LCOV - code coverage report
Current view: top level - src/backend/storage/lmgr - proc.c (source / functions) Hit Total Coverage
Test: PostgreSQL 16devel Lines: 483 527 91.7 %
Date: 2023-03-26 15:11:41 Functions: 25 25 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * proc.c
       4             :  *    routines to manage per-process shared memory data structure
       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/proc.c
      12             :  *
      13             :  *-------------------------------------------------------------------------
      14             :  */
      15             : /*
      16             :  * Interface (a):
      17             :  *      ProcSleep(), ProcWakeup(),
      18             :  *
      19             :  * Waiting for a lock causes the backend to be put to sleep.  Whoever releases
      20             :  * the lock wakes the process up again (and gives it an error code so it knows
      21             :  * whether it was awoken on an error condition).
      22             :  *
      23             :  * Interface (b):
      24             :  *
      25             :  * ProcReleaseLocks -- frees the locks associated with current transaction
      26             :  *
      27             :  * ProcKill -- destroys the shared memory state (and locks)
      28             :  * associated with the process.
      29             :  */
      30             : #include "postgres.h"
      31             : 
      32             : #include <signal.h>
      33             : #include <unistd.h>
      34             : #include <sys/time.h>
      35             : 
      36             : #include "access/transam.h"
      37             : #include "access/twophase.h"
      38             : #include "access/xlogutils.h"
      39             : #include "miscadmin.h"
      40             : #include "pgstat.h"
      41             : #include "postmaster/autovacuum.h"
      42             : #include "replication/slot.h"
      43             : #include "replication/syncrep.h"
      44             : #include "replication/walsender.h"
      45             : #include "storage/condition_variable.h"
      46             : #include "storage/ipc.h"
      47             : #include "storage/lmgr.h"
      48             : #include "storage/pmsignal.h"
      49             : #include "storage/proc.h"
      50             : #include "storage/procarray.h"
      51             : #include "storage/procsignal.h"
      52             : #include "storage/spin.h"
      53             : #include "storage/standby.h"
      54             : #include "utils/timeout.h"
      55             : #include "utils/timestamp.h"
      56             : 
      57             : /* GUC variables */
      58             : int         DeadlockTimeout = 1000;
      59             : int         StatementTimeout = 0;
      60             : int         LockTimeout = 0;
      61             : int         IdleInTransactionSessionTimeout = 0;
      62             : int         IdleSessionTimeout = 0;
      63             : bool        log_lock_waits = false;
      64             : 
      65             : /* Pointer to this process's PGPROC struct, if any */
      66             : PGPROC     *MyProc = NULL;
      67             : 
      68             : /*
      69             :  * This spinlock protects the freelist of recycled PGPROC structures.
      70             :  * We cannot use an LWLock because the LWLock manager depends on already
      71             :  * having a PGPROC and a wait semaphore!  But these structures are touched
      72             :  * relatively infrequently (only at backend startup or shutdown) and not for
      73             :  * very long, so a spinlock is okay.
      74             :  */
      75             : NON_EXEC_STATIC slock_t *ProcStructLock = NULL;
      76             : 
      77             : /* Pointers to shared-memory structures */
      78             : PROC_HDR   *ProcGlobal = NULL;
      79             : NON_EXEC_STATIC PGPROC *AuxiliaryProcs = NULL;
      80             : PGPROC     *PreparedXactProcs = NULL;
      81             : 
      82             : /* If we are waiting for a lock, this points to the associated LOCALLOCK */
      83             : static LOCALLOCK *lockAwaited = NULL;
      84             : 
      85             : static DeadLockState deadlock_state = DS_NOT_YET_CHECKED;
      86             : 
      87             : /* Is a deadlock check pending? */
      88             : static volatile sig_atomic_t got_deadlock_timeout;
      89             : 
      90             : static void RemoveProcFromArray(int code, Datum arg);
      91             : static void ProcKill(int code, Datum arg);
      92             : static void AuxiliaryProcKill(int code, Datum arg);
      93             : static void CheckDeadLock(void);
      94             : 
      95             : 
      96             : /*
      97             :  * Report shared-memory space needed by InitProcGlobal.
      98             :  */
      99             : Size
     100        5192 : ProcGlobalShmemSize(void)
     101             : {
     102        5192 :     Size        size = 0;
     103             :     Size        TotalProcs =
     104        5192 :     add_size(MaxBackends, add_size(NUM_AUXILIARY_PROCS, max_prepared_xacts));
     105             : 
     106             :     /* ProcGlobal */
     107        5192 :     size = add_size(size, sizeof(PROC_HDR));
     108        5192 :     size = add_size(size, mul_size(TotalProcs, sizeof(PGPROC)));
     109        5192 :     size = add_size(size, sizeof(slock_t));
     110             : 
     111        5192 :     size = add_size(size, mul_size(TotalProcs, sizeof(*ProcGlobal->xids)));
     112        5192 :     size = add_size(size, mul_size(TotalProcs, sizeof(*ProcGlobal->subxidStates)));
     113        5192 :     size = add_size(size, mul_size(TotalProcs, sizeof(*ProcGlobal->statusFlags)));
     114             : 
     115        5192 :     return size;
     116             : }
     117             : 
     118             : /*
     119             :  * Report number of semaphores needed by InitProcGlobal.
     120             :  */
     121             : int
     122        5192 : ProcGlobalSemas(void)
     123             : {
     124             :     /*
     125             :      * We need a sema per backend (including autovacuum), plus one for each
     126             :      * auxiliary process.
     127             :      */
     128        5192 :     return MaxBackends + NUM_AUXILIARY_PROCS;
     129             : }
     130             : 
     131             : /*
     132             :  * InitProcGlobal -
     133             :  *    Initialize the global process table during postmaster or standalone
     134             :  *    backend startup.
     135             :  *
     136             :  *    We also create all the per-process semaphores we will need to support
     137             :  *    the requested number of backends.  We used to allocate semaphores
     138             :  *    only when backends were actually started up, but that is bad because
     139             :  *    it lets Postgres fail under load --- a lot of Unix systems are
     140             :  *    (mis)configured with small limits on the number of semaphores, and
     141             :  *    running out when trying to start another backend is a common failure.
     142             :  *    So, now we grab enough semaphores to support the desired max number
     143             :  *    of backends immediately at initialization --- if the sysadmin has set
     144             :  *    MaxConnections, max_worker_processes, max_wal_senders, or
     145             :  *    autovacuum_max_workers higher than his kernel will support, he'll
     146             :  *    find out sooner rather than later.
     147             :  *
     148             :  *    Another reason for creating semaphores here is that the semaphore
     149             :  *    implementation typically requires us to create semaphores in the
     150             :  *    postmaster, not in backends.
     151             :  *
     152             :  * Note: this is NOT called by individual backends under a postmaster,
     153             :  * not even in the EXEC_BACKEND case.  The ProcGlobal and AuxiliaryProcs
     154             :  * pointers must be propagated specially for EXEC_BACKEND operation.
     155             :  */
     156             : void
     157        3456 : InitProcGlobal(void)
     158             : {
     159             :     PGPROC     *procs;
     160             :     int         i,
     161             :                 j;
     162             :     bool        found;
     163        3456 :     uint32      TotalProcs = MaxBackends + NUM_AUXILIARY_PROCS + max_prepared_xacts;
     164             : 
     165             :     /* Create the ProcGlobal shared structure */
     166        3456 :     ProcGlobal = (PROC_HDR *)
     167        3456 :         ShmemInitStruct("Proc Header", sizeof(PROC_HDR), &found);
     168             :     Assert(!found);
     169             : 
     170             :     /*
     171             :      * Initialize the data structures.
     172             :      */
     173        3456 :     ProcGlobal->spins_per_delay = DEFAULT_SPINS_PER_DELAY;
     174        3456 :     dlist_init(&ProcGlobal->freeProcs);
     175        3456 :     dlist_init(&ProcGlobal->autovacFreeProcs);
     176        3456 :     dlist_init(&ProcGlobal->bgworkerFreeProcs);
     177        3456 :     dlist_init(&ProcGlobal->walsenderFreeProcs);
     178        3456 :     ProcGlobal->startupBufferPinWaitBufId = -1;
     179        3456 :     ProcGlobal->walwriterLatch = NULL;
     180        3456 :     ProcGlobal->checkpointerLatch = NULL;
     181        3456 :     pg_atomic_init_u32(&ProcGlobal->procArrayGroupFirst, INVALID_PGPROCNO);
     182        3456 :     pg_atomic_init_u32(&ProcGlobal->clogGroupFirst, INVALID_PGPROCNO);
     183             : 
     184             :     /*
     185             :      * Create and initialize all the PGPROC structures we'll need.  There are
     186             :      * five separate consumers: (1) normal backends, (2) autovacuum workers
     187             :      * and the autovacuum launcher, (3) background workers, (4) auxiliary
     188             :      * processes, and (5) prepared transactions.  Each PGPROC structure is
     189             :      * dedicated to exactly one of these purposes, and they do not move
     190             :      * between groups.
     191             :      */
     192        3456 :     procs = (PGPROC *) ShmemAlloc(TotalProcs * sizeof(PGPROC));
     193        3456 :     MemSet(procs, 0, TotalProcs * sizeof(PGPROC));
     194        3456 :     ProcGlobal->allProcs = procs;
     195             :     /* XXX allProcCount isn't really all of them; it excludes prepared xacts */
     196        3456 :     ProcGlobal->allProcCount = MaxBackends + NUM_AUXILIARY_PROCS;
     197             : 
     198             :     /*
     199             :      * Allocate arrays mirroring PGPROC fields in a dense manner. See
     200             :      * PROC_HDR.
     201             :      *
     202             :      * XXX: It might make sense to increase padding for these arrays, given
     203             :      * how hotly they are accessed.
     204             :      */
     205        6912 :     ProcGlobal->xids =
     206        3456 :         (TransactionId *) ShmemAlloc(TotalProcs * sizeof(*ProcGlobal->xids));
     207        8242 :     MemSet(ProcGlobal->xids, 0, TotalProcs * sizeof(*ProcGlobal->xids));
     208        3456 :     ProcGlobal->subxidStates = (XidCacheStatus *) ShmemAlloc(TotalProcs * sizeof(*ProcGlobal->subxidStates));
     209        3600 :     MemSet(ProcGlobal->subxidStates, 0, TotalProcs * sizeof(*ProcGlobal->subxidStates));
     210        3456 :     ProcGlobal->statusFlags = (uint8 *) ShmemAlloc(TotalProcs * sizeof(*ProcGlobal->statusFlags));
     211        3528 :     MemSet(ProcGlobal->statusFlags, 0, TotalProcs * sizeof(*ProcGlobal->statusFlags));
     212             : 
     213      383312 :     for (i = 0; i < TotalProcs; i++)
     214             :     {
     215      379856 :         PGPROC     *proc = &procs[i];
     216             : 
     217             :         /* Common initialization for all PGPROCs, regardless of type. */
     218             : 
     219             :         /*
     220             :          * Set up per-PGPROC semaphore, latch, and fpInfoLock.  Prepared xact
     221             :          * dummy PGPROCs don't need these though - they're never associated
     222             :          * with a real process
     223             :          */
     224      379856 :         if (i < MaxBackends + NUM_AUXILIARY_PROCS)
     225             :         {
     226      378326 :             proc->sem = PGSemaphoreCreate();
     227      378326 :             InitSharedLatch(&(proc->procLatch));
     228      378326 :             LWLockInitialize(&(proc->fpInfoLock), LWTRANCHE_LOCK_FASTPATH);
     229             :         }
     230      379856 :         proc->pgprocno = i;
     231             : 
     232             :         /*
     233             :          * Newly created PGPROCs for normal backends, autovacuum and bgworkers
     234             :          * must be queued up on the appropriate free list.  Because there can
     235             :          * only ever be a small, fixed number of auxiliary processes, no free
     236             :          * list is used in that case; InitAuxiliaryProcess() instead uses a
     237             :          * linear search.   PGPROCs for prepared transactions are added to a
     238             :          * free list by TwoPhaseShmemInit().
     239             :          */
     240      379856 :         if (i < MaxConnections)
     241             :         {
     242             :             /* PGPROC for normal backend, add to freeProcs list */
     243      288600 :             dlist_push_head(&ProcGlobal->freeProcs, &proc->links);
     244      288600 :             proc->procgloballist = &ProcGlobal->freeProcs;
     245             :         }
     246       91256 :         else if (i < MaxConnections + autovacuum_max_workers + 1)
     247             :         {
     248             :             /* PGPROC for AV launcher/worker, add to autovacFreeProcs list */
     249       13824 :             dlist_push_head(&ProcGlobal->autovacFreeProcs, &proc->links);
     250       13824 :             proc->procgloballist = &ProcGlobal->autovacFreeProcs;
     251             :         }
     252       77432 :         else if (i < MaxConnections + autovacuum_max_workers + 1 + max_worker_processes)
     253             :         {
     254             :             /* PGPROC for bgworker, add to bgworkerFreeProcs list */
     255       27648 :             dlist_push_head(&ProcGlobal->bgworkerFreeProcs, &proc->links);
     256       27648 :             proc->procgloballist = &ProcGlobal->bgworkerFreeProcs;
     257             :         }
     258       49784 :         else if (i < MaxBackends)
     259             :         {
     260             :             /* PGPROC for walsender, add to walsenderFreeProcs list */
     261       30974 :             dlist_push_head(&ProcGlobal->walsenderFreeProcs, &proc->links);
     262       30974 :             proc->procgloballist = &ProcGlobal->walsenderFreeProcs;
     263             :         }
     264             : 
     265             :         /* Initialize myProcLocks[] shared memory queues. */
     266     6457552 :         for (j = 0; j < NUM_LOCK_PARTITIONS; j++)
     267     6077696 :             dlist_init(&(proc->myProcLocks[j]));
     268             : 
     269             :         /* Initialize lockGroupMembers list. */
     270      379856 :         dlist_init(&proc->lockGroupMembers);
     271             : 
     272             :         /*
     273             :          * Initialize the atomic variables, otherwise, it won't be safe to
     274             :          * access them for backends that aren't currently in use.
     275             :          */
     276      379856 :         pg_atomic_init_u32(&(proc->procArrayGroupNext), INVALID_PGPROCNO);
     277      379856 :         pg_atomic_init_u32(&(proc->clogGroupNext), INVALID_PGPROCNO);
     278      379856 :         pg_atomic_init_u64(&(proc->waitStart), 0);
     279             :     }
     280             : 
     281             :     /*
     282             :      * Save pointers to the blocks of PGPROC structures reserved for auxiliary
     283             :      * processes and prepared transactions.
     284             :      */
     285        3456 :     AuxiliaryProcs = &procs[MaxBackends];
     286        3456 :     PreparedXactProcs = &procs[MaxBackends + NUM_AUXILIARY_PROCS];
     287             : 
     288             :     /* Create ProcStructLock spinlock, too */
     289        3456 :     ProcStructLock = (slock_t *) ShmemAlloc(sizeof(slock_t));
     290        3456 :     SpinLockInit(ProcStructLock);
     291        3456 : }
     292             : 
     293             : /*
     294             :  * InitProcess -- initialize a per-process data structure for this backend
     295             :  */
     296             : void
     297       22480 : InitProcess(void)
     298             : {
     299             :     dlist_head *procgloballist;
     300             : 
     301             :     /*
     302             :      * ProcGlobal should be set up already (if we are a backend, we inherit
     303             :      * this by fork() or EXEC_BACKEND mechanism from the postmaster).
     304             :      */
     305       22480 :     if (ProcGlobal == NULL)
     306           0 :         elog(PANIC, "proc header uninitialized");
     307             : 
     308       22480 :     if (MyProc != NULL)
     309           0 :         elog(ERROR, "you already exist");
     310             : 
     311             :     /* Decide which list should supply our PGPROC. */
     312       22480 :     if (IsAnyAutoVacuumProcess())
     313         606 :         procgloballist = &ProcGlobal->autovacFreeProcs;
     314       21874 :     else if (IsBackgroundWorker)
     315        3826 :         procgloballist = &ProcGlobal->bgworkerFreeProcs;
     316       18048 :     else if (am_walsender)
     317        1542 :         procgloballist = &ProcGlobal->walsenderFreeProcs;
     318             :     else
     319       16506 :         procgloballist = &ProcGlobal->freeProcs;
     320             : 
     321             :     /*
     322             :      * Try to get a proc struct from the appropriate free list.  If this
     323             :      * fails, we must be out of PGPROC structures (not to mention semaphores).
     324             :      *
     325             :      * While we are holding the ProcStructLock, also copy the current shared
     326             :      * estimate of spins_per_delay to local storage.
     327             :      */
     328       22480 :     SpinLockAcquire(ProcStructLock);
     329             : 
     330       22480 :     set_spins_per_delay(ProcGlobal->spins_per_delay);
     331             : 
     332       22480 :     if (!dlist_is_empty(procgloballist))
     333             :     {
     334       22476 :         MyProc = (PGPROC*) dlist_pop_head_node(procgloballist);
     335       22476 :         SpinLockRelease(ProcStructLock);
     336             :     }
     337             :     else
     338             :     {
     339             :         /*
     340             :          * If we reach here, all the PGPROCs are in use.  This is one of the
     341             :          * possible places to detect "too many backends", so give the standard
     342             :          * error message.  XXX do we need to give a different failure message
     343             :          * in the autovacuum case?
     344             :          */
     345           4 :         SpinLockRelease(ProcStructLock);
     346           4 :         if (am_walsender)
     347           4 :             ereport(FATAL,
     348             :                     (errcode(ERRCODE_TOO_MANY_CONNECTIONS),
     349             :                      errmsg("number of requested standby connections exceeds max_wal_senders (currently %d)",
     350             :                             max_wal_senders)));
     351           0 :         ereport(FATAL,
     352             :                 (errcode(ERRCODE_TOO_MANY_CONNECTIONS),
     353             :                  errmsg("sorry, too many clients already")));
     354             :     }
     355             : 
     356             :     /*
     357             :      * Cross-check that the PGPROC is of the type we expect; if this were not
     358             :      * the case, it would get returned to the wrong list.
     359             :      */
     360             :     Assert(MyProc->procgloballist == procgloballist);
     361             : 
     362             :     /*
     363             :      * Now that we have a PGPROC, mark ourselves as an active postmaster
     364             :      * child; this is so that the postmaster can detect it if we exit without
     365             :      * cleaning up.  (XXX autovac launcher currently doesn't participate in
     366             :      * this; it probably should.)
     367             :      */
     368       22476 :     if (IsUnderPostmaster && !IsAutoVacuumLauncherProcess())
     369       20724 :         MarkPostmasterChildActive();
     370             : 
     371             :     /*
     372             :      * Initialize all fields of MyProc, except for those previously
     373             :      * initialized by InitProcGlobal.
     374             :      */
     375       22476 :     dlist_node_init(&MyProc->links);
     376       22476 :     MyProc->waitStatus = PROC_WAIT_STATUS_OK;
     377       22476 :     MyProc->lxid = InvalidLocalTransactionId;
     378       22476 :     MyProc->fpVXIDLock = false;
     379       22476 :     MyProc->fpLocalTransactionId = InvalidLocalTransactionId;
     380       22476 :     MyProc->xid = InvalidTransactionId;
     381       22476 :     MyProc->xmin = InvalidTransactionId;
     382       22476 :     MyProc->pid = MyProcPid;
     383             :     /* backendId, databaseId and roleId will be filled in later */
     384       22476 :     MyProc->backendId = InvalidBackendId;
     385       22476 :     MyProc->databaseId = InvalidOid;
     386       22476 :     MyProc->roleId = InvalidOid;
     387       22476 :     MyProc->tempNamespaceId = InvalidOid;
     388       22476 :     MyProc->isBackgroundWorker = IsBackgroundWorker;
     389       22476 :     MyProc->delayChkptFlags = 0;
     390       22476 :     MyProc->statusFlags = 0;
     391             :     /* NB -- autovac launcher intentionally does not set IS_AUTOVACUUM */
     392       22476 :     if (IsAutoVacuumWorkerProcess())
     393          20 :         MyProc->statusFlags |= PROC_IS_AUTOVACUUM;
     394       22476 :     MyProc->lwWaiting = LW_WS_NOT_WAITING;
     395       22476 :     MyProc->lwWaitMode = 0;
     396       22476 :     MyProc->waitLock = NULL;
     397       22476 :     MyProc->waitProcLock = NULL;
     398       22476 :     pg_atomic_write_u64(&MyProc->waitStart, 0);
     399             : #ifdef USE_ASSERT_CHECKING
     400             :     {
     401             :         int         i;
     402             : 
     403             :         /* Last process should have released all locks. */
     404             :         for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
     405             :             Assert(dlist_is_empty(&(MyProc->myProcLocks[i])));
     406             :     }
     407             : #endif
     408       22476 :     MyProc->recoveryConflictPending = false;
     409             : 
     410             :     /* Initialize fields for sync rep */
     411       22476 :     MyProc->waitLSN = 0;
     412       22476 :     MyProc->syncRepState = SYNC_REP_NOT_WAITING;
     413       22476 :     dlist_node_init(&MyProc->syncRepLinks);
     414             : 
     415             :     /* Initialize fields for group XID clearing. */
     416       22476 :     MyProc->procArrayGroupMember = false;
     417       22476 :     MyProc->procArrayGroupMemberXid = InvalidTransactionId;
     418             :     Assert(pg_atomic_read_u32(&MyProc->procArrayGroupNext) == INVALID_PGPROCNO);
     419             : 
     420             :     /* Check that group locking fields are in a proper initial state. */
     421             :     Assert(MyProc->lockGroupLeader == NULL);
     422             :     Assert(dlist_is_empty(&MyProc->lockGroupMembers));
     423             : 
     424             :     /* Initialize wait event information. */
     425       22476 :     MyProc->wait_event_info = 0;
     426             : 
     427             :     /* Initialize fields for group transaction status update. */
     428       22476 :     MyProc->clogGroupMember = false;
     429       22476 :     MyProc->clogGroupMemberXid = InvalidTransactionId;
     430       22476 :     MyProc->clogGroupMemberXidStatus = TRANSACTION_STATUS_IN_PROGRESS;
     431       22476 :     MyProc->clogGroupMemberPage = -1;
     432       22476 :     MyProc->clogGroupMemberLsn = InvalidXLogRecPtr;
     433             :     Assert(pg_atomic_read_u32(&MyProc->clogGroupNext) == INVALID_PGPROCNO);
     434             : 
     435             :     /*
     436             :      * Acquire ownership of the PGPROC's latch, so that we can use WaitLatch
     437             :      * on it.  That allows us to repoint the process latch, which so far
     438             :      * points to process local one, to the shared one.
     439             :      */
     440       22476 :     OwnLatch(&MyProc->procLatch);
     441       22476 :     SwitchToSharedLatch();
     442             : 
     443             :     /* now that we have a proc, report wait events to shared memory */
     444       22476 :     pgstat_set_wait_event_storage(&MyProc->wait_event_info);
     445             : 
     446             :     /*
     447             :      * We might be reusing a semaphore that belonged to a failed process. So
     448             :      * be careful and reinitialize its value here.  (This is not strictly
     449             :      * necessary anymore, but seems like a good idea for cleanliness.)
     450             :      */
     451       22476 :     PGSemaphoreReset(MyProc->sem);
     452             : 
     453             :     /*
     454             :      * Arrange to clean up at backend exit.
     455             :      */
     456       22476 :     on_shmem_exit(ProcKill, 0);
     457             : 
     458             :     /*
     459             :      * Now that we have a PGPROC, we could try to acquire locks, so initialize
     460             :      * local state needed for LWLocks, and the deadlock checker.
     461             :      */
     462       22476 :     InitLWLockAccess();
     463       22476 :     InitDeadLockChecking();
     464       22476 : }
     465             : 
     466             : /*
     467             :  * InitProcessPhase2 -- make MyProc visible in the shared ProcArray.
     468             :  *
     469             :  * This is separate from InitProcess because we can't acquire LWLocks until
     470             :  * we've created a PGPROC, but in the EXEC_BACKEND case ProcArrayAdd won't
     471             :  * work until after we've done CreateSharedMemoryAndSemaphores.
     472             :  */
     473             : void
     474       22458 : InitProcessPhase2(void)
     475             : {
     476             :     Assert(MyProc != NULL);
     477             : 
     478             :     /*
     479             :      * Add our PGPROC to the PGPROC array in shared memory.
     480             :      */
     481       22458 :     ProcArrayAdd(MyProc);
     482             : 
     483             :     /*
     484             :      * Arrange to clean that up at backend exit.
     485             :      */
     486       22458 :     on_shmem_exit(RemoveProcFromArray, 0);
     487       22458 : }
     488             : 
     489             : /*
     490             :  * InitAuxiliaryProcess -- create a per-auxiliary-process data structure
     491             :  *
     492             :  * This is called by bgwriter and similar processes so that they will have a
     493             :  * MyProc value that's real enough to let them wait for LWLocks.  The PGPROC
     494             :  * and sema that are assigned are one of the extra ones created during
     495             :  * InitProcGlobal.
     496             :  *
     497             :  * Auxiliary processes are presently not expected to wait for real (lockmgr)
     498             :  * locks, so we need not set up the deadlock checker.  They are never added
     499             :  * to the ProcArray or the sinval messaging mechanism, either.  They also
     500             :  * don't get a VXID assigned, since this is only useful when we actually
     501             :  * hold lockmgr locks.
     502             :  *
     503             :  * Startup process however uses locks but never waits for them in the
     504             :  * normal backend sense. Startup process also takes part in sinval messaging
     505             :  * as a sendOnly process, so never reads messages from sinval queue. So
     506             :  * Startup process does have a VXID and does show up in pg_locks.
     507             :  */
     508             : void
     509        3360 : InitAuxiliaryProcess(void)
     510             : {
     511             :     PGPROC     *auxproc;
     512             :     int         proctype;
     513             : 
     514             :     /*
     515             :      * ProcGlobal should be set up already (if we are a backend, we inherit
     516             :      * this by fork() or EXEC_BACKEND mechanism from the postmaster).
     517             :      */
     518        3360 :     if (ProcGlobal == NULL || AuxiliaryProcs == NULL)
     519           0 :         elog(PANIC, "proc header uninitialized");
     520             : 
     521        3360 :     if (MyProc != NULL)
     522           0 :         elog(ERROR, "you already exist");
     523             : 
     524             :     /*
     525             :      * We use the ProcStructLock to protect assignment and releasing of
     526             :      * AuxiliaryProcs entries.
     527             :      *
     528             :      * While we are holding the ProcStructLock, also copy the current shared
     529             :      * estimate of spins_per_delay to local storage.
     530             :      */
     531        3360 :     SpinLockAcquire(ProcStructLock);
     532             : 
     533        3360 :     set_spins_per_delay(ProcGlobal->spins_per_delay);
     534             : 
     535             :     /*
     536             :      * Find a free auxproc ... *big* trouble if there isn't one ...
     537             :      */
     538        8332 :     for (proctype = 0; proctype < NUM_AUXILIARY_PROCS; proctype++)
     539             :     {
     540        8332 :         auxproc = &AuxiliaryProcs[proctype];
     541        8332 :         if (auxproc->pid == 0)
     542        3360 :             break;
     543             :     }
     544        3360 :     if (proctype >= NUM_AUXILIARY_PROCS)
     545             :     {
     546           0 :         SpinLockRelease(ProcStructLock);
     547           0 :         elog(FATAL, "all AuxiliaryProcs are in use");
     548             :     }
     549             : 
     550             :     /* Mark auxiliary proc as in use by me */
     551             :     /* use volatile pointer to prevent code rearrangement */
     552        3360 :     ((volatile PGPROC *) auxproc)->pid = MyProcPid;
     553             : 
     554        3360 :     MyProc = auxproc;
     555             : 
     556        3360 :     SpinLockRelease(ProcStructLock);
     557             : 
     558             :     /*
     559             :      * Initialize all fields of MyProc, except for those previously
     560             :      * initialized by InitProcGlobal.
     561             :      */
     562        3360 :     dlist_node_init(&MyProc->links);
     563        3360 :     MyProc->waitStatus = PROC_WAIT_STATUS_OK;
     564        3360 :     MyProc->lxid = InvalidLocalTransactionId;
     565        3360 :     MyProc->fpVXIDLock = false;
     566        3360 :     MyProc->fpLocalTransactionId = InvalidLocalTransactionId;
     567        3360 :     MyProc->xid = InvalidTransactionId;
     568        3360 :     MyProc->xmin = InvalidTransactionId;
     569        3360 :     MyProc->backendId = InvalidBackendId;
     570        3360 :     MyProc->databaseId = InvalidOid;
     571        3360 :     MyProc->roleId = InvalidOid;
     572        3360 :     MyProc->tempNamespaceId = InvalidOid;
     573        3360 :     MyProc->isBackgroundWorker = IsBackgroundWorker;
     574        3360 :     MyProc->delayChkptFlags = 0;
     575        3360 :     MyProc->statusFlags = 0;
     576        3360 :     MyProc->lwWaiting = LW_WS_NOT_WAITING;
     577        3360 :     MyProc->lwWaitMode = 0;
     578        3360 :     MyProc->waitLock = NULL;
     579        3360 :     MyProc->waitProcLock = NULL;
     580        3360 :     pg_atomic_write_u64(&MyProc->waitStart, 0);
     581             : #ifdef USE_ASSERT_CHECKING
     582             :     {
     583             :         int         i;
     584             : 
     585             :         /* Last process should have released all locks. */
     586             :         for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
     587             :             Assert(dlist_is_empty(&(MyProc->myProcLocks[i])));
     588             :     }
     589             : #endif
     590             : 
     591             :     /*
     592             :      * Acquire ownership of the PGPROC's latch, so that we can use WaitLatch
     593             :      * on it.  That allows us to repoint the process latch, which so far
     594             :      * points to process local one, to the shared one.
     595             :      */
     596        3360 :     OwnLatch(&MyProc->procLatch);
     597        3360 :     SwitchToSharedLatch();
     598             : 
     599             :     /* now that we have a proc, report wait events to shared memory */
     600        3360 :     pgstat_set_wait_event_storage(&MyProc->wait_event_info);
     601             : 
     602             :     /* Check that group locking fields are in a proper initial state. */
     603             :     Assert(MyProc->lockGroupLeader == NULL);
     604             :     Assert(dlist_is_empty(&MyProc->lockGroupMembers));
     605             : 
     606             :     /*
     607             :      * We might be reusing a semaphore that belonged to a failed process. So
     608             :      * be careful and reinitialize its value here.  (This is not strictly
     609             :      * necessary anymore, but seems like a good idea for cleanliness.)
     610             :      */
     611        3360 :     PGSemaphoreReset(MyProc->sem);
     612             : 
     613             :     /*
     614             :      * Arrange to clean up at process exit.
     615             :      */
     616        3360 :     on_shmem_exit(AuxiliaryProcKill, Int32GetDatum(proctype));
     617        3360 : }
     618             : 
     619             : /*
     620             :  * Used from bufmgr to share the value of the buffer that Startup waits on,
     621             :  * or to reset the value to "not waiting" (-1). This allows processing
     622             :  * of recovery conflicts for buffer pins. Set is made before backends look
     623             :  * at this value, so locking not required, especially since the set is
     624             :  * an atomic integer set operation.
     625             :  */
     626             : void
     627          44 : SetStartupBufferPinWaitBufId(int bufid)
     628             : {
     629             :     /* use volatile pointer to prevent code rearrangement */
     630          44 :     volatile PROC_HDR *procglobal = ProcGlobal;
     631             : 
     632          44 :     procglobal->startupBufferPinWaitBufId = bufid;
     633          44 : }
     634             : 
     635             : /*
     636             :  * Used by backends when they receive a request to check for buffer pin waits.
     637             :  */
     638             : int
     639          10 : GetStartupBufferPinWaitBufId(void)
     640             : {
     641             :     /* use volatile pointer to prevent code rearrangement */
     642          10 :     volatile PROC_HDR *procglobal = ProcGlobal;
     643             : 
     644          10 :     return procglobal->startupBufferPinWaitBufId;
     645             : }
     646             : 
     647             : /*
     648             :  * Check whether there are at least N free PGPROC objects.  If false is
     649             :  * returned, *nfree will be set to the number of free PGPROC objects.
     650             :  * Otherwise, *nfree will be set to n.
     651             :  *
     652             :  * Note: this is designed on the assumption that N will generally be small.
     653             :  */
     654             : bool
     655         386 : HaveNFreeProcs(int n, int *nfree)
     656             : {
     657             :     dlist_iter  iter;
     658             : 
     659             :     Assert(n > 0);
     660             :     Assert(nfree);
     661             : 
     662         386 :     SpinLockAcquire(ProcStructLock);
     663             : 
     664         386 :     *nfree = 0;
     665        1158 :     dlist_foreach(iter, &ProcGlobal->freeProcs)
     666             :     {
     667        1158 :         (*nfree)++;
     668        1158 :         if (*nfree == n)
     669         386 :             break;
     670             :     }
     671             : 
     672         386 :     SpinLockRelease(ProcStructLock);
     673             : 
     674         386 :     return (*nfree == n);
     675             : }
     676             : 
     677             : /*
     678             :  * Check if the current process is awaiting a lock.
     679             :  */
     680             : bool
     681          16 : IsWaitingForLock(void)
     682             : {
     683          16 :     if (lockAwaited == NULL)
     684          12 :         return false;
     685             : 
     686           4 :     return true;
     687             : }
     688             : 
     689             : /*
     690             :  * Cancel any pending wait for lock, when aborting a transaction, and revert
     691             :  * any strong lock count acquisition for a lock being acquired.
     692             :  *
     693             :  * (Normally, this would only happen if we accept a cancel/die
     694             :  * interrupt while waiting; but an ereport(ERROR) before or during the lock
     695             :  * wait is within the realm of possibility, too.)
     696             :  */
     697             : void
     698      990202 : LockErrorCleanup(void)
     699             : {
     700             :     LWLock     *partitionLock;
     701             :     DisableTimeoutParams timeouts[2];
     702             : 
     703      990202 :     HOLD_INTERRUPTS();
     704             : 
     705      990202 :     AbortStrongLockAcquire();
     706             : 
     707             :     /* Nothing to do if we weren't waiting for a lock */
     708      990202 :     if (lockAwaited == NULL)
     709             :     {
     710      990120 :         RESUME_INTERRUPTS();
     711      990120 :         return;
     712             :     }
     713             : 
     714             :     /*
     715             :      * Turn off the deadlock and lock timeout timers, if they are still
     716             :      * running (see ProcSleep).  Note we must preserve the LOCK_TIMEOUT
     717             :      * indicator flag, since this function is executed before
     718             :      * ProcessInterrupts when responding to SIGINT; else we'd lose the
     719             :      * knowledge that the SIGINT came from a lock timeout and not an external
     720             :      * source.
     721             :      */
     722          82 :     timeouts[0].id = DEADLOCK_TIMEOUT;
     723          82 :     timeouts[0].keep_indicator = false;
     724          82 :     timeouts[1].id = LOCK_TIMEOUT;
     725          82 :     timeouts[1].keep_indicator = true;
     726          82 :     disable_timeouts(timeouts, 2);
     727             : 
     728             :     /* Unlink myself from the wait queue, if on it (might not be anymore!) */
     729          82 :     partitionLock = LockHashPartitionLock(lockAwaited->hashcode);
     730          82 :     LWLockAcquire(partitionLock, LW_EXCLUSIVE);
     731             : 
     732          82 :     if (!dlist_node_is_detached(&MyProc->links))
     733             :     {
     734             :         /* We could not have been granted the lock yet */
     735          82 :         RemoveFromWaitQueue(MyProc, lockAwaited->hashcode);
     736             :     }
     737             :     else
     738             :     {
     739             :         /*
     740             :          * Somebody kicked us off the lock queue already.  Perhaps they
     741             :          * granted us the lock, or perhaps they detected a deadlock. If they
     742             :          * did grant us the lock, we'd better remember it in our local lock
     743             :          * table.
     744             :          */
     745           0 :         if (MyProc->waitStatus == PROC_WAIT_STATUS_OK)
     746           0 :             GrantAwaitedLock();
     747             :     }
     748             : 
     749          82 :     lockAwaited = NULL;
     750             : 
     751          82 :     LWLockRelease(partitionLock);
     752             : 
     753          82 :     RESUME_INTERRUPTS();
     754             : }
     755             : 
     756             : 
     757             : /*
     758             :  * ProcReleaseLocks() -- release locks associated with current transaction
     759             :  *          at main transaction commit or abort
     760             :  *
     761             :  * At main transaction commit, we release standard locks except session locks.
     762             :  * At main transaction abort, we release all locks including session locks.
     763             :  *
     764             :  * Advisory locks are released only if they are transaction-level;
     765             :  * session-level holds remain, whether this is a commit or not.
     766             :  *
     767             :  * At subtransaction commit, we don't release any locks (so this func is not
     768             :  * needed at all); we will defer the releasing to the parent transaction.
     769             :  * At subtransaction abort, we release all locks held by the subtransaction;
     770             :  * this is implemented by retail releasing of the locks under control of
     771             :  * the ResourceOwner mechanism.
     772             :  */
     773             : void
     774      940922 : ProcReleaseLocks(bool isCommit)
     775             : {
     776      940922 :     if (!MyProc)
     777           0 :         return;
     778             :     /* If waiting, get off wait queue (should only be needed after error) */
     779      940922 :     LockErrorCleanup();
     780             :     /* Release standard locks, including session-level if aborting */
     781      940922 :     LockReleaseAll(DEFAULT_LOCKMETHOD, !isCommit);
     782             :     /* Release transaction-level advisory locks */
     783      940922 :     LockReleaseAll(USER_LOCKMETHOD, false);
     784             : }
     785             : 
     786             : 
     787             : /*
     788             :  * RemoveProcFromArray() -- Remove this process from the shared ProcArray.
     789             :  */
     790             : static void
     791       22458 : RemoveProcFromArray(int code, Datum arg)
     792             : {
     793             :     Assert(MyProc != NULL);
     794       22458 :     ProcArrayRemove(MyProc, InvalidTransactionId);
     795       22458 : }
     796             : 
     797             : /*
     798             :  * ProcKill() -- Destroy the per-proc data structure for
     799             :  *      this process. Release any of its held LW locks.
     800             :  */
     801             : static void
     802       22476 : ProcKill(int code, Datum arg)
     803             : {
     804             :     PGPROC     *proc;
     805             :     dlist_head *procgloballist;
     806             : 
     807             :     Assert(MyProc != NULL);
     808             : 
     809             :     /* Make sure we're out of the sync rep lists */
     810       22476 :     SyncRepCleanupAtProcExit();
     811             : 
     812             : #ifdef USE_ASSERT_CHECKING
     813             :     {
     814             :         int         i;
     815             : 
     816             :         /* Last process should have released all locks. */
     817             :         for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
     818             :             Assert(dlist_is_empty(&(MyProc->myProcLocks[i])));
     819             :     }
     820             : #endif
     821             : 
     822             :     /*
     823             :      * Release any LW locks I am holding.  There really shouldn't be any, but
     824             :      * it's cheap to check again before we cut the knees off the LWLock
     825             :      * facility by releasing our PGPROC ...
     826             :      */
     827       22476 :     LWLockReleaseAll();
     828             : 
     829             :     /* Cancel any pending condition variable sleep, too */
     830       22476 :     ConditionVariableCancelSleep();
     831             : 
     832             :     /*
     833             :      * Detach from any lock group of which we are a member.  If the leader
     834             :      * exits before all other group members, its PGPROC will remain allocated
     835             :      * until the last group process exits; that process must return the
     836             :      * leader's PGPROC to the appropriate list.
     837             :      */
     838       22476 :     if (MyProc->lockGroupLeader != NULL)
     839             :     {
     840        2668 :         PGPROC     *leader = MyProc->lockGroupLeader;
     841        2668 :         LWLock     *leader_lwlock = LockHashPartitionLockByProc(leader);
     842             : 
     843        2668 :         LWLockAcquire(leader_lwlock, LW_EXCLUSIVE);
     844             :         Assert(!dlist_is_empty(&leader->lockGroupMembers));
     845        2668 :         dlist_delete(&MyProc->lockGroupLink);
     846        2668 :         if (dlist_is_empty(&leader->lockGroupMembers))
     847             :         {
     848         108 :             leader->lockGroupLeader = NULL;
     849         108 :             if (leader != MyProc)
     850             :             {
     851           0 :                 procgloballist = leader->procgloballist;
     852             : 
     853             :                 /* Leader exited first; return its PGPROC. */
     854           0 :                 SpinLockAcquire(ProcStructLock);
     855           0 :                 dlist_push_head(procgloballist, &leader->links);
     856           0 :                 SpinLockRelease(ProcStructLock);
     857             :             }
     858             :         }
     859        2560 :         else if (leader != MyProc)
     860        2560 :             MyProc->lockGroupLeader = NULL;
     861        2668 :         LWLockRelease(leader_lwlock);
     862             :     }
     863             : 
     864             :     /*
     865             :      * Reset MyLatch to the process local one.  This is so that signal
     866             :      * handlers et al can continue using the latch after the shared latch
     867             :      * isn't ours anymore.
     868             :      *
     869             :      * Similarly, stop reporting wait events to MyProc->wait_event_info.
     870             :      *
     871             :      * After that clear MyProc and disown the shared latch.
     872             :      */
     873       22476 :     SwitchBackToLocalLatch();
     874       22476 :     pgstat_reset_wait_event_storage();
     875             : 
     876       22476 :     proc = MyProc;
     877       22476 :     MyProc = NULL;
     878       22476 :     DisownLatch(&proc->procLatch);
     879             : 
     880       22476 :     procgloballist = proc->procgloballist;
     881       22476 :     SpinLockAcquire(ProcStructLock);
     882             : 
     883             :     /*
     884             :      * If we're still a member of a locking group, that means we're a leader
     885             :      * which has somehow exited before its children.  The last remaining child
     886             :      * will release our PGPROC.  Otherwise, release it now.
     887             :      */
     888       22476 :     if (proc->lockGroupLeader == NULL)
     889             :     {
     890             :         /* Since lockGroupLeader is NULL, lockGroupMembers should be empty. */
     891             :         Assert(dlist_is_empty(&proc->lockGroupMembers));
     892             : 
     893             :         /* Return PGPROC structure (and semaphore) to appropriate freelist */
     894       22476 :         dlist_push_tail(procgloballist, &proc->links);
     895             :     }
     896             : 
     897             :     /* Update shared estimate of spins_per_delay */
     898       22476 :     ProcGlobal->spins_per_delay = update_spins_per_delay(ProcGlobal->spins_per_delay);
     899             : 
     900       22476 :     SpinLockRelease(ProcStructLock);
     901             : 
     902             :     /*
     903             :      * This process is no longer present in shared memory in any meaningful
     904             :      * way, so tell the postmaster we've cleaned up acceptably well. (XXX
     905             :      * autovac launcher should be included here someday)
     906             :      */
     907       22476 :     if (IsUnderPostmaster && !IsAutoVacuumLauncherProcess())
     908       20724 :         MarkPostmasterChildInactive();
     909             : 
     910             :     /* wake autovac launcher if needed -- see comments in FreeWorkerInfo */
     911       22476 :     if (AutovacuumLauncherPid != 0)
     912          20 :         kill(AutovacuumLauncherPid, SIGUSR2);
     913       22476 : }
     914             : 
     915             : /*
     916             :  * AuxiliaryProcKill() -- Cut-down version of ProcKill for auxiliary
     917             :  *      processes (bgwriter, etc).  The PGPROC and sema are not released, only
     918             :  *      marked as not-in-use.
     919             :  */
     920             : static void
     921        3360 : AuxiliaryProcKill(int code, Datum arg)
     922             : {
     923        3360 :     int         proctype = DatumGetInt32(arg);
     924             :     PGPROC     *auxproc PG_USED_FOR_ASSERTS_ONLY;
     925             :     PGPROC     *proc;
     926             : 
     927             :     Assert(proctype >= 0 && proctype < NUM_AUXILIARY_PROCS);
     928             : 
     929        3360 :     auxproc = &AuxiliaryProcs[proctype];
     930             : 
     931             :     Assert(MyProc == auxproc);
     932             : 
     933             :     /* Release any LW locks I am holding (see notes above) */
     934        3360 :     LWLockReleaseAll();
     935             : 
     936             :     /* Cancel any pending condition variable sleep, too */
     937        3360 :     ConditionVariableCancelSleep();
     938             : 
     939             :     /* look at the equivalent ProcKill() code for comments */
     940        3360 :     SwitchBackToLocalLatch();
     941        3360 :     pgstat_reset_wait_event_storage();
     942             : 
     943        3360 :     proc = MyProc;
     944        3360 :     MyProc = NULL;
     945        3360 :     DisownLatch(&proc->procLatch);
     946             : 
     947        3360 :     SpinLockAcquire(ProcStructLock);
     948             : 
     949             :     /* Mark auxiliary proc no longer in use */
     950        3360 :     proc->pid = 0;
     951             : 
     952             :     /* Update shared estimate of spins_per_delay */
     953        3360 :     ProcGlobal->spins_per_delay = update_spins_per_delay(ProcGlobal->spins_per_delay);
     954             : 
     955        3360 :     SpinLockRelease(ProcStructLock);
     956        3360 : }
     957             : 
     958             : /*
     959             :  * AuxiliaryPidGetProc -- get PGPROC for an auxiliary process
     960             :  * given its PID
     961             :  *
     962             :  * Returns NULL if not found.
     963             :  */
     964             : PGPROC *
     965        4250 : AuxiliaryPidGetProc(int pid)
     966             : {
     967        4250 :     PGPROC     *result = NULL;
     968             :     int         index;
     969             : 
     970        4250 :     if (pid == 0)               /* never match dummy PGPROCs */
     971           0 :         return NULL;
     972             : 
     973        8546 :     for (index = 0; index < NUM_AUXILIARY_PROCS; index++)
     974             :     {
     975        8546 :         PGPROC     *proc = &AuxiliaryProcs[index];
     976             : 
     977        8546 :         if (proc->pid == pid)
     978             :         {
     979        4250 :             result = proc;
     980        4250 :             break;
     981             :         }
     982             :     }
     983        4250 :     return result;
     984             : }
     985             : 
     986             : 
     987             : /*
     988             :  * ProcSleep -- put a process to sleep on the specified lock
     989             :  *
     990             :  * Caller must have set MyProc->heldLocks to reflect locks already held
     991             :  * on the lockable object by this process (under all XIDs).
     992             :  *
     993             :  * The lock table's partition lock must be held at entry, and will be held
     994             :  * at exit.
     995             :  *
     996             :  * Result: PROC_WAIT_STATUS_OK if we acquired the lock, PROC_WAIT_STATUS_ERROR if not (deadlock).
     997             :  *
     998             :  * ASSUME: that no one will fiddle with the queue until after
     999             :  *      we release the partition lock.
    1000             :  *
    1001             :  * NOTES: The process queue is now a priority queue for locking.
    1002             :  */
    1003             : ProcWaitStatus
    1004        1996 : ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
    1005             : {
    1006        1996 :     LOCKMODE    lockmode = locallock->tag.mode;
    1007        1996 :     LOCK       *lock = locallock->lock;
    1008        1996 :     PROCLOCK   *proclock = locallock->proclock;
    1009        1996 :     uint32      hashcode = locallock->hashcode;
    1010        1996 :     LWLock     *partitionLock = LockHashPartitionLock(hashcode);
    1011        1996 :     dclist_head *waitQueue = &lock->waitProcs;
    1012        1996 :     PGPROC     *insert_before = NULL;
    1013        1996 :     LOCKMASK    myHeldLocks = MyProc->heldLocks;
    1014        1996 :     TimestampTz standbyWaitStart = 0;
    1015        1996 :     bool        early_deadlock = false;
    1016        1996 :     bool        allow_autovacuum_cancel = true;
    1017        1996 :     bool        logged_recovery_conflict = false;
    1018             :     ProcWaitStatus myWaitStatus;
    1019        1996 :     PGPROC     *leader = MyProc->lockGroupLeader;
    1020             : 
    1021             :     /*
    1022             :      * If group locking is in use, locks held by members of my locking group
    1023             :      * need to be included in myHeldLocks.  This is not required for relation
    1024             :      * extension or page locks which conflict among group members. However,
    1025             :      * including them in myHeldLocks will give group members the priority to
    1026             :      * get those locks as compared to other backends which are also trying to
    1027             :      * acquire those locks.  OTOH, we can avoid giving priority to group
    1028             :      * members for that kind of locks, but there doesn't appear to be a clear
    1029             :      * advantage of the same.
    1030             :      */
    1031        1996 :     if (leader != NULL)
    1032             :     {
    1033             :         dlist_iter  iter;
    1034             : 
    1035          60 :         dlist_foreach(iter, &lock->procLocks)
    1036             :         {
    1037             :             PROCLOCK   *otherproclock;
    1038             : 
    1039          46 :             otherproclock = dlist_container(PROCLOCK, lockLink, iter.cur);
    1040             : 
    1041          46 :             if (otherproclock->groupLeader == leader)
    1042          22 :                 myHeldLocks |= otherproclock->holdMask;
    1043             :         }
    1044             :     }
    1045             : 
    1046             :     /*
    1047             :      * Determine where to add myself in the wait queue.
    1048             :      *
    1049             :      * Normally I should go at the end of the queue.  However, if I already
    1050             :      * hold locks that conflict with the request of any previous waiter, put
    1051             :      * myself in the queue just in front of the first such waiter. This is not
    1052             :      * a necessary step, since deadlock detection would move me to before that
    1053             :      * waiter anyway; but it's relatively cheap to detect such a conflict
    1054             :      * immediately, and avoid delaying till deadlock timeout.
    1055             :      *
    1056             :      * Special case: if I find I should go in front of some waiter, check to
    1057             :      * see if I conflict with already-held locks or the requests before that
    1058             :      * waiter.  If not, then just grant myself the requested lock immediately.
    1059             :      * This is the same as the test for immediate grant in LockAcquire, except
    1060             :      * we are only considering the part of the wait queue before my insertion
    1061             :      * point.
    1062             :      */
    1063        1996 :     if (myHeldLocks != 0 && !dclist_is_empty(waitQueue))
    1064             :     {
    1065           6 :         LOCKMASK    aheadRequests = 0;
    1066             :         dlist_iter  iter;
    1067             : 
    1068           6 :         dclist_foreach(iter, waitQueue)
    1069             :         {
    1070           6 :             PGPROC     *proc = dlist_container(PGPROC, links, iter.cur);
    1071             : 
    1072             :             /*
    1073             :              * If we're part of the same locking group as this waiter, its
    1074             :              * locks neither conflict with ours nor contribute to
    1075             :              * aheadRequests.
    1076             :              */
    1077           6 :             if (leader != NULL && leader == proc->lockGroupLeader)
    1078           0 :                 continue;
    1079             : 
    1080             :             /* Must he wait for me? */
    1081           6 :             if (lockMethodTable->conflictTab[proc->waitLockMode] & myHeldLocks)
    1082             :             {
    1083             :                 /* Must I wait for him ? */
    1084           6 :                 if (lockMethodTable->conflictTab[lockmode] & proc->heldLocks)
    1085             :                 {
    1086             :                     /*
    1087             :                      * Yes, so we have a deadlock.  Easiest way to clean up
    1088             :                      * correctly is to call RemoveFromWaitQueue(), but we
    1089             :                      * can't do that until we are *on* the wait queue. So, set
    1090             :                      * a flag to check below, and break out of loop.  Also,
    1091             :                      * record deadlock info for later message.
    1092             :                      */
    1093           2 :                     RememberSimpleDeadLock(MyProc, lockmode, lock, proc);
    1094           2 :                     early_deadlock = true;
    1095           2 :                     break;
    1096             :                 }
    1097             :                 /* I must go before this waiter.  Check special case. */
    1098           4 :                 if ((lockMethodTable->conflictTab[lockmode] & aheadRequests) == 0 &&
    1099           4 :                     !LockCheckConflicts(lockMethodTable, lockmode, lock,
    1100             :                                         proclock))
    1101             :                 {
    1102             :                     /* Skip the wait and just grant myself the lock. */
    1103           4 :                     GrantLock(lock, proclock, lockmode);
    1104           4 :                     GrantAwaitedLock();
    1105           4 :                     return PROC_WAIT_STATUS_OK;
    1106             :                 }
    1107             : 
    1108             :                 /* Put myself into wait queue before conflicting process */
    1109           0 :                 insert_before = proc;
    1110           0 :                 break;
    1111             :             }
    1112             :             /* Nope, so advance to next waiter */
    1113           0 :             aheadRequests |= LOCKBIT_ON(proc->waitLockMode);
    1114             :         }
    1115             :     }
    1116             : 
    1117             :     /*
    1118             :      * Insert self into queue, at the position determined above.
    1119             :      */
    1120        1992 :     if (insert_before)
    1121           0 :         dclist_insert_before(waitQueue, &insert_before->links, &MyProc->links);
    1122             :     else
    1123        1992 :         dclist_push_tail(waitQueue, &MyProc->links);
    1124             : 
    1125        1992 :     lock->waitMask |= LOCKBIT_ON(lockmode);
    1126             : 
    1127             :     /* Set up wait information in PGPROC object, too */
    1128        1992 :     MyProc->waitLock = lock;
    1129        1992 :     MyProc->waitProcLock = proclock;
    1130        1992 :     MyProc->waitLockMode = lockmode;
    1131             : 
    1132        1992 :     MyProc->waitStatus = PROC_WAIT_STATUS_WAITING;
    1133             : 
    1134             :     /*
    1135             :      * If we detected deadlock, give up without waiting.  This must agree with
    1136             :      * CheckDeadLock's recovery code.
    1137             :      */
    1138        1992 :     if (early_deadlock)
    1139             :     {
    1140           2 :         RemoveFromWaitQueue(MyProc, hashcode);
    1141           2 :         return PROC_WAIT_STATUS_ERROR;
    1142             :     }
    1143             : 
    1144             :     /* mark that we are waiting for a lock */
    1145        1990 :     lockAwaited = locallock;
    1146             : 
    1147             :     /*
    1148             :      * Release the lock table's partition lock.
    1149             :      *
    1150             :      * NOTE: this may also cause us to exit critical-section state, possibly
    1151             :      * allowing a cancel/die interrupt to be accepted. This is OK because we
    1152             :      * have recorded the fact that we are waiting for a lock, and so
    1153             :      * LockErrorCleanup will clean up if cancel/die happens.
    1154             :      */
    1155        1990 :     LWLockRelease(partitionLock);
    1156             : 
    1157             :     /*
    1158             :      * Also, now that we will successfully clean up after an ereport, it's
    1159             :      * safe to check to see if there's a buffer pin deadlock against the
    1160             :      * Startup process.  Of course, that's only necessary if we're doing Hot
    1161             :      * Standby and are not the Startup process ourselves.
    1162             :      */
    1163        1990 :     if (RecoveryInProgress() && !InRecovery)
    1164           2 :         CheckRecoveryConflictDeadlock();
    1165             : 
    1166             :     /* Reset deadlock_state before enabling the timeout handler */
    1167        1990 :     deadlock_state = DS_NOT_YET_CHECKED;
    1168        1990 :     got_deadlock_timeout = false;
    1169             : 
    1170             :     /*
    1171             :      * Set timer so we can wake up after awhile and check for a deadlock. If a
    1172             :      * deadlock is detected, the handler sets MyProc->waitStatus =
    1173             :      * PROC_WAIT_STATUS_ERROR, allowing us to know that we must report failure
    1174             :      * rather than success.
    1175             :      *
    1176             :      * By delaying the check until we've waited for a bit, we can avoid
    1177             :      * running the rather expensive deadlock-check code in most cases.
    1178             :      *
    1179             :      * If LockTimeout is set, also enable the timeout for that.  We can save a
    1180             :      * few cycles by enabling both timeout sources in one call.
    1181             :      *
    1182             :      * If InHotStandby we set lock waits slightly later for clarity with other
    1183             :      * code.
    1184             :      */
    1185        1990 :     if (!InHotStandby)
    1186             :     {
    1187        1988 :         if (LockTimeout > 0)
    1188             :         {
    1189             :             EnableTimeoutParams timeouts[2];
    1190             : 
    1191         230 :             timeouts[0].id = DEADLOCK_TIMEOUT;
    1192         230 :             timeouts[0].type = TMPARAM_AFTER;
    1193         230 :             timeouts[0].delay_ms = DeadlockTimeout;
    1194         230 :             timeouts[1].id = LOCK_TIMEOUT;
    1195         230 :             timeouts[1].type = TMPARAM_AFTER;
    1196         230 :             timeouts[1].delay_ms = LockTimeout;
    1197         230 :             enable_timeouts(timeouts, 2);
    1198             :         }
    1199             :         else
    1200        1758 :             enable_timeout_after(DEADLOCK_TIMEOUT, DeadlockTimeout);
    1201             : 
    1202             :         /*
    1203             :          * Use the current time obtained for the deadlock timeout timer as
    1204             :          * waitStart (i.e., the time when this process started waiting for the
    1205             :          * lock). Since getting the current time newly can cause overhead, we
    1206             :          * reuse the already-obtained time to avoid that overhead.
    1207             :          *
    1208             :          * Note that waitStart is updated without holding the lock table's
    1209             :          * partition lock, to avoid the overhead by additional lock
    1210             :          * acquisition. This can cause "waitstart" in pg_locks to become NULL
    1211             :          * for a very short period of time after the wait started even though
    1212             :          * "granted" is false. This is OK in practice because we can assume
    1213             :          * that users are likely to look at "waitstart" when waiting for the
    1214             :          * lock for a long time.
    1215             :          */
    1216        1988 :         pg_atomic_write_u64(&MyProc->waitStart,
    1217        1988 :                             get_timeout_start_time(DEADLOCK_TIMEOUT));
    1218             :     }
    1219           2 :     else if (log_recovery_conflict_waits)
    1220             :     {
    1221             :         /*
    1222             :          * Set the wait start timestamp if logging is enabled and in hot
    1223             :          * standby.
    1224             :          */
    1225           2 :         standbyWaitStart = GetCurrentTimestamp();
    1226             :     }
    1227             : 
    1228             :     /*
    1229             :      * If somebody wakes us between LWLockRelease and WaitLatch, the latch
    1230             :      * will not wait. But a set latch does not necessarily mean that the lock
    1231             :      * is free now, as there are many other sources for latch sets than
    1232             :      * somebody releasing the lock.
    1233             :      *
    1234             :      * We process interrupts whenever the latch has been set, so cancel/die
    1235             :      * interrupts are processed quickly. This means we must not mind losing
    1236             :      * control to a cancel/die interrupt here.  We don't, because we have no
    1237             :      * shared-state-change work to do after being granted the lock (the
    1238             :      * grantor did it all).  We do have to worry about canceling the deadlock
    1239             :      * timeout and updating the locallock table, but if we lose control to an
    1240             :      * error, LockErrorCleanup will fix that up.
    1241             :      */
    1242             :     do
    1243             :     {
    1244        4870 :         if (InHotStandby)
    1245             :         {
    1246           8 :             bool        maybe_log_conflict =
    1247           8 :             (standbyWaitStart != 0 && !logged_recovery_conflict);
    1248             : 
    1249             :             /* Set a timer and wait for that or for the lock to be granted */
    1250           8 :             ResolveRecoveryConflictWithLock(locallock->tag.lock,
    1251             :                                             maybe_log_conflict);
    1252             : 
    1253             :             /*
    1254             :              * Emit the log message if the startup process is waiting longer
    1255             :              * than deadlock_timeout for recovery conflict on lock.
    1256             :              */
    1257           8 :             if (maybe_log_conflict)
    1258             :             {
    1259           4 :                 TimestampTz now = GetCurrentTimestamp();
    1260             : 
    1261           4 :                 if (TimestampDifferenceExceeds(standbyWaitStart, now,
    1262             :                                                DeadlockTimeout))
    1263             :                 {
    1264             :                     VirtualTransactionId *vxids;
    1265             :                     int         cnt;
    1266             : 
    1267           2 :                     vxids = GetLockConflicts(&locallock->tag.lock,
    1268             :                                              AccessExclusiveLock, &cnt);
    1269             : 
    1270             :                     /*
    1271             :                      * Log the recovery conflict and the list of PIDs of
    1272             :                      * backends holding the conflicting lock. Note that we do
    1273             :                      * logging even if there are no such backends right now
    1274             :                      * because the startup process here has already waited
    1275             :                      * longer than deadlock_timeout.
    1276             :                      */
    1277           2 :                     LogRecoveryConflict(PROCSIG_RECOVERY_CONFLICT_LOCK,
    1278             :                                         standbyWaitStart, now,
    1279           2 :                                         cnt > 0 ? vxids : NULL, true);
    1280           2 :                     logged_recovery_conflict = true;
    1281             :                 }
    1282             :             }
    1283             :         }
    1284             :         else
    1285             :         {
    1286        4862 :             (void) WaitLatch(MyLatch, WL_LATCH_SET | WL_EXIT_ON_PM_DEATH, 0,
    1287        4862 :                              PG_WAIT_LOCK | locallock->tag.lock.locktag_type);
    1288        4862 :             ResetLatch(MyLatch);
    1289             :             /* check for deadlocks first, as that's probably log-worthy */
    1290        4862 :             if (got_deadlock_timeout)
    1291             :             {
    1292          48 :                 CheckDeadLock();
    1293          48 :                 got_deadlock_timeout = false;
    1294             :             }
    1295        4862 :             CHECK_FOR_INTERRUPTS();
    1296             :         }
    1297             : 
    1298             :         /*
    1299             :          * waitStatus could change from PROC_WAIT_STATUS_WAITING to something
    1300             :          * else asynchronously.  Read it just once per loop to prevent
    1301             :          * surprising behavior (such as missing log messages).
    1302             :          */
    1303        4788 :         myWaitStatus = *((volatile ProcWaitStatus *) &MyProc->waitStatus);
    1304             : 
    1305             :         /*
    1306             :          * If we are not deadlocked, but are waiting on an autovacuum-induced
    1307             :          * task, send a signal to interrupt it.
    1308             :          */
    1309        4788 :         if (deadlock_state == DS_BLOCKED_BY_AUTOVACUUM && allow_autovacuum_cancel)
    1310             :         {
    1311           0 :             PGPROC     *autovac = GetBlockingAutoVacuumPgproc();
    1312             :             uint8       statusFlags;
    1313             :             uint8       lockmethod_copy;
    1314             :             LOCKTAG     locktag_copy;
    1315             : 
    1316             :             /*
    1317             :              * Grab info we need, then release lock immediately.  Note this
    1318             :              * coding means that there is a tiny chance that the process
    1319             :              * terminates its current transaction and starts a different one
    1320             :              * before we have a change to send the signal; the worst possible
    1321             :              * consequence is that a for-wraparound vacuum is cancelled.  But
    1322             :              * that could happen in any case unless we were to do kill() with
    1323             :              * the lock held, which is much more undesirable.
    1324             :              */
    1325           0 :             LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
    1326           0 :             statusFlags = ProcGlobal->statusFlags[autovac->pgxactoff];
    1327           0 :             lockmethod_copy = lock->tag.locktag_lockmethodid;
    1328           0 :             locktag_copy = lock->tag;
    1329           0 :             LWLockRelease(ProcArrayLock);
    1330             : 
    1331             :             /*
    1332             :              * Only do it if the worker is not working to protect against Xid
    1333             :              * wraparound.
    1334             :              */
    1335           0 :             if ((statusFlags & PROC_IS_AUTOVACUUM) &&
    1336           0 :                 !(statusFlags & PROC_VACUUM_FOR_WRAPAROUND))
    1337             :             {
    1338           0 :                 int         pid = autovac->pid;
    1339             : 
    1340             :                 /* report the case, if configured to do so */
    1341           0 :                 if (message_level_is_interesting(DEBUG1))
    1342             :                 {
    1343             :                     StringInfoData locktagbuf;
    1344             :                     StringInfoData logbuf;  /* errdetail for server log */
    1345             : 
    1346           0 :                     initStringInfo(&locktagbuf);
    1347           0 :                     initStringInfo(&logbuf);
    1348           0 :                     DescribeLockTag(&locktagbuf, &locktag_copy);
    1349           0 :                     appendStringInfo(&logbuf,
    1350             :                                      "Process %d waits for %s on %s.",
    1351             :                                      MyProcPid,
    1352             :                                      GetLockmodeName(lockmethod_copy, lockmode),
    1353             :                                      locktagbuf.data);
    1354             : 
    1355           0 :                     ereport(DEBUG1,
    1356             :                             (errmsg_internal("sending cancel to blocking autovacuum PID %d",
    1357             :                                              pid),
    1358             :                              errdetail_log("%s", logbuf.data)));
    1359             : 
    1360           0 :                     pfree(locktagbuf.data);
    1361           0 :                     pfree(logbuf.data);
    1362             :                 }
    1363             : 
    1364             :                 /* send the autovacuum worker Back to Old Kent Road */
    1365           0 :                 if (kill(pid, SIGINT) < 0)
    1366             :                 {
    1367             :                     /*
    1368             :                      * There's a race condition here: once we release the
    1369             :                      * ProcArrayLock, it's possible for the autovac worker to
    1370             :                      * close up shop and exit before we can do the kill().
    1371             :                      * Therefore, we do not whinge about no-such-process.
    1372             :                      * Other errors such as EPERM could conceivably happen if
    1373             :                      * the kernel recycles the PID fast enough, but such cases
    1374             :                      * seem improbable enough that it's probably best to issue
    1375             :                      * a warning if we see some other errno.
    1376             :                      */
    1377           0 :                     if (errno != ESRCH)
    1378           0 :                         ereport(WARNING,
    1379             :                                 (errmsg("could not send signal to process %d: %m",
    1380             :                                         pid)));
    1381             :                 }
    1382             :             }
    1383             : 
    1384             :             /* prevent signal from being sent again more than once */
    1385           0 :             allow_autovacuum_cancel = false;
    1386             :         }
    1387             : 
    1388             :         /*
    1389             :          * If awoken after the deadlock check interrupt has run, and
    1390             :          * log_lock_waits is on, then report about the wait.
    1391             :          */
    1392        4788 :         if (log_lock_waits && deadlock_state != DS_NOT_YET_CHECKED)
    1393             :         {
    1394             :             StringInfoData buf,
    1395             :                         lock_waiters_sbuf,
    1396             :                         lock_holders_sbuf;
    1397             :             const char *modename;
    1398             :             long        secs;
    1399             :             int         usecs;
    1400             :             long        msecs;
    1401             :             dlist_iter  proc_iter;
    1402             :             PROCLOCK   *curproclock;
    1403          32 :             bool        first_holder = true,
    1404          32 :                         first_waiter = true;
    1405          32 :             int         lockHoldersNum = 0;
    1406             : 
    1407          32 :             initStringInfo(&buf);
    1408          32 :             initStringInfo(&lock_waiters_sbuf);
    1409          32 :             initStringInfo(&lock_holders_sbuf);
    1410             : 
    1411          32 :             DescribeLockTag(&buf, &locallock->tag.lock);
    1412          32 :             modename = GetLockmodeName(locallock->tag.lock.locktag_lockmethodid,
    1413             :                                        lockmode);
    1414          32 :             TimestampDifference(get_timeout_start_time(DEADLOCK_TIMEOUT),
    1415             :                                 GetCurrentTimestamp(),
    1416             :                                 &secs, &usecs);
    1417          32 :             msecs = secs * 1000 + usecs / 1000;
    1418          32 :             usecs = usecs % 1000;
    1419             : 
    1420             :             /*
    1421             :              * we loop over the lock's procLocks to gather a list of all
    1422             :              * holders and waiters. Thus we will be able to provide more
    1423             :              * detailed information for lock debugging purposes.
    1424             :              *
    1425             :              * lock->procLocks contains all processes which hold or wait for
    1426             :              * this lock.
    1427             :              */
    1428             : 
    1429          32 :             LWLockAcquire(partitionLock, LW_SHARED);
    1430             : 
    1431         106 :             dlist_foreach(proc_iter, &lock->procLocks)
    1432             :             {
    1433          74 :                 curproclock =
    1434          74 :                     dlist_container(PROCLOCK, lockLink, proc_iter.cur);
    1435             : 
    1436             :                 /*
    1437             :                  * we are a waiter if myProc->waitProcLock == curproclock; we
    1438             :                  * are a holder if it is NULL or something different
    1439             :                  */
    1440          74 :                 if (curproclock->tag.myProc->waitProcLock == curproclock)
    1441             :                 {
    1442          34 :                     if (first_waiter)
    1443             :                     {
    1444          18 :                         appendStringInfo(&lock_waiters_sbuf, "%d",
    1445          18 :                                          curproclock->tag.myProc->pid);
    1446          18 :                         first_waiter = false;
    1447             :                     }
    1448             :                     else
    1449          16 :                         appendStringInfo(&lock_waiters_sbuf, ", %d",
    1450          16 :                                          curproclock->tag.myProc->pid);
    1451             :                 }
    1452             :                 else
    1453             :                 {
    1454          40 :                     if (first_holder)
    1455             :                     {
    1456          32 :                         appendStringInfo(&lock_holders_sbuf, "%d",
    1457          32 :                                          curproclock->tag.myProc->pid);
    1458          32 :                         first_holder = false;
    1459             :                     }
    1460             :                     else
    1461           8 :                         appendStringInfo(&lock_holders_sbuf, ", %d",
    1462           8 :                                          curproclock->tag.myProc->pid);
    1463             : 
    1464          40 :                     lockHoldersNum++;
    1465             :                 }
    1466             :             }
    1467             : 
    1468          32 :             LWLockRelease(partitionLock);
    1469             : 
    1470          32 :             if (deadlock_state == DS_SOFT_DEADLOCK)
    1471           6 :                 ereport(LOG,
    1472             :                         (errmsg("process %d avoided deadlock for %s on %s by rearranging queue order after %ld.%03d ms",
    1473             :                                 MyProcPid, modename, buf.data, msecs, usecs),
    1474             :                          (errdetail_log_plural("Process holding the lock: %s. Wait queue: %s.",
    1475             :                                                "Processes holding the lock: %s. Wait queue: %s.",
    1476             :                                                lockHoldersNum, lock_holders_sbuf.data, lock_waiters_sbuf.data))));
    1477          26 :             else if (deadlock_state == DS_HARD_DEADLOCK)
    1478             :             {
    1479             :                 /*
    1480             :                  * This message is a bit redundant with the error that will be
    1481             :                  * reported subsequently, but in some cases the error report
    1482             :                  * might not make it to the log (eg, if it's caught by an
    1483             :                  * exception handler), and we want to ensure all long-wait
    1484             :                  * events get logged.
    1485             :                  */
    1486           2 :                 ereport(LOG,
    1487             :                         (errmsg("process %d detected deadlock while waiting for %s on %s after %ld.%03d ms",
    1488             :                                 MyProcPid, modename, buf.data, msecs, usecs),
    1489             :                          (errdetail_log_plural("Process holding the lock: %s. Wait queue: %s.",
    1490             :                                                "Processes holding the lock: %s. Wait queue: %s.",
    1491             :                                                lockHoldersNum, lock_holders_sbuf.data, lock_waiters_sbuf.data))));
    1492             :             }
    1493             : 
    1494          32 :             if (myWaitStatus == PROC_WAIT_STATUS_WAITING)
    1495          16 :                 ereport(LOG,
    1496             :                         (errmsg("process %d still waiting for %s on %s after %ld.%03d ms",
    1497             :                                 MyProcPid, modename, buf.data, msecs, usecs),
    1498             :                          (errdetail_log_plural("Process holding the lock: %s. Wait queue: %s.",
    1499             :                                                "Processes holding the lock: %s. Wait queue: %s.",
    1500             :                                                lockHoldersNum, lock_holders_sbuf.data, lock_waiters_sbuf.data))));
    1501          16 :             else if (myWaitStatus == PROC_WAIT_STATUS_OK)
    1502          14 :                 ereport(LOG,
    1503             :                         (errmsg("process %d acquired %s on %s after %ld.%03d ms",
    1504             :                                 MyProcPid, modename, buf.data, msecs, usecs)));
    1505             :             else
    1506             :             {
    1507             :                 Assert(myWaitStatus == PROC_WAIT_STATUS_ERROR);
    1508             : 
    1509             :                 /*
    1510             :                  * Currently, the deadlock checker always kicks its own
    1511             :                  * process, which means that we'll only see
    1512             :                  * PROC_WAIT_STATUS_ERROR when deadlock_state ==
    1513             :                  * DS_HARD_DEADLOCK, and there's no need to print redundant
    1514             :                  * messages.  But for completeness and future-proofing, print
    1515             :                  * a message if it looks like someone else kicked us off the
    1516             :                  * lock.
    1517             :                  */
    1518           2 :                 if (deadlock_state != DS_HARD_DEADLOCK)
    1519           0 :                     ereport(LOG,
    1520             :                             (errmsg("process %d failed to acquire %s on %s after %ld.%03d ms",
    1521             :                                     MyProcPid, modename, buf.data, msecs, usecs),
    1522             :                              (errdetail_log_plural("Process holding the lock: %s. Wait queue: %s.",
    1523             :                                                    "Processes holding the lock: %s. Wait queue: %s.",
    1524             :                                                    lockHoldersNum, lock_holders_sbuf.data, lock_waiters_sbuf.data))));
    1525             :             }
    1526             : 
    1527             :             /*
    1528             :              * At this point we might still need to wait for the lock. Reset
    1529             :              * state so we don't print the above messages again.
    1530             :              */
    1531          32 :             deadlock_state = DS_NO_DEADLOCK;
    1532             : 
    1533          32 :             pfree(buf.data);
    1534          32 :             pfree(lock_holders_sbuf.data);
    1535          32 :             pfree(lock_waiters_sbuf.data);
    1536             :         }
    1537        4788 :     } while (myWaitStatus == PROC_WAIT_STATUS_WAITING);
    1538             : 
    1539             :     /*
    1540             :      * Disable the timers, if they are still running.  As in LockErrorCleanup,
    1541             :      * we must preserve the LOCK_TIMEOUT indicator flag: if a lock timeout has
    1542             :      * already caused QueryCancelPending to become set, we want the cancel to
    1543             :      * be reported as a lock timeout, not a user cancel.
    1544             :      */
    1545        1908 :     if (!InHotStandby)
    1546             :     {
    1547        1906 :         if (LockTimeout > 0)
    1548             :         {
    1549             :             DisableTimeoutParams timeouts[2];
    1550             : 
    1551         218 :             timeouts[0].id = DEADLOCK_TIMEOUT;
    1552         218 :             timeouts[0].keep_indicator = false;
    1553         218 :             timeouts[1].id = LOCK_TIMEOUT;
    1554         218 :             timeouts[1].keep_indicator = true;
    1555         218 :             disable_timeouts(timeouts, 2);
    1556             :         }
    1557             :         else
    1558        1688 :             disable_timeout(DEADLOCK_TIMEOUT, false);
    1559             :     }
    1560             : 
    1561             :     /*
    1562             :      * Emit the log message if recovery conflict on lock was resolved but the
    1563             :      * startup process waited longer than deadlock_timeout for it.
    1564             :      */
    1565        1908 :     if (InHotStandby && logged_recovery_conflict)
    1566           2 :         LogRecoveryConflict(PROCSIG_RECOVERY_CONFLICT_LOCK,
    1567             :                             standbyWaitStart, GetCurrentTimestamp(),
    1568             :                             NULL, false);
    1569             : 
    1570             :     /*
    1571             :      * Re-acquire the lock table's partition lock.  We have to do this to hold
    1572             :      * off cancel/die interrupts before we can mess with lockAwaited (else we
    1573             :      * might have a missed or duplicated locallock update).
    1574             :      */
    1575        1908 :     LWLockAcquire(partitionLock, LW_EXCLUSIVE);
    1576             : 
    1577             :     /*
    1578             :      * We no longer want LockErrorCleanup to do anything.
    1579             :      */
    1580        1908 :     lockAwaited = NULL;
    1581             : 
    1582             :     /*
    1583             :      * If we got the lock, be sure to remember it in the locallock table.
    1584             :      */
    1585        1908 :     if (MyProc->waitStatus == PROC_WAIT_STATUS_OK)
    1586        1900 :         GrantAwaitedLock();
    1587             : 
    1588             :     /*
    1589             :      * We don't have to do anything else, because the awaker did all the
    1590             :      * necessary update of the lock table and MyProc.
    1591             :      */
    1592        1908 :     return MyProc->waitStatus;
    1593             : }
    1594             : 
    1595             : 
    1596             : /*
    1597             :  * ProcWakeup -- wake up a process by setting its latch.
    1598             :  *
    1599             :  *   Also remove the process from the wait queue and set its links invalid.
    1600             :  *
    1601             :  * The appropriate lock partition lock must be held by caller.
    1602             :  *
    1603             :  * XXX: presently, this code is only used for the "success" case, and only
    1604             :  * works correctly for that case.  To clean up in failure case, would need
    1605             :  * to twiddle the lock's request counts too --- see RemoveFromWaitQueue.
    1606             :  * Hence, in practice the waitStatus parameter must be PROC_WAIT_STATUS_OK.
    1607             :  */
    1608             : void
    1609        1904 : ProcWakeup(PGPROC *proc, ProcWaitStatus waitStatus)
    1610             : {
    1611        1904 :     if (dlist_node_is_detached(&proc->links))
    1612           0 :         return;
    1613             : 
    1614             :     Assert(proc->waitStatus == PROC_WAIT_STATUS_WAITING);
    1615             : 
    1616             :     /* Remove process from wait queue */
    1617        1904 :     dclist_delete_from_thoroughly(&proc->waitLock->waitProcs, &proc->links);
    1618             : 
    1619             :     /* Clean up process' state and pass it the ok/fail signal */
    1620        1904 :     proc->waitLock = NULL;
    1621        1904 :     proc->waitProcLock = NULL;
    1622        1904 :     proc->waitStatus = waitStatus;
    1623        1904 :     pg_atomic_write_u64(&MyProc->waitStart, 0);
    1624             : 
    1625             :     /* And awaken it */
    1626        1904 :     SetLatch(&proc->procLatch);
    1627             : }
    1628             : 
    1629             : /*
    1630             :  * ProcLockWakeup -- routine for waking up processes when a lock is
    1631             :  *      released (or a prior waiter is aborted).  Scan all waiters
    1632             :  *      for lock, waken any that are no longer blocked.
    1633             :  *
    1634             :  * The appropriate lock partition lock must be held by caller.
    1635             :  */
    1636             : void
    1637        1948 : ProcLockWakeup(LockMethod lockMethodTable, LOCK *lock)
    1638             : {
    1639        1948 :     dclist_head *waitQueue = &lock->waitProcs;
    1640        1948 :     LOCKMASK    aheadRequests = 0;
    1641             :     dlist_mutable_iter miter;
    1642             : 
    1643        1948 :     if (dclist_is_empty(waitQueue))
    1644          90 :         return;
    1645             : 
    1646        3866 :     dclist_foreach_modify(miter, waitQueue)
    1647             :     {
    1648        2008 :         PGPROC     *proc = dlist_container(PGPROC, links, miter.cur);
    1649        2008 :         LOCKMODE    lockmode = proc->waitLockMode;
    1650             : 
    1651             :         /*
    1652             :          * Waken if (a) doesn't conflict with requests of earlier waiters, and
    1653             :          * (b) doesn't conflict with already-held locks.
    1654             :          */
    1655        2008 :         if ((lockMethodTable->conflictTab[lockmode] & aheadRequests) == 0 &&
    1656        1990 :             !LockCheckConflicts(lockMethodTable, lockmode, lock,
    1657             :                                 proc->waitProcLock))
    1658             :         {
    1659             :             /* OK to waken */
    1660        1904 :             GrantLock(lock, proc->waitProcLock, lockmode);
    1661             :             /* removes proc from the lock's waiting process queue */
    1662        1904 :             ProcWakeup(proc, PROC_WAIT_STATUS_OK);
    1663             :         }
    1664             :         else
    1665             :         {
    1666             :             /*
    1667             :              * Lock conflicts: Don't wake, but remember requested mode for
    1668             :              * later checks.
    1669             :              */
    1670         104 :             aheadRequests |= LOCKBIT_ON(lockmode);
    1671             :         }
    1672             :     }
    1673             : }
    1674             : 
    1675             : /*
    1676             :  * CheckDeadLock
    1677             :  *
    1678             :  * We only get to this routine, if DEADLOCK_TIMEOUT fired while waiting for a
    1679             :  * lock to be released by some other process.  Check if there's a deadlock; if
    1680             :  * not, just return.  (But signal ProcSleep to log a message, if
    1681             :  * log_lock_waits is true.)  If we have a real deadlock, remove ourselves from
    1682             :  * the lock's wait queue and signal an error to ProcSleep.
    1683             :  */
    1684             : static void
    1685          48 : CheckDeadLock(void)
    1686             : {
    1687             :     int         i;
    1688             : 
    1689             :     /*
    1690             :      * Acquire exclusive lock on the entire shared lock data structures. Must
    1691             :      * grab LWLocks in partition-number order to avoid LWLock deadlock.
    1692             :      *
    1693             :      * Note that the deadlock check interrupt had better not be enabled
    1694             :      * anywhere that this process itself holds lock partition locks, else this
    1695             :      * will wait forever.  Also note that LWLockAcquire creates a critical
    1696             :      * section, so that this routine cannot be interrupted by cancel/die
    1697             :      * interrupts.
    1698             :      */
    1699         816 :     for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
    1700         768 :         LWLockAcquire(LockHashPartitionLockByIndex(i), LW_EXCLUSIVE);
    1701             : 
    1702             :     /*
    1703             :      * Check to see if we've been awoken by anyone in the interim.
    1704             :      *
    1705             :      * If we have, we can return and resume our transaction -- happy day.
    1706             :      * Before we are awoken the process releasing the lock grants it to us so
    1707             :      * we know that we don't have to wait anymore.
    1708             :      *
    1709             :      * We check by looking to see if we've been unlinked from the wait queue.
    1710             :      * This is safe because we hold the lock partition lock.
    1711             :      */
    1712          48 :     if (MyProc->links.prev == NULL ||
    1713          46 :         MyProc->links.next == NULL)
    1714           2 :         goto check_done;
    1715             : 
    1716             : #ifdef LOCK_DEBUG
    1717             :     if (Debug_deadlocks)
    1718             :         DumpAllLocks();
    1719             : #endif
    1720             : 
    1721             :     /* Run the deadlock check, and set deadlock_state for use by ProcSleep */
    1722          46 :     deadlock_state = DeadLockCheck(MyProc);
    1723             : 
    1724          46 :     if (deadlock_state == DS_HARD_DEADLOCK)
    1725             :     {
    1726             :         /*
    1727             :          * Oops.  We have a deadlock.
    1728             :          *
    1729             :          * Get this process out of wait state. (Note: we could do this more
    1730             :          * efficiently by relying on lockAwaited, but use this coding to
    1731             :          * preserve the flexibility to kill some other transaction than the
    1732             :          * one detecting the deadlock.)
    1733             :          *
    1734             :          * RemoveFromWaitQueue sets MyProc->waitStatus to
    1735             :          * PROC_WAIT_STATUS_ERROR, so ProcSleep will report an error after we
    1736             :          * return from the signal handler.
    1737             :          */
    1738             :         Assert(MyProc->waitLock != NULL);
    1739           8 :         RemoveFromWaitQueue(MyProc, LockTagHashCode(&(MyProc->waitLock->tag)));
    1740             : 
    1741             :         /*
    1742             :          * We're done here.  Transaction abort caused by the error that
    1743             :          * ProcSleep will raise will cause any other locks we hold to be
    1744             :          * released, thus allowing other processes to wake up; we don't need
    1745             :          * to do that here.  NOTE: an exception is that releasing locks we
    1746             :          * hold doesn't consider the possibility of waiters that were blocked
    1747             :          * behind us on the lock we just failed to get, and might now be
    1748             :          * wakable because we're not in front of them anymore.  However,
    1749             :          * RemoveFromWaitQueue took care of waking up any such processes.
    1750             :          */
    1751             :     }
    1752             : 
    1753             :     /*
    1754             :      * And release locks.  We do this in reverse order for two reasons: (1)
    1755             :      * Anyone else who needs more than one of the locks will be trying to lock
    1756             :      * them in increasing order; we don't want to release the other process
    1757             :      * until it can get all the locks it needs. (2) This avoids O(N^2)
    1758             :      * behavior inside LWLockRelease.
    1759             :      */
    1760          38 : check_done:
    1761         816 :     for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
    1762         768 :         LWLockRelease(LockHashPartitionLockByIndex(i));
    1763          48 : }
    1764             : 
    1765             : /*
    1766             :  * CheckDeadLockAlert - Handle the expiry of deadlock_timeout.
    1767             :  *
    1768             :  * NB: Runs inside a signal handler, be careful.
    1769             :  */
    1770             : void
    1771          48 : CheckDeadLockAlert(void)
    1772             : {
    1773          48 :     int         save_errno = errno;
    1774             : 
    1775          48 :     got_deadlock_timeout = true;
    1776             : 
    1777             :     /*
    1778             :      * Have to set the latch again, even if handle_sig_alarm already did. Back
    1779             :      * then got_deadlock_timeout wasn't yet set... It's unlikely that this
    1780             :      * ever would be a problem, but setting a set latch again is cheap.
    1781             :      *
    1782             :      * Note that, when this function runs inside procsignal_sigusr1_handler(),
    1783             :      * the handler function sets the latch again after the latch is set here.
    1784             :      */
    1785          48 :     SetLatch(MyLatch);
    1786          48 :     errno = save_errno;
    1787          48 : }
    1788             : 
    1789             : /*
    1790             :  * ProcWaitForSignal - wait for a signal from another backend.
    1791             :  *
    1792             :  * As this uses the generic process latch the caller has to be robust against
    1793             :  * unrelated wakeups: Always check that the desired state has occurred, and
    1794             :  * wait again if not.
    1795             :  */
    1796             : void
    1797          38 : ProcWaitForSignal(uint32 wait_event_info)
    1798             : {
    1799          38 :     (void) WaitLatch(MyLatch, WL_LATCH_SET | WL_EXIT_ON_PM_DEATH, 0,
    1800             :                      wait_event_info);
    1801          38 :     ResetLatch(MyLatch);
    1802          38 :     CHECK_FOR_INTERRUPTS();
    1803          38 : }
    1804             : 
    1805             : /*
    1806             :  * ProcSendSignal - set the latch of a backend identified by pgprocno
    1807             :  */
    1808             : void
    1809           8 : ProcSendSignal(int pgprocno)
    1810             : {
    1811           8 :     if (pgprocno < 0 || pgprocno >= ProcGlobal->allProcCount)
    1812           0 :         elog(ERROR, "pgprocno out of range");
    1813             : 
    1814           8 :     SetLatch(&ProcGlobal->allProcs[pgprocno].procLatch);
    1815           8 : }
    1816             : 
    1817             : /*
    1818             :  * BecomeLockGroupLeader - designate process as lock group leader
    1819             :  *
    1820             :  * Once this function has returned, other processes can join the lock group
    1821             :  * by calling BecomeLockGroupMember.
    1822             :  */
    1823             : void
    1824        1048 : BecomeLockGroupLeader(void)
    1825             : {
    1826             :     LWLock     *leader_lwlock;
    1827             : 
    1828             :     /* If we already did it, we don't need to do it again. */
    1829        1048 :     if (MyProc->lockGroupLeader == MyProc)
    1830         940 :         return;
    1831             : 
    1832             :     /* We had better not be a follower. */
    1833             :     Assert(MyProc->lockGroupLeader == NULL);
    1834             : 
    1835             :     /* Create single-member group, containing only ourselves. */
    1836         108 :     leader_lwlock = LockHashPartitionLockByProc(MyProc);
    1837         108 :     LWLockAcquire(leader_lwlock, LW_EXCLUSIVE);
    1838         108 :     MyProc->lockGroupLeader = MyProc;
    1839         108 :     dlist_push_head(&MyProc->lockGroupMembers, &MyProc->lockGroupLink);
    1840         108 :     LWLockRelease(leader_lwlock);
    1841             : }
    1842             : 
    1843             : /*
    1844             :  * BecomeLockGroupMember - designate process as lock group member
    1845             :  *
    1846             :  * This is pretty straightforward except for the possibility that the leader
    1847             :  * whose group we're trying to join might exit before we manage to do so;
    1848             :  * and the PGPROC might get recycled for an unrelated process.  To avoid
    1849             :  * that, we require the caller to pass the PID of the intended PGPROC as
    1850             :  * an interlock.  Returns true if we successfully join the intended lock
    1851             :  * group, and false if not.
    1852             :  */
    1853             : bool
    1854        2560 : BecomeLockGroupMember(PGPROC *leader, int pid)
    1855             : {
    1856             :     LWLock     *leader_lwlock;
    1857        2560 :     bool        ok = false;
    1858             : 
    1859             :     /* Group leader can't become member of group */
    1860             :     Assert(MyProc != leader);
    1861             : 
    1862             :     /* Can't already be a member of a group */
    1863             :     Assert(MyProc->lockGroupLeader == NULL);
    1864             : 
    1865             :     /* PID must be valid. */
    1866             :     Assert(pid != 0);
    1867             : 
    1868             :     /*
    1869             :      * Get lock protecting the group fields.  Note LockHashPartitionLockByProc
    1870             :      * accesses leader->pgprocno in a PGPROC that might be free.  This is safe
    1871             :      * because all PGPROCs' pgprocno fields are set during shared memory
    1872             :      * initialization and never change thereafter; so we will acquire the
    1873             :      * correct lock even if the leader PGPROC is in process of being recycled.
    1874             :      */
    1875        2560 :     leader_lwlock = LockHashPartitionLockByProc(leader);
    1876        2560 :     LWLockAcquire(leader_lwlock, LW_EXCLUSIVE);
    1877             : 
    1878             :     /* Is this the leader we're looking for? */
    1879        2560 :     if (leader->pid == pid && leader->lockGroupLeader == leader)
    1880             :     {
    1881             :         /* OK, join the group */
    1882        2560 :         ok = true;
    1883        2560 :         MyProc->lockGroupLeader = leader;
    1884        2560 :         dlist_push_tail(&leader->lockGroupMembers, &MyProc->lockGroupLink);
    1885             :     }
    1886        2560 :     LWLockRelease(leader_lwlock);
    1887             : 
    1888        2560 :     return ok;
    1889             : }

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