        1154 :     dlist_foreach(proclock_iter, &lock->procLocks)
    1489             :     {
    1490        1094 :         PROCLOCK   *otherproclock =
    1491        1094 :             dlist_container(PROCLOCK, lockLink, proclock_iter.cur);
    1492             : 
    1493        1094 :         if (proclock != otherproclock &&
    1494        1034 :             proclock->groupLeader == otherproclock->groupLeader &&
    1495         890 :             (otherproclock->holdMask & conflictMask) != 0)
    1496             :         {
    1497         886 :             int         intersectMask = otherproclock->holdMask & conflictMask;
    1498             : 
    1499        7974 :             for (i = 1; i <= numLockModes; i++)
    1500             :             {
    1501        7088 :                 if ((intersectMask & LOCKBIT_ON(i)) != 0)
    1502             :                 {
    1503         900 :                     if (conflictsRemaining[i] <= 0)
    1504           0 :                         elog(PANIC, "proclocks held do not match lock");
    1505         900 :                     conflictsRemaining[i]--;
    1506         900 :                     totalConflictsRemaining--;
    1507             :                 }
    1508             :             }
    1509             : 
    1510         886 :             if (totalConflictsRemaining == 0)
    1511             :             {
    1512             :                 PROCLOCK_PRINT("LockCheckConflicts: resolved (group)",
    1513             :                                proclock);
    1514         886 :                 return false;
    1515             :             }
    1516             :         }
    1517             :     }
    1518             : 
    1519             :     /* Nope, it's a real conflict. */
    1520             :     PROCLOCK_PRINT("LockCheckConflicts: conflicting (group)", proclock);
    1521          60 :     return true;
    1522             : }
    1523             : 
    1524             : /*
    1525             :  * GrantLock -- update the lock and proclock data structures to show
    1526             :  *      the lock request has been granted.
    1527             :  *
    1528             :  * NOTE: if proc was blocked, it also needs to be removed from the wait list
    1529             :  * and have its waitLock/waitProcLock fields cleared.  That's not done here.
    1530             :  *
    1531             :  * NOTE: the lock grant also has to be recorded in the associated LOCALLOCK
    1532             :  * table entry; but since we may be awaking some other process, we can't do
    1533             :  * that here; it's done by GrantLockLocal, instead.
    1534             :  */
    1535             : void
    1536     3410818 : GrantLock(LOCK *lock, PROCLOCK *proclock, LOCKMODE lockmode)
    1537             : {
    1538     3410818 :     lock->nGranted++;
    1539     3410818 :     lock->granted[lockmode]++;
    1540     3410818 :     lock->grantMask |= LOCKBIT_ON(lockmode);
    1541     3410818 :     if (lock->granted[lockmode] == lock->requested[lockmode])
    1542     3410562 :         lock->waitMask &= LOCKBIT_OFF(lockmode);
    1543     3410818 :     proclock->holdMask |= LOCKBIT_ON(lockmode);
    1544             :     LOCK_PRINT("GrantLock", lock, lockmode);
    1545             :     Assert((lock->nGranted > 0) && (lock->granted[lockmode] > 0));
    1546             :     Assert(lock->nGranted <= lock->nRequested);
    1547     3410818 : }
    1548             : 
    1549             : /*
    1550             :  * UnGrantLock -- opposite of GrantLock.
    1551             :  *
    1552             :  * Updates the lock and proclock data structures to show that the lock
    1553             :  * is no longer held nor requested by the current holder.
    1554             :  *
    1555             :  * Returns true if there were any waiters waiting on the lock that
    1556             :  * should now be woken up with ProcLockWakeup.
    1557             :  */
    1558             : static bool
    1559     3410654 : UnGrantLock(LOCK *lock, LOCKMODE lockmode,
    1560             :             PROCLOCK *proclock, LockMethod lockMethodTable)
    1561             : {
    1562     3410654 :     bool        wakeupNeeded = false;
    1563             : 
    1564             :     Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
    1565             :     Assert((lock->nGranted > 0) && (lock->granted[lockmode] > 0));
    1566             :     Assert(lock->nGranted <= lock->nRequested);
    1567             : 
    1568             :     /*
    1569             :      * fix the general lock stats
    1570             :      */
    1571     3410654 :     lock->nRequested--;
    1572     3410654 :     lock->requested[lockmode]--;
    1573     3410654 :     lock->nGranted--;
    1574     3410654 :     lock->granted[lockmode]--;
    1575             : 
    1576     3410654 :     if (lock->granted[lockmode] == 0)
    1577             :     {
    1578             :         /* change the conflict mask.  No more of this lock type. */
    1579     3394894 :         lock->grantMask &= LOCKBIT_OFF(lockmode);
    1580             :     }
    1581             : 
    1582             :     LOCK_PRINT("UnGrantLock: updated", lock, lockmode);
    1583             : 
    1584             :     /*
    1585             :      * We need only run ProcLockWakeup if the released lock conflicts with at
    1586             :      * least one of the lock types requested by waiter(s).  Otherwise whatever
    1587             :      * conflict made them wait must still exist.  NOTE: before MVCC, we could
    1588             :      * skip wakeup if lock->granted[lockmode] was still positive. But that's
    1589             :      * not true anymore, because the remaining granted locks might belong to
    1590             :      * some waiter, who could now be awakened because he doesn't conflict with
    1591             :      * his own locks.
    1592             :      */
    1593     3410654 :     if (lockMethodTable->conflictTab[lockmode] & lock->waitMask)
    1594        2016 :         wakeupNeeded = true;
    1595             : 
    1596             :     /*
    1597             :      * Now fix the per-proclock state.
    1598             :      */
    1599     3410654 :     proclock->holdMask &= LOCKBIT_OFF(lockmode);
    1600             :     PROCLOCK_PRINT("UnGrantLock: updated", proclock);
    1601             : 
    1602     3410654 :     return wakeupNeeded;
    1603             : }
    1604             : 
    1605             : /*
    1606             :  * CleanUpLock -- clean up after releasing a lock.  We garbage-collect the
    1607             :  * proclock and lock objects if possible, and call ProcLockWakeup if there
    1608             :  * are remaining requests and the caller says it's OK.  (Normally, this
    1609             :  * should be called after UnGrantLock, and wakeupNeeded is the result from
    1610             :  * UnGrantLock.)
    1611             :  *
    1612             :  * The appropriate partition lock must be held at entry, and will be
    1613             :  * held at exit.
    1614             :  */
    1615             : static void
    1616     3367272 : CleanUpLock(LOCK *lock, PROCLOCK *proclock,
    1617             :             LockMethod lockMethodTable, uint32 hashcode,
    1618             :             bool wakeupNeeded)
    1619             : {
    1620             :     /*
    1621             :      * If this was my last hold on this lock, delete my entry in the proclock
    1622             :      * table.
    1623             :      */
    1624     3367272 :     if (proclock->holdMask == 0)
    1625             :     {
    1626             :         uint32      proclock_hashcode;
    1627             : 
    1628             :         PROCLOCK_PRINT("CleanUpLock: deleting", proclock);
    1629     3091834 :         dlist_delete(&proclock->lockLink);
    1630     3091834 :         dlist_delete(&proclock->procLink);
    1631     3091834 :         proclock_hashcode = ProcLockHashCode(&proclock->tag, hashcode);
    1632     3091834 :         if (!hash_search_with_hash_value(LockMethodProcLockHash,
    1633     3091834 :                                          &(proclock->tag),
    1634             :                                          proclock_hashcode,
    1635             :                                          HASH_REMOVE,
    1636             :                                          NULL))
    1637           0 :             elog(PANIC, "proclock table corrupted");
    1638             :     }
    1639             : 
    1640     3367272 :     if (lock->nRequested == 0)
    1641             :     {
    1642             :         /*
    1643             :          * The caller just released the last lock, so garbage-collect the lock
    1644             :          * object.
    1645             :          */
    1646             :         LOCK_PRINT("CleanUpLock: deleting", lock, 0);
    1647             :         Assert(dlist_is_empty(&lock->procLocks));
    1648     3071438 :         if (!hash_search_with_hash_value(LockMethodLockHash,
    1649     3071438 :                                          &(lock->tag),
    1650             :                                          hashcode,
    1651             :                                          HASH_REMOVE,
    1652             :                                          NULL))
    1653           0 :             elog(PANIC, "lock table corrupted");
    1654             :     }
    1655      295834 :     else if (wakeupNeeded)
    1656             :     {
    1657             :         /* There are waiters on this lock, so wake them up. */
    1658        2100 :         ProcLockWakeup(lockMethodTable, lock);
    1659             :     }
    1660     3367272 : }
    1661             : 
    1662             : /*
    1663             :  * GrantLockLocal -- update the locallock data structures to show
    1664             :  *      the lock request has been granted.
    1665             :  *
    1666             :  * We expect that LockAcquire made sure there is room to add a new
    1667             :  * ResourceOwner entry.
    1668             :  */
    1669             : static void
    1670    29347038 : GrantLockLocal(LOCALLOCK *locallock, ResourceOwner owner)
    1671             : {
    1672    29347038 :     LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
    1673             :     int         i;
    1674             : 
    1675             :     Assert(locallock->numLockOwners < locallock->maxLockOwners);
    1676             :     /* Count the total */
    1677    29347038 :     locallock->nLocks++;
    1678             :     /* Count the per-owner lock */
    1679    30393316 :     for (i = 0; i < locallock->numLockOwners; i++)
    1680             :     {
    1681     3387286 :         if (lockOwners[i].owner == owner)
    1682             :         {
    1683     2341008 :             lockOwners[i].nLocks++;
    1684     2341008 :             return;
    1685             :         }
    1686             :     }
    1687    27006030 :     lockOwners[i].owner = owner;
    1688    27006030 :     lockOwners[i].nLocks = 1;
    1689    27006030 :     locallock->numLockOwners++;
    1690    27006030 :     if (owner != NULL)
    1691    26942086 :         ResourceOwnerRememberLock(owner, locallock);
    1692             : 
    1693             :     /* Indicate that the lock is acquired for certain types of locks. */
    1694    27006030 :     CheckAndSetLockHeld(locallock, true);
    1695             : }
    1696             : 
    1697             : /*
    1698             :  * BeginStrongLockAcquire - inhibit use of fastpath for a given LOCALLOCK,
    1699             :  * and arrange for error cleanup if it fails
    1700             :  */
    1701             : static void
    1702      307402 : BeginStrongLockAcquire(LOCALLOCK *locallock, uint32 fasthashcode)
    1703             : {
    1704             :     Assert(StrongLockInProgress == NULL);
    1705             :     Assert(locallock->holdsStrongLockCount == false);
    1706             : 
    1707             :     /*
    1708             :      * Adding to a memory location is not atomic, so we take a spinlock to
    1709             :      * ensure we don't collide with someone else trying to bump the count at
    1710             :      * the same time.
    1711             :      *
    1712             :      * XXX: It might be worth considering using an atomic fetch-and-add
    1713             :      * instruction here, on architectures where that is supported.
    1714             :      */
    1715             : 
    1716      307402 :     SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
    1717      307402 :     FastPathStrongRelationLocks->count[fasthashcode]++;
    1718      307402 :     locallock->holdsStrongLockCount = true;
    1719      307402 :     StrongLockInProgress = locallock;
    1720      307402 :     SpinLockRelease(&FastPathStrongRelationLocks->mutex);
    1721      307402 : }
    1722             : 
    1723             : /*
    1724             :  * FinishStrongLockAcquire - cancel pending cleanup for a strong lock
    1725             :  * acquisition once it's no longer needed
    1726             :  */
    1727             : static void
    1728     3407320 : FinishStrongLockAcquire(void)
    1729             : {
    1730     3407320 :     StrongLockInProgress = NULL;
    1731     3407320 : }
    1732             : 
    1733             : /*
    1734             :  * AbortStrongLockAcquire - undo strong lock state changes performed by
    1735             :  * BeginStrongLockAcquire.
    1736             :  */
    1737             : void
    1738      621280 : AbortStrongLockAcquire(void)
    1739             : {
    1740             :     uint32      fasthashcode;
    1741      621280 :     LOCALLOCK  *locallock = StrongLockInProgress;
    1742             : 
    1743      621280 :     if (locallock == NULL)
    1744      620856 :         return;
    1745             : 
    1746         424 :     fasthashcode = FastPathStrongLockHashPartition(locallock->hashcode);
    1747             :     Assert(locallock->holdsStrongLockCount == true);
    1748         424 :     SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
    1749             :     Assert(FastPathStrongRelationLocks->count[fasthashcode] > 0);
    1750         424 :     FastPathStrongRelationLocks->count[fasthashcode]--;
    1751         424 :     locallock->holdsStrongLockCount = false;
    1752         424 :     StrongLockInProgress = NULL;
    1753         424 :     SpinLockRelease(&FastPathStrongRelationLocks->mutex);
    1754             : }
    1755             : 
    1756             : /*
    1757             :  * GrantAwaitedLock -- call GrantLockLocal for the lock we are doing
    1758             :  *      WaitOnLock on.
    1759             :  *
    1760             :  * proc.c needs this for the case where we are booted off the lock by
    1761             :  * timeout, but discover that someone granted us the lock anyway.
    1762             :  *
    1763             :  * We could just export GrantLockLocal, but that would require including
    1764             :  * resowner.h in lock.h, which creates circularity.
    1765             :  */
    1766             : void
    1767        2072 : GrantAwaitedLock(void)
    1768             : {
    1769        2072 :     GrantLockLocal(awaitedLock, awaitedOwner);
    1770        2072 : }
    1771             : 
    1772             : /*
    1773             :  * MarkLockClear -- mark an acquired lock as "clear"
    1774             :  *
    1775             :  * This means that we know we have absorbed all sinval messages that other
    1776             :  * sessions generated before we acquired this lock, and so we can confidently
    1777             :  * assume we know about any catalog changes protected by this lock.
    1778             :  */
    1779             : void
    1780    25504352 : MarkLockClear(LOCALLOCK *locallock)
    1781             : {
    1782             :     Assert(locallock->nLocks > 0);
    1783    25504352 :     locallock->lockCleared = true;
    1784    25504352 : }
    1785             : 
    1786             : /*
    1787             :  * WaitOnLock -- wait to acquire a lock
    1788             :  *
    1789             :  * Caller must have set MyProc->heldLocks to reflect locks already held
    1790             :  * on the lockable object by this process.
    1791             :  *
    1792             :  * The appropriate partition lock must be held at entry, and will still be
    1793             :  * held at exit.
    1794             :  */
    1795             : static void
    1796        3452 : WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner, bool dontWait)
    1797             : {
    1798        3452 :     LOCKMETHODID lockmethodid = LOCALLOCK_LOCKMETHOD(*locallock);
    1799        3452 :     LockMethod  lockMethodTable = LockMethods[lockmethodid];
    1800             : 
    1801             :     LOCK_PRINT("WaitOnLock: sleeping on lock",
    1802             :                locallock->lock, locallock->tag.mode);
    1803             : 
    1804             :     /* adjust the process title to indicate that it's waiting */
    1805        3452 :     set_ps_display_suffix("waiting");
    1806             : 
    1807        3452 :     awaitedLock = locallock;
    1808        3452 :     awaitedOwner = owner;
    1809             : 
    1810             :     /*
    1811             :      * NOTE: Think not to put any shared-state cleanup after the call to
    1812             :      * ProcSleep, in either the normal or failure path.  The lock state must
    1813             :      * be fully set by the lock grantor, or by CheckDeadLock if we give up
    1814             :      * waiting for the lock.  This is necessary because of the possibility
    1815             :      * that a cancel/die interrupt will interrupt ProcSleep after someone else
    1816             :      * grants us the lock, but before we've noticed it. Hence, after granting,
    1817             :      * the locktable state must fully reflect the fact that we own the lock;
    1818             :      * we can't do additional work on return.
    1819             :      *
    1820             :      * We can and do use a PG_TRY block to try to clean up after failure, but
    1821             :      * this still has a major limitation: elog(FATAL) can occur while waiting
    1822             :      * (eg, a "die" interrupt), and then control won't come back here. So all
    1823             :      * cleanup of essential state should happen in LockErrorCleanup, not here.
    1824             :      * We can use PG_TRY to clear the "waiting" status flags, since doing that
    1825             :      * is unimportant if the process exits.
    1826             :      */
    1827        3452 :     PG_TRY();
    1828             :     {
    1829             :         /*
    1830             :          * If dontWait = true, we handle success and failure in the same way
    1831             :          * here. The caller will be able to sort out what has happened.
    1832             :          */
    1833        3452 :         if (ProcSleep(locallock, lockMethodTable, dontWait) != PROC_WAIT_STATUS_OK
    1834        1300 :             && !dontWait)
    1835             :         {
    1836             : 
    1837             :             /*
    1838             :              * We failed as a result of a deadlock, see CheckDeadLock(). Quit
    1839             :              * now.
    1840             :              */
    1841          10 :             awaitedLock = NULL;
    1842             :             LOCK_PRINT("WaitOnLock: aborting on lock",
    1843             :                        locallock->lock, locallock->tag.mode);
    1844          10 :             LWLockRelease(LockHashPartitionLock(locallock->hashcode));
    1845             : 
    1846             :             /*
    1847             :              * Now that we aren't holding the partition lock, we can give an
    1848             :              * error report including details about the detected deadlock.
    1849             :              */
    1850          10 :             DeadLockReport();
    1851             :             /* not reached */
    1852             :         }
    1853             :     }
    1854          82 :     PG_CATCH();
    1855             :     {
    1856             :         /* In this path, awaitedLock remains set until LockErrorCleanup */
    1857             : 
    1858             :         /* reset ps display to remove the suffix */
    1859          82 :         set_ps_display_remove_suffix();
    1860             : 
    1861             :         /* and propagate the error */
    1862          82 :         PG_RE_THROW();
    1863             :     }
    1864        3362 :     PG_END_TRY();
    1865             : 
    1866        3362 :     awaitedLock = NULL;
    1867             : 
    1868             :     /* reset ps display to remove the suffix */
    1869        3362 :     set_ps_display_remove_suffix();
    1870             : 
    1871             :     LOCK_PRINT("WaitOnLock: wakeup on lock",
    1872             :                locallock->lock, locallock->tag.mode);
    1873        3362 : }
    1874             : 
    1875             : /*
    1876             :  * Remove a proc from the wait-queue it is on (caller must know it is on one).
    1877             :  * This is only used when the proc has failed to get the lock, so we set its
    1878             :  * waitStatus to PROC_WAIT_STATUS_ERROR.
    1879             :  *
    1880             :  * Appropriate partition lock must be held by caller.  Also, caller is
    1881             :  * responsible for signaling the proc if needed.
    1882             :  *
    1883             :  * NB: this does not clean up any locallock object that may exist for the lock.
    1884             :  */
    1885             : void
    1886          90 : RemoveFromWaitQueue(PGPROC *proc, uint32 hashcode)
    1887             : {
    1888          90 :     LOCK       *waitLock = proc->waitLock;
    1889          90 :     PROCLOCK   *proclock = proc->waitProcLock;
    1890          90 :     LOCKMODE    lockmode = proc->waitLockMode;
    1891          90 :     LOCKMETHODID lockmethodid = LOCK_LOCKMETHOD(*waitLock);
    1892             : 
    1893             :     /* Make sure proc is waiting */
    1894             :     Assert(proc->waitStatus == PROC_WAIT_STATUS_WAITING);
    1895             :     Assert(proc->links.next != NULL);
    1896             :     Assert(waitLock);
    1897             :     Assert(!dclist_is_empty(&waitLock->waitProcs));
    1898             :     Assert(0 < lockmethodid && lockmethodid < lengthof(LockMethods));
    1899             : 
    1900             :     /* Remove proc from lock's wait queue */
    1901          90 :     dclist_delete_from_thoroughly(&waitLock->waitProcs, &proc->links);
    1902             : 
    1903             :     /* Undo increments of request counts by waiting process */
    1904             :     Assert(waitLock->nRequested > 0);
    1905             :     Assert(waitLock->nRequested > proc->waitLock->nGranted);
    1906          90 :     waitLock->nRequested--;
    1907             :     Assert(waitLock->requested[lockmode] > 0);
    1908          90 :     waitLock->requested[lockmode]--;
    1909             :     /* don't forget to clear waitMask bit if appropriate */
    1910          90 :     if (waitLock->granted[lockmode] == waitLock->requested[lockmode])
    1911          88 :         waitLock->waitMask &= LOCKBIT_OFF(lockmode);
    1912             : 
    1913             :     /* Clean up the proc's own state, and pass it the ok/fail signal */
    1914          90 :     proc->waitLock = NULL;
    1915          90 :     proc->waitProcLock = NULL;
    1916          90 :     proc->waitStatus = PROC_WAIT_STATUS_ERROR;
    1917             : 
    1918             :     /*
    1919             :      * Delete the proclock immediately if it represents no already-held locks.
    1920             :      * (This must happen now because if the owner of the lock decides to
    1921             :      * release it, and the requested/granted counts then go to zero,
    1922             :      * LockRelease expects there to be no remaining proclocks.) Then see if
    1923             :      * any other waiters for the lock can be woken up now.
    1924             :      */
    1925          90 :     CleanUpLock(waitLock, proclock,
    1926             :                 LockMethods[lockmethodid], hashcode,
    1927             :                 true);
    1928          90 : }
    1929             : 
    1930             : /*
    1931             :  * LockRelease -- look up 'locktag' and release one 'lockmode' lock on it.
    1932             :  *      Release a session lock if 'sessionLock' is true, else release a
    1933             :  *      regular transaction lock.
    1934             :  *
    1935             :  * Side Effects: find any waiting processes that are now wakable,
    1936             :  *      grant them their requested locks and awaken them.
    1937             :  *      (We have to grant the lock here to avoid a race between
    1938             :  *      the waking process and any new process to
    1939             :  *      come along and request the lock.)
    1940             :  */
    1941             : bool
    1942    25944262 : LockRelease(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
    1943             : {
    1944    25944262 :     LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
    1945             :     LockMethod  lockMethodTable;
    1946             :     LOCALLOCKTAG localtag;
    1947             :     LOCALLOCK  *locallock;
    1948             :     LOCK       *lock;
    1949             :     PROCLOCK   *proclock;
    1950             :     LWLock     *partitionLock;
    1951             :     bool        wakeupNeeded;
    1952             : 
    1953    25944262 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
    1954           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    1955    25944262 :     lockMethodTable = LockMethods[lockmethodid];
    1956    25944262 :     if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
    1957           0 :         elog(ERROR, "unrecognized lock mode: %d", lockmode);
    1958             : 
    1959             : #ifdef LOCK_DEBUG
    1960             :     if (LOCK_DEBUG_ENABLED(locktag))
    1961             :         elog(LOG, "LockRelease: lock [%u,%u] %s",
    1962             :              locktag->locktag_field1, locktag->locktag_field2,
    1963             :              lockMethodTable->lockModeNames[lockmode]);
    1964             : #endif
    1965             : 
    1966             :     /*
    1967             :      * Find the LOCALLOCK entry for this lock and lockmode
    1968             :      */
    1969    25944262 :     MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
    1970    25944262 :     localtag.lock = *locktag;
    1971    25944262 :     localtag.mode = lockmode;
    1972             : 
    1973    25944262 :     locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
    1974             :                                           &localtag,
    1975             :                                           HASH_FIND, NULL);
    1976             : 
    1977             :     /*
    1978             :      * let the caller print its own error message, too. Do not ereport(ERROR).
    1979             :      */
    1980    25944262 :     if (!locallock || locallock->nLocks <= 0)
    1981             :     {
    1982          26 :         elog(WARNING, "you don't own a lock of type %s",
    1983             :              lockMethodTable->lockModeNames[lockmode]);
    1984          26 :         return false;
    1985             :     }
    1986             : 
    1987             :     /*
    1988             :      * Decrease the count for the resource owner.
    1989             :      */
    1990             :     {
    1991    25944236 :         LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
    1992             :         ResourceOwner owner;
    1993             :         int         i;
    1994             : 
    1995             :         /* Identify owner for lock */
    1996    25944236 :         if (sessionLock)
    1997       63914 :             owner = NULL;
    1998             :         else
    1999    25880322 :             owner = CurrentResourceOwner;
    2000             : 
    2001    25946162 :         for (i = locallock->numLockOwners - 1; i >= 0; i--)
    2002             :         {
    2003    25946138 :             if (lockOwners[i].owner == owner)
    2004             :             {
    2005             :                 Assert(lockOwners[i].nLocks > 0);
    2006    25944212 :                 if (--lockOwners[i].nLocks == 0)
    2007             :                 {
    2008    25089466 :                     if (owner != NULL)
    2009    25025596 :                         ResourceOwnerForgetLock(owner, locallock);
    2010             :                     /* compact out unused slot */
    2011    25089466 :                     locallock->numLockOwners--;
    2012    25089466 :                     if (i < locallock->numLockOwners)
    2013         104 :                         lockOwners[i] = lockOwners[locallock->numLockOwners];
    2014             :                 }
    2015    25944212 :                 break;
    2016             :             }
    2017             :         }
    2018    25944236 :         if (i < 0)
    2019             :         {
    2020             :             /* don't release a lock belonging to another owner */
    2021          24 :             elog(WARNING, "you don't own a lock of type %s",
    2022             :                  lockMethodTable->lockModeNames[lockmode]);
    2023          24 :             return false;
    2024             :         }
    2025             :     }
    2026             : 
    2027             :     /*
    2028             :      * Decrease the total local count.  If we're still holding the lock, we're
    2029             :      * done.
    2030             :      */
    2031    25944212 :     locallock->nLocks--;
    2032             : 
    2033    25944212 :     if (locallock->nLocks > 0)
    2034     1353704 :         return true;
    2035             : 
    2036             :     /*
    2037             :      * At this point we can no longer suppose we are clear of invalidation
    2038             :      * messages related to this lock.  Although we'll delete the LOCALLOCK
    2039             :      * object before any intentional return from this routine, it seems worth
    2040             :      * the trouble to explicitly reset lockCleared right now, just in case
    2041             :      * some error prevents us from deleting the LOCALLOCK.
    2042             :      */
    2043    24590508 :     locallock->lockCleared = false;
    2044             : 
    2045             :     /* Attempt fast release of any lock eligible for the fast path. */
    2046    24590508 :     if (EligibleForRelationFastPath(locktag, lockmode) &&
    2047    22857916 :         FastPathLocalUseCount > 0)
    2048             :     {
    2049             :         bool        released;
    2050             : 
    2051             :         /*
    2052             :          * We might not find the lock here, even if we originally entered it
    2053             :          * here.  Another backend may have moved it to the main table.
    2054             :          */
    2055    22715220 :         LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
    2056    22715220 :         released = FastPathUnGrantRelationLock(locktag->locktag_field2,
    2057             :                                                lockmode);
    2058    22715220 :         LWLockRelease(&MyProc->fpInfoLock);
    2059    22715220 :         if (released)
    2060             :         {
    2061    22055470 :             RemoveLocalLock(locallock);
    2062    22055470 :             return true;
    2063             :         }
    2064             :     }
    2065             : 
    2066             :     /*
    2067             :      * Otherwise we've got to mess with the shared lock table.
    2068             :      */
    2069     2535038 :     partitionLock = LockHashPartitionLock(locallock->hashcode);
    2070             : 
    2071     2535038 :     LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    2072             : 
    2073             :     /*
    2074             :      * Normally, we don't need to re-find the lock or proclock, since we kept
    2075             :      * their addresses in the locallock table, and they couldn't have been
    2076             :      * removed while we were holding a lock on them.  But it's possible that
    2077             :      * the lock was taken fast-path and has since been moved to the main hash
    2078             :      * table by another backend, in which case we will need to look up the
    2079             :      * objects here.  We assume the lock field is NULL if so.
    2080             :      */
    2081     2535038 :     lock = locallock->lock;
    2082     2535038 :     if (!lock)
    2083             :     {
    2084             :         PROCLOCKTAG proclocktag;
    2085             : 
    2086             :         Assert(EligibleForRelationFastPath(locktag, lockmode));
    2087           6 :         lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
    2088             :                                                     locktag,
    2089             :                                                     locallock->hashcode,
    2090             :                                                     HASH_FIND,
    2091             :                                                     NULL);
    2092           6 :         if (!lock)
    2093           0 :             elog(ERROR, "failed to re-find shared lock object");
    2094           6 :         locallock->lock = lock;
    2095             : 
    2096           6 :         proclocktag.myLock = lock;
    2097           6 :         proclocktag.myProc = MyProc;
    2098           6 :         locallock->proclock = (PROCLOCK *) hash_search(LockMethodProcLockHash,
    2099             :                                                        &proclocktag,
    2100             :                                                        HASH_FIND,
    2101             :                                                        NULL);
    2102           6 :         if (!locallock->proclock)
    2103           0 :             elog(ERROR, "failed to re-find shared proclock object");
    2104             :     }
    2105             :     LOCK_PRINT("LockRelease: found", lock, lockmode);
    2106     2535038 :     proclock = locallock->proclock;
    2107             :     PROCLOCK_PRINT("LockRelease: found", proclock);
    2108             : 
    2109             :     /*
    2110             :      * Double-check that we are actually holding a lock of the type we want to
    2111             :      * release.
    2112             :      */
    2113     2535038 :     if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
    2114             :     {
    2115             :         PROCLOCK_PRINT("LockRelease: WRONGTYPE", proclock);
    2116           0 :         LWLockRelease(partitionLock);
    2117           0 :         elog(WARNING, "you don't own a lock of type %s",
    2118             :              lockMethodTable->lockModeNames[lockmode]);
    2119           0 :         RemoveLocalLock(locallock);
    2120           0 :         return false;
    2121             :     }
    2122             : 
    2123             :     /*
    2124             :      * Do the releasing.  CleanUpLock will waken any now-wakable waiters.
    2125             :      */
    2126     2535038 :     wakeupNeeded = UnGrantLock(lock, lockmode, proclock, lockMethodTable);
    2127             : 
    2128     2535038 :     CleanUpLock(lock, proclock,
    2129             :                 lockMethodTable, locallock->hashcode,
    2130             :                 wakeupNeeded);
    2131             : 
    2132     2535038 :     LWLockRelease(partitionLock);
    2133             : 
    2134     2535038 :     RemoveLocalLock(locallock);
    2135     2535038 :     return true;
    2136             : }
    2137             : 
    2138             : /*
    2139             :  * LockReleaseAll -- Release all locks of the specified lock method that
    2140             :  *      are held by the current process.
    2141             :  *
    2142             :  * Well, not necessarily *all* locks.  The available behaviors are:
    2143             :  *      allLocks == true: release all locks including session locks.
    2144             :  *      allLocks == false: release all non-session locks.
    2145             :  */
    2146             : void
    2147     1156772 : LockReleaseAll(LOCKMETHODID lockmethodid, bool allLocks)
    2148             : {
    2149             :     HASH_SEQ_STATUS status;
    2150             :     LockMethod  lockMethodTable;
    2151             :     int         i,
    2152             :                 numLockModes;
    2153             :     LOCALLOCK  *locallock;
    2154             :     LOCK       *lock;
    2155             :     int         partition;
    2156     1156772 :     bool        have_fast_path_lwlock = false;
    2157             : 
    2158     1156772 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
    2159           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    2160     1156772 :     lockMethodTable = LockMethods[lockmethodid];
    2161             : 
    2162             : #ifdef LOCK_DEBUG
    2163             :     if (*(lockMethodTable->trace_flag))
    2164             :         elog(LOG, "LockReleaseAll: lockmethod=%d", lockmethodid);
    2165             : #endif
    2166             : 
    2167             :     /*
    2168             :      * Get rid of our fast-path VXID lock, if appropriate.  Note that this is
    2169             :      * the only way that the lock we hold on our own VXID can ever get
    2170             :      * released: it is always and only released when a toplevel transaction
    2171             :      * ends.
    2172             :      */
    2173     1156772 :     if (lockmethodid == DEFAULT_LOCKMETHOD)
    2174      565944 :         VirtualXactLockTableCleanup();
    2175             : 
    2176     1156772 :     numLockModes = lockMethodTable->numLockModes;
    2177             : 
    2178             :     /*
    2179             :      * First we run through the locallock table and get rid of unwanted
    2180             :      * entries, then we scan the process's proclocks and get rid of those. We
    2181             :      * do this separately because we may have multiple locallock entries
    2182             :      * pointing to the same proclock, and we daren't end up with any dangling
    2183             :      * pointers.  Fast-path locks are cleaned up during the locallock table
    2184             :      * scan, though.
    2185             :      */
    2186     1156772 :     hash_seq_init(&status, LockMethodLocalHash);
    2187             : 
    2188     2933430 :     while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    2189             :     {
    2190             :         /*
    2191             :          * If the LOCALLOCK entry is unused, we must've run out of shared
    2192             :          * memory while trying to set up this lock.  Just forget the local
    2193             :          * entry.
    2194             :          */
    2195     1776658 :         if (locallock->nLocks == 0)
    2196             :         {
    2197          90 :             RemoveLocalLock(locallock);
    2198          90 :             continue;
    2199             :         }
    2200             : 
    2201             :         /* Ignore items that are not of the lockmethod to be removed */
    2202     1776568 :         if (LOCALLOCK_LOCKMETHOD(*locallock) != lockmethodid)
    2203       44894 :             continue;
    2204             : 
    2205             :         /*
    2206             :          * If we are asked to release all locks, we can just zap the entry.
    2207             :          * Otherwise, must scan to see if there are session locks. We assume
    2208             :          * there is at most one lockOwners entry for session locks.
    2209             :          */
    2210     1731674 :         if (!allLocks)
    2211             :         {
    2212     1598090 :             LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
    2213             : 
    2214             :             /* If session lock is above array position 0, move it down to 0 */
    2215     3223450 :             for (i = 0; i < locallock->numLockOwners; i++)
    2216             :             {
    2217     1625360 :                 if (lockOwners[i].owner == NULL)
    2218       44728 :                     lockOwners[0] = lockOwners[i];
    2219             :                 else
    2220     1580632 :                     ResourceOwnerForgetLock(lockOwners[i].owner, locallock);
    2221             :             }
    2222             : 
    2223     1598090 :             if (locallock->numLockOwners > 0 &&
    2224     1598090 :                 lockOwners[0].owner == NULL &&
    2225       44728 :                 lockOwners[0].nLocks > 0)
    2226             :             {
    2227             :                 /* Fix the locallock to show just the session locks */
    2228       44728 :                 locallock->nLocks = lockOwners[0].nLocks;
    2229       44728 :                 locallock->numLockOwners = 1;
    2230             :                 /* We aren't deleting this locallock, so done */
    2231       44728 :                 continue;
    2232             :             }
    2233             :             else
    2234     1553362 :                 locallock->numLockOwners = 0;
    2235             :         }
    2236             : 
    2237             :         /*
    2238             :          * If the lock or proclock pointers are NULL, this lock was taken via
    2239             :          * the relation fast-path (and is not known to have been transferred).
    2240             :          */
    2241     1686946 :         if (locallock->proclock == NULL || locallock->lock == NULL)
    2242             :         {
    2243      815628 :             LOCKMODE    lockmode = locallock->tag.mode;
    2244             :             Oid         relid;
    2245             : 
    2246             :             /* Verify that a fast-path lock is what we've got. */
    2247      815628 :             if (!EligibleForRelationFastPath(&locallock->tag.lock, lockmode))
    2248           0 :                 elog(PANIC, "locallock table corrupted");
    2249             : 
    2250             :             /*
    2251             :              * If we don't currently hold the LWLock that protects our
    2252             :              * fast-path data structures, we must acquire it before attempting
    2253             :              * to release the lock via the fast-path.  We will continue to
    2254             :              * hold the LWLock until we're done scanning the locallock table,
    2255             :              * unless we hit a transferred fast-path lock.  (XXX is this
    2256             :              * really such a good idea?  There could be a lot of entries ...)
    2257             :              */
    2258      815628 :             if (!have_fast_path_lwlock)
    2259             :             {
    2260      249474 :                 LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
    2261      249474 :                 have_fast_path_lwlock = true;
    2262             :             }
    2263             : 
    2264             :             /* Attempt fast-path release. */
    2265      815628 :             relid = locallock->tag.lock.locktag_field2;
    2266      815628 :             if (FastPathUnGrantRelationLock(relid, lockmode))
    2267             :             {
    2268      813644 :                 RemoveLocalLock(locallock);
    2269      813644 :                 continue;
    2270             :             }
    2271             : 
    2272             :             /*
    2273             :              * Our lock, originally taken via the fast path, has been
    2274             :              * transferred to the main lock table.  That's going to require
    2275             :              * some extra work, so release our fast-path lock before starting.
    2276             :              */
    2277        1984 :             LWLockRelease(&MyProc->fpInfoLock);
    2278        1984 :             have_fast_path_lwlock = false;
    2279             : 
    2280             :             /*
    2281             :              * Now dump the lock.  We haven't got a pointer to the LOCK or
    2282             :              * PROCLOCK in this case, so we have to handle this a bit
    2283             :              * differently than a normal lock release.  Unfortunately, this
    2284             :              * requires an extra LWLock acquire-and-release cycle on the
    2285             :              * partitionLock, but hopefully it shouldn't happen often.
    2286             :              */
    2287        1984 :             LockRefindAndRelease(lockMethodTable, MyProc,
    2288             :                                  &locallock->tag.lock, lockmode, false);
    2289        1984 :             RemoveLocalLock(locallock);
    2290        1984 :             continue;
    2291             :         }
    2292             : 
    2293             :         /* Mark the proclock to show we need to release this lockmode */
    2294      871318 :         if (locallock->nLocks > 0)
    2295      871318 :             locallock->proclock->releaseMask |= LOCKBIT_ON(locallock->tag.mode);
    2296             : 
    2297             :         /* And remove the locallock hashtable entry */
    2298      871318 :         RemoveLocalLock(locallock);
    2299             :     }
    2300             : 
    2301             :     /* Done with the fast-path data structures */
    2302     1156772 :     if (have_fast_path_lwlock)
    2303      247490 :         LWLockRelease(&MyProc->fpInfoLock);
    2304             : 
    2305             :     /*
    2306             :      * Now, scan each lock partition separately.
    2307             :      */
    2308    19665124 :     for (partition = 0; partition < NUM_LOCK_PARTITIONS; partition++)
    2309             :     {
    2310             :         LWLock     *partitionLock;
    2311    18508352 :         dlist_head *procLocks = &MyProc->myProcLocks[partition];
    2312             :         dlist_mutable_iter proclock_iter;
    2313             : 
    2314    18508352 :         partitionLock = LockHashPartitionLockByIndex(partition);
    2315             : 
    2316             :         /*
    2317             :          * If the proclock list for this partition is empty, we can skip
    2318             :          * acquiring the partition lock.  This optimization is trickier than
    2319             :          * it looks, because another backend could be in process of adding
    2320             :          * something to our proclock list due to promoting one of our
    2321             :          * fast-path locks.  However, any such lock must be one that we
    2322             :          * decided not to delete above, so it's okay to skip it again now;
    2323             :          * we'd just decide not to delete it again.  We must, however, be
    2324             :          * careful to re-fetch the list header once we've acquired the
    2325             :          * partition lock, to be sure we have a valid, up-to-date pointer.
    2326             :          * (There is probably no significant risk if pointer fetch/store is
    2327             :          * atomic, but we don't wish to assume that.)
    2328             :          *
    2329             :          * XXX This argument assumes that the locallock table correctly
    2330             :          * represents all of our fast-path locks.  While allLocks mode
    2331             :          * guarantees to clean up all of our normal locks regardless of the
    2332             :          * locallock situation, we lose that guarantee for fast-path locks.
    2333             :          * This is not ideal.
    2334             :          */
    2335    18508352 :         if (dlist_is_empty(procLocks))
    2336    17780196 :             continue;           /* needn't examine this partition */
    2337             : 
    2338      728156 :         LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    2339             : 
    2340     1644298 :         dlist_foreach_modify(proclock_iter, procLocks)
    2341             :         {
    2342      916142 :             PROCLOCK   *proclock = dlist_container(PROCLOCK, procLink, proclock_iter.cur);
    2343      916142 :             bool        wakeupNeeded = false;
    2344             : 
    2345             :             Assert(proclock->tag.myProc == MyProc);
    2346             : 
    2347      916142 :             lock = proclock->tag.myLock;
    2348             : 
    2349             :             /* Ignore items that are not of the lockmethod to be removed */
    2350      916142 :             if (LOCK_LOCKMETHOD(*lock) != lockmethodid)
    2351       44888 :                 continue;
    2352             : 
    2353             :             /*
    2354             :              * In allLocks mode, force release of all locks even if locallock
    2355             :              * table had problems
    2356             :              */
    2357      871254 :             if (allLocks)
    2358       86964 :                 proclock->releaseMask = proclock->holdMask;
    2359             :             else
    2360             :                 Assert((proclock->releaseMask & ~proclock->holdMask) == 0);
    2361             : 
    2362             :             /*
    2363             :              * Ignore items that have nothing to be released, unless they have
    2364             :              * holdMask == 0 and are therefore recyclable
    2365             :              */
    2366      871254 :             if (proclock->releaseMask == 0 && proclock->holdMask != 0)
    2367       43408 :                 continue;
    2368             : 
    2369             :             PROCLOCK_PRINT("LockReleaseAll", proclock);
    2370             :             LOCK_PRINT("LockReleaseAll", lock, 0);
    2371             :             Assert(lock->nRequested >= 0);
    2372             :             Assert(lock->nGranted >= 0);
    2373             :             Assert(lock->nGranted <= lock->nRequested);
    2374             :             Assert((proclock->holdMask & ~lock->grantMask) == 0);
    2375             : 
    2376             :             /*
    2377             :              * Release the previously-marked lock modes
    2378             :              */
    2379     7450614 :             for (i = 1; i <= numLockModes; i++)
    2380             :             {
    2381     6622768 :                 if (proclock->releaseMask & LOCKBIT_ON(i))
    2382      871318 :                     wakeupNeeded |= UnGrantLock(lock, i, proclock,
    2383             :                                                 lockMethodTable);
    2384             :             }
    2385             :             Assert((lock->nRequested >= 0) && (lock->nGranted >= 0));
    2386             :             Assert(lock->nGranted <= lock->nRequested);
    2387             :             LOCK_PRINT("LockReleaseAll: updated", lock, 0);
    2388             : 
    2389      827846 :             proclock->releaseMask = 0;
    2390             : 
    2391             :             /* CleanUpLock will wake up waiters if needed. */
    2392      827846 :             CleanUpLock(lock, proclock,
    2393             :                         lockMethodTable,
    2394      827846 :                         LockTagHashCode(&lock->tag),
    2395             :                         wakeupNeeded);
    2396             :         }                       /* loop over PROCLOCKs within this partition */
    2397             : 
    2398      728156 :         LWLockRelease(partitionLock);
    2399             :     }                           /* loop over partitions */
    2400             : 
    2401             : #ifdef LOCK_DEBUG
    2402             :     if (*(lockMethodTable->trace_flag))
    2403             :         elog(LOG, "LockReleaseAll done");
    2404             : #endif
    2405     1156772 : }
    2406             : 
    2407             : /*
    2408             :  * LockReleaseSession -- Release all session locks of the specified lock method
    2409             :  *      that are held by the current process.
    2410             :  */
    2411             : void
    2412         238 : LockReleaseSession(LOCKMETHODID lockmethodid)
    2413             : {
    2414             :     HASH_SEQ_STATUS status;
    2415             :     LOCALLOCK  *locallock;
    2416             : 
    2417         238 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
    2418           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    2419             : 
    2420         238 :     hash_seq_init(&status, LockMethodLocalHash);
    2421             : 
    2422         452 :     while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    2423             :     {
    2424             :         /* Ignore items that are not of the specified lock method */
    2425         214 :         if (LOCALLOCK_LOCKMETHOD(*locallock) != lockmethodid)
    2426          20 :             continue;
    2427             : 
    2428         194 :         ReleaseLockIfHeld(locallock, true);
    2429             :     }
    2430         238 : }
    2431             : 
    2432             : /*
    2433             :  * LockReleaseCurrentOwner
    2434             :  *      Release all locks belonging to CurrentResourceOwner
    2435             :  *
    2436             :  * If the caller knows what those locks are, it can pass them as an array.
    2437             :  * That speeds up the call significantly, when a lot of locks are held.
    2438             :  * Otherwise, pass NULL for locallocks, and we'll traverse through our hash
    2439             :  * table to find them.
    2440             :  */
    2441             : void
    2442        9364 : LockReleaseCurrentOwner(LOCALLOCK **locallocks, int nlocks)
    2443             : {
    2444        9364 :     if (locallocks == NULL)
    2445             :     {
    2446             :         HASH_SEQ_STATUS status;
    2447             :         LOCALLOCK  *locallock;
    2448             : 
    2449           8 :         hash_seq_init(&status, LockMethodLocalHash);
    2450             : 
    2451         538 :         while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    2452         530 :             ReleaseLockIfHeld(locallock, false);
    2453             :     }
    2454             :     else
    2455             :     {
    2456             :         int         i;
    2457             : 
    2458       14354 :         for (i = nlocks - 1; i >= 0; i--)
    2459        4998 :             ReleaseLockIfHeld(locallocks[i], false);
    2460             :     }
    2461        9364 : }
    2462             : 
    2463             : /*
    2464             :  * ReleaseLockIfHeld
    2465             :  *      Release any session-level locks on this lockable object if sessionLock
    2466             :  *      is true; else, release any locks held by CurrentResourceOwner.
    2467             :  *
    2468             :  * It is tempting to pass this a ResourceOwner pointer (or NULL for session
    2469             :  * locks), but without refactoring LockRelease() we cannot support releasing
    2470             :  * locks belonging to resource owners other than CurrentResourceOwner.
    2471             :  * If we were to refactor, it'd be a good idea to fix it so we don't have to
    2472             :  * do a hashtable lookup of the locallock, too.  However, currently this
    2473             :  * function isn't used heavily enough to justify refactoring for its
    2474             :  * convenience.
    2475             :  */
    2476             : static void
    2477        5722 : ReleaseLockIfHeld(LOCALLOCK *locallock, bool sessionLock)
    2478             : {
    2479             :     ResourceOwner owner;
    2480             :     LOCALLOCKOWNER *lockOwners;
    2481             :     int         i;
    2482             : 
    2483             :     /* Identify owner for lock (must match LockRelease!) */
    2484        5722 :     if (sessionLock)
    2485         194 :         owner = NULL;
    2486             :     else
    2487        5528 :         owner = CurrentResourceOwner;
    2488             : 
    2489             :     /* Scan to see if there are any locks belonging to the target owner */
    2490        5722 :     lockOwners = locallock->lockOwners;
    2491        6108 :     for (i = locallock->numLockOwners - 1; i >= 0; i--)
    2492             :     {
    2493        5722 :         if (lockOwners[i].owner == owner)
    2494             :         {
    2495             :             Assert(lockOwners[i].nLocks > 0);
    2496        5336 :             if (lockOwners[i].nLocks < locallock->nLocks)
    2497             :             {
    2498             :                 /*
    2499             :                  * We will still hold this lock after forgetting this
    2500             :                  * ResourceOwner.
    2501             :                  */
    2502        1344 :                 locallock->nLocks -= lockOwners[i].nLocks;
    2503             :                 /* compact out unused slot */
    2504        1344 :                 locallock->numLockOwners--;
    2505        1344 :                 if (owner != NULL)
    2506        1344 :                     ResourceOwnerForgetLock(owner, locallock);
    2507        1344 :                 if (i < locallock->numLockOwners)
    2508           0 :                     lockOwners[i] = lockOwners[locallock->numLockOwners];
    2509             :             }
    2510             :             else
    2511             :             {
    2512             :                 Assert(lockOwners[i].nLocks == locallock->nLocks);
    2513             :                 /* We want to call LockRelease just once */
    2514        3992 :                 lockOwners[i].nLocks = 1;
    2515        3992 :                 locallock->nLocks = 1;
    2516        3992 :                 if (!LockRelease(&locallock->tag.lock,
    2517             :                                  locallock->tag.mode,
    2518             :                                  sessionLock))
    2519           0 :                     elog(WARNING, "ReleaseLockIfHeld: failed??");
    2520             :             }
    2521        5336 :             break;
    2522             :         }
    2523             :     }
    2524        5722 : }
    2525             : 
    2526             : /*
    2527             :  * LockReassignCurrentOwner
    2528             :  *      Reassign all locks belonging to CurrentResourceOwner to belong
    2529             :  *      to its parent resource owner.
    2530             :  *
    2531             :  * If the caller knows what those locks are, it can pass them as an array.
    2532             :  * That speeds up the call significantly, when a lot of locks are held
    2533             :  * (e.g pg_dump with a large schema).  Otherwise, pass NULL for locallocks,
    2534             :  * and we'll traverse through our hash table to find them.
    2535             :  */
    2536             : void
    2537      610462 : LockReassignCurrentOwner(LOCALLOCK **locallocks, int nlocks)
    2538             : {
    2539      610462 :     ResourceOwner parent = ResourceOwnerGetParent(CurrentResourceOwner);
    2540             : 
    2541             :     Assert(parent != NULL);
    2542             : 
    2543      610462 :     if (locallocks == NULL)
    2544             :     {
    2545             :         HASH_SEQ_STATUS status;
    2546             :         LOCALLOCK  *locallock;
    2547             : 
    2548        5794 :         hash_seq_init(&status, LockMethodLocalHash);
    2549             : 
    2550      153602 :         while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    2551      147808 :             LockReassignOwner(locallock, parent);
    2552             :     }
    2553             :     else
    2554             :     {
    2555             :         int         i;
    2556             : 
    2557     1260502 :         for (i = nlocks - 1; i >= 0; i--)
    2558      655834 :             LockReassignOwner(locallocks[i], parent);
    2559             :     }
    2560      610462 : }
    2561             : 
    2562             : /*
    2563             :  * Subroutine of LockReassignCurrentOwner. Reassigns a given lock belonging to
    2564             :  * CurrentResourceOwner to its parent.
    2565             :  */
    2566             : static void
    2567      803642 : LockReassignOwner(LOCALLOCK *locallock, ResourceOwner parent)
    2568             : {
    2569             :     LOCALLOCKOWNER *lockOwners;
    2570             :     int         i;
    2571      803642 :     int         ic = -1;
    2572      803642 :     int         ip = -1;
    2573             : 
    2574             :     /*
    2575             :      * Scan to see if there are any locks belonging to current owner or its
    2576             :      * parent
    2577             :      */
    2578      803642 :     lockOwners = locallock->lockOwners;
    2579     1888636 :     for (i = locallock->numLockOwners - 1; i >= 0; i--)
    2580             :     {
    2581     1084994 :         if (lockOwners[i].owner == CurrentResourceOwner)
    2582      785328 :             ic = i;
    2583      299666 :         else if (lockOwners[i].owner == parent)
    2584      216100 :             ip = i;
    2585             :     }
    2586             : 
    2587      803642 :     if (ic < 0)
    2588       18314 :         return;                 /* no current locks */
    2589             : 
    2590      785328 :     if (ip < 0)
    2591             :     {
    2592             :         /* Parent has no slot, so just give it the child's slot */
    2593      587482 :         lockOwners[ic].owner = parent;
    2594      587482 :         ResourceOwnerRememberLock(parent, locallock);
    2595             :     }
    2596             :     else
    2597             :     {
    2598             :         /* Merge child's count with parent's */
    2599      197846 :         lockOwners[ip].nLocks += lockOwners[ic].nLocks;
    2600             :         /* compact out unused slot */
    2601      197846 :         locallock->numLockOwners--;
    2602      197846 :         if (ic < locallock->numLockOwners)
    2603        1390 :             lockOwners[ic] = lockOwners[locallock->numLockOwners];
    2604             :     }
    2605      785328 :     ResourceOwnerForgetLock(CurrentResourceOwner, locallock);
    2606             : }
    2607             : 
    2608             : /*
    2609             :  * FastPathGrantRelationLock
    2610             :  *      Grant lock using per-backend fast-path array, if there is space.
    2611             :  */
    2612             : static bool
    2613    22871876 : FastPathGrantRelationLock(Oid relid, LOCKMODE lockmode)
    2614             : {
    2615             :     uint32      f;
    2616    22871876 :     uint32      unused_slot = FP_LOCK_SLOTS_PER_BACKEND;
    2617             : 
    2618             :     /* Scan for existing entry for this relid, remembering empty slot. */
    2619   387486424 :     for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
    2620             :     {
    2621   365185598 :         if (FAST_PATH_GET_BITS(MyProc, f) == 0)
    2622   318465624 :             unused_slot = f;
    2623    46719974 :         else if (MyProc->fpRelId[f] == relid)
    2624             :         {
    2625             :             Assert(!FAST_PATH_CHECK_LOCKMODE(MyProc, f, lockmode));
    2626      571050 :             FAST_PATH_SET_LOCKMODE(MyProc, f, lockmode);
    2627      571050 :             return true;
    2628             :         }
    2629             :     }
    2630             : 
    2631             :     /* If no existing entry, use any empty slot. */
    2632    22300826 :     if (unused_slot < FP_LOCK_SLOTS_PER_BACKEND)
    2633             :     {
    2634    22300826 :         MyProc->fpRelId[unused_slot] = relid;
    2635    22300826 :         FAST_PATH_SET_LOCKMODE(MyProc, unused_slot, lockmode);
    2636    22300826 :         ++FastPathLocalUseCount;
    2637    22300826 :         return true;
    2638             :     }
    2639             : 
    2640             :     /* No existing entry, and no empty slot. */
    2641           0 :     return false;
    2642             : }
    2643             : 
    2644             : /*
    2645             :  * FastPathUnGrantRelationLock
    2646             :  *      Release fast-path lock, if present.  Update backend-private local
    2647             :  *      use count, while we're at it.
    2648             :  */
    2649             : static bool
    2650    23530848 : FastPathUnGrantRelationLock(Oid relid, LOCKMODE lockmode)
    2651             : {
    2652             :     uint32      f;
    2653    23530848 :     bool        result = false;
    2654             : 
    2655    23530848 :     FastPathLocalUseCount = 0;
    2656   400024416 :     for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
    2657             :     {
    2658   376493568 :         if (MyProc->fpRelId[f] == relid
    2659    27869682 :             && FAST_PATH_CHECK_LOCKMODE(MyProc, f, lockmode))
    2660             :         {
    2661             :             Assert(!result);
    2662    22869114 :             FAST_PATH_CLEAR_LOCKMODE(MyProc, f, lockmode);
    2663    22869114 :             result = true;
    2664             :             /* we continue iterating so as to update FastPathLocalUseCount */
    2665             :         }
    2666   376493568 :         if (FAST_PATH_GET_BITS(MyProc, f) != 0)
    2667    55272692 :             ++FastPathLocalUseCount;
    2668             :     }
    2669    23530848 :     return result;
    2670             : }
    2671             : 
    2672             : /*
    2673             :  * FastPathTransferRelationLocks
    2674             :  *      Transfer locks matching the given lock tag from per-backend fast-path
    2675             :  *      arrays to the shared hash table.
    2676             :  *
    2677             :  * Returns true if successful, false if ran out of shared memory.
    2678             :  */
    2679             : static bool
    2680      307402 : FastPathTransferRelationLocks(LockMethod lockMethodTable, const LOCKTAG *locktag,
    2681             :                               uint32 hashcode)
    2682             : {
    2683      307402 :     LWLock     *partitionLock = LockHashPartitionLock(hashcode);
    2684      307402 :     Oid         relid = locktag->locktag_field2;
    2685             :     uint32      i;
    2686             : 
    2687             :     /*
    2688             :      * Every PGPROC that can potentially hold a fast-path lock is present in
    2689             :      * ProcGlobal->allProcs.  Prepared transactions are not, but any
    2690             :      * outstanding fast-path locks held by prepared transactions are
    2691             :      * transferred to the main lock table.
    2692             :      */
    2693    31680032 :     for (i = 0; i < ProcGlobal->allProcCount; i++)
    2694             :     {
    2695    31372630 :         PGPROC     *proc = &ProcGlobal->allProcs[i];
    2696             :         uint32      f;
    2697             : 
    2698    31372630 :         LWLockAcquire(&proc->fpInfoLock, LW_EXCLUSIVE);
    2699             : 
    2700             :         /*
    2701             :          * If the target backend isn't referencing the same database as the
    2702             :          * lock, then we needn't examine the individual relation IDs at all;
    2703             :          * none of them can be relevant.
    2704             :          *
    2705             :          * proc->databaseId is set at backend startup time and never changes
    2706             :          * thereafter, so it might be safe to perform this test before
    2707             :          * acquiring &proc->fpInfoLock.  In particular, it's certainly safe to
    2708             :          * assume that if the target backend holds any fast-path locks, it
    2709             :          * must have performed a memory-fencing operation (in particular, an
    2710             :          * LWLock acquisition) since setting proc->databaseId.  However, it's
    2711             :          * less clear that our backend is certain to have performed a memory
    2712             :          * fencing operation since the other backend set proc->databaseId.  So
    2713             :          * for now, we test it after acquiring the LWLock just to be safe.
    2714             :          */
    2715    31372630 :         if (proc->databaseId != locktag->locktag_field1)
    2716             :         {
    2717    15311678 :             LWLockRelease(&proc->fpInfoLock);
    2718    15311678 :             continue;
    2719             :         }
    2720             : 
    2721   273033788 :         for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
    2722             :         {
    2723             :             uint32      lockmode;
    2724             : 
    2725             :             /* Look for an allocated slot matching the given relid. */
    2726   256974730 :             if (relid != proc->fpRelId[f] || FAST_PATH_GET_BITS(proc, f) == 0)
    2727   256972836 :                 continue;
    2728             : 
    2729             :             /* Find or create lock object. */
    2730        1894 :             LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    2731        7576 :             for (lockmode = FAST_PATH_LOCKNUMBER_OFFSET;
    2732             :                  lockmode < FAST_PATH_LOCKNUMBER_OFFSET + FAST_PATH_BITS_PER_SLOT;
    2733        5682 :                  ++lockmode)
    2734             :             {
    2735             :                 PROCLOCK   *proclock;
    2736             : 
    2737        5682 :                 if (!FAST_PATH_CHECK_LOCKMODE(proc, f, lockmode))
    2738        3676 :                     continue;
    2739        2006 :                 proclock = SetupLockInTable(lockMethodTable, proc, locktag,
    2740             :                                             hashcode, lockmode);
    2741        2006 :                 if (!proclock)
    2742             :                 {
    2743           0 :                     LWLockRelease(partitionLock);
    2744           0 :                     LWLockRelease(&proc->fpInfoLock);
    2745           0 :                     return false;
    2746             :                 }
    2747        2006 :                 GrantLock(proclock->tag.myLock, proclock, lockmode);
    2748        2006 :                 FAST_PATH_CLEAR_LOCKMODE(proc, f, lockmode);
    2749             :             }
    2750        1894 :             LWLockRelease(partitionLock);
    2751             : 
    2752             :             /* No need to examine remaining slots. */
    2753        1894 :             break;
    2754             :         }
    2755    16060952 :         LWLockRelease(&proc->fpInfoLock);
    2756             :     }
    2757      307402 :     return true;
    2758             : }
    2759             : 
    2760             : /*
    2761             :  * FastPathGetRelationLockEntry
    2762             :  *      Return the PROCLOCK for a lock originally taken via the fast-path,
    2763             :  *      transferring it to the primary lock table if necessary.
    2764             :  *
    2765             :  * Note: caller takes care of updating the locallock object.
    2766             :  */
    2767             : static PROCLOCK *
    2768         772 : FastPathGetRelationLockEntry(LOCALLOCK *locallock)
    2769             : {
    2770         772 :     LockMethod  lockMethodTable = LockMethods[DEFAULT_LOCKMETHOD];
    2771         772 :     LOCKTAG    *locktag = &locallock->tag.lock;
    2772         772 :     PROCLOCK   *proclock = NULL;
    2773         772 :     LWLock     *partitionLock = LockHashPartitionLock(locallock->hashcode);
    2774         772 :     Oid         relid = locktag->locktag_field2;
    2775             :     uint32      f;
    2776             : 
    2777         772 :     LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
    2778             : 
    2779       12328 :     for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
    2780             :     {
    2781             :         uint32      lockmode;
    2782             : 
    2783             :         /* Look for an allocated slot matching the given relid. */
    2784       12312 :         if (relid != MyProc->fpRelId[f] || FAST_PATH_GET_BITS(MyProc, f) == 0)
    2785       11556 :             continue;
    2786             : 
    2787             :         /* If we don't have a lock of the given mode, forget it! */
    2788         756 :         lockmode = locallock->tag.mode;
    2789         756 :         if (!FAST_PATH_CHECK_LOCKMODE(MyProc, f, lockmode))
    2790           0 :             break;
    2791             : 
    2792             :         /* Find or create lock object. */
    2793         756 :         LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    2794             : 
    2795         756 :         proclock = SetupLockInTable(lockMethodTable, MyProc, locktag,
    2796             :                                     locallock->hashcode, lockmode);
    2797         756 :         if (!proclock)
    2798             :         {
    2799           0 :             LWLockRelease(partitionLock);
    2800           0 :             LWLockRelease(&MyProc->fpInfoLock);
    2801           0 :             ereport(ERROR,
    2802             :                     (errcode(ERRCODE_OUT_OF_MEMORY),
    2803             :                      errmsg("out of shared memory"),
    2804             :                      errhint("You might need to increase %s.", "max_locks_per_transaction")));
    2805             :         }
    2806         756 :         GrantLock(proclock->tag.myLock, proclock, lockmode);
    2807         756 :         FAST_PATH_CLEAR_LOCKMODE(MyProc, f, lockmode);
    2808             : 
    2809         756 :         LWLockRelease(partitionLock);
    2810             : 
    2811             :         /* No need to examine remaining slots. */
    2812         756 :         break;
    2813             :     }
    2814             : 
    2815         772 :     LWLockRelease(&MyProc->fpInfoLock);
    2816             : 
    2817             :     /* Lock may have already been transferred by some other backend. */
    2818         772 :     if (proclock == NULL)
    2819             :     {
    2820             :         LOCK       *lock;
    2821             :         PROCLOCKTAG proclocktag;
    2822             :         uint32      proclock_hashcode;
    2823             : 
    2824          16 :         LWLockAcquire(partitionLock, LW_SHARED);
    2825             : 
    2826          16 :         lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
    2827             :                                                     locktag,
    2828             :                                                     locallock->hashcode,
    2829             :                                                     HASH_FIND,
    2830             :                                                     NULL);
    2831          16 :         if (!lock)
    2832           0 :             elog(ERROR, "failed to re-find shared lock object");
    2833             : 
    2834          16 :         proclocktag.myLock = lock;
    2835          16 :         proclocktag.myProc = MyProc;
    2836             : 
    2837          16 :         proclock_hashcode = ProcLockHashCode(&proclocktag, locallock->hashcode);
    2838             :         proclock = (PROCLOCK *)
    2839          16 :             hash_search_with_hash_value(LockMethodProcLockHash,
    2840             :                                         &proclocktag,
    2841             :                                         proclock_hashcode,
    2842             :                                         HASH_FIND,
    2843             :                                         NULL);
    2844          16 :         if (!proclock)
    2845           0 :             elog(ERROR, "failed to re-find shared proclock object");
    2846          16 :         LWLockRelease(partitionLock);
    2847             :     }
    2848             : 
    2849         772 :     return proclock;
    2850             : }
    2851             : 
    2852             : /*
    2853             :  * GetLockConflicts
    2854             :  *      Get an array of VirtualTransactionIds of xacts currently holding locks
    2855             :  *      that would conflict with the specified lock/lockmode.
    2856             :  *      xacts merely awaiting such a lock are NOT reported.
    2857             :  *
    2858             :  * The result array is palloc'd and is terminated with an invalid VXID.
    2859             :  * *countp, if not null, is updated to the number of items set.
    2860             :  *
    2861             :  * Of course, the result could be out of date by the time it's returned, so
    2862             :  * use of this function has to be thought about carefully.  Similarly, a
    2863             :  * PGPROC with no "lxid" will be considered non-conflicting regardless of any
    2864             :  * lock it holds.  Existing callers don't care about a locker after that
    2865             :  * locker's pg_xact updates complete.  CommitTransaction() clears "lxid" after
    2866             :  * pg_xact updates and before releasing locks.
    2867             :  *
    2868             :  * Note we never include the current xact's vxid in the result array,
    2869             :  * since an xact never blocks itself.
    2870             :  */
    2871             : VirtualTransactionId *
    2872        2544 : GetLockConflicts(const LOCKTAG *locktag, LOCKMODE lockmode, int *countp)
    2873             : {
    2874             :     static VirtualTransactionId *vxids;
    2875        2544 :     LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
    2876             :     LockMethod  lockMethodTable;
    2877             :     LOCK       *lock;
    2878             :     LOCKMASK    conflictMask;
    2879             :     dlist_iter  proclock_iter;
    2880             :     PROCLOCK   *proclock;
    2881             :     uint32      hashcode;
    2882             :     LWLock     *partitionLock;
    2883        2544 :     int         count = 0;
    2884        2544 :     int         fast_count = 0;
    2885             : 
    2886        2544 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
    2887           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    2888        2544 :     lockMethodTable = LockMethods[lockmethodid];
    2889        2544 :     if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
    2890           0 :         elog(ERROR, "unrecognized lock mode: %d", lockmode);
    2891             : 
    2892             :     /*
    2893             :      * Allocate memory to store results, and fill with InvalidVXID.  We only
    2894             :      * need enough space for MaxBackends + max_prepared_xacts + a terminator.
    2895             :      * InHotStandby allocate once in TopMemoryContext.
    2896             :      */
    2897        2544 :     if (InHotStandby)
    2898             :     {
    2899           8 :         if (vxids == NULL)
    2900           2 :             vxids = (VirtualTransactionId *)
    2901           2 :                 MemoryContextAlloc(TopMemoryContext,
    2902             :                                    sizeof(VirtualTransactionId) *
    2903           2 :                                    (MaxBackends + max_prepared_xacts + 1));
    2904             :     }
    2905             :     else
    2906        2536 :         vxids = (VirtualTransactionId *)
    2907        2536 :             palloc0(sizeof(VirtualTransactionId) *
    2908        2536 :                     (MaxBackends + max_prepared_xacts + 1));
    2909             : 
    2910             :     /* Compute hash code and partition lock, and look up conflicting modes. */
    2911        2544 :     hashcode = LockTagHashCode(locktag);
    2912        2544 :     partitionLock = LockHashPartitionLock(hashcode);
    2913        2544 :     conflictMask = lockMethodTable->conflictTab[lockmode];
    2914             : 
    2915             :     /*
    2916             :      * Fast path locks might not have been entered in the primary lock table.
    2917             :      * If the lock we're dealing with could conflict with such a lock, we must
    2918             :      * examine each backend's fast-path array for conflicts.
    2919             :      */
    2920        2544 :     if (ConflictsWithRelationFastPath(locktag, lockmode))
    2921             :     {
    2922             :         int         i;
    2923        2544 :         Oid         relid = locktag->locktag_field2;
    2924             :         VirtualTransactionId vxid;
    2925             : 
    2926             :         /*
    2927             :          * Iterate over relevant PGPROCs.  Anything held by a prepared
    2928             :          * transaction will have been transferred to the primary lock table,
    2929             :          * so we need not worry about those.  This is all a bit fuzzy, because
    2930             :          * new locks could be taken after we've visited a particular
    2931             :          * partition, but the callers had better be prepared to deal with that
    2932             :          * anyway, since the locks could equally well be taken between the
    2933             :          * time we return the value and the time the caller does something
    2934             :          * with it.
    2935             :          */
    2936      287556 :         for (i = 0; i < ProcGlobal->allProcCount; i++)
    2937             :         {
    2938      285012 :             PGPROC     *proc = &ProcGlobal->allProcs[i];
    2939             :             uint32      f;
    2940             : 
    2941             :             /* A backend never blocks itself */
    2942      285012 :             if (proc == MyProc)
    2943        2544 :                 continue;
    2944             : 
    2945      282468 :             LWLockAcquire(&proc->fpInfoLock, LW_SHARED);
    2946             : 
    2947             :             /*
    2948             :              * If the target backend isn't referencing the same database as
    2949             :              * the lock, then we needn't examine the individual relation IDs
    2950             :              * at all; none of them can be relevant.
    2951             :              *
    2952             :              * See FastPathTransferRelationLocks() for discussion of why we do
    2953             :              * this test after acquiring the lock.
    2954             :              */
    2955      282468 :             if (proc->databaseId != locktag->locktag_field1)
    2956             :             {
    2957      123060 :                 LWLockRelease(&proc->fpInfoLock);
    2958      123060 :                 continue;
    2959             :             }
    2960             : 
    2961     2709390 :             for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
    2962             :             {
    2963             :                 uint32      lockmask;
    2964             : 
    2965             :                 /* Look for an allocated slot matching the given relid. */
    2966     2550432 :                 if (relid != proc->fpRelId[f])
    2967     2548122 :                     continue;
    2968        2310 :                 lockmask = FAST_PATH_GET_BITS(proc, f);
    2969        2310 :                 if (!lockmask)
    2970        1860 :                     continue;
    2971         450 :                 lockmask <<= FAST_PATH_LOCKNUMBER_OFFSET;
    2972             : 
    2973             :                 /*
    2974             :                  * There can only be one entry per relation, so if we found it
    2975             :                  * and it doesn't conflict, we can skip the rest of the slots.
    2976             :                  */
    2977         450 :                 if ((lockmask & conflictMask) == 0)
    2978          10 :                     break;
    2979             : 
    2980             :                 /* Conflict! */
    2981         440 :                 GET_VXID_FROM_PGPROC(vxid, *proc);
    2982             : 
    2983         440 :                 if (VirtualTransactionIdIsValid(vxid))
    2984         440 :                     vxids[count++] = vxid;
    2985             :                 /* else, xact already committed or aborted */
    2986             : 
    2987             :                 /* No need to examine remaining slots. */
    2988         440 :                 break;
    2989             :             }
    2990             : 
    2991      159408 :             LWLockRelease(&proc->fpInfoLock);
    2992             :         }
    2993             :     }
    2994             : 
    2995             :     /* Remember how many fast-path conflicts we found. */
    2996        2544 :     fast_count = count;
    2997             : 
    2998             :     /*
    2999             :      * Look up the lock object matching the tag.
    3000             :      */
    3001        2544 :     LWLockAcquire(partitionLock, LW_SHARED);
    3002             : 
    3003        2544 :     lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
    3004             :                                                 locktag,
    3005             :                                                 hashcode,
    3006             :                                                 HASH_FIND,
    3007             :                                                 NULL);
    3008        2544 :     if (!lock)
    3009             :     {
    3010             :         /*
    3011             :          * If the lock object doesn't exist, there is nothing holding a lock
    3012             :          * on this lockable object.
    3013             :          */
    3014         140 :         LWLockRelease(partitionLock);
    3015         140 :         vxids[count].procNumber = INVALID_PROC_NUMBER;
    3016         140 :         vxids[count].localTransactionId = InvalidLocalTransactionId;
    3017         140 :         if (countp)
    3018           0 :             *countp = count;
    3019         140 :         return vxids;
    3020             :     }
    3021             : 
    3022             :     /*
    3023             :      * Examine each existing holder (or awaiter) of the lock.
    3024             :      */
    3025        4846 :     dlist_foreach(proclock_iter, &lock->procLocks)
    3026             :     {
    3027        2442 :         proclock = dlist_container(PROCLOCK, lockLink, proclock_iter.cur);
    3028             : 
    3029        2442 :         if (conflictMask & proclock->holdMask)
    3030             :         {
    3031        2434 :             PGPROC     *proc = proclock->tag.myProc;
    3032             : 
    3033             :             /* A backend never blocks itself */
    3034        2434 :             if (proc != MyProc)
    3035             :             {
    3036             :                 VirtualTransactionId vxid;
    3037             : 
    3038          38 :                 GET_VXID_FROM_PGPROC(vxid, *proc);
    3039             : 
    3040          38 :                 if (VirtualTransactionIdIsValid(vxid))
    3041             :                 {
    3042             :                     int         i;
    3043             : 
    3044             :                     /* Avoid duplicate entries. */
    3045          66 :                     for (i = 0; i < fast_count; ++i)
    3046          28 :                         if (VirtualTransactionIdEquals(vxids[i], vxid))
    3047           0 :                             break;
    3048          38 :                     if (i >= fast_count)
    3049          38 :                         vxids[count++] = vxid;
    3050             :                 }
    3051             :                 /* else, xact already committed or aborted */
    3052             :             }
    3053             :         }
    3054             :     }
    3055             : 
    3056        2404 :     LWLockRelease(partitionLock);
    3057             : 
    3058        2404 :     if (count > MaxBackends + max_prepared_xacts)    /* should never happen */
    3059           0 :         elog(PANIC, "too many conflicting locks found");
    3060             : 
    3061        2404 :     vxids[count].procNumber = INVALID_PROC_NUMBER;
    3062        2404 :     vxids[count].localTransactionId = InvalidLocalTransactionId;
    3063        2404 :     if (countp)
    3064        2398 :         *countp = count;
    3065        2404 :     return vxids;
    3066             : }
    3067             : 
    3068             : /*
    3069             :  * Find a lock in the shared lock table and release it.  It is the caller's
    3070             :  * responsibility to verify that this is a sane thing to do.  (For example, it
    3071             :  * would be bad to release a lock here if there might still be a LOCALLOCK
    3072             :  * object with pointers to it.)
    3073             :  *
    3074             :  * We currently use this in two situations: first, to release locks held by
    3075             :  * prepared transactions on commit (see lock_twophase_postcommit); and second,
    3076             :  * to release locks taken via the fast-path, transferred to the main hash
    3077             :  * table, and then released (see LockReleaseAll).
    3078             :  */
    3079             : static void
    3080        4298 : LockRefindAndRelease(LockMethod lockMethodTable, PGPROC *proc,
    3081             :                      LOCKTAG *locktag, LOCKMODE lockmode,
    3082             :                      bool decrement_strong_lock_count)
    3083             : {
    3084             :     LOCK       *lock;
    3085             :     PROCLOCK   *proclock;
    3086             :     PROCLOCKTAG proclocktag;
    3087             :     uint32      hashcode;
    3088             :     uint32      proclock_hashcode;
    3089             :     LWLock     *partitionLock;
    3090             :     bool        wakeupNeeded;
    3091             : 
    3092        4298 :     hashcode = LockTagHashCode(locktag);
    3093        4298 :     partitionLock = LockHashPartitionLock(hashcode);
    3094             : 
    3095        4298 :     LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    3096             : 
    3097             :     /*
    3098             :      * Re-find the lock object (it had better be there).
    3099             :      */
    3100        4298 :     lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
    3101             :                                                 locktag,
    3102             :                                                 hashcode,
    3103             :                                                 HASH_FIND,
    3104             :                                                 NULL);
    3105        4298 :     if (!lock)
    3106           0 :         elog(PANIC, "failed to re-find shared lock object");
    3107             : 
    3108             :     /*
    3109             :      * Re-find the proclock object (ditto).
    3110             :      */
    3111        4298 :     proclocktag.myLock = lock;
    3112        4298 :     proclocktag.myProc = proc;
    3113             : 
    3114        4298 :     proclock_hashcode = ProcLockHashCode(&proclocktag, hashcode);
    3115             : 
    3116        4298 :     proclock = (PROCLOCK *) hash_search_with_hash_value(LockMethodProcLockHash,
    3117             :                                                         &proclocktag,
    3118             :                                                         proclock_hashcode,
    3119             :                                                         HASH_FIND,
    3120             :                                                         NULL);
    3121        4298 :     if (!proclock)
    3122           0 :         elog(PANIC, "failed to re-find shared proclock object");
    3123             : 
    3124             :     /*
    3125             :      * Double-check that we are actually holding a lock of the type we want to
    3126             :      * release.
    3127             :      */
    3128        4298 :     if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
    3129             :     {
    3130             :         PROCLOCK_PRINT("lock_twophase_postcommit: WRONGTYPE", proclock);
    3131           0 :         LWLockRelease(partitionLock);
    3132           0 :         elog(WARNING, "you don't own a lock of type %s",
    3133             :              lockMethodTable->lockModeNames[lockmode]);
    3134           0 :         return;
    3135             :     }
    3136             : 
    3137             :     /*
    3138             :      * Do the releasing.  CleanUpLock will waken any now-wakable waiters.
    3139             :      */
    3140        4298 :     wakeupNeeded = UnGrantLock(lock, lockmode, proclock, lockMethodTable);
    3141             : 
    3142        4298 :     CleanUpLock(lock, proclock,
    3143             :                 lockMethodTable, hashcode,
    3144             :                 wakeupNeeded);
    3145             : 
    3146        4298 :     LWLockRelease(partitionLock);
    3147             : 
    3148             :     /*
    3149             :      * Decrement strong lock count.  This logic is needed only for 2PC.
    3150             :      */
    3151        4298 :     if (decrement_strong_lock_count
    3152        1748 :         && ConflictsWithRelationFastPath(locktag, lockmode))
    3153             :     {
    3154         128 :         uint32      fasthashcode = FastPathStrongLockHashPartition(hashcode);
    3155             : 
    3156         128 :         SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
    3157             :         Assert(FastPathStrongRelationLocks->count[fasthashcode] > 0);
    3158         128 :         FastPathStrongRelationLocks->count[fasthashcode]--;
    3159         128 :         SpinLockRelease(&FastPathStrongRelationLocks->mutex);
    3160             :     }
    3161             : }
    3162             : 
    3163             : /*
    3164             :  * CheckForSessionAndXactLocks
    3165             :  *      Check to see if transaction holds both session-level and xact-level
    3166             :  *      locks on the same object; if so, throw an error.
    3167             :  *
    3168             :  * If we have both session- and transaction-level locks on the same object,
    3169             :  * PREPARE TRANSACTION must fail.  This should never happen with regular
    3170             :  * locks, since we only take those at session level in some special operations
    3171             :  * like VACUUM.  It's possible to hit this with advisory locks, though.
    3172             :  *
    3173             :  * It would be nice if we could keep the session hold and give away the
    3174             :  * transactional hold to the prepared xact.  However, that would require two
    3175             :  * PROCLOCK objects, and we cannot be sure that another PROCLOCK will be
    3176             :  * available when it comes time for PostPrepare_Locks to do the deed.
    3177             :  * So for now, we error out while we can still do so safely.
    3178             :  *
    3179             :  * Since the LOCALLOCK table stores a separate entry for each lockmode,
    3180             :  * we can't implement this check by examining LOCALLOCK entries in isolation.
    3181             :  * We must build a transient hashtable that is indexed by locktag only.
    3182             :  */
    3183             : static void
    3184         758 : CheckForSessionAndXactLocks(void)
    3185             : {
    3186             :     typedef struct
    3187             :     {
    3188             :         LOCKTAG     lock;       /* identifies the lockable object */
    3189             :         bool        sessLock;   /* is any lockmode held at session level? */
    3190             :         bool        xactLock;   /* is any lockmode held at xact level? */
    3191             :     } PerLockTagEntry;
    3192             : 
    3193             :     HASHCTL     hash_ctl;
    3194             :     HTAB       *lockhtab;
    3195             :     HASH_SEQ_STATUS status;
    3196             :     LOCALLOCK  *locallock;
    3197             : 
    3198             :     /* Create a local hash table keyed by LOCKTAG only */
    3199         758 :     hash_ctl.keysize = sizeof(LOCKTAG);
    3200         758 :     hash_ctl.entrysize = sizeof(PerLockTagEntry);
    3201         758 :     hash_ctl.hcxt = CurrentMemoryContext;
    3202             : 
    3203         758 :     lockhtab = hash_create("CheckForSessionAndXactLocks table",
    3204             :                            256, /* arbitrary initial size */
    3205             :                            &hash_ctl,
    3206             :                            HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
    3207             : 
    3208             :     /* Scan local lock table to find entries for each LOCKTAG */
    3209         758 :     hash_seq_init(&status, LockMethodLocalHash);
    3210             : 
    3211        2522 :     while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    3212             :     {
    3213        1768 :         LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
    3214             :         PerLockTagEntry *hentry;
    3215             :         bool        found;
    3216             :         int         i;
    3217             : 
    3218             :         /*
    3219             :          * Ignore VXID locks.  We don't want those to be held by prepared
    3220             :          * transactions, since they aren't meaningful after a restart.
    3221             :          */
    3222        1768 :         if (locallock->tag.lock.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
    3223           0 :             continue;
    3224             : 
    3225             :         /* Ignore it if we don't actually hold the lock */
    3226        1768 :         if (locallock->nLocks <= 0)
    3227           0 :             continue;
    3228             : 
    3229             :         /* Otherwise, find or make an entry in lockhtab */
    3230        1768 :         hentry = (PerLockTagEntry *) hash_search(lockhtab,
    3231        1768 :                                                  &locallock->tag.lock,
    3232             :                                                  HASH_ENTER, &found);
    3233        1768 :         if (!found)             /* initialize, if newly created */
    3234        1676 :             hentry->sessLock = hentry->xactLock = false;
    3235             : 
    3236             :         /* Scan to see if we hold lock at session or xact level or both */
    3237        3536 :         for (i = locallock->numLockOwners - 1; i >= 0; i--)
    3238             :         {
    3239        1768 :             if (lockOwners[i].owner == NULL)
    3240          18 :                 hentry->sessLock = true;
    3241             :             else
    3242        1750 :                 hentry->xactLock = true;
    3243             :         }
    3244             : 
    3245             :         /*
    3246             :          * We can throw error immediately when we see both types of locks; no
    3247             :          * need to wait around to see if there are more violations.
    3248             :          */
    3249        1768 :         if (hentry->sessLock && hentry->xactLock)
    3250           4 :             ereport(ERROR,
    3251             :                     (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
    3252             :                      errmsg("cannot PREPARE while holding both session-level and transaction-level locks on the same object")));
    3253             :     }
    3254             : 
    3255             :     /* Success, so clean up */
    3256         754 :     hash_destroy(lockhtab);
    3257         754 : }
    3258             : 
    3259             : /*
    3260             :  * AtPrepare_Locks
    3261             :  *      Do the preparatory work for a PREPARE: make 2PC state file records
    3262             :  *      for all locks currently held.
    3263             :  *
    3264             :  * Session-level locks are ignored, as are VXID locks.
    3265             :  *
    3266             :  * For the most part, we don't need to touch shared memory for this ---
    3267             :  * all the necessary state information is in the locallock table.
    3268             :  * Fast-path locks are an exception, however: we move any such locks to
    3269             :  * the main table before allowing PREPARE TRANSACTION to succeed.
    3270             :  */
    3271             : void
    3272         758 : AtPrepare_Locks(void)
    3273             : {
    3274             :     HASH_SEQ_STATUS status;
    3275             :     LOCALLOCK  *locallock;
    3276             : 
    3277             :     /* First, verify there aren't locks of both xact and session level */
    3278         758 :     CheckForSessionAndXactLocks();
    3279             : 
    3280             :     /* Now do the per-locallock cleanup work */
    3281         754 :     hash_seq_init(&status, LockMethodLocalHash);
    3282             : 
    3283        2510 :     while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    3284             :     {
    3285             :         TwoPhaseLockRecord record;
    3286        1756 :         LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
    3287             :         bool        haveSessionLock;
    3288             :         bool        haveXactLock;
    3289             :         int         i;
    3290             : 
    3291             :         /*
    3292             :          * Ignore VXID locks.  We don't want those to be held by prepared
    3293             :          * transactions, since they aren't meaningful after a restart.
    3294             :          */
    3295        1756 :         if (locallock->tag.lock.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
    3296          14 :             continue;
    3297             : 
    3298             :         /* Ignore it if we don't actually hold the lock */
    3299        1756 :         if (locallock->nLocks <= 0)
    3300           0 :             continue;
    3301             : 
    3302             :         /* Scan to see whether we hold it at session or transaction level */
    3303        1756 :         haveSessionLock = haveXactLock = false;
    3304        3512 :         for (i = locallock->numLockOwners - 1; i >= 0; i--)
    3305             :         {
    3306        1756 :             if (lockOwners[i].owner == NULL)
    3307          14 :                 haveSessionLock = true;
    3308             :             else
    3309        1742 :                 haveXactLock = true;
    3310             :         }
    3311             : 
    3312             :         /* Ignore it if we have only session lock */
    3313        1756 :         if (!haveXactLock)
    3314          14 :             continue;
    3315             : 
    3316             :         /* This can't happen, because we already checked it */
    3317        1742 :         if (haveSessionLock)
    3318           0 :             ereport(ERROR,
    3319             :                     (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
    3320             :                      errmsg("cannot PREPARE while holding both session-level and transaction-level locks on the same object")));
    3321             : 
    3322             :         /*
    3323             :          * If the local lock was taken via the fast-path, we need to move it
    3324             :          * to the primary lock table, or just get a pointer to the existing
    3325             :          * primary lock table entry if by chance it's already been
    3326             :          * transferred.
    3327             :          */
    3328        1742 :         if (locallock->proclock == NULL)
    3329             :         {
    3330         772 :             locallock->proclock = FastPathGetRelationLockEntry(locallock);
    3331         772 :             locallock->lock = locallock->proclock->tag.myLock;
    3332             :         }
    3333             : 
    3334             :         /*
    3335             :          * Arrange to not release any strong lock count held by this lock
    3336             :          * entry.  We must retain the count until the prepared transaction is
    3337             :          * committed or rolled back.
    3338             :          */
    3339        1742 :         locallock->holdsStrongLockCount = false;
    3340             : 
    3341             :         /*
    3342             :          * Create a 2PC record.
    3343             :          */
    3344        1742 :         memcpy(&(record.locktag), &(locallock->tag.lock), sizeof(LOCKTAG));
    3345        1742 :         record.lockmode = locallock->tag.mode;
    3346             : 
    3347        1742 :         RegisterTwoPhaseRecord(TWOPHASE_RM_LOCK_ID, 0,
    3348             :                                &record, sizeof(TwoPhaseLockRecord));
    3349             :     }
    3350         754 : }
    3351             : 
    3352             : /*
    3353             :  * PostPrepare_Locks
    3354             :  *      Clean up after successful PREPARE
    3355             :  *
    3356             :  * Here, we want to transfer ownership of our locks to a dummy PGPROC
    3357             :  * that's now associated with the prepared transaction, and we want to
    3358             :  * clean out the corresponding entries in the LOCALLOCK table.
    3359             :  *
    3360             :  * Note: by removing the LOCALLOCK entries, we are leaving dangling
    3361             :  * pointers in the transaction's resource owner.  This is OK at the
    3362             :  * moment since resowner.c doesn't try to free locks retail at a toplevel
    3363             :  * transaction commit or abort.  We could alternatively zero out nLocks
    3364             :  * and leave the LOCALLOCK entries to be garbage-collected by LockReleaseAll,
    3365             :  * but that probably costs more cycles.
    3366             :  */
    3367             : void
    3368         754 : PostPrepare_Locks(TransactionId xid)
    3369             : {
    3370         754 :     PGPROC     *newproc = TwoPhaseGetDummyProc(xid, false);
    3371             :     HASH_SEQ_STATUS status;
    3372             :     LOCALLOCK  *locallock;
    3373             :     LOCK       *lock;
    3374             :     PROCLOCK   *proclock;
    3375             :     PROCLOCKTAG proclocktag;
    3376             :     int         partition;
    3377             : 
    3378             :     /* Can't prepare a lock group follower. */
    3379             :     Assert(MyProc->lockGroupLeader == NULL ||
    3380             :            MyProc->lockGroupLeader == MyProc);
    3381             : 
    3382             :     /* This is a critical section: any error means big trouble */
    3383         754 :     START_CRIT_SECTION();
    3384             : 
    3385             :     /*
    3386             :      * First we run through the locallock table and get rid of unwanted
    3387             :      * entries, then we scan the process's proclocks and transfer them to the
    3388             :      * target proc.
    3389             :      *
    3390             :      * We do this separately because we may have multiple locallock entries
    3391             :      * pointing to the same proclock, and we daren't end up with any dangling
    3392             :      * pointers.
    3393             :      */
    3394         754 :     hash_seq_init(&status, LockMethodLocalHash);
    3395             : 
    3396        2510 :     while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    3397             :     {
    3398        1756 :         LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
    3399             :         bool        haveSessionLock;
    3400             :         bool        haveXactLock;
    3401             :         int         i;
    3402             : 
    3403        1756 :         if (locallock->proclock == NULL || locallock->lock == NULL)
    3404             :         {
    3405             :             /*
    3406             :              * We must've run out of shared memory while trying to set up this
    3407             :              * lock.  Just forget the local entry.
    3408             :              */
    3409             :             Assert(locallock->nLocks == 0);
    3410           0 :             RemoveLocalLock(locallock);
    3411           0 :             continue;
    3412             :         }
    3413             : 
    3414             :         /* Ignore VXID locks */
    3415        1756 :         if (locallock->tag.lock.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
    3416           0 :             continue;
    3417             : 
    3418             :         /* Scan to see whether we hold it at session or transaction level */
    3419        1756 :         haveSessionLock = haveXactLock = false;
    3420        3512 :         for (i = locallock->numLockOwners - 1; i >= 0; i--)
    3421             :         {
    3422        1756 :             if (lockOwners[i].owner == NULL)
    3423          14 :                 haveSessionLock = true;
    3424             :             else
    3425        1742 :                 haveXactLock = true;
    3426             :         }
    3427             : 
    3428             :         /* Ignore it if we have only session lock */
    3429        1756 :         if (!haveXactLock)
    3430          14 :             continue;
    3431             : 
    3432             :         /* This can't happen, because we already checked it */
    3433        1742 :         if (haveSessionLock)
    3434           0 :             ereport(PANIC,
    3435             :                     (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
    3436             :                      errmsg("cannot PREPARE while holding both session-level and transaction-level locks on the same object")));
    3437             : 
    3438             :         /* Mark the proclock to show we need to release this lockmode */
    3439        1742 :         if (locallock->nLocks > 0)
    3440        1742 :             locallock->proclock->releaseMask |= LOCKBIT_ON(locallock->tag.mode);
    3441             : 
    3442             :         /* And remove the locallock hashtable entry */
    3443        1742 :         RemoveLocalLock(locallock);
    3444             :     }
    3445             : 
    3446             :     /*
    3447             :      * Now, scan each lock partition separately.
    3448             :      */
    3449       12818 :     for (partition = 0; partition < NUM_LOCK_PARTITIONS; partition++)
    3450             :     {
    3451             :         LWLock     *partitionLock;
    3452       12064 :         dlist_head *procLocks = &(MyProc->myProcLocks[partition]);
    3453             :         dlist_mutable_iter proclock_iter;
    3454             : 
    3455       12064 :         partitionLock = LockHashPartitionLockByIndex(partition);
    3456             : 
    3457             :         /*
    3458             :          * If the proclock list for this partition is empty, we can skip
    3459             :          * acquiring the partition lock.  This optimization is safer than the
    3460             :          * situation in LockReleaseAll, because we got rid of any fast-path
    3461             :          * locks during AtPrepare_Locks, so there cannot be any case where
    3462             :          * another backend is adding something to our lists now.  For safety,
    3463             :          * though, we code this the same way as in LockReleaseAll.
    3464             :          */
    3465       12064 :         if (dlist_is_empty(procLocks))
    3466       10382 :             continue;           /* needn't examine this partition */
    3467             : 
    3468        1682 :         LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    3469             : 
    3470        3442 :         dlist_foreach_modify(proclock_iter, procLocks)
    3471             :         {
    3472        1760 :             proclock = dlist_container(PROCLOCK, procLink, proclock_iter.cur);
    3473             : 
    3474             :             Assert(proclock->tag.myProc == MyProc);
    3475             : 
    3476        1760 :             lock = proclock->tag.myLock;
    3477             : 
    3478             :             /* Ignore VXID locks */
    3479        1760 :             if (lock->tag.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
    3480          92 :                 continue;
    3481             : 
    3482             :             PROCLOCK_PRINT("PostPrepare_Locks", proclock);
    3483             :             LOCK_PRINT("PostPrepare_Locks", lock, 0);
    3484             :             Assert(lock->nRequested >= 0);
    3485             :             Assert(lock->nGranted >= 0);
    3486             :             Assert(lock->nGranted <= lock->nRequested);
    3487             :             Assert((proclock->holdMask & ~lock->grantMask) == 0);
    3488             : 
    3489             :             /* Ignore it if nothing to release (must be a session lock) */
    3490        1668 :             if (proclock->releaseMask == 0)
    3491          14 :                 continue;
    3492             : 
    3493             :             /* Else we should be releasing all locks */
    3494        1654 :             if (proclock->releaseMask != proclock->holdMask)
    3495           0 :                 elog(PANIC, "we seem to have dropped a bit somewhere");
    3496             : 
    3497             :             /*
    3498             :              * We cannot simply modify proclock->tag.myProc to reassign
    3499             :              * ownership of the lock, because that's part of the hash key and
    3500             :              * the proclock would then be in the wrong hash chain.  Instead
    3501             :              * use hash_update_hash_key.  (We used to create a new hash entry,
    3502             :              * but that risks out-of-memory failure if other processes are
    3503             :              * busy making proclocks too.)  We must unlink the proclock from
    3504             :              * our procLink chain and put it into the new proc's chain, too.
    3505             :              *
    3506             :              * Note: the updated proclock hash key will still belong to the
    3507             :              * same hash partition, cf proclock_hash().  So the partition lock
    3508             :              * we already hold is sufficient for this.
    3509             :              */
    3510        1654 :             dlist_delete(&proclock->procLink);
    3511             : 
    3512             :             /*
    3513             :              * Create the new hash key for the proclock.
    3514             :              */
    3515        1654 :             proclocktag.myLock = lock;
    3516        1654 :             proclocktag.myProc = newproc;
    3517             : 
    3518             :             /*
    3519             :              * Update groupLeader pointer to point to the new proc.  (We'd
    3520             :              * better not be a member of somebody else's lock group!)
    3521             :              */
    3522             :             Assert(proclock->groupLeader == proclock->tag.myProc);
    3523        1654 :             proclock->groupLeader = newproc;
    3524             : 
    3525             :             /*
    3526             :              * Update the proclock.  We should not find any existing entry for
    3527             :              * the same hash key, since there can be only one entry for any
    3528             :              * given lock with my own proc.
    3529             :              */
    3530        1654 :             if (!hash_update_hash_key(LockMethodProcLockHash,
    3531             :                                       proclock,
    3532             :                                       &proclocktag))
    3533           0 :                 elog(PANIC, "duplicate entry found while reassigning a prepared transaction's locks");
    3534             : 
    3535             :             /* Re-link into the new proc's proclock list */
    3536        1654 :             dlist_push_tail(&newproc->myProcLocks[partition], &proclock->procLink);
    3537             : 
    3538             :             PROCLOCK_PRINT("PostPrepare_Locks: updated", proclock);
    3539             :         }                       /* loop over PROCLOCKs within this partition */
    3540             : 
    3541        1682 :         LWLockRelease(partitionLock);
    3542             :     }                           /* loop over partitions */
    3543             : 
    3544         754 :     END_CRIT_SECTION();
    3545         754 : }
    3546             : 
    3547             : 
    3548             : /*
    3549             :  * Estimate shared-memory space used for lock tables
    3550             :  */
    3551             : Size
    3552        3298 : LockShmemSize(void)
    3553             : {
    3554        3298 :     Size        size = 0;
    3555             :     long        max_table_size;
    3556             : 
    3557             :     /* lock hash table */
    3558        3298 :     max_table_size = NLOCKENTS();
    3559        3298 :     size = add_size(size, hash_estimate_size(max_table_size, sizeof(LOCK)));
    3560             : 
    3561             :     /* proclock hash table */
    3562        3298 :     max_table_size *= 2;
    3563        3298 :     size = add_size(size, hash_estimate_size(max_table_size, sizeof(PROCLOCK)));
    3564             : 
    3565             :     /*
    3566             :      * Since NLOCKENTS is only an estimate, add 10% safety margin.
    3567             :      */
    3568        3298 :     size = add_size(size, size / 10);
    3569             : 
    3570        3298 :     return size;
    3571             : }
    3572             : 
    3573             : /*
    3574             :  * GetLockStatusData - Return a summary of the lock manager's internal
    3575             :  * status, for use in a user-level reporting function.
    3576             :  *
    3577             :  * The return data consists of an array of LockInstanceData objects,
    3578             :  * which are a lightly abstracted version of the PROCLOCK data structures,
    3579             :  * i.e. there is one entry for each unique lock and interested PGPROC.
    3580             :  * It is the caller's responsibility to match up related items (such as
    3581             :  * references to the same lockable object or PGPROC) if wanted.
    3582             :  *
    3583             :  * The design goal is to hold the LWLocks for as short a time as possible;
    3584             :  * thus, this function simply makes a copy of the necessary data and releases
    3585             :  * the locks, allowing the caller to contemplate and format the data for as
    3586             :  * long as it pleases.
    3587             :  */
    3588             : LockData *
    3589         422 : GetLockStatusData(void)
    3590             : {
    3591             :     LockData   *data;
    3592             :     PROCLOCK   *proclock;
    3593             :     HASH_SEQ_STATUS seqstat;
    3594             :     int         els;
    3595             :     int         el;
    3596             :     int         i;
    3597             : 
    3598         422 :     data = (LockData *) palloc(sizeof(LockData));
    3599             : 
    3600             :     /* Guess how much space we'll need. */
    3601         422 :     els = MaxBackends;
    3602         422 :     el = 0;
    3603         422 :     data->locks = (LockInstanceData *) palloc(sizeof(LockInstanceData) * els);
    3604             : 
    3605             :     /*
    3606             :      * First, we iterate through the per-backend fast-path arrays, locking
    3607             :      * them one at a time.  This might produce an inconsistent picture of the
    3608             :      * system state, but taking all of those LWLocks at the same time seems
    3609             :      * impractical (in particular, note MAX_SIMUL_LWLOCKS).  It shouldn't
    3610             :      * matter too much, because none of these locks can be involved in lock
    3611             :      * conflicts anyway - anything that might must be present in the main lock
    3612             :      * table.  (For the same reason, we don't sweat about making leaderPid
    3613             :      * completely valid.  We cannot safely dereference another backend's
    3614             :      * lockGroupLeader field without holding all lock partition locks, and
    3615             :      * it's not worth that.)
    3616             :      */
    3617       43218 :     for (i = 0; i < ProcGlobal->allProcCount; ++i)
    3618             :     {
    3619       42796 :         PGPROC     *proc = &ProcGlobal->allProcs[i];
    3620             :         uint32      f;
    3621             : 
    3622       42796 :         LWLockAcquire(&proc->fpInfoLock, LW_SHARED);
    3623             : 
    3624      727532 :         for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; ++f)
    3625             :         {
    3626             :             LockInstanceData *instance;
    3627      684736 :             uint32      lockbits = FAST_PATH_GET_BITS(proc, f);
    3628             : 
    3629             :             /* Skip unallocated slots. */
    3630      684736 :             if (!lockbits)
    3631      680112 :                 continue;
    3632             : 
    3633        4624 :             if (el >= els)
    3634             :             {
    3635           4 :                 els += MaxBackends;
    3636           4 :                 data->locks = (LockInstanceData *)
    3637           4 :                     repalloc(data->locks, sizeof(LockInstanceData) * els);
    3638             :             }
    3639             : 
    3640        4624 :             instance = &data->locks[el];
    3641        4624 :             SET_LOCKTAG_RELATION(instance->locktag, proc->databaseId,
    3642             :                                  proc->fpRelId[f]);
    3643        4624 :             instance->holdMask = lockbits << FAST_PATH_LOCKNUMBER_OFFSET;
    3644        4624 :             instance->waitLockMode = NoLock;
    3645        4624 :             instance->vxid.procNumber = proc->vxid.procNumber;
    3646        4624 :             instance->vxid.localTransactionId = proc->vxid.lxid;
    3647        4624 :             instance->pid = proc->pid;
    3648        4624 :             instance->leaderPid = proc->pid;
    3649        4624 :             instance->fastpath = true;
    3650             : 
    3651             :             /*
    3652             :              * Successfully taking fast path lock means there were no
    3653             :              * conflicting locks.
    3654             :              */
    3655        4624 :             instance->waitStart = 0;
    3656             : 
    3657        4624 :             el++;
    3658             :         }
    3659             : 
    3660       42796 :         if (proc->fpVXIDLock)
    3661             :         {
    3662             :             VirtualTransactionId vxid;
    3663             :             LockInstanceData *instance;
    3664             : 
    3665        1366 :             if (el >= els)
    3666             :             {
    3667           0 :                 els += MaxBackends;
    3668           0 :                 data->locks = (LockInstanceData *)
    3669           0 :                     repalloc(data->locks, sizeof(LockInstanceData) * els);
    3670             :             }
    3671             : 
    3672        1366 :             vxid.procNumber = proc->vxid.procNumber;
    3673        1366 :             vxid.localTransactionId = proc->fpLocalTransactionId;
    3674             : 
    3675        1366 :             instance = &data->locks[el];
    3676        1366 :             SET_LOCKTAG_VIRTUALTRANSACTION(instance->locktag, vxid);
    3677        1366 :             instance->holdMask = LOCKBIT_ON(ExclusiveLock);
    3678        1366 :             instance->waitLockMode = NoLock;
    3679        1366 :             instance->vxid.procNumber = proc->vxid.procNumber;
    3680        1366 :             instance->vxid.localTransactionId = proc->vxid.lxid;
    3681        1366 :             instance->pid = proc->pid;
    3682        1366 :             instance->leaderPid = proc->pid;
    3683        1366 :             instance->fastpath = true;
    3684        1366 :             instance->waitStart = 0;
    3685             : 
    3686        1366 :             el++;
    3687             :         }
    3688             : 
    3689       42796 :         LWLockRelease(&proc->fpInfoLock);
    3690             :     }
    3691             : 
    3692             :     /*
    3693             :      * Next, acquire lock on the entire shared lock data structure.  We do
    3694             :      * this so that, at least for locks in the primary lock table, the state
    3695             :      * will be self-consistent.
    3696             :      *
    3697             :      * Since this is a read-only operation, we take shared instead of
    3698             :      * exclusive lock.  There's not a whole lot of point to this, because all
    3699             :      * the normal operations require exclusive lock, but it doesn't hurt
    3700             :      * anything either. It will at least allow two backends to do
    3701             :      * GetLockStatusData in parallel.
    3702             :      *
    3703             :      * Must grab LWLocks in partition-number order to avoid LWLock deadlock.
    3704             :      */
    3705        7174 :     for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
    3706        6752 :         LWLockAcquire(LockHashPartitionLockByIndex(i), LW_SHARED);
    3707             : 
    3708             :     /* Now we can safely count the number of proclocks */
    3709         422 :     data->nelements = el + hash_get_num_entries(LockMethodProcLockHash);
    3710         422 :     if (data->nelements > els)
    3711             :     {
    3712          18 :         els = data->nelements;
    3713          18 :         data->locks = (LockInstanceData *)
    3714          18 :             repalloc(data->locks, sizeof(LockInstanceData) * els);
    3715             :     }
    3716             : 
    3717             :     /* Now scan the tables to copy the data */
    3718         422 :     hash_seq_init(&seqstat, LockMethodProcLockHash);
    3719             : 
    3720        2892 :     while ((proclock = (PROCLOCK *) hash_seq_search(&seqstat)))
    3721             :     {
    3722        2470 :         PGPROC     *proc = proclock->tag.myProc;
    3723        2470 :         LOCK       *lock = proclock->tag.myLock;
    3724        2470 :         LockInstanceData *instance = &data->locks[el];
    3725             : 
    3726        2470 :         memcpy(&instance->locktag, &lock->tag, sizeof(LOCKTAG));
    3727        2470 :         instance->holdMask = proclock->holdMask;
    3728        2470 :         if (proc->waitLock == proclock->tag.myLock)
    3729          18 :             instance->waitLockMode = proc->waitLockMode;
    3730             :         else
    3731        2452 :             instance->waitLockMode = NoLock;
    3732        2470 :         instance->vxid.procNumber = proc->vxid.procNumber;
    3733        2470 :         instance->vxid.localTransactionId = proc->vxid.lxid;
    3734        2470 :         instance->pid = proc->pid;
    3735        2470 :         instance->leaderPid = proclock->groupLeader->pid;
    3736        2470 :         instance->fastpath = false;
    3737        2470 :         instance->waitStart = (TimestampTz) pg_atomic_read_u64(&proc->waitStart);
    3738             : 
    3739        2470 :         el++;
    3740             :     }
    3741             : 
    3742             :     /*
    3743             :      * And release locks.  We do this in reverse order for two reasons: (1)
    3744             :      * Anyone else who needs more than one of the locks will be trying to lock
    3745             :      * them in increasing order; we don't want to release the other process
    3746             :      * until it can get all the locks it needs. (2) This avoids O(N^2)
    3747             :      * behavior inside LWLockRelease.
    3748             :      */
    3749        7174 :     for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
    3750        6752 :         LWLockRelease(LockHashPartitionLockByIndex(i));
    3751             : 
    3752             :     Assert(el == data->nelements);
    3753             : 
    3754         422 :     return data;
    3755             : }
    3756             : 
    3757             : /*
    3758             :  * GetBlockerStatusData - Return a summary of the lock manager's state
    3759             :  * concerning locks that are blocking the specified PID or any member of
    3760             :  * the PID's lock group, for use in a user-level reporting function.
    3761             :  *
    3762             :  * For each PID within the lock group that is awaiting some heavyweight lock,
    3763             :  * the return data includes an array of LockInstanceData objects, which are
    3764             :  * the same data structure used by GetLockStatusData; but unlike that function,
    3765             :  * this one reports only the PROCLOCKs associated with the lock that that PID
    3766             :  * is blocked on.  (Hence, all the locktags should be the same for any one
    3767             :  * blocked PID.)  In addition, we return an array of the PIDs of those backends
    3768             :  * that are ahead of the blocked PID in the lock's wait queue.  These can be
    3769             :  * compared with the PIDs in the LockInstanceData objects to determine which
    3770             :  * waiters are ahead of or behind the blocked PID in the queue.
    3771             :  *
    3772             :  * If blocked_pid isn't a valid backend PID or nothing in its lock group is
    3773             :  * waiting on any heavyweight lock, return empty arrays.
    3774             :  *
    3775             :  * The design goal is to hold the LWLocks for as short a time as possible;
    3776             :  * thus, this function simply makes a copy of the necessary data and releases
    3777             :  * the locks, allowing the caller to contemplate and format the data for as
    3778             :  * long as it pleases.
    3779             :  */
    3780             : BlockedProcsData *
    3781        3048 : GetBlockerStatusData(int blocked_pid)
    3782             : {
    3783             :     BlockedProcsData *data;
    3784             :     PGPROC     *proc;
    3785             :     int         i;
    3786             : 
    3787        3048 :     data = (BlockedProcsData *) palloc(sizeof(BlockedProcsData));
    3788             : 
    3789             :     /*
    3790             :      * Guess how much space we'll need, and preallocate.  Most of the time
    3791             :      * this will avoid needing to do repalloc while holding the LWLocks.  (We
    3792             :      * assume, but check with an Assert, that MaxBackends is enough entries
    3793             :      * for the procs[] array; the other two could need enlargement, though.)
    3794             :      */
    3795        3048 :     data->nprocs = data->nlocks = data->npids = 0;
    3796        3048 :     data->maxprocs = data->maxlocks = data->maxpids = MaxBackends;
    3797        3048 :     data->procs = (BlockedProcData *) palloc(sizeof(BlockedProcData) * data->maxprocs);
    3798        3048 :     data->locks = (LockInstanceData *) palloc(sizeof(LockInstanceData) * data->maxlocks);
    3799        3048 :     data->waiter_pids = (int *) palloc(sizeof(int) * data->maxpids);
    3800             : 
    3801             :     /*
    3802             :      * In order to search the ProcArray for blocked_pid and assume that that
    3803             :      * entry won't immediately disappear under us, we must hold ProcArrayLock.
    3804             :      * In addition, to examine the lock grouping fields of any other backend,
    3805             :      * we must hold all the hash partition locks.  (Only one of those locks is
    3806             :      * actually relevant for any one lock group, but we can't know which one
    3807             :      * ahead of time.)  It's fairly annoying to hold all those locks
    3808             :      * throughout this, but it's no worse than GetLockStatusData(), and it
    3809             :      * does have the advantage that we're guaranteed to return a
    3810             :      * self-consistent instantaneous state.
    3811             :      */
    3812        3048 :     LWLockAcquire(ProcArrayLock, LW_SHARED);
    3813             : 
    3814        3048 :     proc = BackendPidGetProcWithLock(blocked_pid);
    3815             : 
    3816             :     /* Nothing to do if it's gone */
    3817        3048 :     if (proc != NULL)
    3818             :     {
    3819             :         /*
    3820             :          * Acquire lock on the entire shared lock data structure.  See notes
    3821             :          * in GetLockStatusData().
    3822             :          */
    3823       51816 :         for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
    3824       48768 :             LWLockAcquire(LockHashPartitionLockByIndex(i), LW_SHARED);
    3825             : 
    3826        3048 :         if (proc->lockGroupLeader == NULL)
    3827             :         {
    3828             :             /* Easy case, proc is not a lock group member */
    3829        2644 :             GetSingleProcBlockerStatusData(proc, data);
    3830             :         }
    3831             :         else
    3832             :         {
    3833             :             /* Examine all procs in proc's lock group */
    3834             :             dlist_iter  iter;
    3835             : 
    3836         910 :             dlist_foreach(iter, &proc->lockGroupLeader->lockGroupMembers)
    3837             :             {
    3838             :                 PGPROC     *memberProc;
    3839             : 
    3840         506 :                 memberProc = dlist_container(PGPROC, lockGroupLink, iter.cur);
    3841         506 :                 GetSingleProcBlockerStatusData(memberProc, data);
    3842             :             }
    3843             :         }
    3844             : 
    3845             :         /*
    3846             :          * And release locks.  See notes in GetLockStatusData().
    3847             :          */
    3848       51816 :         for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
    3849       48768 :             LWLockRelease(LockHashPartitionLockByIndex(i));
    3850             : 
    3851             :         Assert(data->nprocs <= data->maxprocs);
    3852             :     }
    3853             : 
    3854        3048 :     LWLockRelease(ProcArrayLock);
    3855             : 
    3856        3048 :     return data;
    3857             : }
    3858             : 
    3859             : /* Accumulate data about one possibly-blocked proc for GetBlockerStatusData */
    3860             : static void
    3861        3150 : GetSingleProcBlockerStatusData(PGPROC *blocked_proc, BlockedProcsData *data)
    3862             : {
    3863        3150 :     LOCK       *theLock = blocked_proc->waitLock;
    3864             :     BlockedProcData *bproc;
    3865             :     dlist_iter  proclock_iter;
    3866             :     dlist_iter  proc_iter;
    3867             :     dclist_head *waitQueue;
    3868             :     int         queue_size;
    3869             : 
    3870             :     /* Nothing to do if this proc is not blocked */
    3871        3150 :     if (theLock == NULL)
    3872         952 :         return;
    3873             : 
    3874             :     /* Set up a procs[] element */
    3875        2198 :     bproc = &data->procs[data->nprocs++];
    3876        2198 :     bproc->pid = blocked_proc->pid;
    3877        2198 :     bproc->first_lock = data->nlocks;
    3878        2198 :     bproc->first_waiter = data->npids;
    3879             : 
    3880             :     /*
    3881             :      * We may ignore the proc's fast-path arrays, since nothing in those could
    3882             :      * be related to a contended lock.
    3883             :      */
    3884             : 
    3885             :     /* Collect all PROCLOCKs associated with theLock */
    3886        6682 :     dlist_foreach(proclock_iter, &theLock->procLocks)
    3887             :     {
    3888        4484 :         PROCLOCK   *proclock =
    3889        4484 :             dlist_container(PROCLOCK, lockLink, proclock_iter.cur);
    3890        4484 :         PGPROC     *proc = proclock->tag.myProc;
    3891        4484 :         LOCK       *lock = proclock->tag.myLock;
    3892             :         LockInstanceData *instance;
    3893             : 
    3894        4484 :         if (data->nlocks >= data->maxlocks)
    3895             :         {
    3896           0 :             data->maxlocks += MaxBackends;
    3897           0 :             data->locks = (LockInstanceData *)
    3898           0 :                 repalloc(data->locks, sizeof(LockInstanceData) * data->maxlocks);
    3899             :         }
    3900             : 
    3901        4484 :         instance = &data->locks[data->nlocks];
    3902        4484 :         memcpy(&instance->locktag, &lock->tag, sizeof(LOCKTAG));
    3903        4484 :         instance->holdMask = proclock->holdMask;
    3904        4484 :         if (proc->waitLock == lock)
    3905        2270 :             instance->waitLockMode = proc->waitLockMode;
    3906             :         else
    3907        2214 :             instance->waitLockMode = NoLock;
    3908        4484 :         instance->vxid.procNumber = proc->vxid.procNumber;
    3909        4484 :         instance->vxid.localTransactionId = proc->vxid.lxid;
    3910        4484 :         instance->pid = proc->pid;
    3911        4484 :         instance->leaderPid = proclock->groupLeader->pid;
    3912        4484 :         instance->fastpath = false;
    3913        4484 :         data->nlocks++;
    3914             :     }
    3915             : 
    3916             :     /* Enlarge waiter_pids[] if it's too small to hold all wait queue PIDs */
    3917        2198 :     waitQueue = &(theLock->waitProcs);
    3918        2198 :     queue_size = dclist_count(waitQueue);
    3919             : 
    3920        2198 :     if (queue_size > data->maxpids - data->npids)
    3921             :     {
    3922           0 :         data->maxpids = Max(data->maxpids + MaxBackends,
    3923             :                             data->npids + queue_size);
    3924           0 :         data->waiter_pids = (int *) repalloc(data->waiter_pids,
    3925           0 :                                              sizeof(int) * data->maxpids);
    3926             :     }
    3927             : 
    3928             :     /* Collect PIDs from the lock's wait queue, stopping at blocked_proc */
    3929        2234 :     dclist_foreach(proc_iter, waitQueue)
    3930             :     {
    3931        2234 :         PGPROC     *queued_proc = dlist_container(PGPROC, links, proc_iter.cur);
    3932             : 
    3933        2234 :         if (queued_proc == blocked_proc)
    3934        2198 :             break;
    3935          36 :         data->waiter_pids[data->npids++] = queued_proc->pid;
    3936          36 :         queued_proc = (PGPROC *) queued_proc->links.next;
    3937             :     }
    3938             : 
    3939        2198 :     bproc->num_locks = data->nlocks - bproc->first_lock;
    3940        2198 :     bproc->num_waiters = data->npids - bproc->first_waiter;
    3941             : }
    3942             : 
    3943             : /*
    3944             :  * Returns a list of currently held AccessExclusiveLocks, for use by
    3945             :  * LogStandbySnapshot().  The result is a palloc'd array,
    3946             :  * with the number of elements returned into *nlocks.
    3947             :  *
    3948             :  * XXX This currently takes a lock on all partitions of the lock table,
    3949             :  * but it's possible to do better.  By reference counting locks and storing
    3950             :  * the value in the ProcArray entry for each backend we could tell if any
    3951             :  * locks need recording without having to acquire the partition locks and
    3952             :  * scan the lock table.  Whether that's worth the additional overhead
    3953             :  * is pretty dubious though.
    3954             :  */
    3955             : xl_standby_lock *
    3956        1474 : GetRunningTransactionLocks(int *nlocks)
    3957             : {
    3958             :     xl_standby_lock *accessExclusiveLocks;
    3959             :     PROCLOCK   *proclock;
    3960             :     HASH_SEQ_STATUS seqstat;
    3961             :     int         i;
    3962             :     int         index;
    3963             :     int         els;
    3964             : 
    3965             :     /*
    3966             :      * Acquire lock on the entire shared lock data structure.
    3967             :      *
    3968             :      * Must grab LWLocks in partition-number order to avoid LWLock deadlock.
    3969             :      */
    3970       25058 :     for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
    3971       23584 :         LWLockAcquire(LockHashPartitionLockByIndex(i), LW_SHARED);
    3972             : 
    3973             :     /* Now we can safely count the number of proclocks */
    3974        1474 :     els = hash_get_num_entries(LockMethodProcLockHash);
    3975             : 
    3976             :     /*
    3977             :      * Allocating enough space for all locks in the lock table is overkill,
    3978             :      * but it's more convenient and faster than having to enlarge the array.
    3979             :      */
    3980        1474 :     accessExclusiveLocks = palloc(els * sizeof(xl_standby_lock));
    3981             : 
    3982             :     /* Now scan the tables to copy the data */
    3983        1474 :     hash_seq_init(&seqstat, LockMethodProcLockHash);
    3984             : 
    3985             :     /*
    3986             :      * If lock is a currently granted AccessExclusiveLock then it will have
    3987             :      * just one proclock holder, so locks are never accessed twice in this
    3988             :      * particular case. Don't copy this code for use elsewhere because in the
    3989             :      * general case this will give you duplicate locks when looking at
    3990             :      * non-exclusive lock types.
    3991             :      */
    3992        1474 :     index = 0;
    3993        3106 :     while ((proclock = (PROCLOCK *) hash_seq_search(&seqstat)))
    3994             :     {
    3995             :         /* make sure this definition matches the one used in LockAcquire */
    3996        1632 :         if ((proclock->holdMask & LOCKBIT_ON(AccessExclusiveLock)) &&
    3997         192 :             proclock->tag.myLock->tag.locktag_type == LOCKTAG_RELATION)
    3998             :         {
    3999         134 :             PGPROC     *proc = proclock->tag.myProc;
    4000         134 :             LOCK       *lock = proclock->tag.myLock;
    4001         134 :             TransactionId xid = proc->xid;
    4002             : 
    4003             :             /*
    4004             :              * Don't record locks for transactions if we know they have
    4005             :              * already issued their WAL record for commit but not yet released
    4006             :              * lock. It is still possible that we see locks held by already
    4007             :              * complete transactions, if they haven't yet zeroed their xids.
    4008             :              */
    4009         134 :             if (!TransactionIdIsValid(xid))
    4010           0 :                 continue;
    4011             : 
    4012         134 :             accessExclusiveLocks[index].xid = xid;
    4013         134 :             accessExclusiveLocks[index].dbOid = lock->tag.locktag_field1;
    4014         134 :             accessExclusiveLocks[index].relOid = lock->tag.locktag_field2;
    4015             : 
    4016         134 :             index++;
    4017             :         }
    4018             :     }
    4019             : 
    4020             :     Assert(index <= els);
    4021             : 
    4022             :     /*
    4023             :      * And release locks.  We do this in reverse order for two reasons: (1)
    4024             :      * Anyone else who needs more than one of the locks will be trying to lock
    4025             :      * them in increasing order; we don't want to release the other process
    4026             :      * until it can get all the locks it needs. (2) This avoids O(N^2)
    4027             :      * behavior inside LWLockRelease.
    4028             :      */
    4029       25058 :     for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
    4030       23584 :         LWLockRelease(LockHashPartitionLockByIndex(i));
    4031             : 
    4032        1474 :     *nlocks = index;
    4033        1474 :     return accessExclusiveLocks;
    4034             : }
    4035             : 
    4036             : /* Provide the textual name of any lock mode */
    4037             : const char *
    4038        8692 : GetLockmodeName(LOCKMETHODID lockmethodid, LOCKMODE mode)
    4039             : {
    4040             :     Assert(lockmethodid > 0 && lockmethodid < lengthof(LockMethods));
    4041             :     Assert(mode > 0 && mode <= LockMethods[lockmethodid]->numLockModes);
    4042        8692 :     return LockMethods[lockmethodid]->lockModeNames[mode];
    4043             : }
    4044             : 
    4045             : #ifdef LOCK_DEBUG
    4046             : /*
    4047             :  * Dump all locks in the given proc's myProcLocks lists.
    4048             :  *
    4049             :  * Caller is responsible for having acquired appropriate LWLocks.
    4050             :  */
    4051             : void
    4052             : DumpLocks(PGPROC *proc)
    4053             : {
    4054             :     int         i;
    4055             : 
    4056             :     if (proc == NULL)
    4057             :         return;
    4058             : 
    4059             :     if (proc->waitLock)
    4060             :         LOCK_PRINT("DumpLocks: waiting on", proc->waitLock, 0);
    4061             : 
    4062             :     for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
    4063             :     {
    4064             :         dlist_head *procLocks = &proc->myProcLocks[i];
    4065             :         dlist_iter  iter;
    4066             : 
    4067             :         dlist_foreach(iter, procLocks)
    4068             :         {
    4069             :             PROCLOCK   *proclock = dlist_container(PROCLOCK, procLink, iter.cur);
    4070             :             LOCK       *lock = proclock->tag.myLock;
    4071             : 
    4072             :             Assert(proclock->tag.myProc == proc);
    4073             :             PROCLOCK_PRINT("DumpLocks", proclock);
    4074             :             LOCK_PRINT("DumpLocks", lock, 0);
    4075             :         }
    4076             :     }
    4077             : }
    4078             : 
    4079             : /*
    4080             :  * Dump all lmgr locks.
    4081             :  *
    4082             :  * Caller is responsible for having acquired appropriate LWLocks.
    4083             :  */
    4084             : void
    4085             : DumpAllLocks(void)
    4086             : {
    4087             :     PGPROC     *proc;
    4088             :     PROCLOCK   *proclock;
    4089             :     LOCK       *lock;
    4090             :     HASH_SEQ_STATUS status;
    4091             : 
    4092             :     proc = MyProc;
    4093             : 
    4094             :     if (proc && proc->waitLock)
    4095             :         LOCK_PRINT("DumpAllLocks: waiting on", proc->waitLock, 0);
    4096             : 
    4097             :     hash_seq_init(&status, LockMethodProcLockHash);
    4098             : 
    4099             :     while ((proclock = (PROCLOCK *) hash_seq_search(&status)) != NULL)
    4100             :     {
    4101             :         PROCLOCK_PRINT("DumpAllLocks", proclock);
    4102             : 
    4103             :         lock = proclock->tag.myLock;
    4104             :         if (lock)
    4105             :             LOCK_PRINT("DumpAllLocks", lock, 0);
    4106             :         else
    4107             :             elog(LOG, "DumpAllLocks: proclock->tag.myLock = NULL");
    4108             :     }
    4109             : }
    4110             : #endif                          /* LOCK_DEBUG */
    4111             : 
    4112             : /*
    4113             :  * LOCK 2PC resource manager's routines
    4114             :  */
    4115             : 
    4116             : /*
    4117             :  * Re-acquire a lock belonging to a transaction that was prepared.
    4118             :  *
    4119             :  * Because this function is run at db startup, re-acquiring the locks should
    4120             :  * never conflict with running transactions because there are none.  We
    4121             :  * assume that the lock state represented by the stored 2PC files is legal.
    4122             :  *
    4123             :  * When switching from Hot Standby mode to normal operation, the locks will
    4124             :  * be already held by the startup process. The locks are acquired for the new
    4125             :  * procs without checking for conflicts, so we don't get a conflict between the
    4126             :  * startup process and the dummy procs, even though we will momentarily have
    4127             :  * a situation where two procs are holding the same AccessExclusiveLock,
    4128             :  * which isn't normally possible because the conflict. If we're in standby
    4129             :  * mode, but a recovery snapshot hasn't been established yet, it's possible
    4130             :  * that some but not all of the locks are already held by the startup process.
    4131             :  *
    4132             :  * This approach is simple, but also a bit dangerous, because if there isn't
    4133             :  * enough shared memory to acquire the locks, an error will be thrown, which
    4134             :  * is promoted to FATAL and recovery will abort, bringing down postmaster.
    4135             :  * A safer approach would be to transfer the locks like we do in
    4136             :  * AtPrepare_Locks, but then again, in hot standby mode it's possible for
    4137             :  * read-only backends to use up all the shared lock memory anyway, so that
    4138             :  * replaying the WAL record that needs to acquire a lock will throw an error
    4139             :  * and PANIC anyway.
    4140             :  */
    4141             : void
    4142         164 : lock_twophase_recover(TransactionId xid, uint16 info,
    4143             :                       void *recdata, uint32 len)
    4144             : {
    4145         164 :     TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
    4146         164 :     PGPROC     *proc = TwoPhaseGetDummyProc(xid, false);
    4147             :     LOCKTAG    *locktag;
    4148             :     LOCKMODE    lockmode;
    4149             :     LOCKMETHODID lockmethodid;
    4150             :     LOCK       *lock;
    4151             :     PROCLOCK   *proclock;
    4152             :     PROCLOCKTAG proclocktag;
    4153             :     bool        found;
    4154             :     uint32      hashcode;
    4155             :     uint32      proclock_hashcode;
    4156             :     int         partition;
    4157             :     LWLock     *partitionLock;
    4158             :     LockMethod  lockMethodTable;
    4159             : 
    4160             :     Assert(len == sizeof(TwoPhaseLockRecord));
    4161         164 :     locktag = &rec->locktag;
    4162         164 :     lockmode = rec->lockmode;
    4163         164 :     lockmethodid = locktag->locktag_lockmethodid;
    4164             : 
    4165         164 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
    4166           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    4167         164 :     lockMethodTable = LockMethods[lockmethodid];
    4168             : 
    4169         164 :     hashcode = LockTagHashCode(locktag);
    4170         164 :     partition = LockHashPartition(hashcode);
    4171         164 :     partitionLock = LockHashPartitionLock(hashcode);
    4172             : 
    4173         164 :     LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    4174             : 
    4175             :     /*
    4176             :      * Find or create a lock with this tag.
    4177             :      */
    4178         164 :     lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
    4179             :                                                 locktag,
    4180             :                                                 hashcode,
    4181             :                                                 HASH_ENTER_NULL,
    4182             :                                                 &found);
    4183         164 :     if (!lock)
    4184             :     {
    4185           0 :         LWLockRelease(partitionLock);
    4186           0 :         ereport(ERROR,
    4187             :                 (errcode(ERRCODE_OUT_OF_MEMORY),
    4188             :                  errmsg("out of shared memory"),
    4189             :                  errhint("You might need to increase %s.", "max_locks_per_transaction")));
    4190             :     }
    4191             : 
    4192             :     /*
    4193             :      * if it's a new lock object, initialize it
    4194             :      */
    4195         164 :     if (!found)
    4196             :     {
    4197         148 :         lock->grantMask = 0;
    4198         148 :         lock->waitMask = 0;
    4199         148 :         dlist_init(&lock->procLocks);
    4200         148 :         dclist_init(&lock->waitProcs);
    4201         148 :         lock->nRequested = 0;
    4202         148 :         lock->nGranted = 0;
    4203         888 :         MemSet(lock->requested, 0, sizeof(int) * MAX_LOCKMODES);
    4204         148 :         MemSet(lock->granted, 0, sizeof(int) * MAX_LOCKMODES);
    4205             :         LOCK_PRINT("lock_twophase_recover: new", lock, lockmode);
    4206             :     }
    4207             :     else
    4208             :     {
    4209             :         LOCK_PRINT("lock_twophase_recover: found", lock, lockmode);
    4210             :         Assert((lock->nRequested >= 0) && (lock->requested[lockmode] >= 0));
    4211             :         Assert((lock->nGranted >= 0) && (lock->granted[lockmode] >= 0));
    4212             :         Assert(lock->nGranted <= lock->nRequested);
    4213             :     }
    4214             : 
    4215             :     /*
    4216             :      * Create the hash key for the proclock table.
    4217             :      */
    4218         164 :     proclocktag.myLock = lock;
    4219         164 :     proclocktag.myProc = proc;
    4220             : 
    4221         164 :     proclock_hashcode = ProcLockHashCode(&proclocktag, hashcode);
    4222             : 
    4223             :     /*
    4224             :      * Find or create a proclock entry with this tag
    4225             :      */
    4226         164 :     proclock = (PROCLOCK *) hash_search_with_hash_value(LockMethodProcLockHash,
    4227             :                                                         &proclocktag,
    4228             :                                                         proclock_hashcode,
    4229             :                                                         HASH_ENTER_NULL,
    4230             :                                                         &found);
    4231         164 :     if (!proclock)
    4232             :     {
    4233             :         /* Oops, not enough shmem for the proclock */
    4234           0 :         if (lock->nRequested == 0)
    4235             :         {
    4236             :             /*
    4237             :              * There are no other requestors of this lock, so garbage-collect
    4238             :              * the lock object.  We *must* do this to avoid a permanent leak
    4239             :              * of shared memory, because there won't be anything to cause
    4240             :              * anyone to release the lock object later.
    4241             :              */
    4242             :             Assert(dlist_is_empty(&lock->procLocks));
    4243           0 :             if (!hash_search_with_hash_value(LockMethodLockHash,
    4244           0 :                                              &(lock->tag),
    4245             :                                              hashcode,
    4246             :                                              HASH_REMOVE,
    4247             :                                              NULL))
    4248           0 :                 elog(PANIC, "lock table corrupted");
    4249             :         }
    4250           0 :         LWLockRelease(partitionLock);
    4251           0 :         ereport(ERROR,
    4252             :                 (errcode(ERRCODE_OUT_OF_MEMORY),
    4253             :                  errmsg("out of shared memory"),
    4254             :                  errhint("You might need to increase %s.", "max_locks_per_transaction")));
    4255             :     }
    4256             : 
    4257             :     /*
    4258             :      * If new, initialize the new entry
    4259             :      */
    4260         164 :     if (!found)
    4261             :     {
    4262             :         Assert(proc->lockGroupLeader == NULL);
    4263         156 :         proclock->groupLeader = proc;
    4264         156 :         proclock->holdMask = 0;
    4265         156 :         proclock->releaseMask = 0;
    4266             :         /* Add proclock to appropriate lists */
    4267         156 :         dlist_push_tail(&lock->procLocks, &proclock->lockLink);
    4268         156 :         dlist_push_tail(&proc->myProcLocks[partition],
    4269             :                         &proclock->procLink);
    4270             :         PROCLOCK_PRINT("lock_twophase_recover: new", proclock);
    4271             :     }
    4272             :     else
    4273             :     {
    4274             :         PROCLOCK_PRINT("lock_twophase_recover: found", proclock);
    4275             :         Assert((proclock->holdMask & ~lock->grantMask) == 0);
    4276             :     }
    4277             : 
    4278             :     /*
    4279             :      * lock->nRequested and lock->requested[] count the total number of
    4280             :      * requests, whether granted or waiting, so increment those immediately.
    4281             :      */
    4282         164 :     lock->nRequested++;
    4283         164 :     lock->requested[lockmode]++;
    4284             :     Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
    4285             : 
    4286             :     /*
    4287             :      * We shouldn't already hold the desired lock.
    4288             :      */
    4289         164 :     if (proclock->holdMask & LOCKBIT_ON(lockmode))
    4290           0 :         elog(ERROR, "lock %s on object %u/%u/%u is already held",
    4291             :              lockMethodTable->lockModeNames[lockmode],
    4292             :              lock->tag.locktag_field1, lock->tag.locktag_field2,
    4293             :              lock->tag.locktag_field3);
    4294             : 
    4295             :     /*
    4296             :      * We ignore any possible conflicts and just grant ourselves the lock. Not
    4297             :      * only because we don't bother, but also to avoid deadlocks when
    4298             :      * switching from standby to normal mode. See function comment.
    4299             :      */
    4300         164 :     GrantLock(lock, proclock, lockmode);
    4301             : 
    4302             :     /*
    4303             :      * Bump strong lock count, to make sure any fast-path lock requests won't
    4304             :      * be granted without consulting the primary lock table.
    4305             :      */
    4306         164 :     if (ConflictsWithRelationFastPath(&lock->tag, lockmode))
    4307             :     {
    4308          28 :         uint32      fasthashcode = FastPathStrongLockHashPartition(hashcode);
    4309             : 
    4310          28 :         SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
    4311          28 :         FastPathStrongRelationLocks->count[fasthashcode]++;
    4312          28 :         SpinLockRelease(&FastPathStrongRelationLocks->mutex);
    4313             :     }
    4314             : 
    4315         164 :     LWLockRelease(partitionLock);
    4316         164 : }
    4317             : 
    4318             : /*
    4319             :  * Re-acquire a lock belonging to a transaction that was prepared, when
    4320             :  * starting up into hot standby mode.
    4321             :  */
    4322             : void
    4323           0 : lock_twophase_standby_recover(TransactionId xid, uint16 info,
    4324             :                               void *recdata, uint32 len)
    4325             : {
    4326           0 :     TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
    4327             :     LOCKTAG    *locktag;
    4328             :     LOCKMODE    lockmode;
    4329             :     LOCKMETHODID lockmethodid;
    4330             : 
    4331             :     Assert(len == sizeof(TwoPhaseLockRecord));
    4332           0 :     locktag = &rec->locktag;
    4333           0 :     lockmode = rec->lockmode;
    4334           0 :     lockmethodid = locktag->locktag_lockmethodid;
    4335             : 
    4336           0 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
    4337           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    4338             : 
    4339           0 :     if (lockmode == AccessExclusiveLock &&
    4340           0 :         locktag->locktag_type == LOCKTAG_RELATION)
    4341             :     {
    4342           0 :         StandbyAcquireAccessExclusiveLock(xid,
    4343             :                                           locktag->locktag_field1 /* dboid */ ,
    4344             :                                           locktag->locktag_field2 /* reloid */ );
    4345             :     }
    4346           0 : }
    4347             : 
    4348             : 
    4349             : /*
    4350             :  * 2PC processing routine for COMMIT PREPARED case.
    4351             :  *
    4352             :  * Find and release the lock indicated by the 2PC record.
    4353             :  */
    4354             : void
    4355        1748 : lock_twophase_postcommit(TransactionId xid, uint16 info,
    4356             :                          void *recdata, uint32 len)
    4357             : {
    4358        1748 :     TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
    4359        1748 :     PGPROC     *proc = TwoPhaseGetDummyProc(xid, true);
    4360             :     LOCKTAG    *locktag;
    4361             :     LOCKMETHODID lockmethodid;
    4362             :     LockMethod  lockMethodTable;
    4363             : 
    4364             :     Assert(len == sizeof(TwoPhaseLockRecord));
    4365        1748 :     locktag = &rec->locktag;
    4366        1748 :     lockmethodid = locktag->locktag_lockmethodid;
    4367             : 
    4368        1748 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
    4369           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    4370        1748 :     lockMethodTable = LockMethods[lockmethodid];
    4371             : 
    4372        1748 :     LockRefindAndRelease(lockMethodTable, proc, locktag, rec->lockmode, true);
    4373        1748 : }
    4374             : 
    4375             : /*
    4376             :  * 2PC processing routine for ROLLBACK PREPARED case.
    4377             :  *
    4378             :  * This is actually just the same as the COMMIT case.
    4379             :  */
    4380             : void
    4381         244 : lock_twophase_postabort(TransactionId xid, uint16 info,
    4382             :                         void *recdata, uint32 len)
    4383             : {
    4384         244 :     lock_twophase_postcommit(xid, info, recdata, len);
    4385         244 : }
    4386             : 
    4387             : /*
    4388             :  *      VirtualXactLockTableInsert
    4389             :  *
    4390             :  *      Take vxid lock via the fast-path.  There can't be any pre-existing
    4391             :  *      lockers, as we haven't advertised this vxid via the ProcArray yet.
    4392             :  *
    4393             :  *      Since MyProc->fpLocalTransactionId will normally contain the same data
    4394             :  *      as MyProc->vxid.lxid, you might wonder if we really need both.  The
    4395             :  *      difference is that MyProc->vxid.lxid is set and cleared unlocked, and
    4396             :  *      examined by procarray.c, while fpLocalTransactionId is protected by
    4397             :  *      fpInfoLock and is used only by the locking subsystem.  Doing it this
    4398             :  *      way makes it easier to verify that there are no funny race conditions.
    4399             :  *
    4400             :  *      We don't bother recording this lock in the local lock table, since it's
    4401             :  *      only ever released at the end of a transaction.  Instead,
    4402             :  *      LockReleaseAll() calls VirtualXactLockTableCleanup().
    4403             :  */
    4404             : void
    4405      565390 : VirtualXactLockTableInsert(VirtualTransactionId vxid)
    4406             : {
    4407             :     Assert(VirtualTransactionIdIsValid(vxid));
    4408             : 
    4409      565390 :     LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
    4410             : 
    4411             :     Assert(MyProc->vxid.procNumber == vxid.procNumber);
    4412             :     Assert(MyProc->fpLocalTransactionId == InvalidLocalTransactionId);
    4413             :     Assert(MyProc->fpVXIDLock == false);
    4414             : 
    4415      565390 :     MyProc->fpVXIDLock = true;
    4416      565390 :     MyProc->fpLocalTransactionId = vxid.localTransactionId;
    4417             : 
    4418      565390 :     LWLockRelease(&MyProc->fpInfoLock);
    4419      565390 : }
    4420             : 
    4421             : /*
    4422             :  *      VirtualXactLockTableCleanup
    4423             :  *
    4424             :  *      Check whether a VXID lock has been materialized; if so, release it,
    4425             :  *      unblocking waiters.
    4426             :  */
    4427             : void
    4428      566130 : VirtualXactLockTableCleanup(void)
    4429             : {
    4430             :     bool        fastpath;
    4431             :     LocalTransactionId lxid;
    4432             : 
    4433             :     Assert(MyProc->vxid.procNumber != INVALID_PROC_NUMBER);
    4434             : 
    4435             :     /*
    4436             :      * Clean up shared memory state.
    4437             :      */
    4438      566130 :     LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
    4439             : 
    4440      566130 :     fastpath = MyProc->fpVXIDLock;
    4441      566130 :     lxid = MyProc->fpLocalTransactionId;
    4442      566130 :     MyProc->fpVXIDLock = false;
    4443      566130 :     MyProc->fpLocalTransactionId = InvalidLocalTransactionId;
    4444             : 
    4445      566130 :     LWLockRelease(&MyProc->fpInfoLock);
    4446             : 
    4447             :     /*
    4448             :      * If fpVXIDLock has been cleared without touching fpLocalTransactionId,
    4449             :      * that means someone transferred the lock to the main lock table.
    4450             :      */
    4451      566130 :     if (!fastpath && LocalTransactionIdIsValid(lxid))
    4452             :     {
    4453             :         VirtualTransactionId vxid;
    4454             :         LOCKTAG     locktag;
    4455             : 
    4456         566 :         vxid.procNumber = MyProcNumber;
    4457         566 :         vxid.localTransactionId = lxid;
    4458         566 :         SET_LOCKTAG_VIRTUALTRANSACTION(locktag, vxid);
    4459             : 
    4460         566 :         LockRefindAndRelease(LockMethods[DEFAULT_LOCKMETHOD], MyProc,
    4461             :                              &locktag, ExclusiveLock, false);
    4462             :     }
    4463      566130 : }
    4464             : 
    4465             : /*
    4466             :  *      XactLockForVirtualXact
    4467             :  *
    4468             :  * If TransactionIdIsValid(xid), this is essentially XactLockTableWait(xid,
    4469             :  * NULL, NULL, XLTW_None) or ConditionalXactLockTableWait(xid).  Unlike those
    4470             :  * functions, it assumes "xid" is never a subtransaction and that "xid" is
    4471             :  * prepared, committed, or aborted.
    4472             :  *
    4473             :  * If !TransactionIdIsValid(xid), this locks every prepared XID having been
    4474             :  * known as "vxid" before its PREPARE TRANSACTION.
    4475             :  */
    4476             : static bool
    4477         618 : XactLockForVirtualXact(VirtualTransactionId vxid,
    4478             :                        TransactionId xid, bool wait)
    4479             : {
    4480         618 :     bool        more = false;
    4481             : 
    4482             :     /* There is no point to wait for 2PCs if you have no 2PCs. */
    4483         618 :     if (max_prepared_xacts == 0)
    4484         204 :         return true;
    4485             : 
    4486             :     do
    4487             :     {
    4488             :         LockAcquireResult lar;
    4489             :         LOCKTAG     tag;
    4490             : 
    4491             :         /* Clear state from previous iterations. */
    4492         414 :         if (more)
    4493             :         {
    4494           0 :             xid = InvalidTransactionId;
    4495           0 :             more = false;
    4496             :         }
    4497             : 
    4498             :         /* If we have no xid, try to find one. */
    4499         414 :         if (!TransactionIdIsValid(xid))
    4500         226 :             xid = TwoPhaseGetXidByVirtualXID(vxid, &more);
    4501         414 :         if (!TransactionIdIsValid(xid))
    4502             :         {
    4503             :             Assert(!more);
    4504         196 :             return true;
    4505             :         }
    4506             : 
    4507             :         /* Check or wait for XID completion. */
    4508         218 :         SET_LOCKTAG_TRANSACTION(tag, xid);
    4509         218 :         lar = LockAcquire(&tag, ShareLock, false, !wait);
    4510         218 :         if (lar == LOCKACQUIRE_NOT_AVAIL)
    4511           0 :             return false;
    4512         218 :         LockRelease(&tag, ShareLock, false);
    4513         218 :     } while (more);
    4514             : 
    4515         218 :     return true;
    4516             : }
    4517             : 
    4518             : /*
    4519             :  *      VirtualXactLock
    4520             :  *
    4521             :  * If wait = true, wait as long as the given VXID or any XID acquired by the
    4522             :  * same transaction is still running.  Then, return true.
    4523             :  *
    4524             :  * If wait = false, just check whether that VXID or one of those XIDs is still
    4525             :  * running, and return true or false.
    4526             :  */
    4527             : bool
    4528         698 : VirtualXactLock(VirtualTransactionId vxid, bool wait)
    4529             : {
    4530             :     LOCKTAG     tag;
    4531             :     PGPROC     *proc;
    4532         698 :     TransactionId xid = InvalidTransactionId;
    4533             : 
    4534             :     Assert(VirtualTransactionIdIsValid(vxid));
    4535             : 
    4536         698 :     if (VirtualTransactionIdIsRecoveredPreparedXact(vxid))
    4537             :         /* no vxid lock; localTransactionId is a normal, locked XID */
    4538           2 :         return XactLockForVirtualXact(vxid, vxid.localTransactionId, wait);
    4539             : 
    4540         696 :     SET_LOCKTAG_VIRTUALTRANSACTION(tag, vxid);
    4541             : 
    4542             :     /*
    4543             :      * If a lock table entry must be made, this is the PGPROC on whose behalf
    4544             :      * it must be done.  Note that the transaction might end or the PGPROC
    4545             :      * might be reassigned to a new backend before we get around to examining
    4546             :      * it, but it doesn't matter.  If we find upon examination that the
    4547             :      * relevant lxid is no longer running here, that's enough to prove that
    4548             :      * it's no longer running anywhere.
    4549             :      */
    4550         696 :     proc = ProcNumberGetProc(vxid.procNumber);
    4551         696 :     if (proc == NULL)
    4552           6 :         return XactLockForVirtualXact(vxid, InvalidTransactionId, wait);
    4553             : 
    4554             :     /*
    4555             :      * We must acquire this lock before checking the procNumber and lxid
    4556             :      * against the ones we're waiting for.  The target backend will only set
    4557             :      * or clear lxid while holding this lock.
    4558             :      */
    4559         690 :     LWLockAcquire(&proc->fpInfoLock, LW_EXCLUSIVE);
    4560             : 
    4561         690 :     if (proc->vxid.procNumber != vxid.procNumber
    4562         690 :         || proc->fpLocalTransactionId != vxid.localTransactionId)
    4563             :     {
    4564             :         /* VXID ended */
    4565          82 :         LWLockRelease(&proc->fpInfoLock);
    4566          82 :         return XactLockForVirtualXact(vxid, InvalidTransactionId, wait);
    4567             :     }
    4568             : 
    4569             :     /*
    4570             :      * If we aren't asked to wait, there's no need to set up a lock table
    4571             :      * entry.  The transaction is still in progress, so just return false.
    4572             :      */
    4573         608 :     if (!wait)
    4574             :     {
    4575          30 :         LWLockRelease(&proc->fpInfoLock);
    4576          30 :         return false;
    4577             :     }
    4578             : 
    4579             :     /*
    4580             :      * OK, we're going to need to sleep on the VXID.  But first, we must set
    4581             :      * up the primary lock table entry, if needed (ie, convert the proc's
    4582             :      * fast-path lock on its VXID to a regular lock).
    4583             :      */
    4584         578 :     if (proc->fpVXIDLock)
    4585             :     {
    4586             :         PROCLOCK   *proclock;
    4587             :         uint32      hashcode;
    4588             :         LWLock     *partitionLock;
    4589             : 
    4590         566 :         hashcode = LockTagHashCode(&tag);
    4591             : 
    4592         566 :         partitionLock = LockHashPartitionLock(hashcode);
    4593         566 :         LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    4594             : 
    4595         566 :         proclock = SetupLockInTable(LockMethods[DEFAULT_LOCKMETHOD], proc,
    4596             :                                     &tag, hashcode, ExclusiveLock);
    4597         566 :         if (!proclock)
    4598             :         {
    4599           0 :             LWLockRelease(partitionLock);
    4600           0 :             LWLockRelease(&proc->fpInfoLock);
    4601           0 :             ereport(ERROR,
    4602             :                     (errcode(ERRCODE_OUT_OF_MEMORY),
    4603             :                      errmsg("out of shared memory"),
    4604             :                      errhint("You might need to increase %s.", "max_locks_per_transaction")));
    4605             :         }
    4606         566 :         GrantLock(proclock->tag.myLock, proclock, ExclusiveLock);
    4607             : 
    4608         566 :         LWLockRelease(partitionLock);
    4609             : 
    4610         566 :         proc->fpVXIDLock = false;
    4611             :     }
    4612             : 
    4613             :     /*
    4614             :      * If the proc has an XID now, we'll avoid a TwoPhaseGetXidByVirtualXID()
    4615             :      * search.  The proc might have assigned this XID but not yet locked it,
    4616             :      * in which case the proc will lock this XID before releasing the VXID.
    4617             :      * The fpInfoLock critical section excludes VirtualXactLockTableCleanup(),
    4618             :      * so we won't save an XID of a different VXID.  It doesn't matter whether
    4619             :      * we save this before or after setting up the primary lock table entry.
    4620             :      */
    4621         578 :     xid = proc->xid;
    4622             : 
    4623             :     /* Done with proc->fpLockBits */
    4624         578 :     LWLockRelease(&proc->fpInfoLock);
    4625             : 
    4626             :     /* Time to wait. */
    4627         578 :     (void) LockAcquire(&tag, ShareLock, false, false);
    4628             : 
    4629         528 :     LockRelease(&tag, ShareLock, false);
    4630         528 :     return XactLockForVirtualXact(vxid, xid, wait);
    4631             : }
    4632             : 
    4633             : /*
    4634             :  * LockWaiterCount
    4635             :  *
    4636             :  * Find the number of lock requester on this locktag
    4637             :  */
    4638             : int
    4639      111780 : LockWaiterCount(const LOCKTAG *locktag)
    4640             : {
    4641      111780 :     LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
    4642             :     LOCK       *lock;
    4643             :     bool        found;
    4644             :     uint32      hashcode;
    4645             :     LWLock     *partitionLock;
    4646      111780 :     int         waiters = 0;
    4647             : 
    4648      111780 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
    4649           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    4650             : 
    4651      111780 :     hashcode = LockTagHashCode(locktag);
    4652      111780 :     partitionLock = LockHashPartitionLock(hashcode);
    4653      111780 :     LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    4654             : 
    4655      111780 :     lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
    4656             :                                                 locktag,
    4657             :                                                 hashcode,
    4658             :                                                 HASH_FIND,
    4659             :                                                 &found);
    4660      111780 :     if (found)
    4661             :     {
    4662             :         Assert(lock != NULL);
    4663          58 :         waiters = lock->nRequested;
    4664             :     }
    4665      111780 :     LWLockRelease(partitionLock);
    4666             : 
    4667      111780 :     return waiters;
    4668             : }

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