LCOV - code coverage report
Current view: top level - src/backend/storage/lmgr - lock.c (source / functions) Hit Total Coverage
Test: PostgreSQL 16devel Lines: 1086 1236 87.9 %
Date: 2023-03-26 15:11:41 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) 1996-2023, 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/xact.h"
      39             : #include "access/xlog.h"
      40             : #include "access/xlogutils.h"
      41             : #include "miscadmin.h"
      42             : #include "pg_trace.h"
      43             : #include "pgstat.h"
      44             : #include "storage/proc.h"
      45             : #include "storage/procarray.h"
      46             : #include "storage/sinvaladt.h"
      47             : #include "storage/spin.h"
      48             : #include "storage/standby.h"
      49             : #include "utils/memutils.h"
      50             : #include "utils/ps_status.h"
      51             : #include "utils/resowner_private.h"
      52             : 
      53             : 
      54             : /* This configuration variable is used to set the lock table size */
      55             : int         max_locks_per_xact; /* set by guc.c */
      56             : 
      57             : #define NLOCKENTS() \
      58             :     mul_size(max_locks_per_xact, add_size(MaxBackends, max_prepared_xacts))
      59             : 
      60             : 
      61             : /*
      62             :  * Data structures defining the semantics of the standard lock methods.
      63             :  *
      64             :  * The conflict table defines the semantics of the various lock modes.
      65             :  */
      66             : static const LOCKMASK LockConflicts[] = {
      67             :     0,
      68             : 
      69             :     /* AccessShareLock */
      70             :     LOCKBIT_ON(AccessExclusiveLock),
      71             : 
      72             :     /* RowShareLock */
      73             :     LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock),
      74             : 
      75             :     /* RowExclusiveLock */
      76             :     LOCKBIT_ON(ShareLock) | LOCKBIT_ON(ShareRowExclusiveLock) |
      77             :     LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock),
      78             : 
      79             :     /* ShareUpdateExclusiveLock */
      80             :     LOCKBIT_ON(ShareUpdateExclusiveLock) |
      81             :     LOCKBIT_ON(ShareLock) | LOCKBIT_ON(ShareRowExclusiveLock) |
      82             :     LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock),
      83             : 
      84             :     /* ShareLock */
      85             :     LOCKBIT_ON(RowExclusiveLock) | LOCKBIT_ON(ShareUpdateExclusiveLock) |
      86             :     LOCKBIT_ON(ShareRowExclusiveLock) |
      87             :     LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock),
      88             : 
      89             :     /* ShareRowExclusiveLock */
      90             :     LOCKBIT_ON(RowExclusiveLock) | LOCKBIT_ON(ShareUpdateExclusiveLock) |
      91             :     LOCKBIT_ON(ShareLock) | LOCKBIT_ON(ShareRowExclusiveLock) |
      92             :     LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock),
      93             : 
      94             :     /* ExclusiveLock */
      95             :     LOCKBIT_ON(RowShareLock) |
      96             :     LOCKBIT_ON(RowExclusiveLock) | LOCKBIT_ON(ShareUpdateExclusiveLock) |
      97             :     LOCKBIT_ON(ShareLock) | LOCKBIT_ON(ShareRowExclusiveLock) |
      98             :     LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock),
      99             : 
     100             :     /* AccessExclusiveLock */
     101             :     LOCKBIT_ON(AccessShareLock) | LOCKBIT_ON(RowShareLock) |
     102             :     LOCKBIT_ON(RowExclusiveLock) | LOCKBIT_ON(ShareUpdateExclusiveLock) |
     103             :     LOCKBIT_ON(ShareLock) | LOCKBIT_ON(ShareRowExclusiveLock) |
     104             :     LOCKBIT_ON(ExclusiveLock) | LOCKBIT_ON(AccessExclusiveLock)
     105             : 
     106             : };
     107             : 
     108             : /* Names of lock modes, for debug printouts */
     109             : static const char *const lock_mode_names[] =
     110             : {
     111             :     "INVALID",
     112             :     "AccessShareLock",
     113             :     "RowShareLock",
     114             :     "RowExclusiveLock",
     115             :     "ShareUpdateExclusiveLock",
     116             :     "ShareLock",
     117             :     "ShareRowExclusiveLock",
     118             :     "ExclusiveLock",
     119             :     "AccessExclusiveLock"
     120             : };
     121             : 
     122             : #ifndef LOCK_DEBUG
     123             : static bool Dummy_trace = false;
     124             : #endif
     125             : 
     126             : static const LockMethodData default_lockmethod = {
     127             :     MaxLockMode,
     128             :     LockConflicts,
     129             :     lock_mode_names,
     130             : #ifdef LOCK_DEBUG
     131             :     &Trace_locks
     132             : #else
     133             :     &Dummy_trace
     134             : #endif
     135             : };
     136             : 
     137             : static const LockMethodData user_lockmethod = {
     138             :     MaxLockMode,
     139             :     LockConflicts,
     140             :     lock_mode_names,
     141             : #ifdef LOCK_DEBUG
     142             :     &Trace_userlocks
     143             : #else
     144             :     &Dummy_trace
     145             : #endif
     146             : };
     147             : 
     148             : /*
     149             :  * map from lock method id to the lock table data structures
     150             :  */
     151             : static const LockMethod LockMethods[] = {
     152             :     NULL,
     153             :     &default_lockmethod,
     154             :     &user_lockmethod
     155             : };
     156             : 
     157             : 
     158             : /* Record that's written to 2PC state file when a lock is persisted */
     159             : typedef struct TwoPhaseLockRecord
     160             : {
     161             :     LOCKTAG     locktag;
     162             :     LOCKMODE    lockmode;
     163             : } TwoPhaseLockRecord;
     164             : 
     165             : 
     166             : /*
     167             :  * Count of the number of fast path lock slots we believe to be used.  This
     168             :  * might be higher than the real number if another backend has transferred
     169             :  * our locks to the primary lock table, but it can never be lower than the
     170             :  * real value, since only we can acquire locks on our own behalf.
     171             :  */
     172             : static int  FastPathLocalUseCount = 0;
     173             : 
     174             : /*
     175             :  * Flag to indicate if the relation extension lock is held by this backend.
     176             :  * This flag is used to ensure that while holding the relation extension lock
     177             :  * we don't try to acquire a heavyweight lock on any other object.  This
     178             :  * restriction implies that the relation extension lock won't ever participate
     179             :  * in the deadlock cycle because we can never wait for any other heavyweight
     180             :  * lock after acquiring this lock.
     181             :  *
     182             :  * Such a restriction is okay for relation extension locks as unlike other
     183             :  * heavyweight locks these are not held till the transaction end.  These are
     184             :  * taken for a short duration to extend a particular relation and then
     185             :  * released.
     186             :  */
     187             : static bool IsRelationExtensionLockHeld PG_USED_FOR_ASSERTS_ONLY = false;
     188             : 
     189             : /*
     190             :  * Flag to indicate if the page lock is held by this backend.  We don't
     191             :  * acquire any other heavyweight lock while holding the page lock except for
     192             :  * relation extension.  However, these locks are never taken in reverse order
     193             :  * which implies that page locks will also never participate in the deadlock
     194             :  * cycle.
     195             :  *
     196             :  * Similar to relation extension, page locks are also held for a short
     197             :  * duration, so imposing such a restriction won't hurt.
     198             :  */
     199             : static bool IsPageLockHeld PG_USED_FOR_ASSERTS_ONLY = false;
     200             : 
     201             : /* Macros for manipulating proc->fpLockBits */
     202             : #define FAST_PATH_BITS_PER_SLOT         3
     203             : #define FAST_PATH_LOCKNUMBER_OFFSET     1
     204             : #define FAST_PATH_MASK                  ((1 << FAST_PATH_BITS_PER_SLOT) - 1)
     205             : #define FAST_PATH_GET_BITS(proc, n) \
     206             :     (((proc)->fpLockBits >> (FAST_PATH_BITS_PER_SLOT * n)) & FAST_PATH_MASK)
     207             : #define FAST_PATH_BIT_POSITION(n, l) \
     208             :     (AssertMacro((l) >= FAST_PATH_LOCKNUMBER_OFFSET), \
     209             :      AssertMacro((l) < FAST_PATH_BITS_PER_SLOT+FAST_PATH_LOCKNUMBER_OFFSET), \
     210             :      AssertMacro((n) < FP_LOCK_SLOTS_PER_BACKEND), \
     211             :      ((l) - FAST_PATH_LOCKNUMBER_OFFSET + FAST_PATH_BITS_PER_SLOT * (n)))
     212             : #define FAST_PATH_SET_LOCKMODE(proc, n, l) \
     213             :      (proc)->fpLockBits |= UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l)
     214             : #define FAST_PATH_CLEAR_LOCKMODE(proc, n, l) \
     215             :      (proc)->fpLockBits &= ~(UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l))
     216             : #define FAST_PATH_CHECK_LOCKMODE(proc, n, l) \
     217             :      ((proc)->fpLockBits & (UINT64CONST(1) << FAST_PATH_BIT_POSITION(n, l)))
     218             : 
     219             : /*
     220             :  * The fast-path lock mechanism is concerned only with relation locks on
     221             :  * unshared relations by backends bound to a database.  The fast-path
     222             :  * mechanism exists mostly to accelerate acquisition and release of locks
     223             :  * that rarely conflict.  Because ShareUpdateExclusiveLock is
     224             :  * self-conflicting, it can't use the fast-path mechanism; but it also does
     225             :  * not conflict with any of the locks that do, so we can ignore it completely.
     226             :  */
     227             : #define EligibleForRelationFastPath(locktag, mode) \
     228             :     ((locktag)->locktag_lockmethodid == DEFAULT_LOCKMETHOD && \
     229             :     (locktag)->locktag_type == LOCKTAG_RELATION && \
     230             :     (locktag)->locktag_field1 == MyDatabaseId && \
     231             :     MyDatabaseId != InvalidOid && \
     232             :     (mode) < ShareUpdateExclusiveLock)
     233             : #define ConflictsWithRelationFastPath(locktag, mode) \
     234             :     ((locktag)->locktag_lockmethodid == DEFAULT_LOCKMETHOD && \
     235             :     (locktag)->locktag_type == LOCKTAG_RELATION && \
     236             :     (locktag)->locktag_field1 != InvalidOid && \
     237             :     (mode) > ShareUpdateExclusiveLock)
     238             : 
     239             : static bool FastPathGrantRelationLock(Oid relid, LOCKMODE lockmode);
     240             : static bool FastPathUnGrantRelationLock(Oid relid, LOCKMODE lockmode);
     241             : static bool FastPathTransferRelationLocks(LockMethod lockMethodTable,
     242             :                                           const LOCKTAG *locktag, uint32 hashcode);
     243             : static PROCLOCK *FastPathGetRelationLockEntry(LOCALLOCK *locallock);
     244             : 
     245             : /*
     246             :  * To make the fast-path lock mechanism work, we must have some way of
     247             :  * preventing the use of the fast-path when a conflicting lock might be present.
     248             :  * We partition* the locktag space into FAST_PATH_STRONG_LOCK_HASH_PARTITIONS,
     249             :  * and maintain an integer count of the number of "strong" lockers
     250             :  * in each partition.  When any "strong" lockers are present (which is
     251             :  * hopefully not very often), the fast-path mechanism can't be used, and we
     252             :  * must fall back to the slower method of pushing matching locks directly
     253             :  * into the main lock tables.
     254             :  *
     255             :  * The deadlock detector does not know anything about the fast path mechanism,
     256             :  * so any locks that might be involved in a deadlock must be transferred from
     257             :  * the fast-path queues to the main lock table.
     258             :  */
     259             : 
     260             : #define FAST_PATH_STRONG_LOCK_HASH_BITS         10
     261             : #define FAST_PATH_STRONG_LOCK_HASH_PARTITIONS \
     262             :     (1 << FAST_PATH_STRONG_LOCK_HASH_BITS)
     263             : #define FastPathStrongLockHashPartition(hashcode) \
     264             :     ((hashcode) % FAST_PATH_STRONG_LOCK_HASH_PARTITIONS)
     265             : 
     266             : typedef struct
     267             : {
     268             :     slock_t     mutex;
     269             :     uint32      count[FAST_PATH_STRONG_LOCK_HASH_PARTITIONS];
     270             : } FastPathStrongRelationLockData;
     271             : 
     272             : static volatile FastPathStrongRelationLockData *FastPathStrongRelationLocks;
     273             : 
     274             : 
     275             : /*
     276             :  * Pointers to hash tables containing lock state
     277             :  *
     278             :  * The LockMethodLockHash and LockMethodProcLockHash hash tables are in
     279             :  * shared memory; LockMethodLocalHash is local to each backend.
     280             :  */
     281             : static HTAB *LockMethodLockHash;
     282             : static HTAB *LockMethodProcLockHash;
     283             : static HTAB *LockMethodLocalHash;
     284             : 
     285             : 
     286             : /* private state for error cleanup */
     287             : static LOCALLOCK *StrongLockInProgress;
     288             : static LOCALLOCK *awaitedLock;
     289             : static ResourceOwner awaitedOwner;
     290             : 
     291             : 
     292             : #ifdef LOCK_DEBUG
     293             : 
     294             : /*------
     295             :  * The following configuration options are available for lock debugging:
     296             :  *
     297             :  *     TRACE_LOCKS      -- give a bunch of output what's going on in this file
     298             :  *     TRACE_USERLOCKS  -- same but for user locks
     299             :  *     TRACE_LOCK_OIDMIN-- do not trace locks for tables below this oid
     300             :  *                         (use to avoid output on system tables)
     301             :  *     TRACE_LOCK_TABLE -- trace locks on this table (oid) unconditionally
     302             :  *     DEBUG_DEADLOCKS  -- currently dumps locks at untimely occasions ;)
     303             :  *
     304             :  * Furthermore, but in storage/lmgr/lwlock.c:
     305             :  *     TRACE_LWLOCKS    -- trace lightweight locks (pretty useless)
     306             :  *
     307             :  * Define LOCK_DEBUG at compile time to get all these enabled.
     308             :  * --------
     309             :  */
     310             : 
     311             : int         Trace_lock_oidmin = FirstNormalObjectId;
     312             : bool        Trace_locks = false;
     313             : bool        Trace_userlocks = false;
     314             : int         Trace_lock_table = 0;
     315             : bool        Debug_deadlocks = false;
     316             : 
     317             : 
     318             : inline static bool
     319             : LOCK_DEBUG_ENABLED(const LOCKTAG *tag)
     320             : {
     321             :     return
     322             :         (*(LockMethods[tag->locktag_lockmethodid]->trace_flag) &&
     323             :          ((Oid) tag->locktag_field2 >= (Oid) Trace_lock_oidmin))
     324             :         || (Trace_lock_table &&
     325             :             (tag->locktag_field2 == Trace_lock_table));
     326             : }
     327             : 
     328             : 
     329             : inline static void
     330             : LOCK_PRINT(const char *where, const LOCK *lock, LOCKMODE type)
     331             : {
     332             :     if (LOCK_DEBUG_ENABLED(&lock->tag))
     333             :         elog(LOG,
     334             :              "%s: lock(%p) id(%u,%u,%u,%u,%u,%u) grantMask(%x) "
     335             :              "req(%d,%d,%d,%d,%d,%d,%d)=%d "
     336             :              "grant(%d,%d,%d,%d,%d,%d,%d)=%d wait(%d) type(%s)",
     337             :              where, lock,
     338             :              lock->tag.locktag_field1, lock->tag.locktag_field2,
     339             :              lock->tag.locktag_field3, lock->tag.locktag_field4,
     340             :              lock->tag.locktag_type, lock->tag.locktag_lockmethodid,
     341             :              lock->grantMask,
     342             :              lock->requested[1], lock->requested[2], lock->requested[3],
     343             :              lock->requested[4], lock->requested[5], lock->requested[6],
     344             :              lock->requested[7], lock->nRequested,
     345             :              lock->granted[1], lock->granted[2], lock->granted[3],
     346             :              lock->granted[4], lock->granted[5], lock->granted[6],
     347             :              lock->granted[7], lock->nGranted,
     348             :              dclist_count(&lock->waitProcs),
     349             :              LockMethods[LOCK_LOCKMETHOD(*lock)]->lockModeNames[type]);
     350             : }
     351             : 
     352             : 
     353             : inline static void
     354             : PROCLOCK_PRINT(const char *where, const PROCLOCK *proclockP)
     355             : {
     356             :     if (LOCK_DEBUG_ENABLED(&proclockP->tag.myLock->tag))
     357             :         elog(LOG,
     358             :              "%s: proclock(%p) lock(%p) method(%u) proc(%p) hold(%x)",
     359             :              where, proclockP, proclockP->tag.myLock,
     360             :              PROCLOCK_LOCKMETHOD(*(proclockP)),
     361             :              proclockP->tag.myProc, (int) proclockP->holdMask);
     362             : }
     363             : #else                           /* not LOCK_DEBUG */
     364             : 
     365             : #define LOCK_PRINT(where, lock, type)  ((void) 0)
     366             : #define PROCLOCK_PRINT(where, proclockP)  ((void) 0)
     367             : #endif                          /* not LOCK_DEBUG */
     368             : 
     369             : 
     370             : static uint32 proclock_hash(const void *key, Size keysize);
     371             : static void RemoveLocalLock(LOCALLOCK *locallock);
     372             : static PROCLOCK *SetupLockInTable(LockMethod lockMethodTable, PGPROC *proc,
     373             :                                   const LOCKTAG *locktag, uint32 hashcode, LOCKMODE lockmode);
     374             : static void GrantLockLocal(LOCALLOCK *locallock, ResourceOwner owner);
     375             : static void BeginStrongLockAcquire(LOCALLOCK *locallock, uint32 fasthashcode);
     376             : static void FinishStrongLockAcquire(void);
     377             : static void WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner);
     378             : static void ReleaseLockIfHeld(LOCALLOCK *locallock, bool sessionLock);
     379             : static void LockReassignOwner(LOCALLOCK *locallock, ResourceOwner parent);
     380             : static bool UnGrantLock(LOCK *lock, LOCKMODE lockmode,
     381             :                         PROCLOCK *proclock, LockMethod lockMethodTable);
     382             : static void CleanUpLock(LOCK *lock, PROCLOCK *proclock,
     383             :                         LockMethod lockMethodTable, uint32 hashcode,
     384             :                         bool wakeupNeeded);
     385             : static void LockRefindAndRelease(LockMethod lockMethodTable, PGPROC *proc,
     386             :                                  LOCKTAG *locktag, LOCKMODE lockmode,
     387             :                                  bool decrement_strong_lock_count);
     388             : static void GetSingleProcBlockerStatusData(PGPROC *blocked_proc,
     389             :                                            BlockedProcsData *data);
     390             : 
     391             : 
     392             : /*
     393             :  * InitLocks -- Initialize the lock manager's data structures.
     394             :  *
     395             :  * This is called from CreateSharedMemoryAndSemaphores(), which see for
     396             :  * more comments.  In the normal postmaster case, the shared hash tables
     397             :  * are created here, as well as a locallock hash table that will remain
     398             :  * unused and empty in the postmaster itself.  Backends inherit the pointers
     399             :  * to the shared tables via fork(), and also inherit an image of the locallock
     400             :  * hash table, which they proceed to use.  In the EXEC_BACKEND case, each
     401             :  * backend re-executes this code to obtain pointers to the already existing
     402             :  * shared hash tables and to create its locallock hash table.
     403             :  */
     404             : void
     405        3456 : InitLocks(void)
     406             : {
     407             :     HASHCTL     info;
     408             :     long        init_table_size,
     409             :                 max_table_size;
     410             :     bool        found;
     411             : 
     412             :     /*
     413             :      * Compute init/max size to request for lock hashtables.  Note these
     414             :      * calculations must agree with LockShmemSize!
     415             :      */
     416        3456 :     max_table_size = NLOCKENTS();
     417        3456 :     init_table_size = max_table_size / 2;
     418             : 
     419             :     /*
     420             :      * Allocate hash table for LOCK structs.  This stores per-locked-object
     421             :      * information.
     422             :      */
     423        3456 :     info.keysize = sizeof(LOCKTAG);
     424        3456 :     info.entrysize = sizeof(LOCK);
     425        3456 :     info.num_partitions = NUM_LOCK_PARTITIONS;
     426             : 
     427        3456 :     LockMethodLockHash = ShmemInitHash("LOCK hash",
     428             :                                        init_table_size,
     429             :                                        max_table_size,
     430             :                                        &info,
     431             :                                        HASH_ELEM | HASH_BLOBS | HASH_PARTITION);
     432             : 
     433             :     /* Assume an average of 2 holders per lock */
     434        3456 :     max_table_size *= 2;
     435        3456 :     init_table_size *= 2;
     436             : 
     437             :     /*
     438             :      * Allocate hash table for PROCLOCK structs.  This stores
     439             :      * per-lock-per-holder information.
     440             :      */
     441        3456 :     info.keysize = sizeof(PROCLOCKTAG);
     442        3456 :     info.entrysize = sizeof(PROCLOCK);
     443        3456 :     info.hash = proclock_hash;
     444        3456 :     info.num_partitions = NUM_LOCK_PARTITIONS;
     445             : 
     446        3456 :     LockMethodProcLockHash = ShmemInitHash("PROCLOCK hash",
     447             :                                            init_table_size,
     448             :                                            max_table_size,
     449             :                                            &info,
     450             :                                            HASH_ELEM | HASH_FUNCTION | HASH_PARTITION);
     451             : 
     452             :     /*
     453             :      * Allocate fast-path structures.
     454             :      */
     455        3456 :     FastPathStrongRelationLocks =
     456        3456 :         ShmemInitStruct("Fast Path Strong Relation Lock Data",
     457             :                         sizeof(FastPathStrongRelationLockData), &found);
     458        3456 :     if (!found)
     459        3456 :         SpinLockInit(&FastPathStrongRelationLocks->mutex);
     460             : 
     461             :     /*
     462             :      * Allocate non-shared hash table for LOCALLOCK structs.  This stores lock
     463             :      * counts and resource owner information.
     464             :      *
     465             :      * The non-shared table could already exist in this process (this occurs
     466             :      * when the postmaster is recreating shared memory after a backend crash).
     467             :      * If so, delete and recreate it.  (We could simply leave it, since it
     468             :      * ought to be empty in the postmaster, but for safety let's zap it.)
     469             :      */
     470        3456 :     if (LockMethodLocalHash)
     471           8 :         hash_destroy(LockMethodLocalHash);
     472             : 
     473        3456 :     info.keysize = sizeof(LOCALLOCKTAG);
     474        3456 :     info.entrysize = sizeof(LOCALLOCK);
     475             : 
     476        3456 :     LockMethodLocalHash = hash_create("LOCALLOCK hash",
     477             :                                       16,
     478             :                                       &info,
     479             :                                       HASH_ELEM | HASH_BLOBS);
     480        3456 : }
     481             : 
     482             : 
     483             : /*
     484             :  * Fetch the lock method table associated with a given lock
     485             :  */
     486             : LockMethod
     487         180 : GetLocksMethodTable(const LOCK *lock)
     488             : {
     489         180 :     LOCKMETHODID lockmethodid = LOCK_LOCKMETHOD(*lock);
     490             : 
     491             :     Assert(0 < lockmethodid && lockmethodid < lengthof(LockMethods));
     492         180 :     return LockMethods[lockmethodid];
     493             : }
     494             : 
     495             : /*
     496             :  * Fetch the lock method table associated with a given locktag
     497             :  */
     498             : LockMethod
     499        2178 : GetLockTagsMethodTable(const LOCKTAG *locktag)
     500             : {
     501        2178 :     LOCKMETHODID lockmethodid = (LOCKMETHODID) locktag->locktag_lockmethodid;
     502             : 
     503             :     Assert(0 < lockmethodid && lockmethodid < lengthof(LockMethods));
     504        2178 :     return LockMethods[lockmethodid];
     505             : }
     506             : 
     507             : 
     508             : /*
     509             :  * Compute the hash code associated with a LOCKTAG.
     510             :  *
     511             :  * To avoid unnecessary recomputations of the hash code, we try to do this
     512             :  * just once per function, and then pass it around as needed.  Aside from
     513             :  * passing the hashcode to hash_search_with_hash_value(), we can extract
     514             :  * the lock partition number from the hashcode.
     515             :  */
     516             : uint32
     517    43019478 : LockTagHashCode(const LOCKTAG *locktag)
     518             : {
     519    43019478 :     return get_hash_value(LockMethodLockHash, (const void *) locktag);
     520             : }
     521             : 
     522             : /*
     523             :  * Compute the hash code associated with a PROCLOCKTAG.
     524             :  *
     525             :  * Because we want to use just one set of partition locks for both the
     526             :  * LOCK and PROCLOCK hash tables, we have to make sure that PROCLOCKs
     527             :  * fall into the same partition number as their associated LOCKs.
     528             :  * dynahash.c expects the partition number to be the low-order bits of
     529             :  * the hash code, and therefore a PROCLOCKTAG's hash code must have the
     530             :  * same low-order bits as the associated LOCKTAG's hash code.  We achieve
     531             :  * this with this specialized hash function.
     532             :  */
     533             : static uint32
     534        1612 : proclock_hash(const void *key, Size keysize)
     535             : {
     536        1612 :     const PROCLOCKTAG *proclocktag = (const PROCLOCKTAG *) key;
     537             :     uint32      lockhash;
     538             :     Datum       procptr;
     539             : 
     540             :     Assert(keysize == sizeof(PROCLOCKTAG));
     541             : 
     542             :     /* Look into the associated LOCK object, and compute its hash code */
     543        1612 :     lockhash = LockTagHashCode(&proclocktag->myLock->tag);
     544             : 
     545             :     /*
     546             :      * To make the hash code also depend on the PGPROC, we xor the proc
     547             :      * struct's address into the hash code, left-shifted so that the
     548             :      * partition-number bits don't change.  Since this is only a hash, we
     549             :      * don't care if we lose high-order bits of the address; use an
     550             :      * intermediate variable to suppress cast-pointer-to-int warnings.
     551             :      */
     552        1612 :     procptr = PointerGetDatum(proclocktag->myProc);
     553        1612 :     lockhash ^= ((uint32) procptr) << LOG2_NUM_LOCK_PARTITIONS;
     554             : 
     555        1612 :     return lockhash;
     556             : }
     557             : 
     558             : /*
     559             :  * Compute the hash code associated with a PROCLOCKTAG, given the hashcode
     560             :  * for its underlying LOCK.
     561             :  *
     562             :  * We use this just to avoid redundant calls of LockTagHashCode().
     563             :  */
     564             : static inline uint32
     565     9019384 : ProcLockHashCode(const PROCLOCKTAG *proclocktag, uint32 hashcode)
     566             : {
     567     9019384 :     uint32      lockhash = hashcode;
     568             :     Datum       procptr;
     569             : 
     570             :     /*
     571             :      * This must match proclock_hash()!
     572             :      */
     573     9019384 :     procptr = PointerGetDatum(proclocktag->myProc);
     574     9019384 :     lockhash ^= ((uint32) procptr) << LOG2_NUM_LOCK_PARTITIONS;
     575             : 
     576     9019384 :     return lockhash;
     577             : }
     578             : 
     579             : /*
     580             :  * Given two lock modes, return whether they would conflict.
     581             :  */
     582             : bool
     583         416 : DoLockModesConflict(LOCKMODE mode1, LOCKMODE mode2)
     584             : {
     585         416 :     LockMethod  lockMethodTable = LockMethods[DEFAULT_LOCKMETHOD];
     586             : 
     587         416 :     if (lockMethodTable->conflictTab[mode1] & LOCKBIT_ON(mode2))
     588         244 :         return true;
     589             : 
     590         172 :     return false;
     591             : }
     592             : 
     593             : /*
     594             :  * LockHeldByMe -- test whether lock 'locktag' is held with mode 'lockmode'
     595             :  *      by the current transaction
     596             :  */
     597             : bool
     598           0 : LockHeldByMe(const LOCKTAG *locktag, LOCKMODE lockmode)
     599             : {
     600             :     LOCALLOCKTAG localtag;
     601             :     LOCALLOCK  *locallock;
     602             : 
     603             :     /*
     604             :      * See if there is a LOCALLOCK entry for this lock and lockmode
     605             :      */
     606           0 :     MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
     607           0 :     localtag.lock = *locktag;
     608           0 :     localtag.mode = lockmode;
     609             : 
     610           0 :     locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
     611             :                                           &localtag,
     612             :                                           HASH_FIND, NULL);
     613             : 
     614           0 :     return (locallock && locallock->nLocks > 0);
     615             : }
     616             : 
     617             : #ifdef USE_ASSERT_CHECKING
     618             : /*
     619             :  * GetLockMethodLocalHash -- return the hash of local locks, for modules that
     620             :  *      evaluate assertions based on all locks held.
     621             :  */
     622             : HTAB *
     623             : GetLockMethodLocalHash(void)
     624             : {
     625             :     return LockMethodLocalHash;
     626             : }
     627             : #endif
     628             : 
     629             : /*
     630             :  * LockHasWaiters -- look up 'locktag' and check if releasing this
     631             :  *      lock would wake up other processes waiting for it.
     632             :  */
     633             : bool
     634           0 : LockHasWaiters(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
     635             : {
     636           0 :     LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
     637             :     LockMethod  lockMethodTable;
     638             :     LOCALLOCKTAG localtag;
     639             :     LOCALLOCK  *locallock;
     640             :     LOCK       *lock;
     641             :     PROCLOCK   *proclock;
     642             :     LWLock     *partitionLock;
     643           0 :     bool        hasWaiters = false;
     644             : 
     645           0 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
     646           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
     647           0 :     lockMethodTable = LockMethods[lockmethodid];
     648           0 :     if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
     649           0 :         elog(ERROR, "unrecognized lock mode: %d", lockmode);
     650             : 
     651             : #ifdef LOCK_DEBUG
     652             :     if (LOCK_DEBUG_ENABLED(locktag))
     653             :         elog(LOG, "LockHasWaiters: lock [%u,%u] %s",
     654             :              locktag->locktag_field1, locktag->locktag_field2,
     655             :              lockMethodTable->lockModeNames[lockmode]);
     656             : #endif
     657             : 
     658             :     /*
     659             :      * Find the LOCALLOCK entry for this lock and lockmode
     660             :      */
     661           0 :     MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
     662           0 :     localtag.lock = *locktag;
     663           0 :     localtag.mode = lockmode;
     664             : 
     665           0 :     locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
     666             :                                           &localtag,
     667             :                                           HASH_FIND, NULL);
     668             : 
     669             :     /*
     670             :      * let the caller print its own error message, too. Do not ereport(ERROR).
     671             :      */
     672           0 :     if (!locallock || locallock->nLocks <= 0)
     673             :     {
     674           0 :         elog(WARNING, "you don't own a lock of type %s",
     675             :              lockMethodTable->lockModeNames[lockmode]);
     676           0 :         return false;
     677             :     }
     678             : 
     679             :     /*
     680             :      * Check the shared lock table.
     681             :      */
     682           0 :     partitionLock = LockHashPartitionLock(locallock->hashcode);
     683             : 
     684           0 :     LWLockAcquire(partitionLock, LW_SHARED);
     685             : 
     686             :     /*
     687             :      * We don't need to re-find the lock or proclock, since we kept their
     688             :      * addresses in the locallock table, and they couldn't have been removed
     689             :      * while we were holding a lock on them.
     690             :      */
     691           0 :     lock = locallock->lock;
     692             :     LOCK_PRINT("LockHasWaiters: found", lock, lockmode);
     693           0 :     proclock = locallock->proclock;
     694             :     PROCLOCK_PRINT("LockHasWaiters: found", proclock);
     695             : 
     696             :     /*
     697             :      * Double-check that we are actually holding a lock of the type we want to
     698             :      * release.
     699             :      */
     700           0 :     if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
     701             :     {
     702             :         PROCLOCK_PRINT("LockHasWaiters: WRONGTYPE", proclock);
     703           0 :         LWLockRelease(partitionLock);
     704           0 :         elog(WARNING, "you don't own a lock of type %s",
     705             :              lockMethodTable->lockModeNames[lockmode]);
     706           0 :         RemoveLocalLock(locallock);
     707           0 :         return false;
     708             :     }
     709             : 
     710             :     /*
     711             :      * Do the checking.
     712             :      */
     713           0 :     if ((lockMethodTable->conflictTab[lockmode] & lock->waitMask) != 0)
     714           0 :         hasWaiters = true;
     715             : 
     716           0 :     LWLockRelease(partitionLock);
     717             : 
     718           0 :     return hasWaiters;
     719             : }
     720             : 
     721             : /*
     722             :  * LockAcquire -- Check for lock conflicts, sleep if conflict found,
     723             :  *      set lock if/when no conflicts.
     724             :  *
     725             :  * Inputs:
     726             :  *  locktag: unique identifier for the lockable object
     727             :  *  lockmode: lock mode to acquire
     728             :  *  sessionLock: if true, acquire lock for session not current transaction
     729             :  *  dontWait: if true, don't wait to acquire lock
     730             :  *
     731             :  * Returns one of:
     732             :  *      LOCKACQUIRE_NOT_AVAIL       lock not available, and dontWait=true
     733             :  *      LOCKACQUIRE_OK              lock successfully acquired
     734             :  *      LOCKACQUIRE_ALREADY_HELD    incremented count for lock already held
     735             :  *      LOCKACQUIRE_ALREADY_CLEAR   incremented count for lock already clear
     736             :  *
     737             :  * In the normal case where dontWait=false and the caller doesn't need to
     738             :  * distinguish a freshly acquired lock from one already taken earlier in
     739             :  * this same transaction, there is no need to examine the return value.
     740             :  *
     741             :  * Side Effects: The lock is acquired and recorded in lock tables.
     742             :  *
     743             :  * NOTE: if we wait for the lock, there is no way to abort the wait
     744             :  * short of aborting the transaction.
     745             :  */
     746             : LockAcquireResult
     747     1541356 : LockAcquire(const LOCKTAG *locktag,
     748             :             LOCKMODE lockmode,
     749             :             bool sessionLock,
     750             :             bool dontWait)
     751             : {
     752     1541356 :     return LockAcquireExtended(locktag, lockmode, sessionLock, dontWait,
     753             :                                true, NULL);
     754             : }
     755             : 
     756             : /*
     757             :  * LockAcquireExtended - allows us to specify additional options
     758             :  *
     759             :  * reportMemoryError specifies whether a lock request that fills the lock
     760             :  * table should generate an ERROR or not.  Passing "false" allows the caller
     761             :  * to attempt to recover from lock-table-full situations, perhaps by forcibly
     762             :  * canceling other lock holders and then retrying.  Note, however, that the
     763             :  * return code for that is LOCKACQUIRE_NOT_AVAIL, so that it's unsafe to use
     764             :  * in combination with dontWait = true, as the cause of failure couldn't be
     765             :  * distinguished.
     766             :  *
     767             :  * If locallockp isn't NULL, *locallockp receives a pointer to the LOCALLOCK
     768             :  * table entry if a lock is successfully acquired, or NULL if not.
     769             :  */
     770             : LockAcquireResult
     771    44879958 : LockAcquireExtended(const LOCKTAG *locktag,
     772             :                     LOCKMODE lockmode,
     773             :                     bool sessionLock,
     774             :                     bool dontWait,
     775             :                     bool reportMemoryError,
     776             :                     LOCALLOCK **locallockp)
     777             : {
     778    44879958 :     LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
     779             :     LockMethod  lockMethodTable;
     780             :     LOCALLOCKTAG localtag;
     781             :     LOCALLOCK  *locallock;
     782             :     LOCK       *lock;
     783             :     PROCLOCK   *proclock;
     784             :     bool        found;
     785             :     ResourceOwner owner;
     786             :     uint32      hashcode;
     787             :     LWLock     *partitionLock;
     788             :     bool        found_conflict;
     789    44879958 :     bool        log_lock = false;
     790             : 
     791    44879958 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
     792           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
     793    44879958 :     lockMethodTable = LockMethods[lockmethodid];
     794    44879958 :     if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
     795           0 :         elog(ERROR, "unrecognized lock mode: %d", lockmode);
     796             : 
     797    44879958 :     if (RecoveryInProgress() && !InRecovery &&
     798      283920 :         (locktag->locktag_type == LOCKTAG_OBJECT ||
     799      283920 :          locktag->locktag_type == LOCKTAG_RELATION) &&
     800             :         lockmode > RowExclusiveLock)
     801           0 :         ereport(ERROR,
     802             :                 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
     803             :                  errmsg("cannot acquire lock mode %s on database objects while recovery is in progress",
     804             :                         lockMethodTable->lockModeNames[lockmode]),
     805             :                  errhint("Only RowExclusiveLock or less can be acquired on database objects during recovery.")));
     806             : 
     807             : #ifdef LOCK_DEBUG
     808             :     if (LOCK_DEBUG_ENABLED(locktag))
     809             :         elog(LOG, "LockAcquire: lock [%u,%u] %s",
     810             :              locktag->locktag_field1, locktag->locktag_field2,
     811             :              lockMethodTable->lockModeNames[lockmode]);
     812             : #endif
     813             : 
     814             :     /* Identify owner for lock */
     815    44879958 :     if (sessionLock)
     816      111786 :         owner = NULL;
     817             :     else
     818    44768172 :         owner = CurrentResourceOwner;
     819             : 
     820             :     /*
     821             :      * Find or create a LOCALLOCK entry for this lock and lockmode
     822             :      */
     823    44879958 :     MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
     824    44879958 :     localtag.lock = *locktag;
     825    44879958 :     localtag.mode = lockmode;
     826             : 
     827    44879958 :     locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
     828             :                                           &localtag,
     829             :                                           HASH_ENTER, &found);
     830             : 
     831             :     /*
     832             :      * if it's a new locallock object, initialize it
     833             :      */
     834    44879958 :     if (!found)
     835             :     {
     836    41434366 :         locallock->lock = NULL;
     837    41434366 :         locallock->proclock = NULL;
     838    41434366 :         locallock->hashcode = LockTagHashCode(&(localtag.lock));
     839    41434366 :         locallock->nLocks = 0;
     840    41434366 :         locallock->holdsStrongLockCount = false;
     841    41434366 :         locallock->lockCleared = false;
     842    41434366 :         locallock->numLockOwners = 0;
     843    41434366 :         locallock->maxLockOwners = 8;
     844    41434366 :         locallock->lockOwners = NULL;    /* in case next line fails */
     845    41434366 :         locallock->lockOwners = (LOCALLOCKOWNER *)
     846    41434366 :             MemoryContextAlloc(TopMemoryContext,
     847    41434366 :                                locallock->maxLockOwners * sizeof(LOCALLOCKOWNER));
     848             :     }
     849             :     else
     850             :     {
     851             :         /* Make sure there will be room to remember the lock */
     852     3445592 :         if (locallock->numLockOwners >= locallock->maxLockOwners)
     853             :         {
     854          38 :             int         newsize = locallock->maxLockOwners * 2;
     855             : 
     856          38 :             locallock->lockOwners = (LOCALLOCKOWNER *)
     857          38 :                 repalloc(locallock->lockOwners,
     858             :                          newsize * sizeof(LOCALLOCKOWNER));
     859          38 :             locallock->maxLockOwners = newsize;
     860             :         }
     861             :     }
     862    44879958 :     hashcode = locallock->hashcode;
     863             : 
     864    44879958 :     if (locallockp)
     865    43338602 :         *locallockp = locallock;
     866             : 
     867             :     /*
     868             :      * If we already hold the lock, we can just increase the count locally.
     869             :      *
     870             :      * If lockCleared is already set, caller need not worry about absorbing
     871             :      * sinval messages related to the lock's object.
     872             :      */
     873    44879958 :     if (locallock->nLocks > 0)
     874             :     {
     875     3445592 :         GrantLockLocal(locallock, owner);
     876     3445592 :         if (locallock->lockCleared)
     877     3248942 :             return LOCKACQUIRE_ALREADY_CLEAR;
     878             :         else
     879      196650 :             return LOCKACQUIRE_ALREADY_HELD;
     880             :     }
     881             : 
     882             :     /*
     883             :      * We don't acquire any other heavyweight lock while holding the relation
     884             :      * extension lock.  We do allow to acquire the same relation extension
     885             :      * lock more than once but that case won't reach here.
     886             :      */
     887             :     Assert(!IsRelationExtensionLockHeld);
     888             : 
     889             :     /*
     890             :      * We don't acquire any other heavyweight lock while holding the page lock
     891             :      * except for relation extension.
     892             :      */
     893             :     Assert(!IsPageLockHeld ||
     894             :            (locktag->locktag_type == LOCKTAG_RELATION_EXTEND));
     895             : 
     896             :     /*
     897             :      * Prepare to emit a WAL record if acquisition of this lock needs to be
     898             :      * replayed in a standby server.
     899             :      *
     900             :      * Here we prepare to log; after lock is acquired we'll issue log record.
     901             :      * This arrangement simplifies error recovery in case the preparation step
     902             :      * fails.
     903             :      *
     904             :      * Only AccessExclusiveLocks can conflict with lock types that read-only
     905             :      * transactions can acquire in a standby server. Make sure this definition
     906             :      * matches the one in GetRunningTransactionLocks().
     907             :      */
     908    41434366 :     if (lockmode >= AccessExclusiveLock &&
     909      570842 :         locktag->locktag_type == LOCKTAG_RELATION &&
     910      461498 :         !RecoveryInProgress() &&
     911      424352 :         XLogStandbyInfoActive())
     912             :     {
     913      378290 :         LogAccessExclusiveLockPrepare();
     914      378290 :         log_lock = true;
     915             :     }
     916             : 
     917             :     /*
     918             :      * Attempt to take lock via fast path, if eligible.  But if we remember
     919             :      * having filled up the fast path array, we don't attempt to make any
     920             :      * further use of it until we release some locks.  It's possible that some
     921             :      * other backend has transferred some of those locks to the shared hash
     922             :      * table, leaving space free, but it's not worth acquiring the LWLock just
     923             :      * to check.  It's also possible that we're acquiring a second or third
     924             :      * lock type on a relation we have already locked using the fast-path, but
     925             :      * for now we don't worry about that case either.
     926             :      */
     927    41434366 :     if (EligibleForRelationFastPath(locktag, lockmode) &&
     928    37835992 :         FastPathLocalUseCount < FP_LOCK_SLOTS_PER_BACKEND)
     929             :     {
     930    37402984 :         uint32      fasthashcode = FastPathStrongLockHashPartition(hashcode);
     931             :         bool        acquired;
     932             : 
     933             :         /*
     934             :          * LWLockAcquire acts as a memory sequencing point, so it's safe to
     935             :          * assume that any strong locker whose increment to
     936             :          * FastPathStrongRelationLocks->counts becomes visible after we test
     937             :          * it has yet to begin to transfer fast-path locks.
     938             :          */
     939    37402984 :         LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
     940    37402984 :         if (FastPathStrongRelationLocks->count[fasthashcode] != 0)
     941      951702 :             acquired = false;
     942             :         else
     943    36451282 :             acquired = FastPathGrantRelationLock(locktag->locktag_field2,
     944             :                                                  lockmode);
     945    37402984 :         LWLockRelease(&MyProc->fpInfoLock);
     946    37402984 :         if (acquired)
     947             :         {
     948             :             /*
     949             :              * The locallock might contain stale pointers to some old shared
     950             :              * objects; we MUST reset these to null before considering the
     951             :              * lock to be acquired via fast-path.
     952             :              */
     953    36451282 :             locallock->lock = NULL;
     954    36451282 :             locallock->proclock = NULL;
     955    36451282 :             GrantLockLocal(locallock, owner);
     956    36451282 :             return LOCKACQUIRE_OK;
     957             :         }
     958             :     }
     959             : 
     960             :     /*
     961             :      * If this lock could potentially have been taken via the fast-path by
     962             :      * some other backend, we must (temporarily) disable further use of the
     963             :      * fast-path for this lock tag, and migrate any locks already taken via
     964             :      * this method to the main lock table.
     965             :      */
     966     4983084 :     if (ConflictsWithRelationFastPath(locktag, lockmode))
     967             :     {
     968      522042 :         uint32      fasthashcode = FastPathStrongLockHashPartition(hashcode);
     969             : 
     970      522042 :         BeginStrongLockAcquire(locallock, fasthashcode);
     971      522042 :         if (!FastPathTransferRelationLocks(lockMethodTable, locktag,
     972             :                                            hashcode))
     973             :         {
     974           0 :             AbortStrongLockAcquire();
     975           0 :             if (locallock->nLocks == 0)
     976           0 :                 RemoveLocalLock(locallock);
     977           0 :             if (locallockp)
     978           0 :                 *locallockp = NULL;
     979           0 :             if (reportMemoryError)
     980           0 :                 ereport(ERROR,
     981             :                         (errcode(ERRCODE_OUT_OF_MEMORY),
     982             :                          errmsg("out of shared memory"),
     983             :                          errhint("You might need to increase max_locks_per_transaction.")));
     984             :             else
     985           0 :                 return LOCKACQUIRE_NOT_AVAIL;
     986             :         }
     987             :     }
     988             : 
     989             :     /*
     990             :      * We didn't find the lock in our LOCALLOCK table, and we didn't manage to
     991             :      * take it via the fast-path, either, so we've got to mess with the shared
     992             :      * lock table.
     993             :      */
     994     4983084 :     partitionLock = LockHashPartitionLock(hashcode);
     995             : 
     996     4983084 :     LWLockAcquire(partitionLock, LW_EXCLUSIVE);
     997             : 
     998             :     /*
     999             :      * Find or create lock and proclock entries with this tag
    1000             :      *
    1001             :      * Note: if the locallock object already existed, it might have a pointer
    1002             :      * to the lock already ... but we should not assume that that pointer is
    1003             :      * valid, since a lock object with zero hold and request counts can go
    1004             :      * away anytime.  So we have to use SetupLockInTable() to recompute the
    1005             :      * lock and proclock pointers, even if they're already set.
    1006             :      */
    1007     4983084 :     proclock = SetupLockInTable(lockMethodTable, MyProc, locktag,
    1008             :                                 hashcode, lockmode);
    1009     4983084 :     if (!proclock)
    1010             :     {
    1011           0 :         AbortStrongLockAcquire();
    1012           0 :         LWLockRelease(partitionLock);
    1013           0 :         if (locallock->nLocks == 0)
    1014           0 :             RemoveLocalLock(locallock);
    1015           0 :         if (locallockp)
    1016           0 :             *locallockp = NULL;
    1017           0 :         if (reportMemoryError)
    1018           0 :             ereport(ERROR,
    1019             :                     (errcode(ERRCODE_OUT_OF_MEMORY),
    1020             :                      errmsg("out of shared memory"),
    1021             :                      errhint("You might need to increase max_locks_per_transaction.")));
    1022             :         else
    1023           0 :             return LOCKACQUIRE_NOT_AVAIL;
    1024             :     }
    1025     4983084 :     locallock->proclock = proclock;
    1026     4983084 :     lock = proclock->tag.myLock;
    1027     4983084 :     locallock->lock = lock;
    1028             : 
    1029             :     /*
    1030             :      * If lock requested conflicts with locks requested by waiters, must join
    1031             :      * wait queue.  Otherwise, check for conflict with already-held locks.
    1032             :      * (That's last because most complex check.)
    1033             :      */
    1034     4983084 :     if (lockMethodTable->conflictTab[lockmode] & lock->waitMask)
    1035          92 :         found_conflict = true;
    1036             :     else
    1037     4982992 :         found_conflict = LockCheckConflicts(lockMethodTable, lockmode,
    1038             :                                             lock, proclock);
    1039             : 
    1040     4983084 :     if (!found_conflict)
    1041             :     {
    1042             :         /* No conflict with held or previously requested locks */
    1043     4979676 :         GrantLock(lock, proclock, lockmode);
    1044     4979676 :         GrantLockLocal(locallock, owner);
    1045             :     }
    1046             :     else
    1047             :     {
    1048             :         /*
    1049             :          * We can't acquire the lock immediately.  If caller specified no
    1050             :          * blocking, remove useless table entries and return
    1051             :          * LOCKACQUIRE_NOT_AVAIL without waiting.
    1052             :          */
    1053        3408 :         if (dontWait)
    1054             :         {
    1055        1412 :             AbortStrongLockAcquire();
    1056        1412 :             if (proclock->holdMask == 0)
    1057             :             {
    1058             :                 uint32      proclock_hashcode;
    1059             : 
    1060        1004 :                 proclock_hashcode = ProcLockHashCode(&proclock->tag, hashcode);
    1061        1004 :                 dlist_delete(&proclock->lockLink);
    1062        1004 :                 dlist_delete(&proclock->procLink);
    1063        1004 :                 if (!hash_search_with_hash_value(LockMethodProcLockHash,
    1064        1004 :                                                  &(proclock->tag),
    1065             :                                                  proclock_hashcode,
    1066             :                                                  HASH_REMOVE,
    1067             :                                                  NULL))
    1068           0 :                     elog(PANIC, "proclock table corrupted");
    1069             :             }
    1070             :             else
    1071             :                 PROCLOCK_PRINT("LockAcquire: NOWAIT", proclock);
    1072        1412 :             lock->nRequested--;
    1073        1412 :             lock->requested[lockmode]--;
    1074             :             LOCK_PRINT("LockAcquire: conditional lock failed", lock, lockmode);
    1075             :             Assert((lock->nRequested > 0) && (lock->requested[lockmode] >= 0));
    1076             :             Assert(lock->nGranted <= lock->nRequested);
    1077        1412 :             LWLockRelease(partitionLock);
    1078        1412 :             if (locallock->nLocks == 0)
    1079        1412 :                 RemoveLocalLock(locallock);
    1080        1412 :             if (locallockp)
    1081         452 :                 *locallockp = NULL;
    1082        1412 :             return LOCKACQUIRE_NOT_AVAIL;
    1083             :         }
    1084             : 
    1085             :         /*
    1086             :          * Set bitmask of locks this process already holds on this object.
    1087             :          */
    1088        1996 :         MyProc->heldLocks = proclock->holdMask;
    1089             : 
    1090             :         /*
    1091             :          * Sleep till someone wakes me up.
    1092             :          */
    1093             : 
    1094             :         TRACE_POSTGRESQL_LOCK_WAIT_START(locktag->locktag_field1,
    1095             :                                          locktag->locktag_field2,
    1096             :                                          locktag->locktag_field3,
    1097             :                                          locktag->locktag_field4,
    1098             :                                          locktag->locktag_type,
    1099             :                                          lockmode);
    1100             : 
    1101        1996 :         WaitOnLock(locallock, owner);
    1102             : 
    1103             :         TRACE_POSTGRESQL_LOCK_WAIT_DONE(locktag->locktag_field1,
    1104             :                                         locktag->locktag_field2,
    1105             :                                         locktag->locktag_field3,
    1106             :                                         locktag->locktag_field4,
    1107             :                                         locktag->locktag_type,
    1108             :                                         lockmode);
    1109             : 
    1110             :         /*
    1111             :          * NOTE: do not do any material change of state between here and
    1112             :          * return.  All required changes in locktable state must have been
    1113             :          * done when the lock was granted to us --- see notes in WaitOnLock.
    1114             :          */
    1115             : 
    1116             :         /*
    1117             :          * Check the proclock entry status, in case something in the ipc
    1118             :          * communication doesn't work correctly.
    1119             :          */
    1120        1904 :         if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
    1121             :         {
    1122           0 :             AbortStrongLockAcquire();
    1123             :             PROCLOCK_PRINT("LockAcquire: INCONSISTENT", proclock);
    1124             :             LOCK_PRINT("LockAcquire: INCONSISTENT", lock, lockmode);
    1125             :             /* Should we retry ? */
    1126           0 :             LWLockRelease(partitionLock);
    1127           0 :             elog(ERROR, "LockAcquire failed");
    1128             :         }
    1129             :         PROCLOCK_PRINT("LockAcquire: granted", proclock);
    1130             :         LOCK_PRINT("LockAcquire: granted", lock, lockmode);
    1131             :     }
    1132             : 
    1133             :     /*
    1134             :      * Lock state is fully up-to-date now; if we error out after this, no
    1135             :      * special error cleanup is required.
    1136             :      */
    1137     4981580 :     FinishStrongLockAcquire();
    1138             : 
    1139     4981580 :     LWLockRelease(partitionLock);
    1140             : 
    1141             :     /*
    1142             :      * Emit a WAL record if acquisition of this lock needs to be replayed in a
    1143             :      * standby server.
    1144             :      */
    1145     4981580 :     if (log_lock)
    1146             :     {
    1147             :         /*
    1148             :          * Decode the locktag back to the original values, to avoid sending
    1149             :          * lots of empty bytes with every message.  See lock.h to check how a
    1150             :          * locktag is defined for LOCKTAG_RELATION
    1151             :          */
    1152      377862 :         LogAccessExclusiveLock(locktag->locktag_field1,
    1153             :                                locktag->locktag_field2);
    1154             :     }
    1155             : 
    1156     4981580 :     return LOCKACQUIRE_OK;
    1157             : }
    1158             : 
    1159             : /*
    1160             :  * Find or create LOCK and PROCLOCK objects as needed for a new lock
    1161             :  * request.
    1162             :  *
    1163             :  * Returns the PROCLOCK object, or NULL if we failed to create the objects
    1164             :  * for lack of shared memory.
    1165             :  *
    1166             :  * The appropriate partition lock must be held at entry, and will be
    1167             :  * held at exit.
    1168             :  */
    1169             : static PROCLOCK *
    1170     4986308 : SetupLockInTable(LockMethod lockMethodTable, PGPROC *proc,
    1171             :                  const LOCKTAG *locktag, uint32 hashcode, LOCKMODE lockmode)
    1172             : {
    1173             :     LOCK       *lock;
    1174             :     PROCLOCK   *proclock;
    1175             :     PROCLOCKTAG proclocktag;
    1176             :     uint32      proclock_hashcode;
    1177             :     bool        found;
    1178             : 
    1179             :     /*
    1180             :      * Find or create a lock with this tag.
    1181             :      */
    1182     4986308 :     lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
    1183             :                                                 locktag,
    1184             :                                                 hashcode,
    1185             :                                                 HASH_ENTER_NULL,
    1186             :                                                 &found);
    1187     4986308 :     if (!lock)
    1188           0 :         return NULL;
    1189             : 
    1190             :     /*
    1191             :      * if it's a new lock object, initialize it
    1192             :      */
    1193     4986308 :     if (!found)
    1194             :     {
    1195     4011112 :         lock->grantMask = 0;
    1196     4011112 :         lock->waitMask = 0;
    1197     4011112 :         dlist_init(&lock->procLocks);
    1198     4011112 :         dclist_init(&lock->waitProcs);
    1199     4011112 :         lock->nRequested = 0;
    1200     4011112 :         lock->nGranted = 0;
    1201    24066672 :         MemSet(lock->requested, 0, sizeof(int) * MAX_LOCKMODES);
    1202     4011112 :         MemSet(lock->granted, 0, sizeof(int) * MAX_LOCKMODES);
    1203             :         LOCK_PRINT("LockAcquire: new", lock, lockmode);
    1204             :     }
    1205             :     else
    1206             :     {
    1207             :         LOCK_PRINT("LockAcquire: found", lock, lockmode);
    1208             :         Assert((lock->nRequested >= 0) && (lock->requested[lockmode] >= 0));
    1209             :         Assert((lock->nGranted >= 0) && (lock->granted[lockmode] >= 0));
    1210             :         Assert(lock->nGranted <= lock->nRequested);
    1211             :     }
    1212             : 
    1213             :     /*
    1214             :      * Create the hash key for the proclock table.
    1215             :      */
    1216     4986308 :     proclocktag.myLock = lock;
    1217     4986308 :     proclocktag.myProc = proc;
    1218             : 
    1219     4986308 :     proclock_hashcode = ProcLockHashCode(&proclocktag, hashcode);
    1220             : 
    1221             :     /*
    1222             :      * Find or create a proclock entry with this tag
    1223             :      */
    1224     4986308 :     proclock = (PROCLOCK *) hash_search_with_hash_value(LockMethodProcLockHash,
    1225             :                                                         &proclocktag,
    1226             :                                                         proclock_hashcode,
    1227             :                                                         HASH_ENTER_NULL,
    1228             :                                                         &found);
    1229     4986308 :     if (!proclock)
    1230             :     {
    1231             :         /* Oops, not enough shmem for the proclock */
    1232           0 :         if (lock->nRequested == 0)
    1233             :         {
    1234             :             /*
    1235             :              * There are no other requestors of this lock, so garbage-collect
    1236             :              * the lock object.  We *must* do this to avoid a permanent leak
    1237             :              * of shared memory, because there won't be anything to cause
    1238             :              * anyone to release the lock object later.
    1239             :              */
    1240             :             Assert(dlist_is_empty(&(lock->procLocks)));
    1241           0 :             if (!hash_search_with_hash_value(LockMethodLockHash,
    1242           0 :                                              &(lock->tag),
    1243             :                                              hashcode,
    1244             :                                              HASH_REMOVE,
    1245             :                                              NULL))
    1246           0 :                 elog(PANIC, "lock table corrupted");
    1247             :         }
    1248           0 :         return NULL;
    1249             :     }
    1250             : 
    1251             :     /*
    1252             :      * If new, initialize the new entry
    1253             :      */
    1254     4986308 :     if (!found)
    1255             :     {
    1256     4028720 :         uint32      partition = LockHashPartition(hashcode);
    1257             : 
    1258             :         /*
    1259             :          * It might seem unsafe to access proclock->groupLeader without a
    1260             :          * lock, but it's not really.  Either we are initializing a proclock
    1261             :          * on our own behalf, in which case our group leader isn't changing
    1262             :          * because the group leader for a process can only ever be changed by
    1263             :          * the process itself; or else we are transferring a fast-path lock to
    1264             :          * the main lock table, in which case that process can't change it's
    1265             :          * lock group leader without first releasing all of its locks (and in
    1266             :          * particular the one we are currently transferring).
    1267             :          */
    1268     8057440 :         proclock->groupLeader = proc->lockGroupLeader != NULL ?
    1269     4028720 :             proc->lockGroupLeader : proc;
    1270     4028720 :         proclock->holdMask = 0;
    1271     4028720 :         proclock->releaseMask = 0;
    1272             :         /* Add proclock to appropriate lists */
    1273     4028720 :         dlist_push_tail(&lock->procLocks, &proclock->lockLink);
    1274     4028720 :         dlist_push_tail(&proc->myProcLocks[partition], &proclock->procLink);
    1275             :         PROCLOCK_PRINT("LockAcquire: new", proclock);
    1276             :     }
    1277             :     else
    1278             :     {
    1279             :         PROCLOCK_PRINT("LockAcquire: found", proclock);
    1280             :         Assert((proclock->holdMask & ~lock->grantMask) == 0);
    1281             : 
    1282             : #ifdef CHECK_DEADLOCK_RISK
    1283             : 
    1284             :         /*
    1285             :          * Issue warning if we already hold a lower-level lock on this object
    1286             :          * and do not hold a lock of the requested level or higher. This
    1287             :          * indicates a deadlock-prone coding practice (eg, we'd have a
    1288             :          * deadlock if another backend were following the same code path at
    1289             :          * about the same time).
    1290             :          *
    1291             :          * This is not enabled by default, because it may generate log entries
    1292             :          * about user-level coding practices that are in fact safe in context.
    1293             :          * It can be enabled to help find system-level problems.
    1294             :          *
    1295             :          * XXX Doing numeric comparison on the lockmodes is a hack; it'd be
    1296             :          * better to use a table.  For now, though, this works.
    1297             :          */
    1298             :         {
    1299             :             int         i;
    1300             : 
    1301             :             for (i = lockMethodTable->numLockModes; i > 0; i--)
    1302             :             {
    1303             :                 if (proclock->holdMask & LOCKBIT_ON(i))
    1304             :                 {
    1305             :                     if (i >= (int) lockmode)
    1306             :                         break;  /* safe: we have a lock >= req level */
    1307             :                     elog(LOG, "deadlock risk: raising lock level"
    1308             :                          " from %s to %s on object %u/%u/%u",
    1309             :                          lockMethodTable->lockModeNames[i],
    1310             :                          lockMethodTable->lockModeNames[lockmode],
    1311             :                          lock->tag.locktag_field1, lock->tag.locktag_field2,
    1312             :                          lock->tag.locktag_field3);
    1313             :                     break;
    1314             :                 }
    1315             :             }
    1316             :         }
    1317             : #endif                          /* CHECK_DEADLOCK_RISK */
    1318             :     }
    1319             : 
    1320             :     /*
    1321             :      * lock->nRequested and lock->requested[] count the total number of
    1322             :      * requests, whether granted or waiting, so increment those immediately.
    1323             :      * The other counts don't increment till we get the lock.
    1324             :      */
    1325     4986308 :     lock->nRequested++;
    1326     4986308 :     lock->requested[lockmode]++;
    1327             :     Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
    1328             : 
    1329             :     /*
    1330             :      * We shouldn't already hold the desired lock; else locallock table is
    1331             :      * broken.
    1332             :      */
    1333     4986308 :     if (proclock->holdMask & LOCKBIT_ON(lockmode))
    1334           0 :         elog(ERROR, "lock %s on object %u/%u/%u is already held",
    1335             :              lockMethodTable->lockModeNames[lockmode],
    1336             :              lock->tag.locktag_field1, lock->tag.locktag_field2,
    1337             :              lock->tag.locktag_field3);
    1338             : 
    1339     4986308 :     return proclock;
    1340             : }
    1341             : 
    1342             : /*
    1343             :  * Check and set/reset the flag that we hold the relation extension/page lock.
    1344             :  *
    1345             :  * It is callers responsibility that this function is called after
    1346             :  * acquiring/releasing the relation extension/page lock.
    1347             :  *
    1348             :  * Pass acquired as true if lock is acquired, false otherwise.
    1349             :  */
    1350             : static inline void
    1351    83539334 : CheckAndSetLockHeld(LOCALLOCK *locallock, bool acquired)
    1352             : {
    1353             : #ifdef USE_ASSERT_CHECKING
    1354             :     if (LOCALLOCK_LOCKTAG(*locallock) == LOCKTAG_RELATION_EXTEND)
    1355             :         IsRelationExtensionLockHeld = acquired;
    1356             :     else if (LOCALLOCK_LOCKTAG(*locallock) == LOCKTAG_PAGE)
    1357             :         IsPageLockHeld = acquired;
    1358             : 
    1359             : #endif
    1360    83539334 : }
    1361             : 
    1362             : /*
    1363             :  * Subroutine to free a locallock entry
    1364             :  */
    1365             : static void
    1366    41434366 : RemoveLocalLock(LOCALLOCK *locallock)
    1367             : {
    1368             :     int         i;
    1369             : 
    1370    41550556 :     for (i = locallock->numLockOwners - 1; i >= 0; i--)
    1371             :     {
    1372      116190 :         if (locallock->lockOwners[i].owner != NULL)
    1373      116122 :             ResourceOwnerForgetLock(locallock->lockOwners[i].owner, locallock);
    1374             :     }
    1375    41434366 :     locallock->numLockOwners = 0;
    1376    41434366 :     if (locallock->lockOwners != NULL)
    1377    41434366 :         pfree(locallock->lockOwners);
    1378    41434366 :     locallock->lockOwners = NULL;
    1379             : 
    1380    41434366 :     if (locallock->holdsStrongLockCount)
    1381             :     {
    1382             :         uint32      fasthashcode;
    1383             : 
    1384      521488 :         fasthashcode = FastPathStrongLockHashPartition(locallock->hashcode);
    1385             : 
    1386      521488 :         SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
    1387             :         Assert(FastPathStrongRelationLocks->count[fasthashcode] > 0);
    1388      521488 :         FastPathStrongRelationLocks->count[fasthashcode]--;
    1389      521488 :         locallock->holdsStrongLockCount = false;
    1390      521488 :         SpinLockRelease(&FastPathStrongRelationLocks->mutex);
    1391             :     }
    1392             : 
    1393    41434366 :     if (!hash_search(LockMethodLocalHash,
    1394    41434366 :                      &(locallock->tag),
    1395             :                      HASH_REMOVE, NULL))
    1396           0 :         elog(WARNING, "locallock table corrupted");
    1397             : 
    1398             :     /*
    1399             :      * Indicate that the lock is released for certain types of locks
    1400             :      */
    1401    41434366 :     CheckAndSetLockHeld(locallock, false);
    1402    41434366 : }
    1403             : 
    1404             : /*
    1405             :  * LockCheckConflicts -- test whether requested lock conflicts
    1406             :  *      with those already granted
    1407             :  *
    1408             :  * Returns true if conflict, false if no conflict.
    1409             :  *
    1410             :  * NOTES:
    1411             :  *      Here's what makes this complicated: one process's locks don't
    1412             :  * conflict with one another, no matter what purpose they are held for
    1413             :  * (eg, session and transaction locks do not conflict).  Nor do the locks
    1414             :  * of one process in a lock group conflict with those of another process in
    1415             :  * the same group.  So, we must subtract off these locks when determining
    1416             :  * whether the requested new lock conflicts with those already held.
    1417             :  */
    1418             : bool
    1419     4984986 : LockCheckConflicts(LockMethod lockMethodTable,
    1420             :                    LOCKMODE lockmode,
    1421             :                    LOCK *lock,
    1422             :                    PROCLOCK *proclock)
    1423             : {
    1424     4984986 :     int         numLockModes = lockMethodTable->numLockModes;
    1425             :     LOCKMASK    myLocks;
    1426     4984986 :     int         conflictMask = lockMethodTable->conflictTab[lockmode];
    1427             :     int         conflictsRemaining[MAX_LOCKMODES];
    1428     4984986 :     int         totalConflictsRemaining = 0;
    1429             :     dlist_iter  proclock_iter;
    1430             :     int         i;
    1431             : 
    1432             :     /*
    1433             :      * first check for global conflicts: If no locks conflict with my request,
    1434             :      * then I get the lock.
    1435             :      *
    1436             :      * Checking for conflict: lock->grantMask represents the types of
    1437             :      * currently held locks.  conflictTable[lockmode] has a bit set for each
    1438             :      * type of lock that conflicts with request.   Bitwise compare tells if
    1439             :      * there is a conflict.
    1440             :      */
    1441     4984986 :     if (!(conflictMask & lock->grantMask))
    1442             :     {
    1443             :         PROCLOCK_PRINT("LockCheckConflicts: no conflict", proclock);
    1444     4494082 :         return false;
    1445             :     }
    1446             : 
    1447             :     /*
    1448             :      * Rats.  Something conflicts.  But it could still be my own lock, or a
    1449             :      * lock held by another member of my locking group.  First, figure out how
    1450             :      * many conflicts remain after subtracting out any locks I hold myself.
    1451             :      */
    1452      490904 :     myLocks = proclock->holdMask;
    1453     4418136 :     for (i = 1; i <= numLockModes; i++)
    1454             :     {
    1455     3927232 :         if ((conflictMask & LOCKBIT_ON(i)) == 0)
    1456             :         {
    1457     2026980 :             conflictsRemaining[i] = 0;
    1458     2026980 :             continue;
    1459             :         }
    1460     1900252 :         conflictsRemaining[i] = lock->granted[i];
    1461     1900252 :         if (myLocks & LOCKBIT_ON(i))
    1462      494726 :             --conflictsRemaining[i];
    1463     1900252 :         totalConflictsRemaining += conflictsRemaining[i];
    1464             :     }
    1465             : 
    1466             :     /* If no conflicts remain, we get the lock. */
    1467      490904 :     if (totalConflictsRemaining == 0)
    1468             :     {
    1469             :         PROCLOCK_PRINT("LockCheckConflicts: resolved (simple)", proclock);
    1470      486674 :         return false;
    1471             :     }
    1472             : 
    1473             :     /* If no group locking, it's definitely a conflict. */
    1474        4230 :     if (proclock->groupLeader == MyProc && MyProc->lockGroupLeader == NULL)
    1475             :     {
    1476             :         Assert(proclock->tag.myProc == MyProc);
    1477             :         PROCLOCK_PRINT("LockCheckConflicts: conflicting (simple)",
    1478             :                        proclock);
    1479        3312 :         return true;
    1480             :     }
    1481             : 
    1482             :     /*
    1483             :      * The relation extension or page lock conflict even between the group
    1484             :      * members.
    1485             :      */
    1486         918 :     if (LOCK_LOCKTAG(*lock) == LOCKTAG_RELATION_EXTEND ||
    1487         892 :         (LOCK_LOCKTAG(*lock) == LOCKTAG_PAGE))
    1488             :     {
    1489             :         PROCLOCK_PRINT("LockCheckConflicts: conflicting (group)",
    1490             :                        proclock);
    1491          26 :         return true;
    1492             :     }
    1493             : 
    1494             :     /*
    1495             :      * Locks held in conflicting modes by members of our own lock group are
    1496             :      * not real conflicts; we can subtract those out and see if we still have
    1497             :      * a conflict.  This is O(N) in the number of processes holding or
    1498             :      * awaiting locks on this object.  We could improve that by making the
    1499             :      * shared memory state more complex (and larger) but it doesn't seem worth
    1500             :      * it.
    1501             :      */
    1502        1134 :     dlist_foreach(proclock_iter, &lock->procLocks)
    1503             :     {
    1504        1070 :         PROCLOCK   *otherproclock =
    1505        1070 :             dlist_container(PROCLOCK, lockLink, proclock_iter.cur);
    1506             : 
    1507        1070 :         if (proclock != otherproclock &&
    1508        1006 :             proclock->groupLeader == otherproclock->groupLeader &&
    1509         832 :             (otherproclock->holdMask & conflictMask) != 0)
    1510             :         {
    1511         828 :             int         intersectMask = otherproclock->holdMask & conflictMask;
    1512             : 
    1513        7452 :             for (i = 1; i <= numLockModes; i++)
    1514             :             {
    1515        6624 :                 if ((intersectMask & LOCKBIT_ON(i)) != 0)
    1516             :                 {
    1517         842 :                     if (conflictsRemaining[i] <= 0)
    1518           0 :                         elog(PANIC, "proclocks held do not match lock");
    1519         842 :                     conflictsRemaining[i]--;
    1520         842 :                     totalConflictsRemaining--;
    1521             :                 }
    1522             :             }
    1523             : 
    1524         828 :             if (totalConflictsRemaining == 0)
    1525             :             {
    1526             :                 PROCLOCK_PRINT("LockCheckConflicts: resolved (group)",
    1527             :                                proclock);
    1528         828 :                 return false;
    1529             :             }
    1530             :         }
    1531             :     }
    1532             : 
    1533             :     /* Nope, it's a real conflict. */
    1534             :     PROCLOCK_PRINT("LockCheckConflicts: conflicting (group)", proclock);
    1535          64 :     return true;
    1536             : }
    1537             : 
    1538             : /*
    1539             :  * GrantLock -- update the lock and proclock data structures to show
    1540             :  *      the lock request has been granted.
    1541             :  *
    1542             :  * NOTE: if proc was blocked, it also needs to be removed from the wait list
    1543             :  * and have its waitLock/waitProcLock fields cleared.  That's not done here.
    1544             :  *
    1545             :  * NOTE: the lock grant also has to be recorded in the associated LOCALLOCK
    1546             :  * table entry; but since we may be awaking some other process, we can't do
    1547             :  * that here; it's done by GrantLockLocal, instead.
    1548             :  */
    1549             : void
    1550     4984966 : GrantLock(LOCK *lock, PROCLOCK *proclock, LOCKMODE lockmode)
    1551             : {
    1552     4984966 :     lock->nGranted++;
    1553     4984966 :     lock->granted[lockmode]++;
    1554     4984966 :     lock->grantMask |= LOCKBIT_ON(lockmode);
    1555     4984966 :     if (lock->granted[lockmode] == lock->requested[lockmode])
    1556     4984730 :         lock->waitMask &= LOCKBIT_OFF(lockmode);
    1557     4984966 :     proclock->holdMask |= LOCKBIT_ON(lockmode);
    1558             :     LOCK_PRINT("GrantLock", lock, lockmode);
    1559             :     Assert((lock->nGranted > 0) && (lock->granted[lockmode] > 0));
    1560             :     Assert(lock->nGranted <= lock->nRequested);
    1561     4984966 : }
    1562             : 
    1563             : /*
    1564             :  * UnGrantLock -- opposite of GrantLock.
    1565             :  *
    1566             :  * Updates the lock and proclock data structures to show that the lock
    1567             :  * is no longer held nor requested by the current holder.
    1568             :  *
    1569             :  * Returns true if there were any waiters waiting on the lock that
    1570             :  * should now be woken up with ProcLockWakeup.
    1571             :  */
    1572             : static bool
    1573     4984818 : UnGrantLock(LOCK *lock, LOCKMODE lockmode,
    1574             :             PROCLOCK *proclock, LockMethod lockMethodTable)
    1575             : {
    1576     4984818 :     bool        wakeupNeeded = false;
    1577             : 
    1578             :     Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
    1579             :     Assert((lock->nGranted > 0) && (lock->granted[lockmode] > 0));
    1580             :     Assert(lock->nGranted <= lock->nRequested);
    1581             : 
    1582             :     /*
    1583             :      * fix the general lock stats
    1584             :      */
    1585     4984818 :     lock->nRequested--;
    1586     4984818 :     lock->requested[lockmode]--;
    1587     4984818 :     lock->nGranted--;
    1588     4984818 :     lock->granted[lockmode]--;
    1589             : 
    1590     4984818 :     if (lock->granted[lockmode] == 0)
    1591             :     {
    1592             :         /* change the conflict mask.  No more of this lock type. */
    1593     4972652 :         lock->grantMask &= LOCKBIT_OFF(lockmode);
    1594             :     }
    1595             : 
    1596             :     LOCK_PRINT("UnGrantLock: updated", lock, lockmode);
    1597             : 
    1598             :     /*
    1599             :      * We need only run ProcLockWakeup if the released lock conflicts with at
    1600             :      * least one of the lock types requested by waiter(s).  Otherwise whatever
    1601             :      * conflict made them wait must still exist.  NOTE: before MVCC, we could
    1602             :      * skip wakeup if lock->granted[lockmode] was still positive. But that's
    1603             :      * not true anymore, because the remaining granted locks might belong to
    1604             :      * some waiter, who could now be awakened because he doesn't conflict with
    1605             :      * his own locks.
    1606             :      */
    1607     4984818 :     if (lockMethodTable->conflictTab[lockmode] & lock->waitMask)
    1608        1854 :         wakeupNeeded = true;
    1609             : 
    1610             :     /*
    1611             :      * Now fix the per-proclock state.
    1612             :      */
    1613     4984818 :     proclock->holdMask &= LOCKBIT_OFF(lockmode);
    1614             :     PROCLOCK_PRINT("UnGrantLock: updated", proclock);
    1615             : 
    1616     4984818 :     return wakeupNeeded;
    1617             : }
    1618             : 
    1619             : /*
    1620             :  * CleanUpLock -- clean up after releasing a lock.  We garbage-collect the
    1621             :  * proclock and lock objects if possible, and call ProcLockWakeup if there
    1622             :  * are remaining requests and the caller says it's OK.  (Normally, this
    1623             :  * should be called after UnGrantLock, and wakeupNeeded is the result from
    1624             :  * UnGrantLock.)
    1625             :  *
    1626             :  * The appropriate partition lock must be held at entry, and will be
    1627             :  * held at exit.
    1628             :  */
    1629             : static void
    1630     4926746 : CleanUpLock(LOCK *lock, PROCLOCK *proclock,
    1631             :             LockMethod lockMethodTable, uint32 hashcode,
    1632             :             bool wakeupNeeded)
    1633             : {
    1634             :     /*
    1635             :      * If this was my last hold on this lock, delete my entry in the proclock
    1636             :      * table.
    1637             :      */
    1638     4926746 :     if (proclock->holdMask == 0)
    1639             :     {
    1640             :         uint32      proclock_hashcode;
    1641             : 
    1642             :         PROCLOCK_PRINT("CleanUpLock: deleting", proclock);
    1643     4027730 :         dlist_delete(&proclock->lockLink);
    1644     4027730 :         dlist_delete(&proclock->procLink);
    1645     4027730 :         proclock_hashcode = ProcLockHashCode(&proclock->tag, hashcode);
    1646     4027730 :         if (!hash_search_with_hash_value(LockMethodProcLockHash,
    1647     4027730 :                                          &(proclock->tag),
    1648             :                                          proclock_hashcode,
    1649             :                                          HASH_REMOVE,
    1650             :                                          NULL))
    1651           0 :             elog(PANIC, "proclock table corrupted");
    1652             :     }
    1653             : 
    1654     4926746 :     if (lock->nRequested == 0)
    1655             :     {
    1656             :         /*
    1657             :          * The caller just released the last lock, so garbage-collect the lock
    1658             :          * object.
    1659             :          */
    1660             :         LOCK_PRINT("CleanUpLock: deleting", lock, 0);
    1661             :         Assert(dlist_is_empty(&lock->procLocks));
    1662     4011122 :         if (!hash_search_with_hash_value(LockMethodLockHash,
    1663     4011122 :                                          &(lock->tag),
    1664             :                                          hashcode,
    1665             :                                          HASH_REMOVE,
    1666             :                                          NULL))
    1667           0 :             elog(PANIC, "lock table corrupted");
    1668             :     }
    1669      915624 :     else if (wakeupNeeded)
    1670             :     {
    1671             :         /* There are waiters on this lock, so wake them up. */
    1672        1942 :         ProcLockWakeup(lockMethodTable, lock);
    1673             :     }
    1674     4926746 : }
    1675             : 
    1676             : /*
    1677             :  * GrantLockLocal -- update the locallock data structures to show
    1678             :  *      the lock request has been granted.
    1679             :  *
    1680             :  * We expect that LockAcquire made sure there is room to add a new
    1681             :  * ResourceOwner entry.
    1682             :  */
    1683             : static void
    1684    44878454 : GrantLockLocal(LOCALLOCK *locallock, ResourceOwner owner)
    1685             : {
    1686    44878454 :     LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
    1687             :     int         i;
    1688             : 
    1689             :     Assert(locallock->numLockOwners < locallock->maxLockOwners);
    1690             :     /* Count the total */
    1691    44878454 :     locallock->nLocks++;
    1692             :     /* Count the per-owner lock */
    1693    45839570 :     for (i = 0; i < locallock->numLockOwners; i++)
    1694             :     {
    1695     3734602 :         if (lockOwners[i].owner == owner)
    1696             :         {
    1697     2773486 :             lockOwners[i].nLocks++;
    1698     2773486 :             return;
    1699             :         }
    1700             :     }
    1701    42104968 :     lockOwners[i].owner = owner;
    1702    42104968 :     lockOwners[i].nLocks = 1;
    1703    42104968 :     locallock->numLockOwners++;
    1704    42104968 :     if (owner != NULL)
    1705    41994104 :         ResourceOwnerRememberLock(owner, locallock);
    1706             : 
    1707             :     /* Indicate that the lock is acquired for certain types of locks. */
    1708    42104968 :     CheckAndSetLockHeld(locallock, true);
    1709             : }
    1710             : 
    1711             : /*
    1712             :  * BeginStrongLockAcquire - inhibit use of fastpath for a given LOCALLOCK,
    1713             :  * and arrange for error cleanup if it fails
    1714             :  */
    1715             : static void
    1716      522042 : BeginStrongLockAcquire(LOCALLOCK *locallock, uint32 fasthashcode)
    1717             : {
    1718             :     Assert(StrongLockInProgress == NULL);
    1719             :     Assert(locallock->holdsStrongLockCount == false);
    1720             : 
    1721             :     /*
    1722             :      * Adding to a memory location is not atomic, so we take a spinlock to
    1723             :      * ensure we don't collide with someone else trying to bump the count at
    1724             :      * the same time.
    1725             :      *
    1726             :      * XXX: It might be worth considering using an atomic fetch-and-add
    1727             :      * instruction here, on architectures where that is supported.
    1728             :      */
    1729             : 
    1730      522042 :     SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
    1731      522042 :     FastPathStrongRelationLocks->count[fasthashcode]++;
    1732      522042 :     locallock->holdsStrongLockCount = true;
    1733      522042 :     StrongLockInProgress = locallock;
    1734      522042 :     SpinLockRelease(&FastPathStrongRelationLocks->mutex);
    1735      522042 : }
    1736             : 
    1737             : /*
    1738             :  * FinishStrongLockAcquire - cancel pending cleanup for a strong lock
    1739             :  * acquisition once it's no longer needed
    1740             :  */
    1741             : static void
    1742     4981580 : FinishStrongLockAcquire(void)
    1743             : {
    1744     4981580 :     StrongLockInProgress = NULL;
    1745     4981580 : }
    1746             : 
    1747             : /*
    1748             :  * AbortStrongLockAcquire - undo strong lock state changes performed by
    1749             :  * BeginStrongLockAcquire.
    1750             :  */
    1751             : void
    1752      991608 : AbortStrongLockAcquire(void)
    1753             : {
    1754             :     uint32      fasthashcode;
    1755      991608 :     LOCALLOCK  *locallock = StrongLockInProgress;
    1756             : 
    1757      991608 :     if (locallock == NULL)
    1758      991184 :         return;
    1759             : 
    1760         424 :     fasthashcode = FastPathStrongLockHashPartition(locallock->hashcode);
    1761             :     Assert(locallock->holdsStrongLockCount == true);
    1762         424 :     SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
    1763             :     Assert(FastPathStrongRelationLocks->count[fasthashcode] > 0);
    1764         424 :     FastPathStrongRelationLocks->count[fasthashcode]--;
    1765         424 :     locallock->holdsStrongLockCount = false;
    1766         424 :     StrongLockInProgress = NULL;
    1767         424 :     SpinLockRelease(&FastPathStrongRelationLocks->mutex);
    1768             : }
    1769             : 
    1770             : /*
    1771             :  * GrantAwaitedLock -- call GrantLockLocal for the lock we are doing
    1772             :  *      WaitOnLock on.
    1773             :  *
    1774             :  * proc.c needs this for the case where we are booted off the lock by
    1775             :  * timeout, but discover that someone granted us the lock anyway.
    1776             :  *
    1777             :  * We could just export GrantLockLocal, but that would require including
    1778             :  * resowner.h in lock.h, which creates circularity.
    1779             :  */
    1780             : void
    1781        1904 : GrantAwaitedLock(void)
    1782             : {
    1783        1904 :     GrantLockLocal(awaitedLock, awaitedOwner);
    1784        1904 : }
    1785             : 
    1786             : /*
    1787             :  * MarkLockClear -- mark an acquired lock as "clear"
    1788             :  *
    1789             :  * This means that we know we have absorbed all sinval messages that other
    1790             :  * sessions generated before we acquired this lock, and so we can confidently
    1791             :  * assume we know about any catalog changes protected by this lock.
    1792             :  */
    1793             : void
    1794    40161636 : MarkLockClear(LOCALLOCK *locallock)
    1795             : {
    1796             :     Assert(locallock->nLocks > 0);
    1797    40161636 :     locallock->lockCleared = true;
    1798    40161636 : }
    1799             : 
    1800             : /*
    1801             :  * WaitOnLock -- wait to acquire a lock
    1802             :  *
    1803             :  * Caller must have set MyProc->heldLocks to reflect locks already held
    1804             :  * on the lockable object by this process.
    1805             :  *
    1806             :  * The appropriate partition lock must be held at entry.
    1807             :  */
    1808             : static void
    1809        1996 : WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner)
    1810             : {
    1811        1996 :     LOCKMETHODID lockmethodid = LOCALLOCK_LOCKMETHOD(*locallock);
    1812        1996 :     LockMethod  lockMethodTable = LockMethods[lockmethodid];
    1813             : 
    1814             :     LOCK_PRINT("WaitOnLock: sleeping on lock",
    1815             :                locallock->lock, locallock->tag.mode);
    1816             : 
    1817             :     /* adjust the process title to indicate that it's waiting */
    1818        1996 :     set_ps_display_suffix("waiting");
    1819             : 
    1820        1996 :     awaitedLock = locallock;
    1821        1996 :     awaitedOwner = owner;
    1822             : 
    1823             :     /*
    1824             :      * NOTE: Think not to put any shared-state cleanup after the call to
    1825             :      * ProcSleep, in either the normal or failure path.  The lock state must
    1826             :      * be fully set by the lock grantor, or by CheckDeadLock if we give up
    1827             :      * waiting for the lock.  This is necessary because of the possibility
    1828             :      * that a cancel/die interrupt will interrupt ProcSleep after someone else
    1829             :      * grants us the lock, but before we've noticed it. Hence, after granting,
    1830             :      * the locktable state must fully reflect the fact that we own the lock;
    1831             :      * we can't do additional work on return.
    1832             :      *
    1833             :      * We can and do use a PG_TRY block to try to clean up after failure, but
    1834             :      * this still has a major limitation: elog(FATAL) can occur while waiting
    1835             :      * (eg, a "die" interrupt), and then control won't come back here. So all
    1836             :      * cleanup of essential state should happen in LockErrorCleanup, not here.
    1837             :      * We can use PG_TRY to clear the "waiting" status flags, since doing that
    1838             :      * is unimportant if the process exits.
    1839             :      */
    1840        1996 :     PG_TRY();
    1841             :     {
    1842        1996 :         if (ProcSleep(locallock, lockMethodTable) != PROC_WAIT_STATUS_OK)
    1843             :         {
    1844             :             /*
    1845             :              * We failed as a result of a deadlock, see CheckDeadLock(). Quit
    1846             :              * now.
    1847             :              */
    1848          10 :             awaitedLock = NULL;
    1849             :             LOCK_PRINT("WaitOnLock: aborting on lock",
    1850             :                        locallock->lock, locallock->tag.mode);
    1851          10 :             LWLockRelease(LockHashPartitionLock(locallock->hashcode));
    1852             : 
    1853             :             /*
    1854             :              * Now that we aren't holding the partition lock, we can give an
    1855             :              * error report including details about the detected deadlock.
    1856             :              */
    1857          10 :             DeadLockReport();
    1858             :             /* not reached */
    1859             :         }
    1860             :     }
    1861          82 :     PG_CATCH();
    1862             :     {
    1863             :         /* In this path, awaitedLock remains set until LockErrorCleanup */
    1864             : 
    1865             :         /* reset ps display to remove the suffix */
    1866          82 :         set_ps_display_remove_suffix();
    1867             : 
    1868             :         /* and propagate the error */
    1869          82 :         PG_RE_THROW();
    1870             :     }
    1871        1904 :     PG_END_TRY();
    1872             : 
    1873        1904 :     awaitedLock = NULL;
    1874             : 
    1875             :     /* reset ps display to remove the suffix */
    1876        1904 :     set_ps_display_remove_suffix();
    1877             : 
    1878             :     LOCK_PRINT("WaitOnLock: wakeup on lock",
    1879             :                locallock->lock, locallock->tag.mode);
    1880        1904 : }
    1881             : 
    1882             : /*
    1883             :  * Remove a proc from the wait-queue it is on (caller must know it is on one).
    1884             :  * This is only used when the proc has failed to get the lock, so we set its
    1885             :  * waitStatus to PROC_WAIT_STATUS_ERROR.
    1886             :  *
    1887             :  * Appropriate partition lock must be held by caller.  Also, caller is
    1888             :  * responsible for signaling the proc if needed.
    1889             :  *
    1890             :  * NB: this does not clean up any locallock object that may exist for the lock.
    1891             :  */
    1892             : void
    1893          92 : RemoveFromWaitQueue(PGPROC *proc, uint32 hashcode)
    1894             : {
    1895          92 :     LOCK       *waitLock = proc->waitLock;
    1896          92 :     PROCLOCK   *proclock = proc->waitProcLock;
    1897          92 :     LOCKMODE    lockmode = proc->waitLockMode;
    1898          92 :     LOCKMETHODID lockmethodid = LOCK_LOCKMETHOD(*waitLock);
    1899             : 
    1900             :     /* Make sure proc is waiting */
    1901             :     Assert(proc->waitStatus == PROC_WAIT_STATUS_WAITING);
    1902             :     Assert(proc->links.next != NULL);
    1903             :     Assert(waitLock);
    1904             :     Assert(!dclist_is_empty(&waitLock->waitProcs));
    1905             :     Assert(0 < lockmethodid && lockmethodid < lengthof(LockMethods));
    1906             : 
    1907             :     /* Remove proc from lock's wait queue */
    1908          92 :     dclist_delete_from(&waitLock->waitProcs, &proc->links);
    1909             : 
    1910             :     /* Undo increments of request counts by waiting process */
    1911             :     Assert(waitLock->nRequested > 0);
    1912             :     Assert(waitLock->nRequested > proc->waitLock->nGranted);
    1913          92 :     waitLock->nRequested--;
    1914             :     Assert(waitLock->requested[lockmode] > 0);
    1915          92 :     waitLock->requested[lockmode]--;
    1916             :     /* don't forget to clear waitMask bit if appropriate */
    1917          92 :     if (waitLock->granted[lockmode] == waitLock->requested[lockmode])
    1918          90 :         waitLock->waitMask &= LOCKBIT_OFF(lockmode);
    1919             : 
    1920             :     /* Clean up the proc's own state, and pass it the ok/fail signal */
    1921          92 :     proc->waitLock = NULL;
    1922          92 :     proc->waitProcLock = NULL;
    1923          92 :     proc->waitStatus = PROC_WAIT_STATUS_ERROR;
    1924             : 
    1925             :     /*
    1926             :      * Delete the proclock immediately if it represents no already-held locks.
    1927             :      * (This must happen now because if the owner of the lock decides to
    1928             :      * release it, and the requested/granted counts then go to zero,
    1929             :      * LockRelease expects there to be no remaining proclocks.) Then see if
    1930             :      * any other waiters for the lock can be woken up now.
    1931             :      */
    1932          92 :     CleanUpLock(waitLock, proclock,
    1933             :                 LockMethods[lockmethodid], hashcode,
    1934             :                 true);
    1935          92 : }
    1936             : 
    1937             : /*
    1938             :  * LockRelease -- look up 'locktag' and release one 'lockmode' lock on it.
    1939             :  *      Release a session lock if 'sessionLock' is true, else release a
    1940             :  *      regular transaction lock.
    1941             :  *
    1942             :  * Side Effects: find any waiting processes that are now wakable,
    1943             :  *      grant them their requested locks and awaken them.
    1944             :  *      (We have to grant the lock here to avoid a race between
    1945             :  *      the waking process and any new process to
    1946             :  *      come along and request the lock.)
    1947             :  */
    1948             : bool
    1949    40207254 : LockRelease(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
    1950             : {
    1951    40207254 :     LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
    1952             :     LockMethod  lockMethodTable;
    1953             :     LOCALLOCKTAG localtag;
    1954             :     LOCALLOCK  *locallock;
    1955             :     LOCK       *lock;
    1956             :     PROCLOCK   *proclock;
    1957             :     LWLock     *partitionLock;
    1958             :     bool        wakeupNeeded;
    1959             : 
    1960    40207254 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
    1961           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    1962    40207254 :     lockMethodTable = LockMethods[lockmethodid];
    1963    40207254 :     if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
    1964           0 :         elog(ERROR, "unrecognized lock mode: %d", lockmode);
    1965             : 
    1966             : #ifdef LOCK_DEBUG
    1967             :     if (LOCK_DEBUG_ENABLED(locktag))
    1968             :         elog(LOG, "LockRelease: lock [%u,%u] %s",
    1969             :              locktag->locktag_field1, locktag->locktag_field2,
    1970             :              lockMethodTable->lockModeNames[lockmode]);
    1971             : #endif
    1972             : 
    1973             :     /*
    1974             :      * Find the LOCALLOCK entry for this lock and lockmode
    1975             :      */
    1976    40207254 :     MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
    1977    40207254 :     localtag.lock = *locktag;
    1978    40207254 :     localtag.mode = lockmode;
    1979             : 
    1980    40207254 :     locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
    1981             :                                           &localtag,
    1982             :                                           HASH_FIND, NULL);
    1983             : 
    1984             :     /*
    1985             :      * let the caller print its own error message, too. Do not ereport(ERROR).
    1986             :      */
    1987    40207254 :     if (!locallock || locallock->nLocks <= 0)
    1988             :     {
    1989          26 :         elog(WARNING, "you don't own a lock of type %s",
    1990             :              lockMethodTable->lockModeNames[lockmode]);
    1991          26 :         return false;
    1992             :     }
    1993             : 
    1994             :     /*
    1995             :      * Decrease the count for the resource owner.
    1996             :      */
    1997             :     {
    1998    40207228 :         LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
    1999             :         ResourceOwner owner;
    2000             :         int         i;
    2001             : 
    2002             :         /* Identify owner for lock */
    2003    40207228 :         if (sessionLock)
    2004      110844 :             owner = NULL;
    2005             :         else
    2006    40096384 :             owner = CurrentResourceOwner;
    2007             : 
    2008    40209654 :         for (i = locallock->numLockOwners - 1; i >= 0; i--)
    2009             :         {
    2010    40209630 :             if (lockOwners[i].owner == owner)
    2011             :             {
    2012             :                 Assert(lockOwners[i].nLocks > 0);
    2013    40207204 :                 if (--lockOwners[i].nLocks == 0)
    2014             :                 {
    2015    39055860 :                     if (owner != NULL)
    2016    38945064 :                         ResourceOwnerForgetLock(owner, locallock);
    2017             :                     /* compact out unused slot */
    2018    39055860 :                     locallock->numLockOwners--;
    2019    39055860 :                     if (i < locallock->numLockOwners)
    2020          90 :                         lockOwners[i] = lockOwners[locallock->numLockOwners];
    2021             :                 }
    2022    40207204 :                 break;
    2023             :             }
    2024             :         }
    2025    40207228 :         if (i < 0)
    2026             :         {
    2027             :             /* don't release a lock belonging to another owner */
    2028          24 :             elog(WARNING, "you don't own a lock of type %s",
    2029             :                  lockMethodTable->lockModeNames[lockmode]);
    2030          24 :             return false;
    2031             :         }
    2032             :     }
    2033             : 
    2034             :     /*
    2035             :      * Decrease the total local count.  If we're still holding the lock, we're
    2036             :      * done.
    2037             :      */
    2038    40207204 :     locallock->nLocks--;
    2039             : 
    2040    40207204 :     if (locallock->nLocks > 0)
    2041     1577838 :         return true;
    2042             : 
    2043             :     /*
    2044             :      * At this point we can no longer suppose we are clear of invalidation
    2045             :      * messages related to this lock.  Although we'll delete the LOCALLOCK
    2046             :      * object before any intentional return from this routine, it seems worth
    2047             :      * the trouble to explicitly reset lockCleared right now, just in case
    2048             :      * some error prevents us from deleting the LOCALLOCK.
    2049             :      */
    2050    38629366 :     locallock->lockCleared = false;
    2051             : 
    2052             :     /* Attempt fast release of any lock eligible for the fast path. */
    2053    38629366 :     if (EligibleForRelationFastPath(locktag, lockmode) &&
    2054    36603282 :         FastPathLocalUseCount > 0)
    2055             :     {
    2056             :         bool        released;
    2057             : 
    2058             :         /*
    2059             :          * We might not find the lock here, even if we originally entered it
    2060             :          * here.  Another backend may have moved it to the main table.
    2061             :          */
    2062    35754286 :         LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
    2063    35754286 :         released = FastPathUnGrantRelationLock(locktag->locktag_field2,
    2064             :                                                lockmode);
    2065    35754286 :         LWLockRelease(&MyProc->fpInfoLock);
    2066    35754286 :         if (released)
    2067             :         {
    2068    35283264 :             RemoveLocalLock(locallock);
    2069    35283264 :             return true;
    2070             :         }
    2071             :     }
    2072             : 
    2073             :     /*
    2074             :      * Otherwise we've got to mess with the shared lock table.
    2075             :      */
    2076     3346102 :     partitionLock = LockHashPartitionLock(locallock->hashcode);
    2077             : 
    2078     3346102 :     LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    2079             : 
    2080             :     /*
    2081             :      * Normally, we don't need to re-find the lock or proclock, since we kept
    2082             :      * their addresses in the locallock table, and they couldn't have been
    2083             :      * removed while we were holding a lock on them.  But it's possible that
    2084             :      * the lock was taken fast-path and has since been moved to the main hash
    2085             :      * table by another backend, in which case we will need to look up the
    2086             :      * objects here.  We assume the lock field is NULL if so.
    2087             :      */
    2088     3346102 :     lock = locallock->lock;
    2089     3346102 :     if (!lock)
    2090             :     {
    2091             :         PROCLOCKTAG proclocktag;
    2092             : 
    2093             :         Assert(EligibleForRelationFastPath(locktag, lockmode));
    2094           8 :         lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
    2095             :                                                     locktag,
    2096             :                                                     locallock->hashcode,
    2097             :                                                     HASH_FIND,
    2098             :                                                     NULL);
    2099           8 :         if (!lock)
    2100           0 :             elog(ERROR, "failed to re-find shared lock object");
    2101           8 :         locallock->lock = lock;
    2102             : 
    2103           8 :         proclocktag.myLock = lock;
    2104           8 :         proclocktag.myProc = MyProc;
    2105           8 :         locallock->proclock = (PROCLOCK *) hash_search(LockMethodProcLockHash,
    2106             :                                                        &proclocktag,
    2107             :                                                        HASH_FIND,
    2108             :                                                        NULL);
    2109           8 :         if (!locallock->proclock)
    2110           0 :             elog(ERROR, "failed to re-find shared proclock object");
    2111             :     }
    2112             :     LOCK_PRINT("LockRelease: found", lock, lockmode);
    2113     3346102 :     proclock = locallock->proclock;
    2114             :     PROCLOCK_PRINT("LockRelease: found", proclock);
    2115             : 
    2116             :     /*
    2117             :      * Double-check that we are actually holding a lock of the type we want to
    2118             :      * release.
    2119             :      */
    2120     3346102 :     if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
    2121             :     {
    2122             :         PROCLOCK_PRINT("LockRelease: WRONGTYPE", proclock);
    2123           0 :         LWLockRelease(partitionLock);
    2124           0 :         elog(WARNING, "you don't own a lock of type %s",
    2125             :              lockMethodTable->lockModeNames[lockmode]);
    2126           0 :         RemoveLocalLock(locallock);
    2127           0 :         return false;
    2128             :     }
    2129             : 
    2130             :     /*
    2131             :      * Do the releasing.  CleanUpLock will waken any now-wakable waiters.
    2132             :      */
    2133     3346102 :     wakeupNeeded = UnGrantLock(lock, lockmode, proclock, lockMethodTable);
    2134             : 
    2135     3346102 :     CleanUpLock(lock, proclock,
    2136             :                 lockMethodTable, locallock->hashcode,
    2137             :                 wakeupNeeded);
    2138             : 
    2139     3346102 :     LWLockRelease(partitionLock);
    2140             : 
    2141     3346102 :     RemoveLocalLock(locallock);
    2142     3346102 :     return true;
    2143             : }
    2144             : 
    2145             : /*
    2146             :  * LockReleaseAll -- Release all locks of the specified lock method that
    2147             :  *      are held by the current process.
    2148             :  *
    2149             :  * Well, not necessarily *all* locks.  The available behaviors are:
    2150             :  *      allLocks == true: release all locks including session locks.
    2151             :  *      allLocks == false: release all non-session locks.
    2152             :  */
    2153             : void
    2154     1904918 : LockReleaseAll(LOCKMETHODID lockmethodid, bool allLocks)
    2155             : {
    2156             :     HASH_SEQ_STATUS status;
    2157             :     LockMethod  lockMethodTable;
    2158             :     int         i,
    2159             :                 numLockModes;
    2160             :     LOCALLOCK  *locallock;
    2161             :     LOCK       *lock;
    2162             :     int         partition;
    2163     1904918 :     bool        have_fast_path_lwlock = false;
    2164             : 
    2165     1904918 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
    2166           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    2167     1904918 :     lockMethodTable = LockMethods[lockmethodid];
    2168             : 
    2169             : #ifdef LOCK_DEBUG
    2170             :     if (*(lockMethodTable->trace_flag))
    2171             :         elog(LOG, "LockReleaseAll: lockmethod=%d", lockmethodid);
    2172             : #endif
    2173             : 
    2174             :     /*
    2175             :      * Get rid of our fast-path VXID lock, if appropriate.  Note that this is
    2176             :      * the only way that the lock we hold on our own VXID can ever get
    2177             :      * released: it is always and only released when a toplevel transaction
    2178             :      * ends.
    2179             :      */
    2180     1904918 :     if (lockmethodid == DEFAULT_LOCKMETHOD)
    2181      941538 :         VirtualXactLockTableCleanup();
    2182             : 
    2183     1904918 :     numLockModes = lockMethodTable->numLockModes;
    2184             : 
    2185             :     /*
    2186             :      * First we run through the locallock table and get rid of unwanted
    2187             :      * entries, then we scan the process's proclocks and get rid of those. We
    2188             :      * do this separately because we may have multiple locallock entries
    2189             :      * pointing to the same proclock, and we daren't end up with any dangling
    2190             :      * pointers.  Fast-path locks are cleaned up during the locallock table
    2191             :      * scan, though.
    2192             :      */
    2193     1904918 :     hash_seq_init(&status, LockMethodLocalHash);
    2194             : 
    2195     4932748 :     while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    2196             :     {
    2197             :         /*
    2198             :          * If the LOCALLOCK entry is unused, we must've run out of shared
    2199             :          * memory while trying to set up this lock.  Just forget the local
    2200             :          * entry.
    2201             :          */
    2202     3027830 :         if (locallock->nLocks == 0)
    2203             :         {
    2204          92 :             RemoveLocalLock(locallock);
    2205          92 :             continue;
    2206             :         }
    2207             : 
    2208             :         /* Ignore items that are not of the lockmethod to be removed */
    2209     3027738 :         if (LOCALLOCK_LOCKMETHOD(*locallock) != lockmethodid)
    2210      113050 :             continue;
    2211             : 
    2212             :         /*
    2213             :          * If we are asked to release all locks, we can just zap the entry.
    2214             :          * Otherwise, must scan to see if there are session locks. We assume
    2215             :          * there is at most one lockOwners entry for session locks.
    2216             :          */
    2217     2914688 :         if (!allLocks)
    2218             :         {
    2219     2801374 :             LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
    2220             : 
    2221             :             /* If session lock is above array position 0, move it down to 0 */
    2222     5680504 :             for (i = 0; i < locallock->numLockOwners; i++)
    2223             :             {
    2224     2879130 :                 if (lockOwners[i].owner == NULL)
    2225      112884 :                     lockOwners[0] = lockOwners[i];
    2226             :                 else
    2227     2766246 :                     ResourceOwnerForgetLock(lockOwners[i].owner, locallock);
    2228             :             }
    2229             : 
    2230     2801374 :             if (locallock->numLockOwners > 0 &&
    2231     2801374 :                 lockOwners[0].owner == NULL &&
    2232      112884 :                 lockOwners[0].nLocks > 0)
    2233             :             {
    2234             :                 /* Fix the locallock to show just the session locks */
    2235      112884 :                 locallock->nLocks = lockOwners[0].nLocks;
    2236      112884 :                 locallock->numLockOwners = 1;
    2237             :                 /* We aren't deleting this locallock, so done */
    2238      112884 :                 continue;
    2239             :             }
    2240             :             else
    2241     2688490 :                 locallock->numLockOwners = 0;
    2242             :         }
    2243             : 
    2244             :         /*
    2245             :          * If the lock or proclock pointers are NULL, this lock was taken via
    2246             :          * the relation fast-path (and is not known to have been transferred).
    2247             :          */
    2248     2801804 :         if (locallock->proclock == NULL || locallock->lock == NULL)
    2249             :         {
    2250     1167256 :             LOCKMODE    lockmode = locallock->tag.mode;
    2251             :             Oid         relid;
    2252             : 
    2253             :             /* Verify that a fast-path lock is what we've got. */
    2254     1167256 :             if (!EligibleForRelationFastPath(&locallock->tag.lock, lockmode))
    2255           0 :                 elog(PANIC, "locallock table corrupted");
    2256             : 
    2257             :             /*
    2258             :              * If we don't currently hold the LWLock that protects our
    2259             :              * fast-path data structures, we must acquire it before attempting
    2260             :              * to release the lock via the fast-path.  We will continue to
    2261             :              * hold the LWLock until we're done scanning the locallock table,
    2262             :              * unless we hit a transferred fast-path lock.  (XXX is this
    2263             :              * really such a good idea?  There could be a lot of entries ...)
    2264             :              */
    2265     1167256 :             if (!have_fast_path_lwlock)
    2266             :             {
    2267      426960 :                 LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
    2268      426960 :                 have_fast_path_lwlock = true;
    2269             :             }
    2270             : 
    2271             :             /* Attempt fast-path release. */
    2272     1167256 :             relid = locallock->tag.lock.locktag_field2;
    2273     1167256 :             if (FastPathUnGrantRelationLock(relid, lockmode))
    2274             :             {
    2275     1165290 :                 RemoveLocalLock(locallock);
    2276     1165290 :                 continue;
    2277             :             }
    2278             : 
    2279             :             /*
    2280             :              * Our lock, originally taken via the fast path, has been
    2281             :              * transferred to the main lock table.  That's going to require
    2282             :              * some extra work, so release our fast-path lock before starting.
    2283             :              */
    2284        1966 :             LWLockRelease(&MyProc->fpInfoLock);
    2285        1966 :             have_fast_path_lwlock = false;
    2286             : 
    2287             :             /*
    2288             :              * Now dump the lock.  We haven't got a pointer to the LOCK or
    2289             :              * PROCLOCK in this case, so we have to handle this a bit
    2290             :              * differently than a normal lock release.  Unfortunately, this
    2291             :              * requires an extra LWLock acquire-and-release cycle on the
    2292             :              * partitionLock, but hopefully it shouldn't happen often.
    2293             :              */
    2294        1966 :             LockRefindAndRelease(lockMethodTable, MyProc,
    2295             :                                  &locallock->tag.lock, lockmode, false);
    2296        1966 :             RemoveLocalLock(locallock);
    2297        1966 :             continue;
    2298             :         }
    2299             : 
    2300             :         /* Mark the proclock to show we need to release this lockmode */
    2301     1634548 :         if (locallock->nLocks > 0)
    2302     1634548 :             locallock->proclock->releaseMask |= LOCKBIT_ON(locallock->tag.mode);
    2303             : 
    2304             :         /* And remove the locallock hashtable entry */
    2305     1634548 :         RemoveLocalLock(locallock);
    2306             :     }
    2307             : 
    2308             :     /* Done with the fast-path data structures */
    2309     1904918 :     if (have_fast_path_lwlock)
    2310      424994 :         LWLockRelease(&MyProc->fpInfoLock);
    2311             : 
    2312             :     /*
    2313             :      * Now, scan each lock partition separately.
    2314             :      */
    2315    32383606 :     for (partition = 0; partition < NUM_LOCK_PARTITIONS; partition++)
    2316             :     {
    2317             :         LWLock     *partitionLock;
    2318    30478688 :         dlist_head *procLocks = &MyProc->myProcLocks[partition];
    2319             :         dlist_mutable_iter proclock_iter;
    2320             : 
    2321    30478688 :         partitionLock = LockHashPartitionLockByIndex(partition);
    2322             : 
    2323             :         /*
    2324             :          * If the proclock list for this partition is empty, we can skip
    2325             :          * acquiring the partition lock.  This optimization is trickier than
    2326             :          * it looks, because another backend could be in process of adding
    2327             :          * something to our proclock list due to promoting one of our
    2328             :          * fast-path locks.  However, any such lock must be one that we
    2329             :          * decided not to delete above, so it's okay to skip it again now;
    2330             :          * we'd just decide not to delete it again.  We must, however, be
    2331             :          * careful to re-fetch the list header once we've acquired the
    2332             :          * partition lock, to be sure we have a valid, up-to-date pointer.
    2333             :          * (There is probably no significant risk if pointer fetch/store is
    2334             :          * atomic, but we don't wish to assume that.)
    2335             :          *
    2336             :          * XXX This argument assumes that the locallock table correctly
    2337             :          * represents all of our fast-path locks.  While allLocks mode
    2338             :          * guarantees to clean up all of our normal locks regardless of the
    2339             :          * locallock situation, we lose that guarantee for fast-path locks.
    2340             :          * This is not ideal.
    2341             :          */
    2342    30478688 :         if (dlist_is_empty(procLocks))
    2343    28999372 :             continue;           /* needn't examine this partition */
    2344             : 
    2345     1479316 :         LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    2346             : 
    2347     3280442 :         dlist_foreach_modify(proclock_iter, procLocks)
    2348             :         {
    2349     1801126 :             PROCLOCK   *proclock = dlist_container(PROCLOCK, procLink, proclock_iter.cur);
    2350     1801126 :             bool        wakeupNeeded = false;
    2351             : 
    2352             :             Assert(proclock->tag.myProc == MyProc);
    2353             : 
    2354     1801126 :             lock = proclock->tag.myLock;
    2355             : 
    2356             :             /* Ignore items that are not of the lockmethod to be removed */
    2357     1801126 :             if (LOCK_LOCKMETHOD(*lock) != lockmethodid)
    2358      113044 :                 continue;
    2359             : 
    2360             :             /*
    2361             :              * In allLocks mode, force release of all locks even if locallock
    2362             :              * table had problems
    2363             :              */
    2364     1688082 :             if (allLocks)
    2365       72422 :                 proclock->releaseMask = proclock->holdMask;
    2366             :             else
    2367             :                 Assert((proclock->releaseMask & ~proclock->holdMask) == 0);
    2368             : 
    2369             :             /*
    2370             :              * Ignore items that have nothing to be released, unless they have
    2371             :              * holdMask == 0 and are therefore recyclable
    2372             :              */
    2373     1688082 :             if (proclock->releaseMask == 0 && proclock->holdMask != 0)
    2374      111698 :                 continue;
    2375             : 
    2376             :             PROCLOCK_PRINT("LockReleaseAll", proclock);
    2377             :             LOCK_PRINT("LockReleaseAll", lock, 0);
    2378             :             Assert(lock->nRequested >= 0);
    2379             :             Assert(lock->nGranted >= 0);
    2380             :             Assert(lock->nGranted <= lock->nRequested);
    2381             :             Assert((proclock->holdMask & ~lock->grantMask) == 0);
    2382             : 
    2383             :             /*
    2384             :              * Release the previously-marked lock modes
    2385             :              */
    2386    14187456 :             for (i = 1; i <= numLockModes; i++)
    2387             :             {
    2388    12611072 :                 if (proclock->releaseMask & LOCKBIT_ON(i))
    2389     1634548 :                     wakeupNeeded |= UnGrantLock(lock, i, proclock,
    2390             :                                                 lockMethodTable);
    2391             :             }
    2392             :             Assert((lock->nRequested >= 0) && (lock->nGranted >= 0));
    2393             :             Assert(lock->nGranted <= lock->nRequested);
    2394             :             LOCK_PRINT("LockReleaseAll: updated", lock, 0);
    2395             : 
    2396     1576384 :             proclock->releaseMask = 0;
    2397             : 
    2398             :             /* CleanUpLock will wake up waiters if needed. */
    2399     1576384 :             CleanUpLock(lock, proclock,
    2400             :                         lockMethodTable,
    2401     1576384 :                         LockTagHashCode(&lock->tag),
    2402             :                         wakeupNeeded);
    2403             :         }                       /* loop over PROCLOCKs within this partition */
    2404             : 
    2405     1479316 :         LWLockRelease(partitionLock);
    2406             :     }                           /* loop over partitions */
    2407             : 
    2408             : #ifdef LOCK_DEBUG
    2409             :     if (*(lockMethodTable->trace_flag))
    2410             :         elog(LOG, "LockReleaseAll done");
    2411             : #endif
    2412     1904918 : }
    2413             : 
    2414             : /*
    2415             :  * LockReleaseSession -- Release all session locks of the specified lock method
    2416             :  *      that are held by the current process.
    2417             :  */
    2418             : void
    2419         238 : LockReleaseSession(LOCKMETHODID lockmethodid)
    2420             : {
    2421             :     HASH_SEQ_STATUS status;
    2422             :     LOCALLOCK  *locallock;
    2423             : 
    2424         238 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
    2425           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    2426             : 
    2427         238 :     hash_seq_init(&status, LockMethodLocalHash);
    2428             : 
    2429         452 :     while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    2430             :     {
    2431             :         /* Ignore items that are not of the specified lock method */
    2432         214 :         if (LOCALLOCK_LOCKMETHOD(*locallock) != lockmethodid)
    2433          20 :             continue;
    2434             : 
    2435         194 :         ReleaseLockIfHeld(locallock, true);
    2436             :     }
    2437         238 : }
    2438             : 
    2439             : /*
    2440             :  * LockReleaseCurrentOwner
    2441             :  *      Release all locks belonging to CurrentResourceOwner
    2442             :  *
    2443             :  * If the caller knows what those locks are, it can pass them as an array.
    2444             :  * That speeds up the call significantly, when a lot of locks are held.
    2445             :  * Otherwise, pass NULL for locallocks, and we'll traverse through our hash
    2446             :  * table to find them.
    2447             :  */
    2448             : void
    2449        9142 : LockReleaseCurrentOwner(LOCALLOCK **locallocks, int nlocks)
    2450             : {
    2451        9142 :     if (locallocks == NULL)
    2452             :     {
    2453             :         HASH_SEQ_STATUS status;
    2454             :         LOCALLOCK  *locallock;
    2455             : 
    2456           8 :         hash_seq_init(&status, LockMethodLocalHash);
    2457             : 
    2458         530 :         while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    2459         522 :             ReleaseLockIfHeld(locallock, false);
    2460             :     }
    2461             :     else
    2462             :     {
    2463             :         int         i;
    2464             : 
    2465       13996 :         for (i = nlocks - 1; i >= 0; i--)
    2466        4862 :             ReleaseLockIfHeld(locallocks[i], false);
    2467             :     }
    2468        9142 : }
    2469             : 
    2470             : /*
    2471             :  * ReleaseLockIfHeld
    2472             :  *      Release any session-level locks on this lockable object if sessionLock
    2473             :  *      is true; else, release any locks held by CurrentResourceOwner.
    2474             :  *
    2475             :  * It is tempting to pass this a ResourceOwner pointer (or NULL for session
    2476             :  * locks), but without refactoring LockRelease() we cannot support releasing
    2477             :  * locks belonging to resource owners other than CurrentResourceOwner.
    2478             :  * If we were to refactor, it'd be a good idea to fix it so we don't have to
    2479             :  * do a hashtable lookup of the locallock, too.  However, currently this
    2480             :  * function isn't used heavily enough to justify refactoring for its
    2481             :  * convenience.
    2482             :  */
    2483             : static void
    2484        5578 : ReleaseLockIfHeld(LOCALLOCK *locallock, bool sessionLock)
    2485             : {
    2486             :     ResourceOwner owner;
    2487             :     LOCALLOCKOWNER *lockOwners;
    2488             :     int         i;
    2489             : 
    2490             :     /* Identify owner for lock (must match LockRelease!) */
    2491        5578 :     if (sessionLock)
    2492         194 :         owner = NULL;
    2493             :     else
    2494        5384 :         owner = CurrentResourceOwner;
    2495             : 
    2496             :     /* Scan to see if there are any locks belonging to the target owner */
    2497        5578 :     lockOwners = locallock->lockOwners;
    2498        5958 :     for (i = locallock->numLockOwners - 1; i >= 0; i--)
    2499             :     {
    2500        5578 :         if (lockOwners[i].owner == owner)
    2501             :         {
    2502             :             Assert(lockOwners[i].nLocks > 0);
    2503        5198 :             if (lockOwners[i].nLocks < locallock->nLocks)
    2504             :             {
    2505             :                 /*
    2506             :                  * We will still hold this lock after forgetting this
    2507             :                  * ResourceOwner.
    2508             :                  */
    2509        1338 :                 locallock->nLocks -= lockOwners[i].nLocks;
    2510             :                 /* compact out unused slot */
    2511        1338 :                 locallock->numLockOwners--;
    2512        1338 :                 if (owner != NULL)
    2513        1338 :                     ResourceOwnerForgetLock(owner, locallock);
    2514        1338 :                 if (i < locallock->numLockOwners)
    2515           0 :                     lockOwners[i] = lockOwners[locallock->numLockOwners];
    2516             :             }
    2517             :             else
    2518             :             {
    2519             :                 Assert(lockOwners[i].nLocks == locallock->nLocks);
    2520             :                 /* We want to call LockRelease just once */
    2521        3860 :                 lockOwners[i].nLocks = 1;
    2522        3860 :                 locallock->nLocks = 1;
    2523        3860 :                 if (!LockRelease(&locallock->tag.lock,
    2524             :                                  locallock->tag.mode,
    2525             :                                  sessionLock))
    2526           0 :                     elog(WARNING, "ReleaseLockIfHeld: failed??");
    2527             :             }
    2528        5198 :             break;
    2529             :         }
    2530             :     }
    2531        5578 : }
    2532             : 
    2533             : /*
    2534             :  * LockReassignCurrentOwner
    2535             :  *      Reassign all locks belonging to CurrentResourceOwner to belong
    2536             :  *      to its parent resource owner.
    2537             :  *
    2538             :  * If the caller knows what those locks are, it can pass them as an array.
    2539             :  * That speeds up the call significantly, when a lot of locks are held
    2540             :  * (e.g pg_dump with a large schema).  Otherwise, pass NULL for locallocks,
    2541             :  * and we'll traverse through our hash table to find them.
    2542             :  */
    2543             : void
    2544      935586 : LockReassignCurrentOwner(LOCALLOCK **locallocks, int nlocks)
    2545             : {
    2546      935586 :     ResourceOwner parent = ResourceOwnerGetParent(CurrentResourceOwner);
    2547             : 
    2548             :     Assert(parent != NULL);
    2549             : 
    2550      935586 :     if (locallocks == NULL)
    2551             :     {
    2552             :         HASH_SEQ_STATUS status;
    2553             :         LOCALLOCK  *locallock;
    2554             : 
    2555        6742 :         hash_seq_init(&status, LockMethodLocalHash);
    2556             : 
    2557      159574 :         while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    2558      152832 :             LockReassignOwner(locallock, parent);
    2559             :     }
    2560             :     else
    2561             :     {
    2562             :         int         i;
    2563             : 
    2564     2081512 :         for (i = nlocks - 1; i >= 0; i--)
    2565     1152668 :             LockReassignOwner(locallocks[i], parent);
    2566             :     }
    2567      935586 : }
    2568             : 
    2569             : /*
    2570             :  * Subroutine of LockReassignCurrentOwner. Reassigns a given lock belonging to
    2571             :  * CurrentResourceOwner to its parent.
    2572             :  */
    2573             : static void
    2574     1305500 : LockReassignOwner(LOCALLOCK *locallock, ResourceOwner parent)
    2575             : {
    2576             :     LOCALLOCKOWNER *lockOwners;
    2577             :     int         i;
    2578     1305500 :     int         ic = -1;
    2579     1305500 :     int         ip = -1;
    2580             : 
    2581             :     /*
    2582             :      * Scan to see if there are any locks belonging to current owner or its
    2583             :      * parent
    2584             :      */
    2585     1305500 :     lockOwners = locallock->lockOwners;
    2586     2859280 :     for (i = locallock->numLockOwners - 1; i >= 0; i--)
    2587             :     {
    2588     1553780 :         if (lockOwners[i].owner == CurrentResourceOwner)
    2589     1287690 :             ic = i;
    2590      266090 :         else if (lockOwners[i].owner == parent)
    2591      183082 :             ip = i;
    2592             :     }
    2593             : 
    2594     1305500 :     if (ic < 0)
    2595       17810 :         return;                 /* no current locks */
    2596             : 
    2597     1287690 :     if (ip < 0)
    2598             :     {
    2599             :         /* Parent has no slot, so just give it the child's slot */
    2600     1122356 :         lockOwners[ic].owner = parent;
    2601     1122356 :         ResourceOwnerRememberLock(parent, locallock);
    2602             :     }
    2603             :     else
    2604             :     {
    2605             :         /* Merge child's count with parent's */
    2606      165334 :         lockOwners[ip].nLocks += lockOwners[ic].nLocks;
    2607             :         /* compact out unused slot */
    2608      165334 :         locallock->numLockOwners--;
    2609      165334 :         if (ic < locallock->numLockOwners)
    2610        1364 :             lockOwners[ic] = lockOwners[locallock->numLockOwners];
    2611             :     }
    2612     1287690 :     ResourceOwnerForgetLock(CurrentResourceOwner, locallock);
    2613             : }
    2614             : 
    2615             : /*
    2616             :  * FastPathGrantRelationLock
    2617             :  *      Grant lock using per-backend fast-path array, if there is space.
    2618             :  */
    2619             : static bool
    2620    36451282 : FastPathGrantRelationLock(Oid relid, LOCKMODE lockmode)
    2621             : {
    2622             :     uint32      f;
    2623    36451282 :     uint32      unused_slot = FP_LOCK_SLOTS_PER_BACKEND;
    2624             : 
    2625             :     /* Scan for existing entry for this relid, remembering empty slot. */
    2626   614182320 :     for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
    2627             :     {
    2628   579568016 :         if (FAST_PATH_GET_BITS(MyProc, f) == 0)
    2629   493832568 :             unused_slot = f;
    2630    85735448 :         else if (MyProc->fpRelId[f] == relid)
    2631             :         {
    2632             :             Assert(!FAST_PATH_CHECK_LOCKMODE(MyProc, f, lockmode));
    2633     1836978 :             FAST_PATH_SET_LOCKMODE(MyProc, f, lockmode);
    2634     1836978 :             return true;
    2635             :         }
    2636             :     }
    2637             : 
    2638             :     /* If no existing entry, use any empty slot. */
    2639    34614304 :     if (unused_slot < FP_LOCK_SLOTS_PER_BACKEND)
    2640             :     {
    2641    34614304 :         MyProc->fpRelId[unused_slot] = relid;
    2642    34614304 :         FAST_PATH_SET_LOCKMODE(MyProc, unused_slot, lockmode);
    2643    34614304 :         ++FastPathLocalUseCount;
    2644    34614304 :         return true;
    2645             :     }
    2646             : 
    2647             :     /* No existing entry, and no empty slot. */
    2648           0 :     return false;
    2649             : }
    2650             : 
    2651             : /*
    2652             :  * FastPathUnGrantRelationLock
    2653             :  *      Release fast-path lock, if present.  Update backend-private local
    2654             :  *      use count, while we're at it.
    2655             :  */
    2656             : static bool
    2657    36921542 : FastPathUnGrantRelationLock(Oid relid, LOCKMODE lockmode)
    2658             : {
    2659             :     uint32      f;
    2660    36921542 :     bool        result = false;
    2661             : 
    2662    36921542 :     FastPathLocalUseCount = 0;
    2663   627666214 :     for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
    2664             :     {
    2665   590744672 :         if (MyProc->fpRelId[f] == relid
    2666    44757302 :             && FAST_PATH_CHECK_LOCKMODE(MyProc, f, lockmode))
    2667             :         {
    2668             :             Assert(!result);
    2669    36448554 :             FAST_PATH_CLEAR_LOCKMODE(MyProc, f, lockmode);
    2670    36448554 :             result = true;
    2671             :             /* we continue iterating so as to update FastPathLocalUseCount */
    2672             :         }
    2673   590744672 :         if (FAST_PATH_GET_BITS(MyProc, f) != 0)
    2674    95618158 :             ++FastPathLocalUseCount;
    2675             :     }
    2676    36921542 :     return result;
    2677             : }
    2678             : 
    2679             : /*
    2680             :  * FastPathTransferRelationLocks
    2681             :  *      Transfer locks matching the given lock tag from per-backend fast-path
    2682             :  *      arrays to the shared hash table.
    2683             :  *
    2684             :  * Returns true if successful, false if ran out of shared memory.
    2685             :  */
    2686             : static bool
    2687      522042 : FastPathTransferRelationLocks(LockMethod lockMethodTable, const LOCKTAG *locktag,
    2688             :                               uint32 hashcode)
    2689             : {
    2690      522042 :     LWLock     *partitionLock = LockHashPartitionLock(hashcode);
    2691      522042 :     Oid         relid = locktag->locktag_field2;
    2692             :     uint32      i;
    2693             : 
    2694             :     /*
    2695             :      * Every PGPROC that can potentially hold a fast-path lock is present in
    2696             :      * ProcGlobal->allProcs.  Prepared transactions are not, but any
    2697             :      * outstanding fast-path locks held by prepared transactions are
    2698             :      * transferred to the main lock table.
    2699             :      */
    2700    59533092 :     for (i = 0; i < ProcGlobal->allProcCount; i++)
    2701             :     {
    2702    59011050 :         PGPROC     *proc = &ProcGlobal->allProcs[i];
    2703             :         uint32      f;
    2704             : 
    2705    59011050 :         LWLockAcquire(&proc->fpInfoLock, LW_EXCLUSIVE);
    2706             : 
    2707             :         /*
    2708             :          * If the target backend isn't referencing the same database as the
    2709             :          * lock, then we needn't examine the individual relation IDs at all;
    2710             :          * none of them can be relevant.
    2711             :          *
    2712             :          * proc->databaseId is set at backend startup time and never changes
    2713             :          * thereafter, so it might be safe to perform this test before
    2714             :          * acquiring &proc->fpInfoLock.  In particular, it's certainly safe to
    2715             :          * assume that if the target backend holds any fast-path locks, it
    2716             :          * must have performed a memory-fencing operation (in particular, an
    2717             :          * LWLock acquisition) since setting proc->databaseId.  However, it's
    2718             :          * less clear that our backend is certain to have performed a memory
    2719             :          * fencing operation since the other backend set proc->databaseId.  So
    2720             :          * for now, we test it after acquiring the LWLock just to be safe.
    2721             :          */
    2722    59011050 :         if (proc->databaseId != locktag->locktag_field1)
    2723             :         {
    2724    44202466 :             LWLockRelease(&proc->fpInfoLock);
    2725    44202466 :             continue;
    2726             :         }
    2727             : 
    2728   251743582 :         for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
    2729             :         {
    2730             :             uint32      lockmode;
    2731             : 
    2732             :             /* Look for an allocated slot matching the given relid. */
    2733   236936876 :             if (relid != proc->fpRelId[f] || FAST_PATH_GET_BITS(proc, f) == 0)
    2734   236934998 :                 continue;
    2735             : 
    2736             :             /* Find or create lock object. */
    2737        1878 :             LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    2738        7512 :             for (lockmode = FAST_PATH_LOCKNUMBER_OFFSET;
    2739             :                  lockmode < FAST_PATH_LOCKNUMBER_OFFSET + FAST_PATH_BITS_PER_SLOT;
    2740        5634 :                  ++lockmode)
    2741             :             {
    2742             :                 PROCLOCK   *proclock;
    2743             : 
    2744        5634 :                 if (!FAST_PATH_CHECK_LOCKMODE(proc, f, lockmode))
    2745        3644 :                     continue;
    2746        1990 :                 proclock = SetupLockInTable(lockMethodTable, proc, locktag,
    2747             :                                             hashcode, lockmode);
    2748        1990 :                 if (!proclock)
    2749             :                 {
    2750           0 :                     LWLockRelease(partitionLock);
    2751           0 :                     LWLockRelease(&proc->fpInfoLock);
    2752           0 :                     return false;
    2753             :                 }
    2754        1990 :                 GrantLock(proclock->tag.myLock, proclock, lockmode);
    2755        1990 :                 FAST_PATH_CLEAR_LOCKMODE(proc, f, lockmode);
    2756             :             }
    2757        1878 :             LWLockRelease(partitionLock);
    2758             : 
    2759             :             /* No need to examine remaining slots. */
    2760        1878 :             break;
    2761             :         }
    2762    14808584 :         LWLockRelease(&proc->fpInfoLock);
    2763             :     }
    2764      522042 :     return true;
    2765             : }
    2766             : 
    2767             : /*
    2768             :  * FastPathGetRelationLockEntry
    2769             :  *      Return the PROCLOCK for a lock originally taken via the fast-path,
    2770             :  *      transferring it to the primary lock table if necessary.
    2771             :  *
    2772             :  * Note: caller takes care of updating the locallock object.
    2773             :  */
    2774             : static PROCLOCK *
    2775         754 : FastPathGetRelationLockEntry(LOCALLOCK *locallock)
    2776             : {
    2777         754 :     LockMethod  lockMethodTable = LockMethods[DEFAULT_LOCKMETHOD];
    2778         754 :     LOCKTAG    *locktag = &locallock->tag.lock;
    2779         754 :     PROCLOCK   *proclock = NULL;
    2780         754 :     LWLock     *partitionLock = LockHashPartitionLock(locallock->hashcode);
    2781         754 :     Oid         relid = locktag->locktag_field2;
    2782             :     uint32      f;
    2783             : 
    2784         754 :     LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
    2785             : 
    2786       12040 :     for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
    2787             :     {
    2788             :         uint32      lockmode;
    2789             : 
    2790             :         /* Look for an allocated slot matching the given relid. */
    2791       12024 :         if (relid != MyProc->fpRelId[f] || FAST_PATH_GET_BITS(MyProc, f) == 0)
    2792       11286 :             continue;
    2793             : 
    2794             :         /* If we don't have a lock of the given mode, forget it! */
    2795         738 :         lockmode = locallock->tag.mode;
    2796         738 :         if (!FAST_PATH_CHECK_LOCKMODE(MyProc, f, lockmode))
    2797           0 :             break;
    2798             : 
    2799             :         /* Find or create lock object. */
    2800         738 :         LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    2801             : 
    2802         738 :         proclock = SetupLockInTable(lockMethodTable, MyProc, locktag,
    2803             :                                     locallock->hashcode, lockmode);
    2804         738 :         if (!proclock)
    2805             :         {
    2806           0 :             LWLockRelease(partitionLock);
    2807           0 :             LWLockRelease(&MyProc->fpInfoLock);
    2808           0 :             ereport(ERROR,
    2809             :                     (errcode(ERRCODE_OUT_OF_MEMORY),
    2810             :                      errmsg("out of shared memory"),
    2811             :                      errhint("You might need to increase max_locks_per_transaction.")));
    2812             :         }
    2813         738 :         GrantLock(proclock->tag.myLock, proclock, lockmode);
    2814         738 :         FAST_PATH_CLEAR_LOCKMODE(MyProc, f, lockmode);
    2815             : 
    2816         738 :         LWLockRelease(partitionLock);
    2817             : 
    2818             :         /* No need to examine remaining slots. */
    2819         738 :         break;
    2820             :     }
    2821             : 
    2822         754 :     LWLockRelease(&MyProc->fpInfoLock);
    2823             : 
    2824             :     /* Lock may have already been transferred by some other backend. */
    2825         754 :     if (proclock == NULL)
    2826             :     {
    2827             :         LOCK       *lock;
    2828             :         PROCLOCKTAG proclocktag;
    2829             :         uint32      proclock_hashcode;
    2830             : 
    2831          16 :         LWLockAcquire(partitionLock, LW_SHARED);
    2832             : 
    2833          16 :         lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
    2834             :                                                     locktag,
    2835             :                                                     locallock->hashcode,
    2836             :                                                     HASH_FIND,
    2837             :                                                     NULL);
    2838          16 :         if (!lock)
    2839           0 :             elog(ERROR, "failed to re-find shared lock object");
    2840             : 
    2841          16 :         proclocktag.myLock = lock;
    2842          16 :         proclocktag.myProc = MyProc;
    2843             : 
    2844          16 :         proclock_hashcode = ProcLockHashCode(&proclocktag, locallock->hashcode);
    2845             :         proclock = (PROCLOCK *)
    2846          16 :             hash_search_with_hash_value(LockMethodProcLockHash,
    2847             :                                         &proclocktag,
    2848             :                                         proclock_hashcode,
    2849             :                                         HASH_FIND,
    2850             :                                         NULL);
    2851          16 :         if (!proclock)
    2852           0 :             elog(ERROR, "failed to re-find shared proclock object");
    2853          16 :         LWLockRelease(partitionLock);
    2854             :     }
    2855             : 
    2856         754 :     return proclock;
    2857             : }
    2858             : 
    2859             : /*
    2860             :  * GetLockConflicts
    2861             :  *      Get an array of VirtualTransactionIds of xacts currently holding locks
    2862             :  *      that would conflict with the specified lock/lockmode.
    2863             :  *      xacts merely awaiting such a lock are NOT reported.
    2864             :  *
    2865             :  * The result array is palloc'd and is terminated with an invalid VXID.
    2866             :  * *countp, if not null, is updated to the number of items set.
    2867             :  *
    2868             :  * Of course, the result could be out of date by the time it's returned, so
    2869             :  * use of this function has to be thought about carefully.  Similarly, a
    2870             :  * PGPROC with no "lxid" will be considered non-conflicting regardless of any
    2871             :  * lock it holds.  Existing callers don't care about a locker after that
    2872             :  * locker's pg_xact updates complete.  CommitTransaction() clears "lxid" after
    2873             :  * pg_xact updates and before releasing locks.
    2874             :  *
    2875             :  * Note we never include the current xact's vxid in the result array,
    2876             :  * since an xact never blocks itself.
    2877             :  */
    2878             : VirtualTransactionId *
    2879        2250 : GetLockConflicts(const LOCKTAG *locktag, LOCKMODE lockmode, int *countp)
    2880             : {
    2881             :     static VirtualTransactionId *vxids;
    2882        2250 :     LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
    2883             :     LockMethod  lockMethodTable;
    2884             :     LOCK       *lock;
    2885             :     LOCKMASK    conflictMask;
    2886             :     dlist_iter  proclock_iter;
    2887             :     PROCLOCK   *proclock;
    2888             :     uint32      hashcode;
    2889             :     LWLock     *partitionLock;
    2890        2250 :     int         count = 0;
    2891        2250 :     int         fast_count = 0;
    2892             : 
    2893        2250 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
    2894           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    2895        2250 :     lockMethodTable = LockMethods[lockmethodid];
    2896        2250 :     if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
    2897           0 :         elog(ERROR, "unrecognized lock mode: %d", lockmode);
    2898             : 
    2899             :     /*
    2900             :      * Allocate memory to store results, and fill with InvalidVXID.  We only
    2901             :      * need enough space for MaxBackends + max_prepared_xacts + a terminator.
    2902             :      * InHotStandby allocate once in TopMemoryContext.
    2903             :      */
    2904        2250 :     if (InHotStandby)
    2905             :     {
    2906           8 :         if (vxids == NULL)
    2907           2 :             vxids = (VirtualTransactionId *)
    2908           2 :                 MemoryContextAlloc(TopMemoryContext,
    2909             :                                    sizeof(VirtualTransactionId) *
    2910           2 :                                    (MaxBackends + max_prepared_xacts + 1));
    2911             :     }
    2912             :     else
    2913        2242 :         vxids = (VirtualTransactionId *)
    2914        2242 :             palloc0(sizeof(VirtualTransactionId) *
    2915        2242 :                     (MaxBackends + max_prepared_xacts + 1));
    2916             : 
    2917             :     /* Compute hash code and partition lock, and look up conflicting modes. */
    2918        2250 :     hashcode = LockTagHashCode(locktag);
    2919        2250 :     partitionLock = LockHashPartitionLock(hashcode);
    2920        2250 :     conflictMask = lockMethodTable->conflictTab[lockmode];
    2921             : 
    2922             :     /*
    2923             :      * Fast path locks might not have been entered in the primary lock table.
    2924             :      * If the lock we're dealing with could conflict with such a lock, we must
    2925             :      * examine each backend's fast-path array for conflicts.
    2926             :      */
    2927        2250 :     if (ConflictsWithRelationFastPath(locktag, lockmode))
    2928             :     {
    2929             :         int         i;
    2930        2250 :         Oid         relid = locktag->locktag_field2;
    2931             :         VirtualTransactionId vxid;
    2932             : 
    2933             :         /*
    2934             :          * Iterate over relevant PGPROCs.  Anything held by a prepared
    2935             :          * transaction will have been transferred to the primary lock table,
    2936             :          * so we need not worry about those.  This is all a bit fuzzy, because
    2937             :          * new locks could be taken after we've visited a particular
    2938             :          * partition, but the callers had better be prepared to deal with that
    2939             :          * anyway, since the locks could equally well be taken between the
    2940             :          * time we return the value and the time the caller does something
    2941             :          * with it.
    2942             :          */
    2943      253070 :         for (i = 0; i < ProcGlobal->allProcCount; i++)
    2944             :         {
    2945      250820 :             PGPROC     *proc = &ProcGlobal->allProcs[i];
    2946             :             uint32      f;
    2947             : 
    2948             :             /* A backend never blocks itself */
    2949      250820 :             if (proc == MyProc)
    2950        2250 :                 continue;
    2951             : 
    2952      248570 :             LWLockAcquire(&proc->fpInfoLock, LW_SHARED);
    2953             : 
    2954             :             /*
    2955             :              * If the target backend isn't referencing the same database as
    2956             :              * the lock, then we needn't examine the individual relation IDs
    2957             :              * at all; none of them can be relevant.
    2958             :              *
    2959             :              * See FastPathTransferRelationLocks() for discussion of why we do
    2960             :              * this test after acquiring the lock.
    2961             :              */
    2962      248570 :             if (proc->databaseId != locktag->locktag_field1)
    2963             :             {
    2964      103238 :                 LWLockRelease(&proc->fpInfoLock);
    2965      103238 :                 continue;
    2966             :             }
    2967             : 
    2968     2470176 :             for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; f++)
    2969             :             {
    2970             :                 uint32      lockmask;
    2971             : 
    2972             :                 /* Look for an allocated slot matching the given relid. */
    2973     2325216 :                 if (relid != proc->fpRelId[f])
    2974     2323476 :                     continue;
    2975        1740 :                 lockmask = FAST_PATH_GET_BITS(proc, f);
    2976        1740 :                 if (!lockmask)
    2977        1368 :                     continue;
    2978         372 :                 lockmask <<= FAST_PATH_LOCKNUMBER_OFFSET;
    2979             : 
    2980             :                 /*
    2981             :                  * There can only be one entry per relation, so if we found it
    2982             :                  * and it doesn't conflict, we can skip the rest of the slots.
    2983             :                  */
    2984         372 :                 if ((lockmask & conflictMask) == 0)
    2985          10 :                     break;
    2986             : 
    2987             :                 /* Conflict! */
    2988         362 :                 GET_VXID_FROM_PGPROC(vxid, *proc);
    2989             : 
    2990         362 :                 if (VirtualTransactionIdIsValid(vxid))
    2991         362 :                     vxids[count++] = vxid;
    2992             :                 /* else, xact already committed or aborted */
    2993             : 
    2994             :                 /* No need to examine remaining slots. */
    2995         362 :                 break;
    2996             :             }
    2997             : 
    2998      145332 :             LWLockRelease(&proc->fpInfoLock);
    2999             :         }
    3000             :     }
    3001             : 
    3002             :     /* Remember how many fast-path conflicts we found. */
    3003        2250 :     fast_count = count;
    3004             : 
    3005             :     /*
    3006             :      * Look up the lock object matching the tag.
    3007             :      */
    3008        2250 :     LWLockAcquire(partitionLock, LW_SHARED);
    3009             : 
    3010        2250 :     lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
    3011             :                                                 locktag,
    3012             :                                                 hashcode,
    3013             :                                                 HASH_FIND,
    3014             :                                                 NULL);
    3015        2250 :     if (!lock)
    3016             :     {
    3017             :         /*
    3018             :          * If the lock object doesn't exist, there is nothing holding a lock
    3019             :          * on this lockable object.
    3020             :          */
    3021         140 :         LWLockRelease(partitionLock);
    3022         140 :         vxids[count].backendId = InvalidBackendId;
    3023         140 :         vxids[count].localTransactionId = InvalidLocalTransactionId;
    3024         140 :         if (countp)
    3025           0 :             *countp = count;
    3026         140 :         return vxids;
    3027             :     }
    3028             : 
    3029             :     /*
    3030             :      * Examine each existing holder (or awaiter) of the lock.
    3031             :      */
    3032        4254 :     dlist_foreach(proclock_iter, &lock->procLocks)
    3033             :     {
    3034        2144 :         proclock = dlist_container(PROCLOCK, lockLink, proclock_iter.cur);
    3035             : 
    3036        2144 :         if (conflictMask & proclock->holdMask)
    3037             :         {
    3038        2136 :             PGPROC     *proc = proclock->tag.myProc;
    3039             : 
    3040             :             /* A backend never blocks itself */
    3041        2136 :             if (proc != MyProc)
    3042             :             {
    3043             :                 VirtualTransactionId vxid;
    3044             : 
    3045          34 :                 GET_VXID_FROM_PGPROC(vxid, *proc);
    3046             : 
    3047          34 :                 if (VirtualTransactionIdIsValid(vxid))
    3048             :                 {
    3049             :                     int         i;
    3050             : 
    3051             :                     /* Avoid duplicate entries. */
    3052          56 :                     for (i = 0; i < fast_count; ++i)
    3053          22 :                         if (VirtualTransactionIdEquals(vxids[i], vxid))
    3054           0 :                             break;
    3055          34 :                     if (i >= fast_count)
    3056          34 :                         vxids[count++] = vxid;
    3057             :                 }
    3058             :                 /* else, xact already committed or aborted */
    3059             :             }
    3060             :         }
    3061             :     }
    3062             : 
    3063        2110 :     LWLockRelease(partitionLock);
    3064             : 
    3065        2110 :     if (count > MaxBackends + max_prepared_xacts)    /* should never happen */
    3066           0 :         elog(PANIC, "too many conflicting locks found");
    3067             : 
    3068        2110 :     vxids[count].backendId = InvalidBackendId;
    3069        2110 :     vxids[count].localTransactionId = InvalidLocalTransactionId;
    3070        2110 :     if (countp)
    3071        2104 :         *countp = count;
    3072        2110 :     return vxids;
    3073             : }
    3074             : 
    3075             : /*
    3076             :  * Find a lock in the shared lock table and release it.  It is the caller's
    3077             :  * responsibility to verify that this is a sane thing to do.  (For example, it
    3078             :  * would be bad to release a lock here if there might still be a LOCALLOCK
    3079             :  * object with pointers to it.)
    3080             :  *
    3081             :  * We currently use this in two situations: first, to release locks held by
    3082             :  * prepared transactions on commit (see lock_twophase_postcommit); and second,
    3083             :  * to release locks taken via the fast-path, transferred to the main hash
    3084             :  * table, and then released (see LockReleaseAll).
    3085             :  */
    3086             : static void
    3087        4168 : LockRefindAndRelease(LockMethod lockMethodTable, PGPROC *proc,
    3088             :                      LOCKTAG *locktag, LOCKMODE lockmode,
    3089             :                      bool decrement_strong_lock_count)
    3090             : {
    3091             :     LOCK       *lock;
    3092             :     PROCLOCK   *proclock;
    3093             :     PROCLOCKTAG proclocktag;
    3094             :     uint32      hashcode;
    3095             :     uint32      proclock_hashcode;
    3096             :     LWLock     *partitionLock;
    3097             :     bool        wakeupNeeded;
    3098             : 
    3099        4168 :     hashcode = LockTagHashCode(locktag);
    3100        4168 :     partitionLock = LockHashPartitionLock(hashcode);
    3101             : 
    3102        4168 :     LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    3103             : 
    3104             :     /*
    3105             :      * Re-find the lock object (it had better be there).
    3106             :      */
    3107        4168 :     lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
    3108             :                                                 locktag,
    3109             :                                                 hashcode,
    3110             :                                                 HASH_FIND,
    3111             :                                                 NULL);
    3112        4168 :     if (!lock)
    3113           0 :         elog(PANIC, "failed to re-find shared lock object");
    3114             : 
    3115             :     /*
    3116             :      * Re-find the proclock object (ditto).
    3117             :      */
    3118        4168 :     proclocktag.myLock = lock;
    3119        4168 :     proclocktag.myProc = proc;
    3120             : 
    3121        4168 :     proclock_hashcode = ProcLockHashCode(&proclocktag, hashcode);
    3122             : 
    3123        4168 :     proclock = (PROCLOCK *) hash_search_with_hash_value(LockMethodProcLockHash,
    3124             :                                                         &proclocktag,
    3125             :                                                         proclock_hashcode,
    3126             :                                                         HASH_FIND,
    3127             :                                                         NULL);
    3128        4168 :     if (!proclock)
    3129           0 :         elog(PANIC, "failed to re-find shared proclock object");
    3130             : 
    3131             :     /*
    3132             :      * Double-check that we are actually holding a lock of the type we want to
    3133             :      * release.
    3134             :      */
    3135        4168 :     if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
    3136             :     {
    3137             :         PROCLOCK_PRINT("lock_twophase_postcommit: WRONGTYPE", proclock);
    3138           0 :         LWLockRelease(partitionLock);
    3139           0 :         elog(WARNING, "you don't own a lock of type %s",
    3140             :              lockMethodTable->lockModeNames[lockmode]);
    3141           0 :         return;
    3142             :     }
    3143             : 
    3144             :     /*
    3145             :      * Do the releasing.  CleanUpLock will waken any now-wakable waiters.
    3146             :      */
    3147        4168 :     wakeupNeeded = UnGrantLock(lock, lockmode, proclock, lockMethodTable);
    3148             : 
    3149        4168 :     CleanUpLock(lock, proclock,
    3150             :                 lockMethodTable, hashcode,
    3151             :                 wakeupNeeded);
    3152             : 
    3153        4168 :     LWLockRelease(partitionLock);
    3154             : 
    3155             :     /*
    3156             :      * Decrement strong lock count.  This logic is needed only for 2PC.
    3157             :      */
    3158        4168 :     if (decrement_strong_lock_count
    3159        1706 :         && ConflictsWithRelationFastPath(locktag, lockmode))
    3160             :     {
    3161         128 :         uint32      fasthashcode = FastPathStrongLockHashPartition(hashcode);
    3162             : 
    3163         128 :         SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
    3164             :         Assert(FastPathStrongRelationLocks->count[fasthashcode] > 0);
    3165         128 :         FastPathStrongRelationLocks->count[fasthashcode]--;
    3166         128 :         SpinLockRelease(&FastPathStrongRelationLocks->mutex);
    3167             :     }
    3168             : }
    3169             : 
    3170             : /*
    3171             :  * CheckForSessionAndXactLocks
    3172             :  *      Check to see if transaction holds both session-level and xact-level
    3173             :  *      locks on the same object; if so, throw an error.
    3174             :  *
    3175             :  * If we have both session- and transaction-level locks on the same object,
    3176             :  * PREPARE TRANSACTION must fail.  This should never happen with regular
    3177             :  * locks, since we only take those at session level in some special operations
    3178             :  * like VACUUM.  It's possible to hit this with advisory locks, though.
    3179             :  *
    3180             :  * It would be nice if we could keep the session hold and give away the
    3181             :  * transactional hold to the prepared xact.  However, that would require two
    3182             :  * PROCLOCK objects, and we cannot be sure that another PROCLOCK will be
    3183             :  * available when it comes time for PostPrepare_Locks to do the deed.
    3184             :  * So for now, we error out while we can still do so safely.
    3185             :  *
    3186             :  * Since the LOCALLOCK table stores a separate entry for each lockmode,
    3187             :  * we can't implement this check by examining LOCALLOCK entries in isolation.
    3188             :  * We must build a transient hashtable that is indexed by locktag only.
    3189             :  */
    3190             : static void
    3191         734 : CheckForSessionAndXactLocks(void)
    3192             : {
    3193             :     typedef struct
    3194             :     {
    3195             :         LOCKTAG     lock;       /* identifies the lockable object */
    3196             :         bool        sessLock;   /* is any lockmode held at session level? */
    3197             :         bool        xactLock;   /* is any lockmode held at xact level? */
    3198             :     } PerLockTagEntry;
    3199             : 
    3200             :     HASHCTL     hash_ctl;
    3201             :     HTAB       *lockhtab;
    3202             :     HASH_SEQ_STATUS status;
    3203             :     LOCALLOCK  *locallock;
    3204             : 
    3205             :     /* Create a local hash table keyed by LOCKTAG only */
    3206         734 :     hash_ctl.keysize = sizeof(LOCKTAG);
    3207         734 :     hash_ctl.entrysize = sizeof(PerLockTagEntry);
    3208         734 :     hash_ctl.hcxt = CurrentMemoryContext;
    3209             : 
    3210         734 :     lockhtab = hash_create("CheckForSessionAndXactLocks table",
    3211             :                            256, /* arbitrary initial size */
    3212             :                            &hash_ctl,
    3213             :                            HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
    3214             : 
    3215             :     /* Scan local lock table to find entries for each LOCKTAG */
    3216         734 :     hash_seq_init(&status, LockMethodLocalHash);
    3217             : 
    3218        2448 :     while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    3219             :     {
    3220        1718 :         LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
    3221             :         PerLockTagEntry *hentry;
    3222             :         bool        found;
    3223             :         int         i;
    3224             : 
    3225             :         /*
    3226             :          * Ignore VXID locks.  We don't want those to be held by prepared
    3227             :          * transactions, since they aren't meaningful after a restart.
    3228             :          */
    3229        1718 :         if (locallock->tag.lock.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
    3230           0 :             continue;
    3231             : 
    3232             :         /* Ignore it if we don't actually hold the lock */
    3233        1718 :         if (locallock->nLocks <= 0)
    3234           0 :             continue;
    3235             : 
    3236             :         /* Otherwise, find or make an entry in lockhtab */
    3237        1718 :         hentry = (PerLockTagEntry *) hash_search(lockhtab,
    3238        1718 :                                                  &locallock->tag.lock,
    3239             :                                                  HASH_ENTER, &found);
    3240        1718 :         if (!found)             /* initialize, if newly created */
    3241        1626 :             hentry->sessLock = hentry->xactLock = false;
    3242             : 
    3243             :         /* Scan to see if we hold lock at session or xact level or both */
    3244        3436 :         for (i = locallock->numLockOwners - 1; i >= 0; i--)
    3245             :         {
    3246        1718 :             if (lockOwners[i].owner == NULL)
    3247          18 :                 hentry->sessLock = true;
    3248             :             else
    3249        1700 :                 hentry->xactLock = true;
    3250             :         }
    3251             : 
    3252             :         /*
    3253             :          * We can throw error immediately when we see both types of locks; no
    3254             :          * need to wait around to see if there are more violations.
    3255             :          */
    3256        1718 :         if (hentry->sessLock && hentry->xactLock)
    3257           4 :             ereport(ERROR,
    3258             :                     (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
    3259             :                      errmsg("cannot PREPARE while holding both session-level and transaction-level locks on the same object")));
    3260             :     }
    3261             : 
    3262             :     /* Success, so clean up */
    3263         730 :     hash_destroy(lockhtab);
    3264         730 : }
    3265             : 
    3266             : /*
    3267             :  * AtPrepare_Locks
    3268             :  *      Do the preparatory work for a PREPARE: make 2PC state file records
    3269             :  *      for all locks currently held.
    3270             :  *
    3271             :  * Session-level locks are ignored, as are VXID locks.
    3272             :  *
    3273             :  * For the most part, we don't need to touch shared memory for this ---
    3274             :  * all the necessary state information is in the locallock table.
    3275             :  * Fast-path locks are an exception, however: we move any such locks to
    3276             :  * the main table before allowing PREPARE TRANSACTION to succeed.
    3277             :  */
    3278             : void
    3279         734 : AtPrepare_Locks(void)
    3280             : {
    3281             :     HASH_SEQ_STATUS status;
    3282             :     LOCALLOCK  *locallock;
    3283             : 
    3284             :     /* First, verify there aren't locks of both xact and session level */
    3285         734 :     CheckForSessionAndXactLocks();
    3286             : 
    3287             :     /* Now do the per-locallock cleanup work */
    3288         730 :     hash_seq_init(&status, LockMethodLocalHash);
    3289             : 
    3290        2436 :     while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    3291             :     {
    3292             :         TwoPhaseLockRecord record;
    3293        1706 :         LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
    3294             :         bool        haveSessionLock;
    3295             :         bool        haveXactLock;
    3296             :         int         i;
    3297             : 
    3298             :         /*
    3299             :          * Ignore VXID locks.  We don't want those to be held by prepared
    3300             :          * transactions, since they aren't meaningful after a restart.
    3301             :          */
    3302        1706 :         if (locallock->tag.lock.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
    3303          14 :             continue;
    3304             : 
    3305             :         /* Ignore it if we don't actually hold the lock */
    3306        1706 :         if (locallock->nLocks <= 0)
    3307           0 :             continue;
    3308             : 
    3309             :         /* Scan to see whether we hold it at session or transaction level */
    3310        1706 :         haveSessionLock = haveXactLock = false;
    3311        3412 :         for (i = locallock->numLockOwners - 1; i >= 0; i--)
    3312             :         {
    3313        1706 :             if (lockOwners[i].owner == NULL)
    3314          14 :                 haveSessionLock = true;
    3315             :             else
    3316        1692 :                 haveXactLock = true;
    3317             :         }
    3318             : 
    3319             :         /* Ignore it if we have only session lock */
    3320        1706 :         if (!haveXactLock)
    3321          14 :             continue;
    3322             : 
    3323             :         /* This can't happen, because we already checked it */
    3324        1692 :         if (haveSessionLock)
    3325           0 :             ereport(ERROR,
    3326             :                     (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
    3327             :                      errmsg("cannot PREPARE while holding both session-level and transaction-level locks on the same object")));
    3328             : 
    3329             :         /*
    3330             :          * If the local lock was taken via the fast-path, we need to move it
    3331             :          * to the primary lock table, or just get a pointer to the existing
    3332             :          * primary lock table entry if by chance it's already been
    3333             :          * transferred.
    3334             :          */
    3335        1692 :         if (locallock->proclock == NULL)
    3336             :         {
    3337         754 :             locallock->proclock = FastPathGetRelationLockEntry(locallock);
    3338         754 :             locallock->lock = locallock->proclock->tag.myLock;
    3339             :         }
    3340             : 
    3341             :         /*
    3342             :          * Arrange to not release any strong lock count held by this lock
    3343             :          * entry.  We must retain the count until the prepared transaction is
    3344             :          * committed or rolled back.
    3345             :          */
    3346        1692 :         locallock->holdsStrongLockCount = false;
    3347             : 
    3348             :         /*
    3349             :          * Create a 2PC record.
    3350             :          */
    3351        1692 :         memcpy(&(record.locktag), &(locallock->tag.lock), sizeof(LOCKTAG));
    3352        1692 :         record.lockmode = locallock->tag.mode;
    3353             : 
    3354        1692 :         RegisterTwoPhaseRecord(TWOPHASE_RM_LOCK_ID, 0,
    3355             :                                &record, sizeof(TwoPhaseLockRecord));
    3356             :     }
    3357         730 : }
    3358             : 
    3359             : /*
    3360             :  * PostPrepare_Locks
    3361             :  *      Clean up after successful PREPARE
    3362             :  *
    3363             :  * Here, we want to transfer ownership of our locks to a dummy PGPROC
    3364             :  * that's now associated with the prepared transaction, and we want to
    3365             :  * clean out the corresponding entries in the LOCALLOCK table.
    3366             :  *
    3367             :  * Note: by removing the LOCALLOCK entries, we are leaving dangling
    3368             :  * pointers in the transaction's resource owner.  This is OK at the
    3369             :  * moment since resowner.c doesn't try to free locks retail at a toplevel
    3370             :  * transaction commit or abort.  We could alternatively zero out nLocks
    3371             :  * and leave the LOCALLOCK entries to be garbage-collected by LockReleaseAll,
    3372             :  * but that probably costs more cycles.
    3373             :  */
    3374             : void
    3375         730 : PostPrepare_Locks(TransactionId xid)
    3376             : {
    3377         730 :     PGPROC     *newproc = TwoPhaseGetDummyProc(xid, false);
    3378             :     HASH_SEQ_STATUS status;
    3379             :     LOCALLOCK  *locallock;
    3380             :     LOCK       *lock;
    3381             :     PROCLOCK   *proclock;
    3382             :     PROCLOCKTAG proclocktag;
    3383             :     int         partition;
    3384             : 
    3385             :     /* Can't prepare a lock group follower. */
    3386             :     Assert(MyProc->lockGroupLeader == NULL ||
    3387             :            MyProc->lockGroupLeader == MyProc);
    3388             : 
    3389             :     /* This is a critical section: any error means big trouble */
    3390         730 :     START_CRIT_SECTION();
    3391             : 
    3392             :     /*
    3393             :      * First we run through the locallock table and get rid of unwanted
    3394             :      * entries, then we scan the process's proclocks and transfer them to the
    3395             :      * target proc.
    3396             :      *
    3397             :      * We do this separately because we may have multiple locallock entries
    3398             :      * pointing to the same proclock, and we daren't end up with any dangling
    3399             :      * pointers.
    3400             :      */
    3401         730 :     hash_seq_init(&status, LockMethodLocalHash);
    3402             : 
    3403        2436 :     while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
    3404             :     {
    3405        1706 :         LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
    3406             :         bool        haveSessionLock;
    3407             :         bool        haveXactLock;
    3408             :         int         i;
    3409             : 
    3410        1706 :         if (locallock->proclock == NULL || locallock->lock == NULL)
    3411             :         {
    3412             :             /*
    3413             :              * We must've run out of shared memory while trying to set up this
    3414             :              * lock.  Just forget the local entry.
    3415             :              */
    3416             :             Assert(locallock->nLocks == 0);
    3417           0 :             RemoveLocalLock(locallock);
    3418           0 :             continue;
    3419             :         }
    3420             : 
    3421             :         /* Ignore VXID locks */
    3422        1706 :         if (locallock->tag.lock.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
    3423           0 :             continue;
    3424             : 
    3425             :         /* Scan to see whether we hold it at session or transaction level */
    3426        1706 :         haveSessionLock = haveXactLock = false;
    3427        3412 :         for (i = locallock->numLockOwners - 1; i >= 0; i--)
    3428             :         {
    3429        1706 :             if (lockOwners[i].owner == NULL)
    3430          14 :                 haveSessionLock = true;
    3431             :             else
    3432        1692 :                 haveXactLock = true;
    3433             :         }
    3434             : 
    3435             :         /* Ignore it if we have only session lock */
    3436        1706 :         if (!haveXactLock)
    3437          14 :             continue;
    3438             : 
    3439             :         /* This can't happen, because we already checked it */
    3440        1692 :         if (haveSessionLock)
    3441           0 :             ereport(PANIC,
    3442             :                     (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
    3443             :                      errmsg("cannot PREPARE while holding both session-level and transaction-level locks on the same object")));
    3444             : 
    3445             :         /* Mark the proclock to show we need to release this lockmode */
    3446        1692 :         if (locallock->nLocks > 0)
    3447        1692 :             locallock->proclock->releaseMask |= LOCKBIT_ON(locallock->tag.mode);
    3448             : 
    3449             :         /* And remove the locallock hashtable entry */
    3450        1692 :         RemoveLocalLock(locallock);
    3451             :     }
    3452             : 
    3453             :     /*
    3454             :      * Now, scan each lock partition separately.
    3455             :      */
    3456       12410 :     for (partition = 0; partition < NUM_LOCK_PARTITIONS; partition++)
    3457             :     {
    3458             :         LWLock     *partitionLock;
    3459       11680 :         dlist_head *procLocks = &(MyProc->myProcLocks[partition]);
    3460             :         dlist_mutable_iter proclock_iter;
    3461             : 
    3462       11680 :         partitionLock = LockHashPartitionLockByIndex(partition);
    3463             : 
    3464             :         /*
    3465             :          * If the proclock list for this partition is empty, we can skip
    3466             :          * acquiring the partition lock.  This optimization is safer than the
    3467             :          * situation in LockReleaseAll, because we got rid of any fast-path
    3468             :          * locks during AtPrepare_Locks, so there cannot be any case where
    3469             :          * another backend is adding something to our lists now.  For safety,
    3470             :          * though, we code this the same way as in LockReleaseAll.
    3471             :          */
    3472       11680 :         if (dlist_is_empty(procLocks))
    3473       10062 :             continue;           /* needn't examine this partition */
    3474             : 
    3475        1618 :         LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    3476             : 
    3477        3320 :         dlist_foreach_modify(proclock_iter, procLocks)
    3478             :         {
    3479        1702 :             proclock = dlist_container(PROCLOCK, procLink, proclock_iter.cur);
    3480             : 
    3481             :             Assert(proclock->tag.myProc == MyProc);
    3482             : 
    3483        1702 :             lock = proclock->tag.myLock;
    3484             : 
    3485             :             /* Ignore VXID locks */
    3486        1702 :             if (lock->tag.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
    3487          84 :                 continue;
    3488             : 
    3489             :             PROCLOCK_PRINT("PostPrepare_Locks", proclock);
    3490             :             LOCK_PRINT("PostPrepare_Locks", lock, 0);
    3491             :             Assert(lock->nRequested >= 0);
    3492             :             Assert(lock->nGranted >= 0);
    3493             :             Assert(lock->nGranted <= lock->nRequested);
    3494             :             Assert((proclock->holdMask & ~lock->grantMask) == 0);
    3495             : 
    3496             :             /* Ignore it if nothing to release (must be a session lock) */
    3497        1618 :             if (proclock->releaseMask == 0)
    3498          14 :                 continue;
    3499             : 
    3500             :             /* Else we should be releasing all locks */
    3501        1604 :             if (proclock->releaseMask != proclock->holdMask)
    3502           0 :                 elog(PANIC, "we seem to have dropped a bit somewhere");
    3503             : 
    3504             :             /*
    3505             :              * We cannot simply modify proclock->tag.myProc to reassign
    3506             :              * ownership of the lock, because that's part of the hash key and
    3507             :              * the proclock would then be in the wrong hash chain.  Instead
    3508             :              * use hash_update_hash_key.  (We used to create a new hash entry,
    3509             :              * but that risks out-of-memory failure if other processes are
    3510             :              * busy making proclocks too.)  We must unlink the proclock from
    3511             :              * our procLink chain and put it into the new proc's chain, too.
    3512             :              *
    3513             :              * Note: the updated proclock hash key will still belong to the
    3514             :              * same hash partition, cf proclock_hash().  So the partition lock
    3515             :              * we already hold is sufficient for this.
    3516             :              */
    3517        1604 :             dlist_delete(&proclock->procLink);
    3518             : 
    3519             :             /*
    3520             :              * Create the new hash key for the proclock.
    3521             :              */
    3522        1604 :             proclocktag.myLock = lock;
    3523        1604 :             proclocktag.myProc = newproc;
    3524             : 
    3525             :             /*
    3526             :              * Update groupLeader pointer to point to the new proc.  (We'd
    3527             :              * better not be a member of somebody else's lock group!)
    3528             :              */
    3529             :             Assert(proclock->groupLeader == proclock->tag.myProc);
    3530        1604 :             proclock->groupLeader = newproc;
    3531             : 
    3532             :             /*
    3533             :              * Update the proclock.  We should not find any existing entry for
    3534             :              * the same hash key, since there can be only one entry for any
    3535             :              * given lock with my own proc.
    3536             :              */
    3537        1604 :             if (!hash_update_hash_key(LockMethodProcLockHash,
    3538             :                                       proclock,
    3539             :                                       &proclocktag))
    3540           0 :                 elog(PANIC, "duplicate entry found while reassigning a prepared transaction's locks");
    3541             : 
    3542             :             /* Re-link into the new proc's proclock list */
    3543        1604 :             dlist_push_tail(&newproc->myProcLocks[partition], &proclock->procLink);
    3544             : 
    3545             :             PROCLOCK_PRINT("PostPrepare_Locks: updated", proclock);
    3546             :         }                       /* loop over PROCLOCKs within this partition */
    3547             : 
    3548        1618 :         LWLockRelease(partitionLock);
    3549             :     }                           /* loop over partitions */
    3550             : 
    3551         730 :     END_CRIT_SECTION();
    3552         730 : }
    3553             : 
    3554             : 
    3555             : /*
    3556             :  * Estimate shared-memory space used for lock tables
    3557             :  */
    3558             : Size
    3559        5192 : LockShmemSize(void)
    3560             : {
    3561        5192 :     Size        size = 0;
    3562             :     long        max_table_size;
    3563             : 
    3564             :     /* lock hash table */
    3565        5192 :     max_table_size = NLOCKENTS();
    3566        5192 :     size = add_size(size, hash_estimate_size(max_table_size, sizeof(LOCK)));
    3567             : 
    3568             :     /* proclock hash table */
    3569        5192 :     max_table_size *= 2;
    3570        5192 :     size = add_size(size, hash_estimate_size(max_table_size, sizeof(PROCLOCK)));
    3571             : 
    3572             :     /*
    3573             :      * Since NLOCKENTS is only an estimate, add 10% safety margin.
    3574             :      */
    3575        5192 :     size = add_size(size, size / 10);
    3576             : 
    3577        5192 :     return size;
    3578             : }
    3579             : 
    3580             : /*
    3581             :  * GetLockStatusData - Return a summary of the lock manager's internal
    3582             :  * status, for use in a user-level reporting function.
    3583             :  *
    3584             :  * The return data consists of an array of LockInstanceData objects,
    3585             :  * which are a lightly abstracted version of the PROCLOCK data structures,
    3586             :  * i.e. there is one entry for each unique lock and interested PGPROC.
    3587             :  * It is the caller's responsibility to match up related items (such as
    3588             :  * references to the same lockable object or PGPROC) if wanted.
    3589             :  *
    3590             :  * The design goal is to hold the LWLocks for as short a time as possible;
    3591             :  * thus, this function simply makes a copy of the necessary data and releases
    3592             :  * the locks, allowing the caller to contemplate and format the data for as
    3593             :  * long as it pleases.
    3594             :  */
    3595             : LockData *
    3596         460 : GetLockStatusData(void)
    3597             : {
    3598             :     LockData   *data;
    3599             :     PROCLOCK   *proclock;
    3600             :     HASH_SEQ_STATUS seqstat;
    3601             :     int         els;
    3602             :     int         el;
    3603             :     int         i;
    3604             : 
    3605         460 :     data = (LockData *) palloc(sizeof(LockData));
    3606             : 
    3607             :     /* Guess how much space we'll need. */
    3608         460 :     els = MaxBackends;
    3609         460 :     el = 0;
    3610         460 :     data->locks = (LockInstanceData *) palloc(sizeof(LockInstanceData) * els);
    3611             : 
    3612             :     /*
    3613             :      * First, we iterate through the per-backend fast-path arrays, locking
    3614             :      * them one at a time.  This might produce an inconsistent picture of the
    3615             :      * system state, but taking all of those LWLocks at the same time seems
    3616             :      * impractical (in particular, note MAX_SIMUL_LWLOCKS).  It shouldn't
    3617             :      * matter too much, because none of these locks can be involved in lock
    3618             :      * conflicts anyway - anything that might must be present in the main lock
    3619             :      * table.  (For the same reason, we don't sweat about making leaderPid
    3620             :      * completely valid.  We cannot safely dereference another backend's
    3621             :      * lockGroupLeader field without holding all lock partition locks, and
    3622             :      * it's not worth that.)
    3623             :      */
    3624       47280 :     for (i = 0; i < ProcGlobal->allProcCount; ++i)
    3625             :     {
    3626       46820 :         PGPROC     *proc = &ProcGlobal->allProcs[i];
    3627             :         uint32      f;
    3628             : 
    3629       46820 :         LWLockAcquire(&proc->fpInfoLock, LW_SHARED);
    3630             : 
    3631      795940 :         for (f = 0; f < FP_LOCK_SLOTS_PER_BACKEND; ++f)
    3632             :         {
    3633             :             LockInstanceData *instance;
    3634      749120 :             uint32      lockbits = FAST_PATH_GET_BITS(proc, f);
    3635             : 
    3636             :             /* Skip unallocated slots. */
    3637      749120 :             if (!lockbits)
    3638      744156 :                 continue;
    3639             : 
    3640        4964 :             if (el >= els)
    3641             :             {
    3642           4 :                 els += MaxBackends;
    3643           4 :                 data->locks = (LockInstanceData *)
    3644           4 :                     repalloc(data->locks, sizeof(LockInstanceData) * els);
    3645             :             }
    3646             : 
    3647        4964 :             instance = &data->locks[el];
    3648        4964 :             SET_LOCKTAG_RELATION(instance->locktag, proc->databaseId,
    3649             :                                  proc->fpRelId[f]);
    3650        4964 :             instance->holdMask = lockbits << FAST_PATH_LOCKNUMBER_OFFSET;
    3651        4964 :             instance->waitLockMode = NoLock;
    3652        4964 :             instance->backend = proc->backendId;
    3653        4964 :             instance->lxid = proc->lxid;
    3654        4964 :             instance->pid = proc->pid;
    3655        4964 :             instance->leaderPid = proc->pid;
    3656        4964 :             instance->fastpath = true;
    3657             : 
    3658             :             /*
    3659             :              * Successfully taking fast path lock means there were no
    3660             :              * conflicting locks.
    3661             :              */
    3662        4964 :             instance->waitStart = 0;
    3663             : 
    3664        4964 :             el++;
    3665             :         }
    3666             : 
    3667       46820 :         if (proc->fpVXIDLock)
    3668             :         {
    3669             :             VirtualTransactionId vxid;
    3670             :             LockInstanceData *instance;
    3671             : 
    3672        1452 :             if (el >= els)
    3673             :             {
    3674           0 :                 els += MaxBackends;
    3675           0 :                 data->locks = (LockInstanceData *)
    3676           0 :                     repalloc(data->locks, sizeof(LockInstanceData) * els);
    3677             :             }
    3678             : 
    3679        1452 :             vxid.backendId = proc->backendId;
    3680        1452 :             vxid.localTransactionId = proc->fpLocalTransactionId;
    3681             : 
    3682        1452 :             instance = &data->locks[el];
    3683        1452 :             SET_LOCKTAG_VIRTUALTRANSACTION(instance->locktag, vxid);
    3684        1452 :             instance->holdMask = LOCKBIT_ON(ExclusiveLock);
    3685        1452 :             instance->waitLockMode = NoLock;
    3686        1452 :             instance->backend = proc->backendId;
    3687        1452 :             instance->lxid = proc->lxid;
    3688        1452 :             instance->pid = proc->pid;
    3689        1452 :             instance->leaderPid = proc->pid;
    3690        1452 :             instance->fastpath = true;
    3691        1452 :             instance->waitStart = 0;
    3692             : 
    3693        1452 :             el++;
    3694             :         }
    3695             : 
    3696       46820 :         LWLockRelease(&proc->fpInfoLock);
    3697             :     }
    3698             : 
    3699             :     /*
    3700             :      * Next, acquire lock on the entire shared lock data structure.  We do
    3701             :      * this so that, at least for locks in the primary lock table, the state
    3702             :      * will be self-consistent.
    3703             :      *
    3704             :      * Since this is a read-only operation, we take shared instead of
    3705             :      * exclusive lock.  There's not a whole lot of point to this, because all
    3706             :      * the normal operations require exclusive lock, but it doesn't hurt
    3707             :      * anything either. It will at least allow two backends to do
    3708             :      * GetLockStatusData in parallel.
    3709             :      *
    3710             :      * Must grab LWLocks in partition-number order to avoid LWLock deadlock.
    3711             :      */
    3712        7820 :     for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
    3713        7360 :         LWLockAcquire(LockHashPartitionLockByIndex(i), LW_SHARED);
    3714             : 
    3715             :     /* Now we can safely count the number of proclocks */
    3716         460 :     data->nelements = el + hash_get_num_entries(LockMethodProcLockHash);
    3717         460 :     if (data->nelements > els)
    3718             :     {
    3719           2 :         els = data->nelements;
    3720           2 :         data->locks = (LockInstanceData *)
    3721           2 :             repalloc(data->locks, sizeof(LockInstanceData) * els);
    3722             :     }
    3723             : 
    3724             :     /* Now scan the tables to copy the data */
    3725         460 :     hash_seq_init(&seqstat, LockMethodProcLockHash);
    3726             : 
    3727        3094 :     while ((proclock = (PROCLOCK *) hash_seq_search(&seqstat)))
    3728             :     {
    3729        2634 :         PGPROC     *proc = proclock->tag.myProc;
    3730        2634 :         LOCK       *lock = proclock->tag.myLock;
    3731        2634 :         LockInstanceData *instance = &data->locks[el];
    3732             : 
    3733        2634 :         memcpy(&instance->locktag, &lock->tag, sizeof(LOCKTAG));
    3734        2634 :         instance->holdMask = proclock->holdMask;
    3735        2634 :         if (proc->waitLock == proclock->tag.myLock)
    3736          16 :             instance->waitLockMode = proc->waitLockMode;
    3737             :         else
    3738        2618 :             instance->waitLockMode = NoLock;
    3739        2634 :         instance->backend = proc->backendId;
    3740        2634 :         instance->lxid = proc->lxid;
    3741        2634 :         instance->pid = proc->pid;
    3742        2634 :         instance->leaderPid = proclock->groupLeader->pid;
    3743        2634 :         instance->fastpath = false;
    3744        2634 :         instance->waitStart = (TimestampTz) pg_atomic_read_u64(&proc->waitStart);
    3745             : 
    3746        2634 :         el++;
    3747             :     }
    3748             : 
    3749             :     /*
    3750             :      * And release locks.  We do this in reverse order for two reasons: (1)
    3751             :      * Anyone else who needs more than one of the locks will be trying to lock
    3752             :      * them in increasing order; we don't want to release the other process
    3753             :      * until it can get all the locks it needs. (2) This avoids O(N^2)
    3754             :      * behavior inside LWLockRelease.
    3755             :      */
    3756        7820 :     for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
    3757        7360 :         LWLockRelease(LockHashPartitionLockByIndex(i));
    3758             : 
    3759             :     Assert(el == data->nelements);
    3760             : 
    3761         460 :     return data;
    3762             : }
    3763             : 
    3764             : /*
    3765             :  * GetBlockerStatusData - Return a summary of the lock manager's state
    3766             :  * concerning locks that are blocking the specified PID or any member of
    3767             :  * the PID's lock group, for use in a user-level reporting function.
    3768             :  *
    3769             :  * For each PID within the lock group that is awaiting some heavyweight lock,
    3770             :  * the return data includes an array of LockInstanceData objects, which are
    3771             :  * the same data structure used by GetLockStatusData; but unlike that function,
    3772             :  * this one reports only the PROCLOCKs associated with the lock that that PID
    3773             :  * is blocked on.  (Hence, all the locktags should be the same for any one
    3774             :  * blocked PID.)  In addition, we return an array of the PIDs of those backends
    3775             :  * that are ahead of the blocked PID in the lock's wait queue.  These can be
    3776             :  * compared with the PIDs in the LockInstanceData objects to determine which
    3777             :  * waiters are ahead of or behind the blocked PID in the queue.
    3778             :  *
    3779             :  * If blocked_pid isn't a valid backend PID or nothing in its lock group is
    3780             :  * waiting on any heavyweight lock, return empty arrays.
    3781             :  *
    3782             :  * The design goal is to hold the LWLocks for as short a time as possible;
    3783             :  * thus, this function simply makes a copy of the necessary data and releases
    3784             :  * the locks, allowing the caller to contemplate and format the data for as
    3785             :  * long as it pleases.
    3786             :  */
    3787             : BlockedProcsData *
    3788        6282 : GetBlockerStatusData(int blocked_pid)
    3789             : {
    3790             :     BlockedProcsData *data;
    3791             :     PGPROC     *proc;
    3792             :     int         i;
    3793             : 
    3794        6282 :     data = (BlockedProcsData *) palloc(sizeof(BlockedProcsData));
    3795             : 
    3796             :     /*
    3797             :      * Guess how much space we'll need, and preallocate.  Most of the time
    3798             :      * this will avoid needing to do repalloc while holding the LWLocks.  (We
    3799             :      * assume, but check with an Assert, that MaxBackends is enough entries
    3800             :      * for the procs[] array; the other two could need enlargement, though.)
    3801             :      */
    3802        6282 :     data->nprocs = data->nlocks = data->npids = 0;
    3803        6282 :     data->maxprocs = data->maxlocks = data->maxpids = MaxBackends;
    3804        6282 :     data->procs = (BlockedProcData *) palloc(sizeof(BlockedProcData) * data->maxprocs);
    3805        6282 :     data->locks = (LockInstanceData *) palloc(sizeof(LockInstanceData) * data->maxlocks);
    3806        6282 :     data->waiter_pids = (int *) palloc(sizeof(int) * data->maxpids);
    3807             : 
    3808             :     /*
    3809             :      * In order to search the ProcArray for blocked_pid and assume that that
    3810             :      * entry won't immediately disappear under us, we must hold ProcArrayLock.
    3811             :      * In addition, to examine the lock grouping fields of any other backend,
    3812             :      * we must hold all the hash partition locks.  (Only one of those locks is
    3813             :      * actually relevant for any one lock group, but we can't know which one
    3814             :      * ahead of time.)  It's fairly annoying to hold all those locks
    3815             :      * throughout this, but it's no worse than GetLockStatusData(), and it
    3816             :      * does have the advantage that we're guaranteed to return a
    3817             :      * self-consistent instantaneous state.
    3818             :      */
    3819        6282 :     LWLockAcquire(ProcArrayLock, LW_SHARED);
    3820             : 
    3821        6282 :     proc = BackendPidGetProcWithLock(blocked_pid);
    3822             : 
    3823             :     /* Nothing to do if it's gone */
    3824        6282 :     if (proc != NULL)
    3825             :     {
    3826             :         /*
    3827             :          * Acquire lock on the entire shared lock data structure.  See notes
    3828             :          * in GetLockStatusData().
    3829             :          */
    3830      106794 :         for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
    3831      100512 :             LWLockAcquire(LockHashPartitionLockByIndex(i), LW_SHARED);
    3832             : 
    3833        6282 :         if (proc->lockGroupLeader == NULL)
    3834             :         {
    3835             :             /* Easy case, proc is not a lock group member */
    3836        6064 :             GetSingleProcBlockerStatusData(proc, data);
    3837             :         }
    3838             :         else
    3839             :         {
    3840             :             /* Examine all procs in proc's lock group */
    3841             :             dlist_iter  iter;
    3842             : 
    3843         514 :             dlist_foreach(iter, &proc->lockGroupLeader->lockGroupMembers)
    3844             :             {
    3845             :                 PGPROC     *memberProc;
    3846             : 
    3847         296 :                 memberProc = dlist_container(PGPROC, lockGroupLink, iter.cur);
    3848         296 :                 GetSingleProcBlockerStatusData(memberProc, data);
    3849             :             }
    3850             :         }
    3851             : 
    3852             :         /*
    3853             :          * And release locks.  See notes in GetLockStatusData().
    3854             :          */
    3855      106794 :         for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
    3856      100512 :             LWLockRelease(LockHashPartitionLockByIndex(i));
    3857             : 
    3858             :         Assert(data->nprocs <= data->maxprocs);
    3859             :     }
    3860             : 
    3861        6282 :     LWLockRelease(ProcArrayLock);
    3862             : 
    3863        6282 :     return data;
    3864             : }
    3865             : 
    3866             : /* Accumulate data about one possibly-blocked proc for GetBlockerStatusData */
    3867             : static void
    3868        6360 : GetSingleProcBlockerStatusData(PGPROC *blocked_proc, BlockedProcsData *data)
    3869             : {
    3870        6360 :     LOCK       *theLock = blocked_proc->waitLock;
    3871             :     BlockedProcData *bproc;
    3872             :     dlist_iter  proclock_iter;
    3873             :     dlist_iter  proc_iter;
    3874             :     dclist_head *waitQueue;
    3875             :     int         queue_size;
    3876             : 
    3877             :     /* Nothing to do if this proc is not blocked */
    3878        6360 :     if (theLock == NULL)
    3879        4182 :         return;
    3880             : 
    3881             :     /* Set up a procs[] element */
    3882        2178 :     bproc = &data->procs[data->nprocs++];
    3883        2178 :     bproc->pid = blocked_proc->pid;
    3884        2178 :     bproc->first_lock = data->nlocks;
    3885        2178 :     bproc->first_waiter = data->npids;
    3886             : 
    3887             :     /*
    3888             :      * We may ignore the proc's fast-path arrays, since nothing in those could
    3889             :      * be related to a contended lock.
    3890             :      */
    3891             : 
    3892             :     /* Collect all PROCLOCKs associated with theLock */
    3893        6624 :     dlist_foreach(proclock_iter, &theLock->procLocks)
    3894             :     {
    3895        4446 :         PROCLOCK   *proclock =
    3896        4446 :             dlist_container(PROCLOCK, lockLink, proclock_iter.cur);
    3897        4446 :         PGPROC     *proc = proclock->tag.myProc;
    3898        4446 :         LOCK       *lock = proclock->tag.myLock;
    3899             :         LockInstanceData *instance;
    3900             : 
    3901        4446 :         if (data->nlocks >= data->maxlocks)
    3902             :         {
    3903           0 :             data->maxlocks += MaxBackends;
    3904           0 :             data->locks = (LockInstanceData *)
    3905           0 :                 repalloc(data->locks, sizeof(LockInstanceData) * data->maxlocks);
    3906             :         }
    3907             : 
    3908        4446 :         instance = &data->locks[data->nlocks];
    3909        4446 :         memcpy(&instance->locktag, &lock->tag, sizeof(LOCKTAG));
    3910        4446 :         instance->holdMask = proclock->holdMask;
    3911        4446 :         if (proc->waitLock == lock)
    3912        2252 :             instance->waitLockMode = proc->waitLockMode;
    3913             :         else
    3914        2194 :             instance->waitLockMode = NoLock;
    3915        4446 :         instance->backend = proc->backendId;
    3916        4446 :         instance->lxid = proc->lxid;
    3917        4446 :         instance->pid = proc->pid;
    3918        4446 :         instance->leaderPid = proclock->groupLeader->pid;
    3919        4446 :         instance->fastpath = false;
    3920        4446 :         data->nlocks++;
    3921             :     }
    3922             : 
    3923             :     /* Enlarge waiter_pids[] if it's too small to hold all wait queue PIDs */
    3924        2178 :     waitQueue = &(theLock->waitProcs);
    3925        2178 :     queue_size = dclist_count(waitQueue);
    3926             : 
    3927        2178 :     if (queue_size > data->maxpids - data->npids)
    3928             :     {
    3929           0 :         data->maxpids = Max(data->maxpids + MaxBackends,
    3930             :                             data->npids + queue_size);
    3931           0 :         data->waiter_pids = (int *) repalloc(data->waiter_pids,
    3932           0 :                                              sizeof(int) * data->maxpids);
    3933             :     }
    3934             : 
    3935             :     /* Collect PIDs from the lock's wait queue, stopping at blocked_proc */
    3936        2214 :     dclist_foreach(proc_iter, waitQueue)
    3937             :     {
    3938        2214 :         PGPROC     *queued_proc = dlist_container(PGPROC, links, proc_iter.cur);
    3939        2214 :         if (queued_proc == blocked_proc)
    3940        2178 :             break;
    3941          36 :         data->waiter_pids[data->npids++] = queued_proc->pid;
    3942          36 :         queued_proc = (PGPROC *) queued_proc->links.next;
    3943             :     }
    3944             : 
    3945        2178 :     bproc->num_locks = data->nlocks - bproc->first_lock;
    3946        2178 :     bproc->num_waiters = data->npids - bproc->first_waiter;
    3947             : }
    3948             : 
    3949             : /*
    3950             :  * Returns a list of currently held AccessExclusiveLocks, for use by
    3951             :  * LogStandbySnapshot().  The result is a palloc'd array,
    3952             :  * with the number of elements returned into *nlocks.
    3953             :  *
    3954             :  * XXX This currently takes a lock on all partitions of the lock table,
    3955             :  * but it's possible to do better.  By reference counting locks and storing
    3956             :  * the value in the ProcArray entry for each backend we could tell if any
    3957             :  * locks need recording without having to acquire the partition locks and
    3958             :  * scan the lock table.  Whether that's worth the additional overhead
    3959             :  * is pretty dubious though.
    3960             :  */
    3961             : xl_standby_lock *
    3962        3266 : GetRunningTransactionLocks(int *nlocks)
    3963             : {
    3964             :     xl_standby_lock *accessExclusiveLocks;
    3965             :     PROCLOCK   *proclock;
    3966             :     HASH_SEQ_STATUS seqstat;
    3967             :     int         i;
    3968             :     int         index;
    3969             :     int         els;
    3970             : 
    3971             :     /*
    3972             :      * Acquire lock on the entire shared lock data structure.
    3973             :      *
    3974             :      * Must grab LWLocks in partition-number order to avoid LWLock deadlock.
    3975             :      */
    3976       55522 :     for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
    3977       52256 :         LWLockAcquire(LockHashPartitionLockByIndex(i), LW_SHARED);
    3978             : 
    3979             :     /* Now we can safely count the number of proclocks */
    3980        3266 :     els = hash_get_num_entries(LockMethodProcLockHash);
    3981             : 
    3982             :     /*
    3983             :      * Allocating enough space for all locks in the lock table is overkill,
    3984             :      * but it's more convenient and faster than having to enlarge the array.
    3985             :      */
    3986        3266 :     accessExclusiveLocks = palloc(els * sizeof(xl_standby_lock));
    3987             : 
    3988             :     /* Now scan the tables to copy the data */
    3989        3266 :     hash_seq_init(&seqstat, LockMethodProcLockHash);
    3990             : 
    3991             :     /*
    3992             :      * If lock is a currently granted AccessExclusiveLock then it will have
    3993             :      * just one proclock holder, so locks are never accessed twice in this
    3994             :      * particular case. Don't copy this code for use elsewhere because in the
    3995             :      * general case this will give you duplicate locks when looking at
    3996             :      * non-exclusive lock types.
    3997             :      */
    3998        3266 :     index = 0;
    3999       11116 :     while ((proclock = (PROCLOCK *) hash_seq_search(&seqstat)))
    4000             :     {
    4001             :         /* make sure this definition matches the one used in LockAcquire */
    4002        7850 :         if ((proclock->holdMask & LOCKBIT_ON(AccessExclusiveLock)) &&
    4003         224 :             proclock->tag.myLock->tag.locktag_type == LOCKTAG_RELATION)
    4004             :         {
    4005         162 :             PGPROC     *proc = proclock->tag.myProc;
    4006         162 :             LOCK       *lock = proclock->tag.myLock;
    4007         162 :             TransactionId xid = proc->xid;
    4008             : 
    4009             :             /*
    4010             :              * Don't record locks for transactions if we know they have
    4011             :              * already issued their WAL record for commit but not yet released
    4012             :              * lock. It is still possible that we see locks held by already
    4013             :              * complete transactions, if they haven't yet zeroed their xids.
    4014             :              */
    4015         162 :             if (!TransactionIdIsValid(xid))
    4016           4 :                 continue;
    4017             : 
    4018         158 :             accessExclusiveLocks[index].xid = xid;
    4019         158 :             accessExclusiveLocks[index].dbOid = lock->tag.locktag_field1;
    4020         158 :             accessExclusiveLocks[index].relOid = lock->tag.locktag_field2;
    4021             : 
    4022         158 :             index++;
    4023             :         }
    4024             :     }
    4025             : 
    4026             :     Assert(index <= els);
    4027             : 
    4028             :     /*
    4029             :      * And release locks.  We do this in reverse order for two reasons: (1)
    4030             :      * Anyone else who needs more than one of the locks will be trying to lock
    4031             :      * them in increasing order; we don't want to release the other process
    4032             :      * until it can get all the locks it needs. (2) This avoids O(N^2)
    4033             :      * behavior inside LWLockRelease.
    4034             :      */
    4035       55522 :     for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
    4036       52256 :         LWLockRelease(LockHashPartitionLockByIndex(i));
    4037             : 
    4038        3266 :     *nlocks = index;
    4039        3266 :     return accessExclusiveLocks;
    4040             : }
    4041             : 
    4042             : /* Provide the textual name of any lock mode */
    4043             : const char *
    4044        9374 : GetLockmodeName(LOCKMETHODID lockmethodid, LOCKMODE mode)
    4045             : {
    4046             :     Assert(lockmethodid > 0 && lockmethodid < lengthof(LockMethods));
    4047             :     Assert(mode > 0 && mode <= LockMethods[lockmethodid]->numLockModes);
    4048        9374 :     return LockMethods[lockmethodid]->lockModeNames[mode];
    4049             : }
    4050             : 
    4051             : #ifdef LOCK_DEBUG
    4052             : /*
    4053             :  * Dump all locks in the given proc's myProcLocks lists.
    4054             :  *
    4055             :  * Caller is responsible for having acquired appropriate LWLocks.
    4056             :  */
    4057             : void
    4058             : DumpLocks(PGPROC *proc)
    4059             : {
    4060             :     int         i;
    4061             : 
    4062             :     if (proc == NULL)
    4063             :         return;
    4064             : 
    4065             :     if (proc->waitLock)
    4066             :         LOCK_PRINT("DumpLocks: waiting on", proc->waitLock, 0);
    4067             : 
    4068             :     for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
    4069             :     {
    4070             :         dlist_head *procLocks = &proc->myProcLocks[i];
    4071             :         dlist_iter  iter;
    4072             : 
    4073             :         dlist_foreach(iter, procLocks)
    4074             :         {
    4075             :             PROCLOCK   *proclock = dlist_container(PROCLOCK, procLink, iter.cur);
    4076             :             LOCK       *lock = proclock->tag.myLock;
    4077             : 
    4078             :             Assert(proclock->tag.myProc == proc);
    4079             :             PROCLOCK_PRINT("DumpLocks", proclock);
    4080             :             LOCK_PRINT("DumpLocks", lock, 0);
    4081             :         }
    4082             :     }
    4083             : }
    4084             : 
    4085             : /*
    4086             :  * Dump all lmgr locks.
    4087             :  *
    4088             :  * Caller is responsible for having acquired appropriate LWLocks.
    4089             :  */
    4090             : void
    4091             : DumpAllLocks(void)
    4092             : {
    4093             :     PGPROC     *proc;
    4094             :     PROCLOCK   *proclock;
    4095             :     LOCK       *lock;
    4096             :     HASH_SEQ_STATUS status;
    4097             : 
    4098             :     proc = MyProc;
    4099             : 
    4100             :     if (proc && proc->waitLock)
    4101             :         LOCK_PRINT("DumpAllLocks: waiting on", proc->waitLock, 0);
    4102             : 
    4103             :     hash_seq_init(&status, LockMethodProcLockHash);
    4104             : 
    4105             :     while ((proclock = (PROCLOCK *) hash_seq_search(&status)) != NULL)
    4106             :     {
    4107             :         PROCLOCK_PRINT("DumpAllLocks", proclock);
    4108             : 
    4109             :         lock = proclock->tag.myLock;
    4110             :         if (lock)
    4111             :             LOCK_PRINT("DumpAllLocks", lock, 0);
    4112             :         else
    4113             :             elog(LOG, "DumpAllLocks: proclock->tag.myLock = NULL");
    4114             :     }
    4115             : }
    4116             : #endif                          /* LOCK_DEBUG */
    4117             : 
    4118             : /*
    4119             :  * LOCK 2PC resource manager's routines
    4120             :  */
    4121             : 
    4122             : /*
    4123             :  * Re-acquire a lock belonging to a transaction that was prepared.
    4124             :  *
    4125             :  * Because this function is run at db startup, re-acquiring the locks should
    4126             :  * never conflict with running transactions because there are none.  We
    4127             :  * assume that the lock state represented by the stored 2PC files is legal.
    4128             :  *
    4129             :  * When switching from Hot Standby mode to normal operation, the locks will
    4130             :  * be already held by the startup process. The locks are acquired for the new
    4131             :  * procs without checking for conflicts, so we don't get a conflict between the
    4132             :  * startup process and the dummy procs, even though we will momentarily have
    4133             :  * a situation where two procs are holding the same AccessExclusiveLock,
    4134             :  * which isn't normally possible because the conflict. If we're in standby
    4135             :  * mode, but a recovery snapshot hasn't been established yet, it's possible
    4136             :  * that some but not all of the locks are already held by the startup process.
    4137             :  *
    4138             :  * This approach is simple, but also a bit dangerous, because if there isn't
    4139             :  * enough shared memory to acquire the locks, an error will be thrown, which
    4140             :  * is promoted to FATAL and recovery will abort, bringing down postmaster.
    4141             :  * A safer approach would be to transfer the locks like we do in
    4142             :  * AtPrepare_Locks, but then again, in hot standby mode it's possible for
    4143             :  * read-only backends to use up all the shared lock memory anyway, so that
    4144             :  * replaying the WAL record that needs to acquire a lock will throw an error
    4145             :  * and PANIC anyway.
    4146             :  */
    4147             : void
    4148         158 : lock_twophase_recover(TransactionId xid, uint16 info,
    4149             :                       void *recdata, uint32 len)
    4150             : {
    4151         158 :     TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
    4152         158 :     PGPROC     *proc = TwoPhaseGetDummyProc(xid, false);
    4153             :     LOCKTAG    *locktag;
    4154             :     LOCKMODE    lockmode;
    4155             :     LOCKMETHODID lockmethodid;
    4156             :     LOCK       *lock;
    4157             :     PROCLOCK   *proclock;
    4158             :     PROCLOCKTAG proclocktag;
    4159             :     bool        found;
    4160             :     uint32      hashcode;
    4161             :     uint32      proclock_hashcode;
    4162             :     int         partition;
    4163             :     LWLock     *partitionLock;
    4164             :     LockMethod  lockMethodTable;
    4165             : 
    4166             :     Assert(len == sizeof(TwoPhaseLockRecord));
    4167         158 :     locktag = &rec->locktag;
    4168         158 :     lockmode = rec->lockmode;
    4169         158 :     lockmethodid = locktag->locktag_lockmethodid;
    4170             : 
    4171         158 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
    4172           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    4173         158 :     lockMethodTable = LockMethods[lockmethodid];
    4174             : 
    4175         158 :     hashcode = LockTagHashCode(locktag);
    4176         158 :     partition = LockHashPartition(hashcode);
    4177         158 :     partitionLock = LockHashPartitionLock(hashcode);
    4178             : 
    4179         158 :     LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    4180             : 
    4181             :     /*
    4182             :      * Find or create a lock with this tag.
    4183             :      */
    4184         158 :     lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
    4185             :                                                 locktag,
    4186             :                                                 hashcode,
    4187             :                                                 HASH_ENTER_NULL,
    4188             :                                                 &found);
    4189         158 :     if (!lock)
    4190             :     {
    4191           0 :         LWLockRelease(partitionLock);
    4192           0 :         ereport(ERROR,
    4193             :                 (errcode(ERRCODE_OUT_OF_MEMORY),
    4194             :                  errmsg("out of shared memory"),
    4195             :                  errhint("You might need to increase max_locks_per_transaction.")));
    4196             :     }
    4197             : 
    4198             :     /*
    4199             :      * if it's a new lock object, initialize it
    4200             :      */
    4201         158 :     if (!found)
    4202             :     {
    4203         142 :         lock->grantMask = 0;
    4204         142 :         lock->waitMask = 0;
    4205         142 :         dlist_init(&lock->procLocks);
    4206         142 :         dclist_init(&lock->waitProcs);
    4207         142 :         lock->nRequested = 0;
    4208         142 :         lock->nGranted = 0;
    4209         852 :         MemSet(lock->requested, 0, sizeof(int) * MAX_LOCKMODES);
    4210         142 :         MemSet(lock->granted, 0, sizeof(int) * MAX_LOCKMODES);
    4211             :         LOCK_PRINT("lock_twophase_recover: new", lock, lockmode);
    4212             :     }
    4213             :     else
    4214             :     {
    4215             :         LOCK_PRINT("lock_twophase_recover: found", lock, lockmode);
    4216             :         Assert((lock->nRequested >= 0) && (lock->requested[lockmode] >= 0));
    4217             :         Assert((lock->nGranted >= 0) && (lock->granted[lockmode] >= 0));
    4218             :         Assert(lock->nGranted <= lock->nRequested);
    4219             :     }
    4220             : 
    4221             :     /*
    4222             :      * Create the hash key for the proclock table.
    4223             :      */
    4224         158 :     proclocktag.myLock = lock;
    4225         158 :     proclocktag.myProc = proc;
    4226             : 
    4227         158 :     proclock_hashcode = ProcLockHashCode(&proclocktag, hashcode);
    4228             : 
    4229             :     /*
    4230             :      * Find or create a proclock entry with this tag
    4231             :      */
    4232         158 :     proclock = (PROCLOCK *) hash_search_with_hash_value(LockMethodProcLockHash,
    4233             :                                                         &proclocktag,
    4234             :                                                         proclock_hashcode,
    4235             :                                                         HASH_ENTER_NULL,
    4236             :                                                         &found);
    4237         158 :     if (!proclock)
    4238             :     {
    4239             :         /* Oops, not enough shmem for the proclock */
    4240           0 :         if (lock->nRequested == 0)
    4241             :         {
    4242             :             /*
    4243             :              * There are no other requestors of this lock, so garbage-collect
    4244             :              * the lock object.  We *must* do this to avoid a permanent leak
    4245             :              * of shared memory, because there won't be anything to cause
    4246             :              * anyone to release the lock object later.
    4247             :              */
    4248             :             Assert(dlist_is_empty(&lock->procLocks));
    4249           0 :             if (!hash_search_with_hash_value(LockMethodLockHash,
    4250           0 :                                              &(lock->tag),
    4251             :                                              hashcode,
    4252             :                                              HASH_REMOVE,
    4253             :                                              NULL))
    4254           0 :                 elog(PANIC, "lock table corrupted");
    4255             :         }
    4256           0 :         LWLockRelease(partitionLock);
    4257           0 :         ereport(ERROR,
    4258             :                 (errcode(ERRCODE_OUT_OF_MEMORY),
    4259             :                  errmsg("out of shared memory"),
    4260             :                  errhint("You might need to increase max_locks_per_transaction.")));
    4261             :     }
    4262             : 
    4263             :     /*
    4264             :      * If new, initialize the new entry
    4265             :      */
    4266         158 :     if (!found)
    4267             :     {
    4268             :         Assert(proc->lockGroupLeader == NULL);
    4269         150 :         proclock->groupLeader = proc;
    4270         150 :         proclock->holdMask = 0;
    4271         150 :         proclock->releaseMask = 0;
    4272             :         /* Add proclock to appropriate lists */
    4273         150 :         dlist_push_tail(&lock->procLocks, &proclock->lockLink);
    4274         150 :         dlist_push_tail(&proc->myProcLocks[partition],
    4275             :                         &proclock->procLink);
    4276             :         PROCLOCK_PRINT("lock_twophase_recover: new", proclock);
    4277             :     }
    4278             :     else
    4279             :     {
    4280             :         PROCLOCK_PRINT("lock_twophase_recover: found", proclock);
    4281             :         Assert((proclock->holdMask & ~lock->grantMask) == 0);
    4282             :     }
    4283             : 
    4284             :     /*
    4285             :      * lock->nRequested and lock->requested[] count the total number of
    4286             :      * requests, whether granted or waiting, so increment those immediately.
    4287             :      */
    4288         158 :     lock->nRequested++;
    4289         158 :     lock->requested[lockmode]++;
    4290             :     Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
    4291             : 
    4292             :     /*
    4293             :      * We shouldn't already hold the desired lock.
    4294             :      */
    4295         158 :     if (proclock->holdMask & LOCKBIT_ON(lockmode))
    4296           0 :         elog(ERROR, "lock %s on object %u/%u/%u is already held",
    4297             :              lockMethodTable->lockModeNames[lockmode],
    4298             :              lock->tag.locktag_field1, lock->tag.locktag_field2,
    4299             :              lock->tag.locktag_field3);
    4300             : 
    4301             :     /*
    4302             :      * We ignore any possible conflicts and just grant ourselves the lock. Not
    4303             :      * only because we don't bother, but also to avoid deadlocks when
    4304             :      * switching from standby to normal mode. See function comment.
    4305             :      */
    4306         158 :     GrantLock(lock, proclock, lockmode);
    4307             : 
    4308             :     /*
    4309             :      * Bump strong lock count, to make sure any fast-path lock requests won't
    4310             :      * be granted without consulting the primary lock table.
    4311             :      */
    4312         158 :     if (ConflictsWithRelationFastPath(&lock->tag, lockmode))
    4313             :     {
    4314          26 :         uint32      fasthashcode = FastPathStrongLockHashPartition(hashcode);
    4315             : 
    4316          26 :         SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
    4317          26 :         FastPathStrongRelationLocks->count[fasthashcode]++;
    4318          26 :         SpinLockRelease(&FastPathStrongRelationLocks->mutex);
    4319             :     }
    4320             : 
    4321         158 :     LWLockRelease(partitionLock);
    4322         158 : }
    4323             : 
    4324             : /*
    4325             :  * Re-acquire a lock belonging to a transaction that was prepared, when
    4326             :  * starting up into hot standby mode.
    4327             :  */
    4328             : void
    4329           0 : lock_twophase_standby_recover(TransactionId xid, uint16 info,
    4330             :                               void *recdata, uint32 len)
    4331             : {
    4332           0 :     TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
    4333             :     LOCKTAG    *locktag;
    4334             :     LOCKMODE    lockmode;
    4335             :     LOCKMETHODID lockmethodid;
    4336             : 
    4337             :     Assert(len == sizeof(TwoPhaseLockRecord));
    4338           0 :     locktag = &rec->locktag;
    4339           0 :     lockmode = rec->lockmode;
    4340           0 :     lockmethodid = locktag->locktag_lockmethodid;
    4341             : 
    4342           0 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
    4343           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    4344             : 
    4345           0 :     if (lockmode == AccessExclusiveLock &&
    4346           0 :         locktag->locktag_type == LOCKTAG_RELATION)
    4347             :     {
    4348           0 :         StandbyAcquireAccessExclusiveLock(xid,
    4349             :                                           locktag->locktag_field1 /* dboid */ ,
    4350             :                                           locktag->locktag_field2 /* reloid */ );
    4351             :     }
    4352           0 : }
    4353             : 
    4354             : 
    4355             : /*
    4356             :  * 2PC processing routine for COMMIT PREPARED case.
    4357             :  *
    4358             :  * Find and release the lock indicated by the 2PC record.
    4359             :  */
    4360             : void
    4361        1706 : lock_twophase_postcommit(TransactionId xid, uint16 info,
    4362             :                          void *recdata, uint32 len)
    4363             : {
    4364        1706 :     TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
    4365        1706 :     PGPROC     *proc = TwoPhaseGetDummyProc(xid, true);
    4366             :     LOCKTAG    *locktag;
    4367             :     LOCKMETHODID lockmethodid;
    4368             :     LockMethod  lockMethodTable;
    4369             : 
    4370             :     Assert(len == sizeof(TwoPhaseLockRecord));
    4371        1706 :     locktag = &rec->locktag;
    4372        1706 :     lockmethodid = locktag->locktag_lockmethodid;
    4373             : 
    4374        1706 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
    4375           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    4376        1706 :     lockMethodTable = LockMethods[lockmethodid];
    4377             : 
    4378        1706 :     LockRefindAndRelease(lockMethodTable, proc, locktag, rec->lockmode, true);
    4379        1706 : }
    4380             : 
    4381             : /*
    4382             :  * 2PC processing routine for ROLLBACK PREPARED case.
    4383             :  *
    4384             :  * This is actually just the same as the COMMIT case.
    4385             :  */
    4386             : void
    4387         238 : lock_twophase_postabort(TransactionId xid, uint16 info,
    4388             :                         void *recdata, uint32 len)
    4389             : {
    4390         238 :     lock_twophase_postcommit(xid, info, recdata, len);
    4391         238 : }
    4392             : 
    4393             : /*
    4394             :  *      VirtualXactLockTableInsert
    4395             :  *
    4396             :  *      Take vxid lock via the fast-path.  There can't be any pre-existing
    4397             :  *      lockers, as we haven't advertised this vxid via the ProcArray yet.
    4398             :  *
    4399             :  *      Since MyProc->fpLocalTransactionId will normally contain the same data
    4400             :  *      as MyProc->lxid, you might wonder if we really need both.  The
    4401             :  *      difference is that MyProc->lxid is set and cleared unlocked, and
    4402             :  *      examined by procarray.c, while fpLocalTransactionId is protected by
    4403             :  *      fpInfoLock and is used only by the locking subsystem.  Doing it this
    4404             :  *      way makes it easier to verify that there are no funny race conditions.
    4405             :  *
    4406             :  *      We don't bother recording this lock in the local lock table, since it's
    4407             :  *      only ever released at the end of a transaction.  Instead,
    4408             :  *      LockReleaseAll() calls VirtualXactLockTableCleanup().
    4409             :  */
    4410             : void
    4411      941054 : VirtualXactLockTableInsert(VirtualTransactionId vxid)
    4412             : {
    4413             :     Assert(VirtualTransactionIdIsValid(vxid));
    4414             : 
    4415      941054 :     LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
    4416             : 
    4417             :     Assert(MyProc->backendId == vxid.backendId);
    4418             :     Assert(MyProc->fpLocalTransactionId == InvalidLocalTransactionId);
    4419             :     Assert(MyProc->fpVXIDLock == false);
    4420             : 
    4421      941054 :     MyProc->fpVXIDLock = true;
    4422      941054 :     MyProc->fpLocalTransactionId = vxid.localTransactionId;
    4423             : 
    4424      941054 :     LWLockRelease(&MyProc->fpInfoLock);
    4425      941054 : }
    4426             : 
    4427             : /*
    4428             :  *      VirtualXactLockTableCleanup
    4429             :  *
    4430             :  *      Check whether a VXID lock has been materialized; if so, release it,
    4431             :  *      unblocking waiters.
    4432             :  */
    4433             : void
    4434      941674 : VirtualXactLockTableCleanup(void)
    4435             : {
    4436             :     bool        fastpath;
    4437             :     LocalTransactionId lxid;
    4438             : 
    4439             :     Assert(MyProc->backendId != InvalidBackendId);
    4440             : 
    4441             :     /*
    4442             :      * Clean up shared memory state.
    4443             :      */
    4444      941674 :     LWLockAcquire(&MyProc->fpInfoLock, LW_EXCLUSIVE);
    4445             : 
    4446      941674 :     fastpath = MyProc->fpVXIDLock;
    4447      941674 :     lxid = MyProc->fpLocalTransactionId;
    4448      941674 :     MyProc->fpVXIDLock = false;
    4449      941674 :     MyProc->fpLocalTransactionId = InvalidLocalTransactionId;
    4450             : 
    4451      941674 :     LWLockRelease(&MyProc->fpInfoLock);
    4452             : 
    4453             :     /*
    4454             :      * If fpVXIDLock has been cleared without touching fpLocalTransactionId,
    4455             :      * that means someone transferred the lock to the main lock table.
    4456             :      */
    4457      941674 :     if (!fastpath && LocalTransactionIdIsValid(lxid))
    4458             :     {
    4459             :         VirtualTransactionId vxid;
    4460             :         LOCKTAG     locktag;
    4461             : 
    4462         496 :         vxid.backendId = MyBackendId;
    4463         496 :         vxid.localTransactionId = lxid;
    4464         496 :         SET_LOCKTAG_VIRTUALTRANSACTION(locktag, vxid);
    4465             : 
    4466         496 :         LockRefindAndRelease(LockMethods[DEFAULT_LOCKMETHOD], MyProc,
    4467             :                              &locktag, ExclusiveLock, false);
    4468             :     }
    4469      941674 : }
    4470             : 
    4471             : /*
    4472             :  *      XactLockForVirtualXact
    4473             :  *
    4474             :  * If TransactionIdIsValid(xid), this is essentially XactLockTableWait(xid,
    4475             :  * NULL, NULL, XLTW_None) or ConditionalXactLockTableWait(xid).  Unlike those
    4476             :  * functions, it assumes "xid" is never a subtransaction and that "xid" is
    4477             :  * prepared, committed, or aborted.
    4478             :  *
    4479             :  * If !TransactionIdIsValid(xid), this locks every prepared XID having been
    4480             :  * known as "vxid" before its PREPARE TRANSACTION.
    4481             :  */
    4482             : static bool
    4483         520 : XactLockForVirtualXact(VirtualTransactionId vxid,
    4484             :                        TransactionId xid, bool wait)
    4485             : {
    4486         520 :     bool        more = false;
    4487             : 
    4488             :     /* There is no point to wait for 2PCs if you have no 2PCs. */
    4489         520 :     if (max_prepared_xacts == 0)
    4490         116 :         return true;
    4491             : 
    4492             :     do
    4493             :     {
    4494             :         LockAcquireResult lar;
    4495             :         LOCKTAG     tag;
    4496             : 
    4497             :         /* Clear state from previous iterations. */
    4498         404 :         if (more)
    4499             :         {
    4500           0 :             xid = InvalidTransactionId;
    4501           0 :             more = false;
    4502             :         }
    4503             : 
    4504             :         /* If we have no xid, try to find one. */
    4505         404 :         if (!TransactionIdIsValid(xid))
    4506         202 :             xid = TwoPhaseGetXidByVirtualXID(vxid, &more);
    4507         404 :         if (!TransactionIdIsValid(xid))
    4508             :         {
    4509             :             Assert(!more);
    4510         176 :             return true;
    4511             :         }
    4512             : 
    4513             :         /* Check or wait for XID completion. */
    4514         228 :         SET_LOCKTAG_TRANSACTION(tag, xid);
    4515         228 :         lar = LockAcquire(&tag, ShareLock, false, !wait);
    4516         228 :         if (lar == LOCKACQUIRE_NOT_AVAIL)
    4517           0 :             return false;
    4518         228 :         LockRelease(&tag, ShareLock, false);
    4519         228 :     } while (more);
    4520             : 
    4521         228 :     return true;
    4522             : }
    4523             : 
    4524             : /*
    4525             :  *      VirtualXactLock
    4526             :  *
    4527             :  * If wait = true, wait as long as the given VXID or any XID acquired by the
    4528             :  * same transaction is still running.  Then, return true.
    4529             :  *
    4530             :  * If wait = false, just check whether that VXID or one of those XIDs is still
    4531             :  * running, and return true or false.
    4532             :  */
    4533             : bool
    4534         600 : VirtualXactLock(VirtualTransactionId vxid, bool wait)
    4535             : {
    4536             :     LOCKTAG     tag;
    4537             :     PGPROC     *proc;
    4538         600 :     TransactionId xid = InvalidTransactionId;
    4539             : 
    4540             :     Assert(VirtualTransactionIdIsValid(vxid));
    4541             : 
    4542         600 :     if (VirtualTransactionIdIsRecoveredPreparedXact(vxid))
    4543             :         /* no vxid lock; localTransactionId is a normal, locked XID */
    4544           2 :         return XactLockForVirtualXact(vxid, vxid.localTransactionId, wait);
    4545             : 
    4546         598 :     SET_LOCKTAG_VIRTUALTRANSACTION(tag, vxid);
    4547             : 
    4548             :     /*
    4549             :      * If a lock table entry must be made, this is the PGPROC on whose behalf
    4550             :      * it must be done.  Note that the transaction might end or the PGPROC
    4551             :      * might be reassigned to a new backend before we get around to examining
    4552             :      * it, but it doesn't matter.  If we find upon examination that the
    4553             :      * relevant lxid is no longer running here, that's enough to prove that
    4554             :      * it's no longer running anywhere.
    4555             :      */
    4556         598 :     proc = BackendIdGetProc(vxid.backendId);
    4557         598 :     if (proc == NULL)
    4558           6 :         return XactLockForVirtualXact(vxid, InvalidTransactionId, wait);
    4559             : 
    4560             :     /*
    4561             :      * We must acquire this lock before checking the backendId and lxid
    4562             :      * against the ones we're waiting for.  The target backend will only set
    4563             :      * or clear lxid while holding this lock.
    4564             :      */
    4565         592 :     LWLockAcquire(&proc->fpInfoLock, LW_EXCLUSIVE);
    4566             : 
    4567         592 :     if (proc->backendId != vxid.backendId
    4568         592 :         || proc->fpLocalTransactionId != vxid.localTransactionId)
    4569             :     {
    4570             :         /* VXID ended */
    4571          54 :         LWLockRelease(&proc->fpInfoLock);
    4572          54 :         return XactLockForVirtualXact(vxid, InvalidTransactionId, wait);
    4573             :     }
    4574             : 
    4575             :     /*
    4576             :      * If we aren't asked to wait, there's no need to set up a lock table
    4577             :      * entry.  The transaction is still in progress, so just return false.
    4578             :      */
    4579         538 :     if (!wait)
    4580             :     {
    4581          30 :         LWLockRelease(&proc->fpInfoLock);
    4582          30 :         return false;
    4583             :     }
    4584             : 
    4585             :     /*
    4586             :      * OK, we're going to need to sleep on the VXID.  But first, we must set
    4587             :      * up the primary lock table entry, if needed (ie, convert the proc's
    4588             :      * fast-path lock on its VXID to a regular lock).
    4589             :      */
    4590         508 :     if (proc->fpVXIDLock)
    4591             :     {
    4592             :         PROCLOCK   *proclock;
    4593             :         uint32      hashcode;
    4594             :         LWLock     *partitionLock;
    4595             : 
    4596         496 :         hashcode = LockTagHashCode(&tag);
    4597             : 
    4598         496 :         partitionLock = LockHashPartitionLock(hashcode);
    4599         496 :         LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    4600             : 
    4601         496 :         proclock = SetupLockInTable(LockMethods[DEFAULT_LOCKMETHOD], proc,
    4602             :                                     &tag, hashcode, ExclusiveLock);
    4603         496 :         if (!proclock)
    4604             :         {
    4605           0 :             LWLockRelease(partitionLock);
    4606           0 :             LWLockRelease(&proc->fpInfoLock);
    4607           0 :             ereport(ERROR,
    4608             :                     (errcode(ERRCODE_OUT_OF_MEMORY),
    4609             :                      errmsg("out of shared memory"),
    4610             :                      errhint("You might need to increase max_locks_per_transaction.")));
    4611             :         }
    4612         496 :         GrantLock(proclock->tag.myLock, proclock, ExclusiveLock);
    4613             : 
    4614         496 :         LWLockRelease(partitionLock);
    4615             : 
    4616         496 :         proc->fpVXIDLock = false;
    4617             :     }
    4618             : 
    4619             :     /*
    4620             :      * If the proc has an XID now, we'll avoid a TwoPhaseGetXidByVirtualXID()
    4621             :      * search.  The proc might have assigned this XID but not yet locked it,
    4622             :      * in which case the proc will lock this XID before releasing the VXID.
    4623             :      * The fpInfoLock critical section excludes VirtualXactLockTableCleanup(),
    4624             :      * so we won't save an XID of a different VXID.  It doesn't matter whether
    4625             :      * we save this before or after setting up the primary lock table entry.
    4626             :      */
    4627         508 :     xid = proc->xid;
    4628             : 
    4629             :     /* Done with proc->fpLockBits */
    4630         508 :     LWLockRelease(&proc->fpInfoLock);
    4631             : 
    4632             :     /* Time to wait. */
    4633         508 :     (void) LockAcquire(&tag, ShareLock, false, false);
    4634             : 
    4635         458 :     LockRelease(&tag, ShareLock, false);
    4636         458 :     return XactLockForVirtualXact(vxid, xid, wait);
    4637             : }
    4638             : 
    4639             : /*
    4640             :  * LockWaiterCount
    4641             :  *
    4642             :  * Find the number of lock requester on this locktag
    4643             :  */
    4644             : int
    4645          36 : LockWaiterCount(const LOCKTAG *locktag)
    4646             : {
    4647          36 :     LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
    4648             :     LOCK       *lock;
    4649             :     bool        found;
    4650             :     uint32      hashcode;
    4651             :     LWLock     *partitionLock;
    4652          36 :     int         waiters = 0;
    4653             : 
    4654          36 :     if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
    4655           0 :         elog(ERROR, "unrecognized lock method: %d", lockmethodid);
    4656             : 
    4657          36 :     hashcode = LockTagHashCode(locktag);
    4658          36 :     partitionLock = LockHashPartitionLock(hashcode);
    4659          36 :     LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    4660             : 
    4661          36 :     lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
    4662             :                                                 locktag,
    4663             :                                                 hashcode,
    4664             :                                                 HASH_FIND,
    4665             :                                                 &found);
    4666          36 :     if (found)
    4667             :     {
    4668             :         Assert(lock != NULL);
    4669          36 :         waiters = lock->nRequested;
    4670             :     }
    4671          36 :     LWLockRelease(partitionLock);
    4672             : 
    4673          36 :     return waiters;
    4674             : }

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