29eedd3122
executed InHotStandby. Cleaner solution than using malloc or palloc depending upon situation, as proposed by Tom.
2741 lines
78 KiB
C
2741 lines
78 KiB
C
/*-------------------------------------------------------------------------
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*
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* lock.c
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* POSTGRES primary lock mechanism
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*
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* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.193 2010/01/29 19:45:12 sriggs Exp $
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*
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* NOTES
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* A lock table is a shared memory hash table. When
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* a process tries to acquire a lock of a type that conflicts
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* with existing locks, it is put to sleep using the routines
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* in storage/lmgr/proc.c.
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*
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* For the most part, this code should be invoked via lmgr.c
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* or another lock-management module, not directly.
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*
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* Interface:
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*
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* InitLocks(), GetLocksMethodTable(),
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* LockAcquire(), LockRelease(), LockReleaseAll(),
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* LockCheckConflicts(), GrantLock()
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include <signal.h>
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#include <unistd.h>
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#include "access/transam.h"
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#include "access/twophase.h"
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#include "access/twophase_rmgr.h"
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#include "miscadmin.h"
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#include "pg_trace.h"
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#include "pgstat.h"
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#include "storage/standby.h"
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#include "utils/memutils.h"
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#include "utils/ps_status.h"
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#include "utils/resowner.h"
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/* This configuration variable is used to set the lock table size */
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int max_locks_per_xact; /* set by guc.c */
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#define NLOCKENTS() \
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mul_size(max_locks_per_xact, add_size(MaxBackends, max_prepared_xacts))
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/*
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* Data structures defining the semantics of the standard lock methods.
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*
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* The conflict table defines the semantics of the various lock modes.
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*/
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static const LOCKMASK LockConflicts[] = {
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0,
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/* AccessShareLock */
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(1 << AccessExclusiveLock),
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/* RowShareLock */
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(1 << ExclusiveLock) | (1 << AccessExclusiveLock),
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/* RowExclusiveLock */
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(1 << ShareLock) | (1 << ShareRowExclusiveLock) |
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(1 << ExclusiveLock) | (1 << AccessExclusiveLock),
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/* ShareUpdateExclusiveLock */
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(1 << ShareUpdateExclusiveLock) |
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(1 << ShareLock) | (1 << ShareRowExclusiveLock) |
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(1 << ExclusiveLock) | (1 << AccessExclusiveLock),
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/* ShareLock */
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(1 << RowExclusiveLock) | (1 << ShareUpdateExclusiveLock) |
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(1 << ShareRowExclusiveLock) |
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(1 << ExclusiveLock) | (1 << AccessExclusiveLock),
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/* ShareRowExclusiveLock */
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(1 << RowExclusiveLock) | (1 << ShareUpdateExclusiveLock) |
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(1 << ShareLock) | (1 << ShareRowExclusiveLock) |
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(1 << ExclusiveLock) | (1 << AccessExclusiveLock),
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/* ExclusiveLock */
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(1 << RowShareLock) |
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(1 << RowExclusiveLock) | (1 << ShareUpdateExclusiveLock) |
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(1 << ShareLock) | (1 << ShareRowExclusiveLock) |
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(1 << ExclusiveLock) | (1 << AccessExclusiveLock),
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/* AccessExclusiveLock */
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(1 << AccessShareLock) | (1 << RowShareLock) |
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(1 << RowExclusiveLock) | (1 << ShareUpdateExclusiveLock) |
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(1 << ShareLock) | (1 << ShareRowExclusiveLock) |
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(1 << ExclusiveLock) | (1 << AccessExclusiveLock)
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};
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/* Names of lock modes, for debug printouts */
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static const char *const lock_mode_names[] =
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{
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"INVALID",
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"AccessShareLock",
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"RowShareLock",
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"RowExclusiveLock",
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"ShareUpdateExclusiveLock",
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"ShareLock",
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"ShareRowExclusiveLock",
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"ExclusiveLock",
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"AccessExclusiveLock"
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};
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#ifndef LOCK_DEBUG
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static bool Dummy_trace = false;
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#endif
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static const LockMethodData default_lockmethod = {
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AccessExclusiveLock, /* highest valid lock mode number */
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true,
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LockConflicts,
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lock_mode_names,
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#ifdef LOCK_DEBUG
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&Trace_locks
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#else
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&Dummy_trace
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#endif
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};
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static const LockMethodData user_lockmethod = {
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AccessExclusiveLock, /* highest valid lock mode number */
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false,
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LockConflicts,
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lock_mode_names,
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#ifdef LOCK_DEBUG
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&Trace_userlocks
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#else
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&Dummy_trace
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#endif
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};
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/*
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* map from lock method id to the lock table data structures
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*/
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static const LockMethod LockMethods[] = {
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NULL,
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&default_lockmethod,
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&user_lockmethod
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};
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/* Record that's written to 2PC state file when a lock is persisted */
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typedef struct TwoPhaseLockRecord
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{
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LOCKTAG locktag;
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LOCKMODE lockmode;
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} TwoPhaseLockRecord;
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/*
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* Pointers to hash tables containing lock state
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*
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* The LockMethodLockHash and LockMethodProcLockHash hash tables are in
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* shared memory; LockMethodLocalHash is local to each backend.
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*/
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static HTAB *LockMethodLockHash;
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static HTAB *LockMethodProcLockHash;
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static HTAB *LockMethodLocalHash;
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/* private state for GrantAwaitedLock */
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static LOCALLOCK *awaitedLock;
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static ResourceOwner awaitedOwner;
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#ifdef LOCK_DEBUG
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/*------
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* The following configuration options are available for lock debugging:
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*
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* TRACE_LOCKS -- give a bunch of output what's going on in this file
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* TRACE_USERLOCKS -- same but for user locks
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* TRACE_LOCK_OIDMIN-- do not trace locks for tables below this oid
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* (use to avoid output on system tables)
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* TRACE_LOCK_TABLE -- trace locks on this table (oid) unconditionally
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* DEBUG_DEADLOCKS -- currently dumps locks at untimely occasions ;)
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*
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* Furthermore, but in storage/lmgr/lwlock.c:
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* TRACE_LWLOCKS -- trace lightweight locks (pretty useless)
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*
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* Define LOCK_DEBUG at compile time to get all these enabled.
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* --------
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*/
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int Trace_lock_oidmin = FirstNormalObjectId;
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bool Trace_locks = false;
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bool Trace_userlocks = false;
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int Trace_lock_table = 0;
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bool Debug_deadlocks = false;
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inline static bool
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LOCK_DEBUG_ENABLED(const LOCKTAG *tag)
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{
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return
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(*(LockMethods[tag->locktag_lockmethodid]->trace_flag) &&
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((Oid) tag->locktag_field2 >= (Oid) Trace_lock_oidmin))
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|| (Trace_lock_table &&
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(tag->locktag_field2 == Trace_lock_table));
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}
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inline static void
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LOCK_PRINT(const char *where, const LOCK *lock, LOCKMODE type)
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{
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if (LOCK_DEBUG_ENABLED(&lock->tag))
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elog(LOG,
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"%s: lock(%p) id(%u,%u,%u,%u,%u,%u) grantMask(%x) "
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"req(%d,%d,%d,%d,%d,%d,%d)=%d "
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"grant(%d,%d,%d,%d,%d,%d,%d)=%d wait(%d) type(%s)",
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where, lock,
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lock->tag.locktag_field1, lock->tag.locktag_field2,
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lock->tag.locktag_field3, lock->tag.locktag_field4,
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lock->tag.locktag_type, lock->tag.locktag_lockmethodid,
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lock->grantMask,
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lock->requested[1], lock->requested[2], lock->requested[3],
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lock->requested[4], lock->requested[5], lock->requested[6],
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lock->requested[7], lock->nRequested,
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lock->granted[1], lock->granted[2], lock->granted[3],
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lock->granted[4], lock->granted[5], lock->granted[6],
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lock->granted[7], lock->nGranted,
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lock->waitProcs.size,
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LockMethods[LOCK_LOCKMETHOD(*lock)]->lockModeNames[type]);
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}
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inline static void
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PROCLOCK_PRINT(const char *where, const PROCLOCK *proclockP)
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{
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if (LOCK_DEBUG_ENABLED(&proclockP->tag.myLock->tag))
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elog(LOG,
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"%s: proclock(%p) lock(%p) method(%u) proc(%p) hold(%x)",
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where, proclockP, proclockP->tag.myLock,
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PROCLOCK_LOCKMETHOD(*(proclockP)),
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proclockP->tag.myProc, (int) proclockP->holdMask);
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}
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#else /* not LOCK_DEBUG */
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#define LOCK_PRINT(where, lock, type)
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#define PROCLOCK_PRINT(where, proclockP)
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#endif /* not LOCK_DEBUG */
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static uint32 proclock_hash(const void *key, Size keysize);
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static void RemoveLocalLock(LOCALLOCK *locallock);
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static void GrantLockLocal(LOCALLOCK *locallock, ResourceOwner owner);
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static void WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner);
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static bool UnGrantLock(LOCK *lock, LOCKMODE lockmode,
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PROCLOCK *proclock, LockMethod lockMethodTable);
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static void CleanUpLock(LOCK *lock, PROCLOCK *proclock,
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LockMethod lockMethodTable, uint32 hashcode,
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bool wakeupNeeded);
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/*
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* InitLocks -- Initialize the lock manager's data structures.
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*
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* This is called from CreateSharedMemoryAndSemaphores(), which see for
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* more comments. In the normal postmaster case, the shared hash tables
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* are created here, as well as a locallock hash table that will remain
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* unused and empty in the postmaster itself. Backends inherit the pointers
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* to the shared tables via fork(), and also inherit an image of the locallock
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* hash table, which they proceed to use. In the EXEC_BACKEND case, each
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* backend re-executes this code to obtain pointers to the already existing
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* shared hash tables and to create its locallock hash table.
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*/
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void
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InitLocks(void)
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{
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HASHCTL info;
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int hash_flags;
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long init_table_size,
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max_table_size;
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/*
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* Compute init/max size to request for lock hashtables. Note these
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* calculations must agree with LockShmemSize!
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*/
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max_table_size = NLOCKENTS();
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init_table_size = max_table_size / 2;
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/*
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* Allocate hash table for LOCK structs. This stores per-locked-object
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* information.
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*/
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MemSet(&info, 0, sizeof(info));
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info.keysize = sizeof(LOCKTAG);
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info.entrysize = sizeof(LOCK);
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info.hash = tag_hash;
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info.num_partitions = NUM_LOCK_PARTITIONS;
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hash_flags = (HASH_ELEM | HASH_FUNCTION | HASH_PARTITION);
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LockMethodLockHash = ShmemInitHash("LOCK hash",
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init_table_size,
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max_table_size,
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&info,
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hash_flags);
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if (!LockMethodLockHash)
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elog(FATAL, "could not initialize lock hash table");
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/* Assume an average of 2 holders per lock */
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max_table_size *= 2;
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init_table_size *= 2;
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/*
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* Allocate hash table for PROCLOCK structs. This stores
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* per-lock-per-holder information.
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*/
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info.keysize = sizeof(PROCLOCKTAG);
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info.entrysize = sizeof(PROCLOCK);
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info.hash = proclock_hash;
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info.num_partitions = NUM_LOCK_PARTITIONS;
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hash_flags = (HASH_ELEM | HASH_FUNCTION | HASH_PARTITION);
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LockMethodProcLockHash = ShmemInitHash("PROCLOCK hash",
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init_table_size,
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max_table_size,
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&info,
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hash_flags);
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if (!LockMethodProcLockHash)
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elog(FATAL, "could not initialize proclock hash table");
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/*
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* Allocate non-shared hash table for LOCALLOCK structs. This stores lock
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* counts and resource owner information.
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*
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* The non-shared table could already exist in this process (this occurs
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* when the postmaster is recreating shared memory after a backend crash).
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* If so, delete and recreate it. (We could simply leave it, since it
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* ought to be empty in the postmaster, but for safety let's zap it.)
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*/
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if (LockMethodLocalHash)
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hash_destroy(LockMethodLocalHash);
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info.keysize = sizeof(LOCALLOCKTAG);
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info.entrysize = sizeof(LOCALLOCK);
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info.hash = tag_hash;
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hash_flags = (HASH_ELEM | HASH_FUNCTION);
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LockMethodLocalHash = hash_create("LOCALLOCK hash",
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128,
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&info,
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hash_flags);
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}
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/*
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* Fetch the lock method table associated with a given lock
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*/
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LockMethod
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GetLocksMethodTable(const LOCK *lock)
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{
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LOCKMETHODID lockmethodid = LOCK_LOCKMETHOD(*lock);
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Assert(0 < lockmethodid && lockmethodid < lengthof(LockMethods));
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return LockMethods[lockmethodid];
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}
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/*
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* Compute the hash code associated with a LOCKTAG.
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*
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* To avoid unnecessary recomputations of the hash code, we try to do this
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* just once per function, and then pass it around as needed. Aside from
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* passing the hashcode to hash_search_with_hash_value(), we can extract
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* the lock partition number from the hashcode.
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*/
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uint32
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LockTagHashCode(const LOCKTAG *locktag)
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{
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return get_hash_value(LockMethodLockHash, (const void *) locktag);
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}
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/*
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* Compute the hash code associated with a PROCLOCKTAG.
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*
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* Because we want to use just one set of partition locks for both the
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* LOCK and PROCLOCK hash tables, we have to make sure that PROCLOCKs
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* fall into the same partition number as their associated LOCKs.
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* dynahash.c expects the partition number to be the low-order bits of
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* the hash code, and therefore a PROCLOCKTAG's hash code must have the
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* same low-order bits as the associated LOCKTAG's hash code. We achieve
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* this with this specialized hash function.
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*/
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static uint32
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proclock_hash(const void *key, Size keysize)
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{
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const PROCLOCKTAG *proclocktag = (const PROCLOCKTAG *) key;
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uint32 lockhash;
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Datum procptr;
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Assert(keysize == sizeof(PROCLOCKTAG));
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/* Look into the associated LOCK object, and compute its hash code */
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lockhash = LockTagHashCode(&proclocktag->myLock->tag);
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/*
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* To make the hash code also depend on the PGPROC, we xor the proc
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* struct's address into the hash code, left-shifted so that the
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* partition-number bits don't change. Since this is only a hash, we
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* don't care if we lose high-order bits of the address; use an
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* intermediate variable to suppress cast-pointer-to-int warnings.
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*/
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procptr = PointerGetDatum(proclocktag->myProc);
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lockhash ^= ((uint32) procptr) << LOG2_NUM_LOCK_PARTITIONS;
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return lockhash;
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}
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/*
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* Compute the hash code associated with a PROCLOCKTAG, given the hashcode
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* for its underlying LOCK.
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*
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* We use this just to avoid redundant calls of LockTagHashCode().
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*/
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static inline uint32
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ProcLockHashCode(const PROCLOCKTAG *proclocktag, uint32 hashcode)
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{
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uint32 lockhash = hashcode;
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Datum procptr;
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/*
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* This must match proclock_hash()!
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*/
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procptr = PointerGetDatum(proclocktag->myProc);
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lockhash ^= ((uint32) procptr) << LOG2_NUM_LOCK_PARTITIONS;
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return lockhash;
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}
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/*
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* LockAcquire -- Check for lock conflicts, sleep if conflict found,
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* set lock if/when no conflicts.
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*
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* Inputs:
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* locktag: unique identifier for the lockable object
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* lockmode: lock mode to acquire
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* sessionLock: if true, acquire lock for session not current transaction
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* dontWait: if true, don't wait to acquire lock
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*
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* Returns one of:
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* LOCKACQUIRE_NOT_AVAIL lock not available, and dontWait=true
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* LOCKACQUIRE_OK lock successfully acquired
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* LOCKACQUIRE_ALREADY_HELD incremented count for lock already held
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*
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* In the normal case where dontWait=false and the caller doesn't need to
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* distinguish a freshly acquired lock from one already taken earlier in
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* this same transaction, there is no need to examine the return value.
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*
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* Side Effects: The lock is acquired and recorded in lock tables.
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*
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* NOTE: if we wait for the lock, there is no way to abort the wait
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* short of aborting the transaction.
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*/
|
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LockAcquireResult
|
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LockAcquire(const LOCKTAG *locktag,
|
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LOCKMODE lockmode,
|
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bool sessionLock,
|
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bool dontWait)
|
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{
|
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return LockAcquireExtended(locktag, lockmode, sessionLock, dontWait, true);
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}
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|
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/*
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* LockAcquireExtended - allows us to specify additional options
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|
*
|
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* reportMemoryError specifies whether a lock request that fills the
|
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* lock table should generate an ERROR or not. This allows a priority
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* caller to note that the lock table is full and then begin taking
|
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* extreme action to reduce the number of other lock holders before
|
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* retrying the action.
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*/
|
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LockAcquireResult
|
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LockAcquireExtended(const LOCKTAG *locktag,
|
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LOCKMODE lockmode,
|
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bool sessionLock,
|
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bool dontWait,
|
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bool reportMemoryError)
|
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{
|
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LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
|
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LockMethod lockMethodTable;
|
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LOCALLOCKTAG localtag;
|
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LOCALLOCK *locallock;
|
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LOCK *lock;
|
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PROCLOCK *proclock;
|
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PROCLOCKTAG proclocktag;
|
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bool found;
|
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ResourceOwner owner;
|
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uint32 hashcode;
|
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uint32 proclock_hashcode;
|
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int partition;
|
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LWLockId partitionLock;
|
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int status;
|
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|
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if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
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elog(ERROR, "unrecognized lock method: %d", lockmethodid);
|
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lockMethodTable = LockMethods[lockmethodid];
|
|
if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
|
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elog(ERROR, "unrecognized lock mode: %d", lockmode);
|
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|
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if (RecoveryInProgress() && !InRecovery &&
|
|
(locktag->locktag_type == LOCKTAG_OBJECT ||
|
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locktag->locktag_type == LOCKTAG_RELATION ) &&
|
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lockmode > RowExclusiveLock)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
|
|
errmsg("cannot acquire lockmode %s on database objects while recovery is in progress",
|
|
lockMethodTable->lockModeNames[lockmode]),
|
|
errhint("Only RowExclusiveLock or less can be acquired on database objects during recovery.")));
|
|
|
|
#ifdef LOCK_DEBUG
|
|
if (LOCK_DEBUG_ENABLED(locktag))
|
|
elog(LOG, "LockAcquire: lock [%u,%u] %s",
|
|
locktag->locktag_field1, locktag->locktag_field2,
|
|
lockMethodTable->lockModeNames[lockmode]);
|
|
#endif
|
|
|
|
/* Session locks are never transactional, else check table */
|
|
if (!sessionLock && lockMethodTable->transactional)
|
|
owner = CurrentResourceOwner;
|
|
else
|
|
owner = NULL;
|
|
|
|
/*
|
|
* Find or create a LOCALLOCK entry for this lock and lockmode
|
|
*/
|
|
MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
|
|
localtag.lock = *locktag;
|
|
localtag.mode = lockmode;
|
|
|
|
locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
|
|
(void *) &localtag,
|
|
HASH_ENTER, &found);
|
|
|
|
/*
|
|
* if it's a new locallock object, initialize it
|
|
*/
|
|
if (!found)
|
|
{
|
|
locallock->lock = NULL;
|
|
locallock->proclock = NULL;
|
|
locallock->hashcode = LockTagHashCode(&(localtag.lock));
|
|
locallock->nLocks = 0;
|
|
locallock->numLockOwners = 0;
|
|
locallock->maxLockOwners = 8;
|
|
locallock->lockOwners = NULL;
|
|
locallock->lockOwners = (LOCALLOCKOWNER *)
|
|
MemoryContextAlloc(TopMemoryContext,
|
|
locallock->maxLockOwners * sizeof(LOCALLOCKOWNER));
|
|
}
|
|
else
|
|
{
|
|
/* Make sure there will be room to remember the lock */
|
|
if (locallock->numLockOwners >= locallock->maxLockOwners)
|
|
{
|
|
int newsize = locallock->maxLockOwners * 2;
|
|
|
|
locallock->lockOwners = (LOCALLOCKOWNER *)
|
|
repalloc(locallock->lockOwners,
|
|
newsize * sizeof(LOCALLOCKOWNER));
|
|
locallock->maxLockOwners = newsize;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If we already hold the lock, we can just increase the count locally.
|
|
*/
|
|
if (locallock->nLocks > 0)
|
|
{
|
|
GrantLockLocal(locallock, owner);
|
|
return LOCKACQUIRE_ALREADY_HELD;
|
|
}
|
|
|
|
/*
|
|
* Otherwise we've got to mess with the shared lock table.
|
|
*/
|
|
hashcode = locallock->hashcode;
|
|
partition = LockHashPartition(hashcode);
|
|
partitionLock = LockHashPartitionLock(hashcode);
|
|
|
|
LWLockAcquire(partitionLock, LW_EXCLUSIVE);
|
|
|
|
/*
|
|
* Find or create a lock with this tag.
|
|
*
|
|
* Note: if the locallock object already existed, it might have a pointer
|
|
* to the lock already ... but we probably should not assume that that
|
|
* pointer is valid, since a lock object with no locks can go away
|
|
* anytime.
|
|
*/
|
|
lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
|
|
(void *) locktag,
|
|
hashcode,
|
|
HASH_ENTER_NULL,
|
|
&found);
|
|
if (!lock)
|
|
{
|
|
LWLockRelease(partitionLock);
|
|
if (reportMemoryError)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_OUT_OF_MEMORY),
|
|
errmsg("out of shared memory"),
|
|
errhint("You might need to increase max_locks_per_transaction.")));
|
|
else
|
|
return LOCKACQUIRE_NOT_AVAIL;
|
|
}
|
|
locallock->lock = lock;
|
|
|
|
/*
|
|
* if it's a new lock object, initialize it
|
|
*/
|
|
if (!found)
|
|
{
|
|
lock->grantMask = 0;
|
|
lock->waitMask = 0;
|
|
SHMQueueInit(&(lock->procLocks));
|
|
ProcQueueInit(&(lock->waitProcs));
|
|
lock->nRequested = 0;
|
|
lock->nGranted = 0;
|
|
MemSet(lock->requested, 0, sizeof(int) * MAX_LOCKMODES);
|
|
MemSet(lock->granted, 0, sizeof(int) * MAX_LOCKMODES);
|
|
LOCK_PRINT("LockAcquire: new", lock, lockmode);
|
|
}
|
|
else
|
|
{
|
|
LOCK_PRINT("LockAcquire: found", lock, lockmode);
|
|
Assert((lock->nRequested >= 0) && (lock->requested[lockmode] >= 0));
|
|
Assert((lock->nGranted >= 0) && (lock->granted[lockmode] >= 0));
|
|
Assert(lock->nGranted <= lock->nRequested);
|
|
}
|
|
|
|
/*
|
|
* Create the hash key for the proclock table.
|
|
*/
|
|
proclocktag.myLock = lock;
|
|
proclocktag.myProc = MyProc;
|
|
|
|
proclock_hashcode = ProcLockHashCode(&proclocktag, hashcode);
|
|
|
|
/*
|
|
* Find or create a proclock entry with this tag
|
|
*/
|
|
proclock = (PROCLOCK *) hash_search_with_hash_value(LockMethodProcLockHash,
|
|
(void *) &proclocktag,
|
|
proclock_hashcode,
|
|
HASH_ENTER_NULL,
|
|
&found);
|
|
if (!proclock)
|
|
{
|
|
/* Ooops, not enough shmem for the proclock */
|
|
if (lock->nRequested == 0)
|
|
{
|
|
/*
|
|
* There are no other requestors of this lock, so garbage-collect
|
|
* the lock object. We *must* do this to avoid a permanent leak
|
|
* of shared memory, because there won't be anything to cause
|
|
* anyone to release the lock object later.
|
|
*/
|
|
Assert(SHMQueueEmpty(&(lock->procLocks)));
|
|
if (!hash_search_with_hash_value(LockMethodLockHash,
|
|
(void *) &(lock->tag),
|
|
hashcode,
|
|
HASH_REMOVE,
|
|
NULL))
|
|
elog(PANIC, "lock table corrupted");
|
|
}
|
|
LWLockRelease(partitionLock);
|
|
if (reportMemoryError)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_OUT_OF_MEMORY),
|
|
errmsg("out of shared memory"),
|
|
errhint("You might need to increase max_locks_per_transaction.")));
|
|
else
|
|
return LOCKACQUIRE_NOT_AVAIL;
|
|
}
|
|
locallock->proclock = proclock;
|
|
|
|
/*
|
|
* If new, initialize the new entry
|
|
*/
|
|
if (!found)
|
|
{
|
|
proclock->holdMask = 0;
|
|
proclock->releaseMask = 0;
|
|
/* Add proclock to appropriate lists */
|
|
SHMQueueInsertBefore(&lock->procLocks, &proclock->lockLink);
|
|
SHMQueueInsertBefore(&(MyProc->myProcLocks[partition]),
|
|
&proclock->procLink);
|
|
PROCLOCK_PRINT("LockAcquire: new", proclock);
|
|
}
|
|
else
|
|
{
|
|
PROCLOCK_PRINT("LockAcquire: found", proclock);
|
|
Assert((proclock->holdMask & ~lock->grantMask) == 0);
|
|
|
|
#ifdef CHECK_DEADLOCK_RISK
|
|
|
|
/*
|
|
* Issue warning if we already hold a lower-level lock on this object
|
|
* and do not hold a lock of the requested level or higher. This
|
|
* indicates a deadlock-prone coding practice (eg, we'd have a
|
|
* deadlock if another backend were following the same code path at
|
|
* about the same time).
|
|
*
|
|
* This is not enabled by default, because it may generate log entries
|
|
* about user-level coding practices that are in fact safe in context.
|
|
* It can be enabled to help find system-level problems.
|
|
*
|
|
* XXX Doing numeric comparison on the lockmodes is a hack; it'd be
|
|
* better to use a table. For now, though, this works.
|
|
*/
|
|
{
|
|
int i;
|
|
|
|
for (i = lockMethodTable->numLockModes; i > 0; i--)
|
|
{
|
|
if (proclock->holdMask & LOCKBIT_ON(i))
|
|
{
|
|
if (i >= (int) lockmode)
|
|
break; /* safe: we have a lock >= req level */
|
|
elog(LOG, "deadlock risk: raising lock level"
|
|
" from %s to %s on object %u/%u/%u",
|
|
lockMethodTable->lockModeNames[i],
|
|
lockMethodTable->lockModeNames[lockmode],
|
|
lock->tag.locktag_field1, lock->tag.locktag_field2,
|
|
lock->tag.locktag_field3);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
#endif /* CHECK_DEADLOCK_RISK */
|
|
}
|
|
|
|
/*
|
|
* lock->nRequested and lock->requested[] count the total number of
|
|
* requests, whether granted or waiting, so increment those immediately.
|
|
* The other counts don't increment till we get the lock.
|
|
*/
|
|
lock->nRequested++;
|
|
lock->requested[lockmode]++;
|
|
Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
|
|
|
|
/*
|
|
* We shouldn't already hold the desired lock; else locallock table is
|
|
* broken.
|
|
*/
|
|
if (proclock->holdMask & LOCKBIT_ON(lockmode))
|
|
elog(ERROR, "lock %s on object %u/%u/%u is already held",
|
|
lockMethodTable->lockModeNames[lockmode],
|
|
lock->tag.locktag_field1, lock->tag.locktag_field2,
|
|
lock->tag.locktag_field3);
|
|
|
|
/*
|
|
* If lock requested conflicts with locks requested by waiters, must join
|
|
* wait queue. Otherwise, check for conflict with already-held locks.
|
|
* (That's last because most complex check.)
|
|
*/
|
|
if (lockMethodTable->conflictTab[lockmode] & lock->waitMask)
|
|
status = STATUS_FOUND;
|
|
else
|
|
status = LockCheckConflicts(lockMethodTable, lockmode,
|
|
lock, proclock, MyProc);
|
|
|
|
if (status == STATUS_OK)
|
|
{
|
|
/* No conflict with held or previously requested locks */
|
|
GrantLock(lock, proclock, lockmode);
|
|
GrantLockLocal(locallock, owner);
|
|
}
|
|
else
|
|
{
|
|
Assert(status == STATUS_FOUND);
|
|
|
|
/*
|
|
* We can't acquire the lock immediately. If caller specified no
|
|
* blocking, remove useless table entries and return NOT_AVAIL without
|
|
* waiting.
|
|
*/
|
|
if (dontWait)
|
|
{
|
|
if (proclock->holdMask == 0)
|
|
{
|
|
SHMQueueDelete(&proclock->lockLink);
|
|
SHMQueueDelete(&proclock->procLink);
|
|
if (!hash_search_with_hash_value(LockMethodProcLockHash,
|
|
(void *) &(proclock->tag),
|
|
proclock_hashcode,
|
|
HASH_REMOVE,
|
|
NULL))
|
|
elog(PANIC, "proclock table corrupted");
|
|
}
|
|
else
|
|
PROCLOCK_PRINT("LockAcquire: NOWAIT", proclock);
|
|
lock->nRequested--;
|
|
lock->requested[lockmode]--;
|
|
LOCK_PRINT("LockAcquire: conditional lock failed", lock, lockmode);
|
|
Assert((lock->nRequested > 0) && (lock->requested[lockmode] >= 0));
|
|
Assert(lock->nGranted <= lock->nRequested);
|
|
LWLockRelease(partitionLock);
|
|
if (locallock->nLocks == 0)
|
|
RemoveLocalLock(locallock);
|
|
return LOCKACQUIRE_NOT_AVAIL;
|
|
}
|
|
|
|
/*
|
|
* Set bitmask of locks this process already holds on this object.
|
|
*/
|
|
MyProc->heldLocks = proclock->holdMask;
|
|
|
|
/*
|
|
* Sleep till someone wakes me up.
|
|
*/
|
|
|
|
TRACE_POSTGRESQL_LOCK_WAIT_START(locktag->locktag_field1,
|
|
locktag->locktag_field2,
|
|
locktag->locktag_field3,
|
|
locktag->locktag_field4,
|
|
locktag->locktag_type,
|
|
lockmode);
|
|
|
|
WaitOnLock(locallock, owner);
|
|
|
|
TRACE_POSTGRESQL_LOCK_WAIT_DONE(locktag->locktag_field1,
|
|
locktag->locktag_field2,
|
|
locktag->locktag_field3,
|
|
locktag->locktag_field4,
|
|
locktag->locktag_type,
|
|
lockmode);
|
|
|
|
/*
|
|
* NOTE: do not do any material change of state between here and
|
|
* return. All required changes in locktable state must have been
|
|
* done when the lock was granted to us --- see notes in WaitOnLock.
|
|
*/
|
|
|
|
/*
|
|
* Check the proclock entry status, in case something in the ipc
|
|
* communication doesn't work correctly.
|
|
*/
|
|
if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
|
|
{
|
|
PROCLOCK_PRINT("LockAcquire: INCONSISTENT", proclock);
|
|
LOCK_PRINT("LockAcquire: INCONSISTENT", lock, lockmode);
|
|
/* Should we retry ? */
|
|
LWLockRelease(partitionLock);
|
|
elog(ERROR, "LockAcquire failed");
|
|
}
|
|
PROCLOCK_PRINT("LockAcquire: granted", proclock);
|
|
LOCK_PRINT("LockAcquire: granted", lock, lockmode);
|
|
}
|
|
|
|
LWLockRelease(partitionLock);
|
|
|
|
/*
|
|
* Emit a WAL record if acquisition of this lock need to be replayed in
|
|
* a standby server. Only AccessExclusiveLocks can conflict with lock
|
|
* types that read-only transactions can acquire in a standby server.
|
|
*
|
|
* Make sure this definition matches the one GetRunningTransactionLocks().
|
|
*/
|
|
if (lockmode >= AccessExclusiveLock &&
|
|
locktag->locktag_type == LOCKTAG_RELATION &&
|
|
!RecoveryInProgress() &&
|
|
XLogStandbyInfoActive())
|
|
{
|
|
/*
|
|
* Decode the locktag back to the original values, to avoid
|
|
* sending lots of empty bytes with every message. See
|
|
* lock.h to check how a locktag is defined for LOCKTAG_RELATION
|
|
*/
|
|
LogAccessExclusiveLock(locktag->locktag_field1,
|
|
locktag->locktag_field2);
|
|
}
|
|
|
|
return LOCKACQUIRE_OK;
|
|
}
|
|
|
|
/*
|
|
* Subroutine to free a locallock entry
|
|
*/
|
|
static void
|
|
RemoveLocalLock(LOCALLOCK *locallock)
|
|
{
|
|
pfree(locallock->lockOwners);
|
|
locallock->lockOwners = NULL;
|
|
if (!hash_search(LockMethodLocalHash,
|
|
(void *) &(locallock->tag),
|
|
HASH_REMOVE, NULL))
|
|
elog(WARNING, "locallock table corrupted");
|
|
}
|
|
|
|
/*
|
|
* LockCheckConflicts -- test whether requested lock conflicts
|
|
* with those already granted
|
|
*
|
|
* Returns STATUS_FOUND if conflict, STATUS_OK if no conflict.
|
|
*
|
|
* NOTES:
|
|
* Here's what makes this complicated: one process's locks don't
|
|
* conflict with one another, no matter what purpose they are held for
|
|
* (eg, session and transaction locks do not conflict).
|
|
* So, we must subtract off our own locks when determining whether the
|
|
* requested new lock conflicts with those already held.
|
|
*/
|
|
int
|
|
LockCheckConflicts(LockMethod lockMethodTable,
|
|
LOCKMODE lockmode,
|
|
LOCK *lock,
|
|
PROCLOCK *proclock,
|
|
PGPROC *proc)
|
|
{
|
|
int numLockModes = lockMethodTable->numLockModes;
|
|
LOCKMASK myLocks;
|
|
LOCKMASK otherLocks;
|
|
int i;
|
|
|
|
/*
|
|
* first check for global conflicts: If no locks conflict with my request,
|
|
* then I get the lock.
|
|
*
|
|
* Checking for conflict: lock->grantMask represents the types of
|
|
* currently held locks. conflictTable[lockmode] has a bit set for each
|
|
* type of lock that conflicts with request. Bitwise compare tells if
|
|
* there is a conflict.
|
|
*/
|
|
if (!(lockMethodTable->conflictTab[lockmode] & lock->grantMask))
|
|
{
|
|
PROCLOCK_PRINT("LockCheckConflicts: no conflict", proclock);
|
|
return STATUS_OK;
|
|
}
|
|
|
|
/*
|
|
* Rats. Something conflicts. But it could still be my own lock. We have
|
|
* to construct a conflict mask that does not reflect our own locks, but
|
|
* only lock types held by other processes.
|
|
*/
|
|
myLocks = proclock->holdMask;
|
|
otherLocks = 0;
|
|
for (i = 1; i <= numLockModes; i++)
|
|
{
|
|
int myHolding = (myLocks & LOCKBIT_ON(i)) ? 1 : 0;
|
|
|
|
if (lock->granted[i] > myHolding)
|
|
otherLocks |= LOCKBIT_ON(i);
|
|
}
|
|
|
|
/*
|
|
* now check again for conflicts. 'otherLocks' describes the types of
|
|
* locks held by other processes. If one of these conflicts with the kind
|
|
* of lock that I want, there is a conflict and I have to sleep.
|
|
*/
|
|
if (!(lockMethodTable->conflictTab[lockmode] & otherLocks))
|
|
{
|
|
/* no conflict. OK to get the lock */
|
|
PROCLOCK_PRINT("LockCheckConflicts: resolved", proclock);
|
|
return STATUS_OK;
|
|
}
|
|
|
|
PROCLOCK_PRINT("LockCheckConflicts: conflicting", proclock);
|
|
return STATUS_FOUND;
|
|
}
|
|
|
|
/*
|
|
* GrantLock -- update the lock and proclock data structures to show
|
|
* the lock request has been granted.
|
|
*
|
|
* NOTE: if proc was blocked, it also needs to be removed from the wait list
|
|
* and have its waitLock/waitProcLock fields cleared. That's not done here.
|
|
*
|
|
* NOTE: the lock grant also has to be recorded in the associated LOCALLOCK
|
|
* table entry; but since we may be awaking some other process, we can't do
|
|
* that here; it's done by GrantLockLocal, instead.
|
|
*/
|
|
void
|
|
GrantLock(LOCK *lock, PROCLOCK *proclock, LOCKMODE lockmode)
|
|
{
|
|
lock->nGranted++;
|
|
lock->granted[lockmode]++;
|
|
lock->grantMask |= LOCKBIT_ON(lockmode);
|
|
if (lock->granted[lockmode] == lock->requested[lockmode])
|
|
lock->waitMask &= LOCKBIT_OFF(lockmode);
|
|
proclock->holdMask |= LOCKBIT_ON(lockmode);
|
|
LOCK_PRINT("GrantLock", lock, lockmode);
|
|
Assert((lock->nGranted > 0) && (lock->granted[lockmode] > 0));
|
|
Assert(lock->nGranted <= lock->nRequested);
|
|
}
|
|
|
|
/*
|
|
* UnGrantLock -- opposite of GrantLock.
|
|
*
|
|
* Updates the lock and proclock data structures to show that the lock
|
|
* is no longer held nor requested by the current holder.
|
|
*
|
|
* Returns true if there were any waiters waiting on the lock that
|
|
* should now be woken up with ProcLockWakeup.
|
|
*/
|
|
static bool
|
|
UnGrantLock(LOCK *lock, LOCKMODE lockmode,
|
|
PROCLOCK *proclock, LockMethod lockMethodTable)
|
|
{
|
|
bool wakeupNeeded = false;
|
|
|
|
Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
|
|
Assert((lock->nGranted > 0) && (lock->granted[lockmode] > 0));
|
|
Assert(lock->nGranted <= lock->nRequested);
|
|
|
|
/*
|
|
* fix the general lock stats
|
|
*/
|
|
lock->nRequested--;
|
|
lock->requested[lockmode]--;
|
|
lock->nGranted--;
|
|
lock->granted[lockmode]--;
|
|
|
|
if (lock->granted[lockmode] == 0)
|
|
{
|
|
/* change the conflict mask. No more of this lock type. */
|
|
lock->grantMask &= LOCKBIT_OFF(lockmode);
|
|
}
|
|
|
|
LOCK_PRINT("UnGrantLock: updated", lock, lockmode);
|
|
|
|
/*
|
|
* We need only run ProcLockWakeup if the released lock conflicts with at
|
|
* least one of the lock types requested by waiter(s). Otherwise whatever
|
|
* conflict made them wait must still exist. NOTE: before MVCC, we could
|
|
* skip wakeup if lock->granted[lockmode] was still positive. But that's
|
|
* not true anymore, because the remaining granted locks might belong to
|
|
* some waiter, who could now be awakened because he doesn't conflict with
|
|
* his own locks.
|
|
*/
|
|
if (lockMethodTable->conflictTab[lockmode] & lock->waitMask)
|
|
wakeupNeeded = true;
|
|
|
|
/*
|
|
* Now fix the per-proclock state.
|
|
*/
|
|
proclock->holdMask &= LOCKBIT_OFF(lockmode);
|
|
PROCLOCK_PRINT("UnGrantLock: updated", proclock);
|
|
|
|
return wakeupNeeded;
|
|
}
|
|
|
|
/*
|
|
* CleanUpLock -- clean up after releasing a lock. We garbage-collect the
|
|
* proclock and lock objects if possible, and call ProcLockWakeup if there
|
|
* are remaining requests and the caller says it's OK. (Normally, this
|
|
* should be called after UnGrantLock, and wakeupNeeded is the result from
|
|
* UnGrantLock.)
|
|
*
|
|
* The appropriate partition lock must be held at entry, and will be
|
|
* held at exit.
|
|
*/
|
|
static void
|
|
CleanUpLock(LOCK *lock, PROCLOCK *proclock,
|
|
LockMethod lockMethodTable, uint32 hashcode,
|
|
bool wakeupNeeded)
|
|
{
|
|
/*
|
|
* If this was my last hold on this lock, delete my entry in the proclock
|
|
* table.
|
|
*/
|
|
if (proclock->holdMask == 0)
|
|
{
|
|
uint32 proclock_hashcode;
|
|
|
|
PROCLOCK_PRINT("CleanUpLock: deleting", proclock);
|
|
SHMQueueDelete(&proclock->lockLink);
|
|
SHMQueueDelete(&proclock->procLink);
|
|
proclock_hashcode = ProcLockHashCode(&proclock->tag, hashcode);
|
|
if (!hash_search_with_hash_value(LockMethodProcLockHash,
|
|
(void *) &(proclock->tag),
|
|
proclock_hashcode,
|
|
HASH_REMOVE,
|
|
NULL))
|
|
elog(PANIC, "proclock table corrupted");
|
|
}
|
|
|
|
if (lock->nRequested == 0)
|
|
{
|
|
/*
|
|
* The caller just released the last lock, so garbage-collect the lock
|
|
* object.
|
|
*/
|
|
LOCK_PRINT("CleanUpLock: deleting", lock, 0);
|
|
Assert(SHMQueueEmpty(&(lock->procLocks)));
|
|
if (!hash_search_with_hash_value(LockMethodLockHash,
|
|
(void *) &(lock->tag),
|
|
hashcode,
|
|
HASH_REMOVE,
|
|
NULL))
|
|
elog(PANIC, "lock table corrupted");
|
|
}
|
|
else if (wakeupNeeded)
|
|
{
|
|
/* There are waiters on this lock, so wake them up. */
|
|
ProcLockWakeup(lockMethodTable, lock);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* GrantLockLocal -- update the locallock data structures to show
|
|
* the lock request has been granted.
|
|
*
|
|
* We expect that LockAcquire made sure there is room to add a new
|
|
* ResourceOwner entry.
|
|
*/
|
|
static void
|
|
GrantLockLocal(LOCALLOCK *locallock, ResourceOwner owner)
|
|
{
|
|
LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
|
|
int i;
|
|
|
|
Assert(locallock->numLockOwners < locallock->maxLockOwners);
|
|
/* Count the total */
|
|
locallock->nLocks++;
|
|
/* Count the per-owner lock */
|
|
for (i = 0; i < locallock->numLockOwners; i++)
|
|
{
|
|
if (lockOwners[i].owner == owner)
|
|
{
|
|
lockOwners[i].nLocks++;
|
|
return;
|
|
}
|
|
}
|
|
lockOwners[i].owner = owner;
|
|
lockOwners[i].nLocks = 1;
|
|
locallock->numLockOwners++;
|
|
}
|
|
|
|
/*
|
|
* GrantAwaitedLock -- call GrantLockLocal for the lock we are doing
|
|
* WaitOnLock on.
|
|
*
|
|
* proc.c needs this for the case where we are booted off the lock by
|
|
* timeout, but discover that someone granted us the lock anyway.
|
|
*
|
|
* We could just export GrantLockLocal, but that would require including
|
|
* resowner.h in lock.h, which creates circularity.
|
|
*/
|
|
void
|
|
GrantAwaitedLock(void)
|
|
{
|
|
GrantLockLocal(awaitedLock, awaitedOwner);
|
|
}
|
|
|
|
/*
|
|
* WaitOnLock -- wait to acquire a lock
|
|
*
|
|
* Caller must have set MyProc->heldLocks to reflect locks already held
|
|
* on the lockable object by this process.
|
|
*
|
|
* The appropriate partition lock must be held at entry.
|
|
*/
|
|
static void
|
|
WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner)
|
|
{
|
|
LOCKMETHODID lockmethodid = LOCALLOCK_LOCKMETHOD(*locallock);
|
|
LockMethod lockMethodTable = LockMethods[lockmethodid];
|
|
char *volatile new_status = NULL;
|
|
|
|
LOCK_PRINT("WaitOnLock: sleeping on lock",
|
|
locallock->lock, locallock->tag.mode);
|
|
|
|
/* Report change to waiting status */
|
|
if (update_process_title)
|
|
{
|
|
const char *old_status;
|
|
int len;
|
|
|
|
old_status = get_ps_display(&len);
|
|
new_status = (char *) palloc(len + 8 + 1);
|
|
memcpy(new_status, old_status, len);
|
|
strcpy(new_status + len, " waiting");
|
|
set_ps_display(new_status, false);
|
|
new_status[len] = '\0'; /* truncate off " waiting" */
|
|
}
|
|
pgstat_report_waiting(true);
|
|
|
|
awaitedLock = locallock;
|
|
awaitedOwner = owner;
|
|
|
|
/*
|
|
* NOTE: Think not to put any shared-state cleanup after the call to
|
|
* ProcSleep, in either the normal or failure path. The lock state must
|
|
* be fully set by the lock grantor, or by CheckDeadLock if we give up
|
|
* waiting for the lock. This is necessary because of the possibility
|
|
* that a cancel/die interrupt will interrupt ProcSleep after someone else
|
|
* grants us the lock, but before we've noticed it. Hence, after granting,
|
|
* the locktable state must fully reflect the fact that we own the lock;
|
|
* we can't do additional work on return.
|
|
*
|
|
* We can and do use a PG_TRY block to try to clean up after failure, but
|
|
* this still has a major limitation: elog(FATAL) can occur while waiting
|
|
* (eg, a "die" interrupt), and then control won't come back here. So all
|
|
* cleanup of essential state should happen in LockWaitCancel, not here.
|
|
* We can use PG_TRY to clear the "waiting" status flags, since doing that
|
|
* is unimportant if the process exits.
|
|
*/
|
|
PG_TRY();
|
|
{
|
|
if (ProcSleep(locallock, lockMethodTable) != STATUS_OK)
|
|
{
|
|
/*
|
|
* We failed as a result of a deadlock, see CheckDeadLock(). Quit
|
|
* now.
|
|
*/
|
|
awaitedLock = NULL;
|
|
LOCK_PRINT("WaitOnLock: aborting on lock",
|
|
locallock->lock, locallock->tag.mode);
|
|
LWLockRelease(LockHashPartitionLock(locallock->hashcode));
|
|
|
|
/*
|
|
* Now that we aren't holding the partition lock, we can give an
|
|
* error report including details about the detected deadlock.
|
|
*/
|
|
DeadLockReport();
|
|
/* not reached */
|
|
}
|
|
}
|
|
PG_CATCH();
|
|
{
|
|
/* In this path, awaitedLock remains set until LockWaitCancel */
|
|
|
|
/* Report change to non-waiting status */
|
|
pgstat_report_waiting(false);
|
|
if (update_process_title)
|
|
{
|
|
set_ps_display(new_status, false);
|
|
pfree(new_status);
|
|
}
|
|
|
|
/* and propagate the error */
|
|
PG_RE_THROW();
|
|
}
|
|
PG_END_TRY();
|
|
|
|
awaitedLock = NULL;
|
|
|
|
/* Report change to non-waiting status */
|
|
pgstat_report_waiting(false);
|
|
if (update_process_title)
|
|
{
|
|
set_ps_display(new_status, false);
|
|
pfree(new_status);
|
|
}
|
|
|
|
LOCK_PRINT("WaitOnLock: wakeup on lock",
|
|
locallock->lock, locallock->tag.mode);
|
|
}
|
|
|
|
/*
|
|
* Remove a proc from the wait-queue it is on (caller must know it is on one).
|
|
* This is only used when the proc has failed to get the lock, so we set its
|
|
* waitStatus to STATUS_ERROR.
|
|
*
|
|
* Appropriate partition lock must be held by caller. Also, caller is
|
|
* responsible for signaling the proc if needed.
|
|
*
|
|
* NB: this does not clean up any locallock object that may exist for the lock.
|
|
*/
|
|
void
|
|
RemoveFromWaitQueue(PGPROC *proc, uint32 hashcode)
|
|
{
|
|
LOCK *waitLock = proc->waitLock;
|
|
PROCLOCK *proclock = proc->waitProcLock;
|
|
LOCKMODE lockmode = proc->waitLockMode;
|
|
LOCKMETHODID lockmethodid = LOCK_LOCKMETHOD(*waitLock);
|
|
|
|
/* Make sure proc is waiting */
|
|
Assert(proc->waitStatus == STATUS_WAITING);
|
|
Assert(proc->links.next != NULL);
|
|
Assert(waitLock);
|
|
Assert(waitLock->waitProcs.size > 0);
|
|
Assert(0 < lockmethodid && lockmethodid < lengthof(LockMethods));
|
|
|
|
/* Remove proc from lock's wait queue */
|
|
SHMQueueDelete(&(proc->links));
|
|
waitLock->waitProcs.size--;
|
|
|
|
/* Undo increments of request counts by waiting process */
|
|
Assert(waitLock->nRequested > 0);
|
|
Assert(waitLock->nRequested > proc->waitLock->nGranted);
|
|
waitLock->nRequested--;
|
|
Assert(waitLock->requested[lockmode] > 0);
|
|
waitLock->requested[lockmode]--;
|
|
/* don't forget to clear waitMask bit if appropriate */
|
|
if (waitLock->granted[lockmode] == waitLock->requested[lockmode])
|
|
waitLock->waitMask &= LOCKBIT_OFF(lockmode);
|
|
|
|
/* Clean up the proc's own state, and pass it the ok/fail signal */
|
|
proc->waitLock = NULL;
|
|
proc->waitProcLock = NULL;
|
|
proc->waitStatus = STATUS_ERROR;
|
|
|
|
/*
|
|
* Delete the proclock immediately if it represents no already-held locks.
|
|
* (This must happen now because if the owner of the lock decides to
|
|
* release it, and the requested/granted counts then go to zero,
|
|
* LockRelease expects there to be no remaining proclocks.) Then see if
|
|
* any other waiters for the lock can be woken up now.
|
|
*/
|
|
CleanUpLock(waitLock, proclock,
|
|
LockMethods[lockmethodid], hashcode,
|
|
true);
|
|
}
|
|
|
|
/*
|
|
* LockRelease -- look up 'locktag' and release one 'lockmode' lock on it.
|
|
* Release a session lock if 'sessionLock' is true, else release a
|
|
* regular transaction lock.
|
|
*
|
|
* Side Effects: find any waiting processes that are now wakable,
|
|
* grant them their requested locks and awaken them.
|
|
* (We have to grant the lock here to avoid a race between
|
|
* the waking process and any new process to
|
|
* come along and request the lock.)
|
|
*/
|
|
bool
|
|
LockRelease(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
|
|
{
|
|
LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
|
|
LockMethod lockMethodTable;
|
|
LOCALLOCKTAG localtag;
|
|
LOCALLOCK *locallock;
|
|
LOCK *lock;
|
|
PROCLOCK *proclock;
|
|
LWLockId partitionLock;
|
|
bool wakeupNeeded;
|
|
|
|
if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
|
|
elog(ERROR, "unrecognized lock method: %d", lockmethodid);
|
|
lockMethodTable = LockMethods[lockmethodid];
|
|
if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
|
|
elog(ERROR, "unrecognized lock mode: %d", lockmode);
|
|
|
|
#ifdef LOCK_DEBUG
|
|
if (LOCK_DEBUG_ENABLED(locktag))
|
|
elog(LOG, "LockRelease: lock [%u,%u] %s",
|
|
locktag->locktag_field1, locktag->locktag_field2,
|
|
lockMethodTable->lockModeNames[lockmode]);
|
|
#endif
|
|
|
|
/*
|
|
* Find the LOCALLOCK entry for this lock and lockmode
|
|
*/
|
|
MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
|
|
localtag.lock = *locktag;
|
|
localtag.mode = lockmode;
|
|
|
|
locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
|
|
(void *) &localtag,
|
|
HASH_FIND, NULL);
|
|
|
|
/*
|
|
* let the caller print its own error message, too. Do not ereport(ERROR).
|
|
*/
|
|
if (!locallock || locallock->nLocks <= 0)
|
|
{
|
|
elog(WARNING, "you don't own a lock of type %s",
|
|
lockMethodTable->lockModeNames[lockmode]);
|
|
return FALSE;
|
|
}
|
|
|
|
/*
|
|
* Decrease the count for the resource owner.
|
|
*/
|
|
{
|
|
LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
|
|
ResourceOwner owner;
|
|
int i;
|
|
|
|
/* Session locks are never transactional, else check table */
|
|
if (!sessionLock && lockMethodTable->transactional)
|
|
owner = CurrentResourceOwner;
|
|
else
|
|
owner = NULL;
|
|
|
|
for (i = locallock->numLockOwners - 1; i >= 0; i--)
|
|
{
|
|
if (lockOwners[i].owner == owner)
|
|
{
|
|
Assert(lockOwners[i].nLocks > 0);
|
|
if (--lockOwners[i].nLocks == 0)
|
|
{
|
|
/* compact out unused slot */
|
|
locallock->numLockOwners--;
|
|
if (i < locallock->numLockOwners)
|
|
lockOwners[i] = lockOwners[locallock->numLockOwners];
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
if (i < 0)
|
|
{
|
|
/* don't release a lock belonging to another owner */
|
|
elog(WARNING, "you don't own a lock of type %s",
|
|
lockMethodTable->lockModeNames[lockmode]);
|
|
return FALSE;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Decrease the total local count. If we're still holding the lock, we're
|
|
* done.
|
|
*/
|
|
locallock->nLocks--;
|
|
|
|
if (locallock->nLocks > 0)
|
|
return TRUE;
|
|
|
|
/*
|
|
* Otherwise we've got to mess with the shared lock table.
|
|
*/
|
|
partitionLock = LockHashPartitionLock(locallock->hashcode);
|
|
|
|
LWLockAcquire(partitionLock, LW_EXCLUSIVE);
|
|
|
|
/*
|
|
* We don't need to re-find the lock or proclock, since we kept their
|
|
* addresses in the locallock table, and they couldn't have been removed
|
|
* while we were holding a lock on them.
|
|
*/
|
|
lock = locallock->lock;
|
|
LOCK_PRINT("LockRelease: found", lock, lockmode);
|
|
proclock = locallock->proclock;
|
|
PROCLOCK_PRINT("LockRelease: found", proclock);
|
|
|
|
/*
|
|
* Double-check that we are actually holding a lock of the type we want to
|
|
* release.
|
|
*/
|
|
if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
|
|
{
|
|
PROCLOCK_PRINT("LockRelease: WRONGTYPE", proclock);
|
|
LWLockRelease(partitionLock);
|
|
elog(WARNING, "you don't own a lock of type %s",
|
|
lockMethodTable->lockModeNames[lockmode]);
|
|
RemoveLocalLock(locallock);
|
|
return FALSE;
|
|
}
|
|
|
|
/*
|
|
* Do the releasing. CleanUpLock will waken any now-wakable waiters.
|
|
*/
|
|
wakeupNeeded = UnGrantLock(lock, lockmode, proclock, lockMethodTable);
|
|
|
|
CleanUpLock(lock, proclock,
|
|
lockMethodTable, locallock->hashcode,
|
|
wakeupNeeded);
|
|
|
|
LWLockRelease(partitionLock);
|
|
|
|
RemoveLocalLock(locallock);
|
|
return TRUE;
|
|
}
|
|
|
|
/*
|
|
* LockReleaseAll -- Release all locks of the specified lock method that
|
|
* are held by the current process.
|
|
*
|
|
* Well, not necessarily *all* locks. The available behaviors are:
|
|
* allLocks == true: release all locks including session locks.
|
|
* allLocks == false: release all non-session locks.
|
|
*/
|
|
void
|
|
LockReleaseAll(LOCKMETHODID lockmethodid, bool allLocks)
|
|
{
|
|
HASH_SEQ_STATUS status;
|
|
LockMethod lockMethodTable;
|
|
int i,
|
|
numLockModes;
|
|
LOCALLOCK *locallock;
|
|
LOCK *lock;
|
|
PROCLOCK *proclock;
|
|
int partition;
|
|
|
|
if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
|
|
elog(ERROR, "unrecognized lock method: %d", lockmethodid);
|
|
lockMethodTable = LockMethods[lockmethodid];
|
|
|
|
#ifdef LOCK_DEBUG
|
|
if (*(lockMethodTable->trace_flag))
|
|
elog(LOG, "LockReleaseAll: lockmethod=%d", lockmethodid);
|
|
#endif
|
|
|
|
numLockModes = lockMethodTable->numLockModes;
|
|
|
|
/*
|
|
* First we run through the locallock table and get rid of unwanted
|
|
* entries, then we scan the process's proclocks and get rid of those. We
|
|
* do this separately because we may have multiple locallock entries
|
|
* pointing to the same proclock, and we daren't end up with any dangling
|
|
* pointers.
|
|
*/
|
|
hash_seq_init(&status, LockMethodLocalHash);
|
|
|
|
while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
|
|
{
|
|
if (locallock->proclock == NULL || locallock->lock == NULL)
|
|
{
|
|
/*
|
|
* We must've run out of shared memory while trying to set up this
|
|
* lock. Just forget the local entry.
|
|
*/
|
|
Assert(locallock->nLocks == 0);
|
|
RemoveLocalLock(locallock);
|
|
continue;
|
|
}
|
|
|
|
/* Ignore items that are not of the lockmethod to be removed */
|
|
if (LOCALLOCK_LOCKMETHOD(*locallock) != lockmethodid)
|
|
continue;
|
|
|
|
/*
|
|
* If we are asked to release all locks, we can just zap the entry.
|
|
* Otherwise, must scan to see if there are session locks. We assume
|
|
* there is at most one lockOwners entry for session locks.
|
|
*/
|
|
if (!allLocks)
|
|
{
|
|
LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
|
|
|
|
/* If it's above array position 0, move it down to 0 */
|
|
for (i = locallock->numLockOwners - 1; i > 0; i--)
|
|
{
|
|
if (lockOwners[i].owner == NULL)
|
|
{
|
|
lockOwners[0] = lockOwners[i];
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (locallock->numLockOwners > 0 &&
|
|
lockOwners[0].owner == NULL &&
|
|
lockOwners[0].nLocks > 0)
|
|
{
|
|
/* Fix the locallock to show just the session locks */
|
|
locallock->nLocks = lockOwners[0].nLocks;
|
|
locallock->numLockOwners = 1;
|
|
/* We aren't deleting this locallock, so done */
|
|
continue;
|
|
}
|
|
}
|
|
|
|
/* Mark the proclock to show we need to release this lockmode */
|
|
if (locallock->nLocks > 0)
|
|
locallock->proclock->releaseMask |= LOCKBIT_ON(locallock->tag.mode);
|
|
|
|
/* And remove the locallock hashtable entry */
|
|
RemoveLocalLock(locallock);
|
|
}
|
|
|
|
/*
|
|
* Now, scan each lock partition separately.
|
|
*/
|
|
for (partition = 0; partition < NUM_LOCK_PARTITIONS; partition++)
|
|
{
|
|
LWLockId partitionLock = FirstLockMgrLock + partition;
|
|
SHM_QUEUE *procLocks = &(MyProc->myProcLocks[partition]);
|
|
|
|
proclock = (PROCLOCK *) SHMQueueNext(procLocks, procLocks,
|
|
offsetof(PROCLOCK, procLink));
|
|
|
|
if (!proclock)
|
|
continue; /* needn't examine this partition */
|
|
|
|
LWLockAcquire(partitionLock, LW_EXCLUSIVE);
|
|
|
|
while (proclock)
|
|
{
|
|
bool wakeupNeeded = false;
|
|
PROCLOCK *nextplock;
|
|
|
|
/* Get link first, since we may unlink/delete this proclock */
|
|
nextplock = (PROCLOCK *)
|
|
SHMQueueNext(procLocks, &proclock->procLink,
|
|
offsetof(PROCLOCK, procLink));
|
|
|
|
Assert(proclock->tag.myProc == MyProc);
|
|
|
|
lock = proclock->tag.myLock;
|
|
|
|
/* Ignore items that are not of the lockmethod to be removed */
|
|
if (LOCK_LOCKMETHOD(*lock) != lockmethodid)
|
|
goto next_item;
|
|
|
|
/*
|
|
* In allLocks mode, force release of all locks even if locallock
|
|
* table had problems
|
|
*/
|
|
if (allLocks)
|
|
proclock->releaseMask = proclock->holdMask;
|
|
else
|
|
Assert((proclock->releaseMask & ~proclock->holdMask) == 0);
|
|
|
|
/*
|
|
* Ignore items that have nothing to be released, unless they have
|
|
* holdMask == 0 and are therefore recyclable
|
|
*/
|
|
if (proclock->releaseMask == 0 && proclock->holdMask != 0)
|
|
goto next_item;
|
|
|
|
PROCLOCK_PRINT("LockReleaseAll", proclock);
|
|
LOCK_PRINT("LockReleaseAll", lock, 0);
|
|
Assert(lock->nRequested >= 0);
|
|
Assert(lock->nGranted >= 0);
|
|
Assert(lock->nGranted <= lock->nRequested);
|
|
Assert((proclock->holdMask & ~lock->grantMask) == 0);
|
|
|
|
/*
|
|
* Release the previously-marked lock modes
|
|
*/
|
|
for (i = 1; i <= numLockModes; i++)
|
|
{
|
|
if (proclock->releaseMask & LOCKBIT_ON(i))
|
|
wakeupNeeded |= UnGrantLock(lock, i, proclock,
|
|
lockMethodTable);
|
|
}
|
|
Assert((lock->nRequested >= 0) && (lock->nGranted >= 0));
|
|
Assert(lock->nGranted <= lock->nRequested);
|
|
LOCK_PRINT("LockReleaseAll: updated", lock, 0);
|
|
|
|
proclock->releaseMask = 0;
|
|
|
|
/* CleanUpLock will wake up waiters if needed. */
|
|
CleanUpLock(lock, proclock,
|
|
lockMethodTable,
|
|
LockTagHashCode(&lock->tag),
|
|
wakeupNeeded);
|
|
|
|
next_item:
|
|
proclock = nextplock;
|
|
} /* loop over PROCLOCKs within this partition */
|
|
|
|
LWLockRelease(partitionLock);
|
|
} /* loop over partitions */
|
|
|
|
#ifdef LOCK_DEBUG
|
|
if (*(lockMethodTable->trace_flag))
|
|
elog(LOG, "LockReleaseAll done");
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* LockReleaseCurrentOwner
|
|
* Release all locks belonging to CurrentResourceOwner
|
|
*/
|
|
void
|
|
LockReleaseCurrentOwner(void)
|
|
{
|
|
HASH_SEQ_STATUS status;
|
|
LOCALLOCK *locallock;
|
|
LOCALLOCKOWNER *lockOwners;
|
|
int i;
|
|
|
|
hash_seq_init(&status, LockMethodLocalHash);
|
|
|
|
while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
|
|
{
|
|
/* Ignore items that must be nontransactional */
|
|
if (!LockMethods[LOCALLOCK_LOCKMETHOD(*locallock)]->transactional)
|
|
continue;
|
|
|
|
/* Scan to see if there are any locks belonging to current owner */
|
|
lockOwners = locallock->lockOwners;
|
|
for (i = locallock->numLockOwners - 1; i >= 0; i--)
|
|
{
|
|
if (lockOwners[i].owner == CurrentResourceOwner)
|
|
{
|
|
Assert(lockOwners[i].nLocks > 0);
|
|
if (lockOwners[i].nLocks < locallock->nLocks)
|
|
{
|
|
/*
|
|
* We will still hold this lock after forgetting this
|
|
* ResourceOwner.
|
|
*/
|
|
locallock->nLocks -= lockOwners[i].nLocks;
|
|
/* compact out unused slot */
|
|
locallock->numLockOwners--;
|
|
if (i < locallock->numLockOwners)
|
|
lockOwners[i] = lockOwners[locallock->numLockOwners];
|
|
}
|
|
else
|
|
{
|
|
Assert(lockOwners[i].nLocks == locallock->nLocks);
|
|
/* We want to call LockRelease just once */
|
|
lockOwners[i].nLocks = 1;
|
|
locallock->nLocks = 1;
|
|
if (!LockRelease(&locallock->tag.lock,
|
|
locallock->tag.mode,
|
|
false))
|
|
elog(WARNING, "LockReleaseCurrentOwner: failed??");
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* LockReassignCurrentOwner
|
|
* Reassign all locks belonging to CurrentResourceOwner to belong
|
|
* to its parent resource owner
|
|
*/
|
|
void
|
|
LockReassignCurrentOwner(void)
|
|
{
|
|
ResourceOwner parent = ResourceOwnerGetParent(CurrentResourceOwner);
|
|
HASH_SEQ_STATUS status;
|
|
LOCALLOCK *locallock;
|
|
LOCALLOCKOWNER *lockOwners;
|
|
|
|
Assert(parent != NULL);
|
|
|
|
hash_seq_init(&status, LockMethodLocalHash);
|
|
|
|
while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
|
|
{
|
|
int i;
|
|
int ic = -1;
|
|
int ip = -1;
|
|
|
|
/* Ignore items that must be nontransactional */
|
|
if (!LockMethods[LOCALLOCK_LOCKMETHOD(*locallock)]->transactional)
|
|
continue;
|
|
|
|
/*
|
|
* Scan to see if there are any locks belonging to current owner or
|
|
* its parent
|
|
*/
|
|
lockOwners = locallock->lockOwners;
|
|
for (i = locallock->numLockOwners - 1; i >= 0; i--)
|
|
{
|
|
if (lockOwners[i].owner == CurrentResourceOwner)
|
|
ic = i;
|
|
else if (lockOwners[i].owner == parent)
|
|
ip = i;
|
|
}
|
|
|
|
if (ic < 0)
|
|
continue; /* no current locks */
|
|
|
|
if (ip < 0)
|
|
{
|
|
/* Parent has no slot, so just give it child's slot */
|
|
lockOwners[ic].owner = parent;
|
|
}
|
|
else
|
|
{
|
|
/* Merge child's count with parent's */
|
|
lockOwners[ip].nLocks += lockOwners[ic].nLocks;
|
|
/* compact out unused slot */
|
|
locallock->numLockOwners--;
|
|
if (ic < locallock->numLockOwners)
|
|
lockOwners[ic] = lockOwners[locallock->numLockOwners];
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
* GetLockConflicts
|
|
* Get an array of VirtualTransactionIds of xacts currently holding locks
|
|
* that would conflict with the specified lock/lockmode.
|
|
* xacts merely awaiting such a lock are NOT reported.
|
|
*
|
|
* The result array is palloc'd and is terminated with an invalid VXID.
|
|
*
|
|
* Of course, the result could be out of date by the time it's returned,
|
|
* so use of this function has to be thought about carefully.
|
|
*
|
|
* Note we never include the current xact's vxid in the result array,
|
|
* since an xact never blocks itself. Also, prepared transactions are
|
|
* ignored, which is a bit more debatable but is appropriate for current
|
|
* uses of the result.
|
|
*/
|
|
VirtualTransactionId *
|
|
GetLockConflicts(const LOCKTAG *locktag, LOCKMODE lockmode)
|
|
{
|
|
static VirtualTransactionId *vxids;
|
|
LOCKMETHODID lockmethodid = locktag->locktag_lockmethodid;
|
|
LockMethod lockMethodTable;
|
|
LOCK *lock;
|
|
LOCKMASK conflictMask;
|
|
SHM_QUEUE *procLocks;
|
|
PROCLOCK *proclock;
|
|
uint32 hashcode;
|
|
LWLockId partitionLock;
|
|
int count = 0;
|
|
|
|
if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
|
|
elog(ERROR, "unrecognized lock method: %d", lockmethodid);
|
|
lockMethodTable = LockMethods[lockmethodid];
|
|
if (lockmode <= 0 || lockmode > lockMethodTable->numLockModes)
|
|
elog(ERROR, "unrecognized lock mode: %d", lockmode);
|
|
|
|
/*
|
|
* Allocate memory to store results, and fill with InvalidVXID. We only
|
|
* need enough space for MaxBackends + a terminator, since prepared xacts
|
|
* don't count. InHotStandby allocate once in TopMemoryContext.
|
|
*/
|
|
if (InHotStandby)
|
|
{
|
|
if (vxids == NULL)
|
|
vxids = (VirtualTransactionId *)
|
|
MemoryContextAlloc(TopMemoryContext,
|
|
sizeof(VirtualTransactionId) * (MaxBackends + 1));
|
|
}
|
|
else
|
|
vxids = (VirtualTransactionId *)
|
|
palloc0(sizeof(VirtualTransactionId) * (MaxBackends + 1));
|
|
|
|
/*
|
|
* Look up the lock object matching the tag.
|
|
*/
|
|
hashcode = LockTagHashCode(locktag);
|
|
partitionLock = LockHashPartitionLock(hashcode);
|
|
|
|
LWLockAcquire(partitionLock, LW_SHARED);
|
|
|
|
lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
|
|
(void *) locktag,
|
|
hashcode,
|
|
HASH_FIND,
|
|
NULL);
|
|
if (!lock)
|
|
{
|
|
/*
|
|
* If the lock object doesn't exist, there is nothing holding a lock
|
|
* on this lockable object.
|
|
*/
|
|
LWLockRelease(partitionLock);
|
|
return vxids;
|
|
}
|
|
|
|
/*
|
|
* Examine each existing holder (or awaiter) of the lock.
|
|
*/
|
|
conflictMask = lockMethodTable->conflictTab[lockmode];
|
|
|
|
procLocks = &(lock->procLocks);
|
|
|
|
proclock = (PROCLOCK *) SHMQueueNext(procLocks, procLocks,
|
|
offsetof(PROCLOCK, lockLink));
|
|
|
|
while (proclock)
|
|
{
|
|
if (conflictMask & proclock->holdMask)
|
|
{
|
|
PGPROC *proc = proclock->tag.myProc;
|
|
|
|
/* A backend never blocks itself */
|
|
if (proc != MyProc)
|
|
{
|
|
VirtualTransactionId vxid;
|
|
|
|
GET_VXID_FROM_PGPROC(vxid, *proc);
|
|
|
|
/*
|
|
* If we see an invalid VXID, then either the xact has already
|
|
* committed (or aborted), or it's a prepared xact. In either
|
|
* case we may ignore it.
|
|
*/
|
|
if (VirtualTransactionIdIsValid(vxid))
|
|
vxids[count++] = vxid;
|
|
}
|
|
}
|
|
|
|
proclock = (PROCLOCK *) SHMQueueNext(procLocks, &proclock->lockLink,
|
|
offsetof(PROCLOCK, lockLink));
|
|
}
|
|
|
|
LWLockRelease(partitionLock);
|
|
|
|
if (count > MaxBackends) /* should never happen */
|
|
elog(PANIC, "too many conflicting locks found");
|
|
|
|
return vxids;
|
|
}
|
|
|
|
|
|
/*
|
|
* AtPrepare_Locks
|
|
* Do the preparatory work for a PREPARE: make 2PC state file records
|
|
* for all locks currently held.
|
|
*
|
|
* Non-transactional locks are ignored, as are VXID locks.
|
|
*
|
|
* There are some special cases that we error out on: we can't be holding
|
|
* any session locks (should be OK since only VACUUM uses those) and we
|
|
* can't be holding any locks on temporary objects (since that would mess
|
|
* up the current backend if it tries to exit before the prepared xact is
|
|
* committed).
|
|
*/
|
|
void
|
|
AtPrepare_Locks(void)
|
|
{
|
|
HASH_SEQ_STATUS status;
|
|
LOCALLOCK *locallock;
|
|
|
|
/*
|
|
* We don't need to touch shared memory for this --- all the necessary
|
|
* state information is in the locallock table.
|
|
*/
|
|
hash_seq_init(&status, LockMethodLocalHash);
|
|
|
|
while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
|
|
{
|
|
TwoPhaseLockRecord record;
|
|
LOCALLOCKOWNER *lockOwners = locallock->lockOwners;
|
|
int i;
|
|
|
|
/* Ignore nontransactional locks */
|
|
if (!LockMethods[LOCALLOCK_LOCKMETHOD(*locallock)]->transactional)
|
|
continue;
|
|
|
|
/*
|
|
* Ignore VXID locks. We don't want those to be held by prepared
|
|
* transactions, since they aren't meaningful after a restart.
|
|
*/
|
|
if (locallock->tag.lock.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
|
|
continue;
|
|
|
|
/* Ignore it if we don't actually hold the lock */
|
|
if (locallock->nLocks <= 0)
|
|
continue;
|
|
|
|
/* Scan to verify there are no session locks */
|
|
for (i = locallock->numLockOwners - 1; i >= 0; i--)
|
|
{
|
|
/* elog not ereport since this should not happen */
|
|
if (lockOwners[i].owner == NULL)
|
|
elog(ERROR, "cannot PREPARE when session locks exist");
|
|
}
|
|
|
|
/*
|
|
* Create a 2PC record.
|
|
*/
|
|
memcpy(&(record.locktag), &(locallock->tag.lock), sizeof(LOCKTAG));
|
|
record.lockmode = locallock->tag.mode;
|
|
|
|
RegisterTwoPhaseRecord(TWOPHASE_RM_LOCK_ID, 0,
|
|
&record, sizeof(TwoPhaseLockRecord));
|
|
}
|
|
}
|
|
|
|
/*
|
|
* PostPrepare_Locks
|
|
* Clean up after successful PREPARE
|
|
*
|
|
* Here, we want to transfer ownership of our locks to a dummy PGPROC
|
|
* that's now associated with the prepared transaction, and we want to
|
|
* clean out the corresponding entries in the LOCALLOCK table.
|
|
*
|
|
* Note: by removing the LOCALLOCK entries, we are leaving dangling
|
|
* pointers in the transaction's resource owner. This is OK at the
|
|
* moment since resowner.c doesn't try to free locks retail at a toplevel
|
|
* transaction commit or abort. We could alternatively zero out nLocks
|
|
* and leave the LOCALLOCK entries to be garbage-collected by LockReleaseAll,
|
|
* but that probably costs more cycles.
|
|
*/
|
|
void
|
|
PostPrepare_Locks(TransactionId xid)
|
|
{
|
|
PGPROC *newproc = TwoPhaseGetDummyProc(xid);
|
|
HASH_SEQ_STATUS status;
|
|
LOCALLOCK *locallock;
|
|
LOCK *lock;
|
|
PROCLOCK *proclock;
|
|
PROCLOCKTAG proclocktag;
|
|
bool found;
|
|
int partition;
|
|
|
|
/* This is a critical section: any error means big trouble */
|
|
START_CRIT_SECTION();
|
|
|
|
/*
|
|
* First we run through the locallock table and get rid of unwanted
|
|
* entries, then we scan the process's proclocks and transfer them to the
|
|
* target proc.
|
|
*
|
|
* We do this separately because we may have multiple locallock entries
|
|
* pointing to the same proclock, and we daren't end up with any dangling
|
|
* pointers.
|
|
*/
|
|
hash_seq_init(&status, LockMethodLocalHash);
|
|
|
|
while ((locallock = (LOCALLOCK *) hash_seq_search(&status)) != NULL)
|
|
{
|
|
if (locallock->proclock == NULL || locallock->lock == NULL)
|
|
{
|
|
/*
|
|
* We must've run out of shared memory while trying to set up this
|
|
* lock. Just forget the local entry.
|
|
*/
|
|
Assert(locallock->nLocks == 0);
|
|
RemoveLocalLock(locallock);
|
|
continue;
|
|
}
|
|
|
|
/* Ignore nontransactional locks */
|
|
if (!LockMethods[LOCALLOCK_LOCKMETHOD(*locallock)]->transactional)
|
|
continue;
|
|
|
|
/* Ignore VXID locks */
|
|
if (locallock->tag.lock.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
|
|
continue;
|
|
|
|
/* We already checked there are no session locks */
|
|
|
|
/* Mark the proclock to show we need to release this lockmode */
|
|
if (locallock->nLocks > 0)
|
|
locallock->proclock->releaseMask |= LOCKBIT_ON(locallock->tag.mode);
|
|
|
|
/* And remove the locallock hashtable entry */
|
|
RemoveLocalLock(locallock);
|
|
}
|
|
|
|
/*
|
|
* Now, scan each lock partition separately.
|
|
*/
|
|
for (partition = 0; partition < NUM_LOCK_PARTITIONS; partition++)
|
|
{
|
|
LWLockId partitionLock = FirstLockMgrLock + partition;
|
|
SHM_QUEUE *procLocks = &(MyProc->myProcLocks[partition]);
|
|
|
|
proclock = (PROCLOCK *) SHMQueueNext(procLocks, procLocks,
|
|
offsetof(PROCLOCK, procLink));
|
|
|
|
if (!proclock)
|
|
continue; /* needn't examine this partition */
|
|
|
|
LWLockAcquire(partitionLock, LW_EXCLUSIVE);
|
|
|
|
while (proclock)
|
|
{
|
|
PROCLOCK *nextplock;
|
|
LOCKMASK holdMask;
|
|
PROCLOCK *newproclock;
|
|
|
|
/* Get link first, since we may unlink/delete this proclock */
|
|
nextplock = (PROCLOCK *)
|
|
SHMQueueNext(procLocks, &proclock->procLink,
|
|
offsetof(PROCLOCK, procLink));
|
|
|
|
Assert(proclock->tag.myProc == MyProc);
|
|
|
|
lock = proclock->tag.myLock;
|
|
|
|
/* Ignore nontransactional locks */
|
|
if (!LockMethods[LOCK_LOCKMETHOD(*lock)]->transactional)
|
|
goto next_item;
|
|
|
|
/* Ignore VXID locks */
|
|
if (lock->tag.locktag_type == LOCKTAG_VIRTUALTRANSACTION)
|
|
goto next_item;
|
|
|
|
PROCLOCK_PRINT("PostPrepare_Locks", proclock);
|
|
LOCK_PRINT("PostPrepare_Locks", lock, 0);
|
|
Assert(lock->nRequested >= 0);
|
|
Assert(lock->nGranted >= 0);
|
|
Assert(lock->nGranted <= lock->nRequested);
|
|
Assert((proclock->holdMask & ~lock->grantMask) == 0);
|
|
|
|
/*
|
|
* Since there were no session locks, we should be releasing all
|
|
* locks
|
|
*/
|
|
if (proclock->releaseMask != proclock->holdMask)
|
|
elog(PANIC, "we seem to have dropped a bit somewhere");
|
|
|
|
holdMask = proclock->holdMask;
|
|
|
|
/*
|
|
* We cannot simply modify proclock->tag.myProc to reassign
|
|
* ownership of the lock, because that's part of the hash key and
|
|
* the proclock would then be in the wrong hash chain. So, unlink
|
|
* and delete the old proclock; create a new one with the right
|
|
* contents; and link it into place. We do it in this order to be
|
|
* certain we won't run out of shared memory (the way dynahash.c
|
|
* works, the deleted object is certain to be available for
|
|
* reallocation).
|
|
*/
|
|
SHMQueueDelete(&proclock->lockLink);
|
|
SHMQueueDelete(&proclock->procLink);
|
|
if (!hash_search(LockMethodProcLockHash,
|
|
(void *) &(proclock->tag),
|
|
HASH_REMOVE, NULL))
|
|
elog(PANIC, "proclock table corrupted");
|
|
|
|
/*
|
|
* Create the hash key for the new proclock table.
|
|
*/
|
|
proclocktag.myLock = lock;
|
|
proclocktag.myProc = newproc;
|
|
|
|
newproclock = (PROCLOCK *) hash_search(LockMethodProcLockHash,
|
|
(void *) &proclocktag,
|
|
HASH_ENTER_NULL, &found);
|
|
if (!newproclock)
|
|
ereport(PANIC, /* should not happen */
|
|
(errcode(ERRCODE_OUT_OF_MEMORY),
|
|
errmsg("out of shared memory"),
|
|
errdetail("Not enough memory for reassigning the prepared transaction's locks.")));
|
|
|
|
/*
|
|
* If new, initialize the new entry
|
|
*/
|
|
if (!found)
|
|
{
|
|
newproclock->holdMask = 0;
|
|
newproclock->releaseMask = 0;
|
|
/* Add new proclock to appropriate lists */
|
|
SHMQueueInsertBefore(&lock->procLocks, &newproclock->lockLink);
|
|
SHMQueueInsertBefore(&(newproc->myProcLocks[partition]),
|
|
&newproclock->procLink);
|
|
PROCLOCK_PRINT("PostPrepare_Locks: new", newproclock);
|
|
}
|
|
else
|
|
{
|
|
PROCLOCK_PRINT("PostPrepare_Locks: found", newproclock);
|
|
Assert((newproclock->holdMask & ~lock->grantMask) == 0);
|
|
}
|
|
|
|
/*
|
|
* Pass over the identified lock ownership.
|
|
*/
|
|
Assert((newproclock->holdMask & holdMask) == 0);
|
|
newproclock->holdMask |= holdMask;
|
|
|
|
next_item:
|
|
proclock = nextplock;
|
|
} /* loop over PROCLOCKs within this partition */
|
|
|
|
LWLockRelease(partitionLock);
|
|
} /* loop over partitions */
|
|
|
|
END_CRIT_SECTION();
|
|
}
|
|
|
|
|
|
/*
|
|
* Estimate shared-memory space used for lock tables
|
|
*/
|
|
Size
|
|
LockShmemSize(void)
|
|
{
|
|
Size size = 0;
|
|
long max_table_size;
|
|
|
|
/* lock hash table */
|
|
max_table_size = NLOCKENTS();
|
|
size = add_size(size, hash_estimate_size(max_table_size, sizeof(LOCK)));
|
|
|
|
/* proclock hash table */
|
|
max_table_size *= 2;
|
|
size = add_size(size, hash_estimate_size(max_table_size, sizeof(PROCLOCK)));
|
|
|
|
/*
|
|
* Since NLOCKENTS is only an estimate, add 10% safety margin.
|
|
*/
|
|
size = add_size(size, size / 10);
|
|
|
|
return size;
|
|
}
|
|
|
|
/*
|
|
* GetLockStatusData - Return a summary of the lock manager's internal
|
|
* status, for use in a user-level reporting function.
|
|
*
|
|
* The return data consists of an array of PROCLOCK objects, with the
|
|
* associated PGPROC and LOCK objects for each. Note that multiple
|
|
* copies of the same PGPROC and/or LOCK objects are likely to appear.
|
|
* It is the caller's responsibility to match up duplicates if wanted.
|
|
*
|
|
* The design goal is to hold the LWLocks for as short a time as possible;
|
|
* thus, this function simply makes a copy of the necessary data and releases
|
|
* the locks, allowing the caller to contemplate and format the data for as
|
|
* long as it pleases.
|
|
*/
|
|
LockData *
|
|
GetLockStatusData(void)
|
|
{
|
|
LockData *data;
|
|
PROCLOCK *proclock;
|
|
HASH_SEQ_STATUS seqstat;
|
|
int els;
|
|
int el;
|
|
int i;
|
|
|
|
data = (LockData *) palloc(sizeof(LockData));
|
|
|
|
/*
|
|
* Acquire lock on the entire shared lock data structure. We can't
|
|
* operate one partition at a time if we want to deliver a self-consistent
|
|
* view of the state.
|
|
*
|
|
* Since this is a read-only operation, we take shared instead of
|
|
* exclusive lock. There's not a whole lot of point to this, because all
|
|
* the normal operations require exclusive lock, but it doesn't hurt
|
|
* anything either. It will at least allow two backends to do
|
|
* GetLockStatusData in parallel.
|
|
*
|
|
* Must grab LWLocks in partition-number order to avoid LWLock deadlock.
|
|
*/
|
|
for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
|
|
LWLockAcquire(FirstLockMgrLock + i, LW_SHARED);
|
|
|
|
/* Now we can safely count the number of proclocks */
|
|
els = hash_get_num_entries(LockMethodProcLockHash);
|
|
|
|
data->nelements = els;
|
|
data->proclocks = (PROCLOCK *) palloc(sizeof(PROCLOCK) * els);
|
|
data->procs = (PGPROC *) palloc(sizeof(PGPROC) * els);
|
|
data->locks = (LOCK *) palloc(sizeof(LOCK) * els);
|
|
|
|
/* Now scan the tables to copy the data */
|
|
hash_seq_init(&seqstat, LockMethodProcLockHash);
|
|
|
|
el = 0;
|
|
while ((proclock = (PROCLOCK *) hash_seq_search(&seqstat)))
|
|
{
|
|
PGPROC *proc = proclock->tag.myProc;
|
|
LOCK *lock = proclock->tag.myLock;
|
|
|
|
memcpy(&(data->proclocks[el]), proclock, sizeof(PROCLOCK));
|
|
memcpy(&(data->procs[el]), proc, sizeof(PGPROC));
|
|
memcpy(&(data->locks[el]), lock, sizeof(LOCK));
|
|
|
|
el++;
|
|
}
|
|
|
|
/*
|
|
* And release locks. We do this in reverse order for two reasons: (1)
|
|
* Anyone else who needs more than one of the locks will be trying to lock
|
|
* them in increasing order; we don't want to release the other process
|
|
* until it can get all the locks it needs. (2) This avoids O(N^2)
|
|
* behavior inside LWLockRelease.
|
|
*/
|
|
for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
|
|
LWLockRelease(FirstLockMgrLock + i);
|
|
|
|
Assert(el == data->nelements);
|
|
|
|
return data;
|
|
}
|
|
|
|
/*
|
|
* Returns a list of currently held AccessExclusiveLocks, for use
|
|
* by GetRunningTransactionData().
|
|
*/
|
|
xl_standby_lock *
|
|
GetRunningTransactionLocks(int *nlocks)
|
|
{
|
|
PROCLOCK *proclock;
|
|
HASH_SEQ_STATUS seqstat;
|
|
int i;
|
|
int index;
|
|
int els;
|
|
xl_standby_lock *accessExclusiveLocks;
|
|
|
|
/*
|
|
* Acquire lock on the entire shared lock data structure.
|
|
*
|
|
* Must grab LWLocks in partition-number order to avoid LWLock deadlock.
|
|
*/
|
|
for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
|
|
LWLockAcquire(FirstLockMgrLock + i, LW_SHARED);
|
|
|
|
/* Now scan the tables to copy the data */
|
|
hash_seq_init(&seqstat, LockMethodProcLockHash);
|
|
|
|
/* Now we can safely count the number of proclocks */
|
|
els = hash_get_num_entries(LockMethodProcLockHash);
|
|
|
|
/*
|
|
* Allocating enough space for all locks in the lock table is overkill,
|
|
* but it's more convenient and faster than having to enlarge the array.
|
|
*/
|
|
accessExclusiveLocks = palloc(els * sizeof(xl_standby_lock));
|
|
|
|
/*
|
|
* If lock is a currently granted AccessExclusiveLock then
|
|
* it will have just one proclock holder, so locks are never
|
|
* accessed twice in this particular case. Don't copy this code
|
|
* for use elsewhere because in the general case this will
|
|
* give you duplicate locks when looking at non-exclusive lock types.
|
|
*/
|
|
index = 0;
|
|
while ((proclock = (PROCLOCK *) hash_seq_search(&seqstat)))
|
|
{
|
|
/* make sure this definition matches the one used in LockAcquire */
|
|
if ((proclock->holdMask & LOCKBIT_ON(AccessExclusiveLock)) &&
|
|
proclock->tag.myLock->tag.locktag_type == LOCKTAG_RELATION)
|
|
{
|
|
PGPROC *proc = proclock->tag.myProc;
|
|
LOCK *lock = proclock->tag.myLock;
|
|
|
|
accessExclusiveLocks[index].xid = proc->xid;
|
|
accessExclusiveLocks[index].dbOid = lock->tag.locktag_field1;
|
|
accessExclusiveLocks[index].relOid = lock->tag.locktag_field2;
|
|
|
|
index++;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* And release locks. We do this in reverse order for two reasons: (1)
|
|
* Anyone else who needs more than one of the locks will be trying to lock
|
|
* them in increasing order; we don't want to release the other process
|
|
* until it can get all the locks it needs. (2) This avoids O(N^2)
|
|
* behavior inside LWLockRelease.
|
|
*/
|
|
for (i = NUM_LOCK_PARTITIONS; --i >= 0;)
|
|
LWLockRelease(FirstLockMgrLock + i);
|
|
|
|
*nlocks = index;
|
|
return accessExclusiveLocks;
|
|
}
|
|
|
|
/* Provide the textual name of any lock mode */
|
|
const char *
|
|
GetLockmodeName(LOCKMETHODID lockmethodid, LOCKMODE mode)
|
|
{
|
|
Assert(lockmethodid > 0 && lockmethodid < lengthof(LockMethods));
|
|
Assert(mode > 0 && mode <= LockMethods[lockmethodid]->numLockModes);
|
|
return LockMethods[lockmethodid]->lockModeNames[mode];
|
|
}
|
|
|
|
#ifdef LOCK_DEBUG
|
|
/*
|
|
* Dump all locks in the given proc's myProcLocks lists.
|
|
*
|
|
* Caller is responsible for having acquired appropriate LWLocks.
|
|
*/
|
|
void
|
|
DumpLocks(PGPROC *proc)
|
|
{
|
|
SHM_QUEUE *procLocks;
|
|
PROCLOCK *proclock;
|
|
LOCK *lock;
|
|
int i;
|
|
|
|
if (proc == NULL)
|
|
return;
|
|
|
|
if (proc->waitLock)
|
|
LOCK_PRINT("DumpLocks: waiting on", proc->waitLock, 0);
|
|
|
|
for (i = 0; i < NUM_LOCK_PARTITIONS; i++)
|
|
{
|
|
procLocks = &(proc->myProcLocks[i]);
|
|
|
|
proclock = (PROCLOCK *) SHMQueueNext(procLocks, procLocks,
|
|
offsetof(PROCLOCK, procLink));
|
|
|
|
while (proclock)
|
|
{
|
|
Assert(proclock->tag.myProc == proc);
|
|
|
|
lock = proclock->tag.myLock;
|
|
|
|
PROCLOCK_PRINT("DumpLocks", proclock);
|
|
LOCK_PRINT("DumpLocks", lock, 0);
|
|
|
|
proclock = (PROCLOCK *)
|
|
SHMQueueNext(procLocks, &proclock->procLink,
|
|
offsetof(PROCLOCK, procLink));
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Dump all lmgr locks.
|
|
*
|
|
* Caller is responsible for having acquired appropriate LWLocks.
|
|
*/
|
|
void
|
|
DumpAllLocks(void)
|
|
{
|
|
PGPROC *proc;
|
|
PROCLOCK *proclock;
|
|
LOCK *lock;
|
|
HASH_SEQ_STATUS status;
|
|
|
|
proc = MyProc;
|
|
|
|
if (proc && proc->waitLock)
|
|
LOCK_PRINT("DumpAllLocks: waiting on", proc->waitLock, 0);
|
|
|
|
hash_seq_init(&status, LockMethodProcLockHash);
|
|
|
|
while ((proclock = (PROCLOCK *) hash_seq_search(&status)) != NULL)
|
|
{
|
|
PROCLOCK_PRINT("DumpAllLocks", proclock);
|
|
|
|
lock = proclock->tag.myLock;
|
|
if (lock)
|
|
LOCK_PRINT("DumpAllLocks", lock, 0);
|
|
else
|
|
elog(LOG, "DumpAllLocks: proclock->tag.myLock = NULL");
|
|
}
|
|
}
|
|
#endif /* LOCK_DEBUG */
|
|
|
|
/*
|
|
* LOCK 2PC resource manager's routines
|
|
*/
|
|
|
|
/*
|
|
* Re-acquire a lock belonging to a transaction that was prepared.
|
|
*
|
|
* Because this function is run at db startup, re-acquiring the locks should
|
|
* never conflict with running transactions because there are none. We
|
|
* assume that the lock state represented by the stored 2PC files is legal.
|
|
*
|
|
* When switching from Hot Standby mode to normal operation, the locks will
|
|
* be already held by the startup process. The locks are acquired for the new
|
|
* procs without checking for conflicts, so we don'get a conflict between the
|
|
* startup process and the dummy procs, even though we will momentarily have
|
|
* a situation where two procs are holding the same AccessExclusiveLock,
|
|
* which isn't normally possible because the conflict. If we're in standby
|
|
* mode, but a recovery snapshot hasn't been established yet, it's possible
|
|
* that some but not all of the locks are already held by the startup process.
|
|
*
|
|
* This approach is simple, but also a bit dangerous, because if there isn't
|
|
* enough shared memory to acquire the locks, an error will be thrown, which
|
|
* is promoted to FATAL and recovery will abort, bringing down postmaster.
|
|
* A safer approach would be to transfer the locks like we do in
|
|
* AtPrepare_Locks, but then again, in hot standby mode it's possible for
|
|
* read-only backends to use up all the shared lock memory anyway, so that
|
|
* replaying the WAL record that needs to acquire a lock will throw an error
|
|
* and PANIC anyway.
|
|
*/
|
|
void
|
|
lock_twophase_recover(TransactionId xid, uint16 info,
|
|
void *recdata, uint32 len)
|
|
{
|
|
TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
|
|
PGPROC *proc = TwoPhaseGetDummyProc(xid);
|
|
LOCKTAG *locktag;
|
|
LOCKMODE lockmode;
|
|
LOCKMETHODID lockmethodid;
|
|
LOCK *lock;
|
|
PROCLOCK *proclock;
|
|
PROCLOCKTAG proclocktag;
|
|
bool found;
|
|
uint32 hashcode;
|
|
uint32 proclock_hashcode;
|
|
int partition;
|
|
LWLockId partitionLock;
|
|
LockMethod lockMethodTable;
|
|
|
|
Assert(len == sizeof(TwoPhaseLockRecord));
|
|
locktag = &rec->locktag;
|
|
lockmode = rec->lockmode;
|
|
lockmethodid = locktag->locktag_lockmethodid;
|
|
|
|
if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
|
|
elog(ERROR, "unrecognized lock method: %d", lockmethodid);
|
|
lockMethodTable = LockMethods[lockmethodid];
|
|
|
|
hashcode = LockTagHashCode(locktag);
|
|
partition = LockHashPartition(hashcode);
|
|
partitionLock = LockHashPartitionLock(hashcode);
|
|
|
|
LWLockAcquire(partitionLock, LW_EXCLUSIVE);
|
|
|
|
/*
|
|
* Find or create a lock with this tag.
|
|
*/
|
|
lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
|
|
(void *) locktag,
|
|
hashcode,
|
|
HASH_ENTER_NULL,
|
|
&found);
|
|
if (!lock)
|
|
{
|
|
LWLockRelease(partitionLock);
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_OUT_OF_MEMORY),
|
|
errmsg("out of shared memory"),
|
|
errhint("You might need to increase max_locks_per_transaction.")));
|
|
}
|
|
|
|
/*
|
|
* if it's a new lock object, initialize it
|
|
*/
|
|
if (!found)
|
|
{
|
|
lock->grantMask = 0;
|
|
lock->waitMask = 0;
|
|
SHMQueueInit(&(lock->procLocks));
|
|
ProcQueueInit(&(lock->waitProcs));
|
|
lock->nRequested = 0;
|
|
lock->nGranted = 0;
|
|
MemSet(lock->requested, 0, sizeof(int) * MAX_LOCKMODES);
|
|
MemSet(lock->granted, 0, sizeof(int) * MAX_LOCKMODES);
|
|
LOCK_PRINT("lock_twophase_recover: new", lock, lockmode);
|
|
}
|
|
else
|
|
{
|
|
LOCK_PRINT("lock_twophase_recover: found", lock, lockmode);
|
|
Assert((lock->nRequested >= 0) && (lock->requested[lockmode] >= 0));
|
|
Assert((lock->nGranted >= 0) && (lock->granted[lockmode] >= 0));
|
|
Assert(lock->nGranted <= lock->nRequested);
|
|
}
|
|
|
|
/*
|
|
* Create the hash key for the proclock table.
|
|
*/
|
|
proclocktag.myLock = lock;
|
|
proclocktag.myProc = proc;
|
|
|
|
proclock_hashcode = ProcLockHashCode(&proclocktag, hashcode);
|
|
|
|
/*
|
|
* Find or create a proclock entry with this tag
|
|
*/
|
|
proclock = (PROCLOCK *) hash_search_with_hash_value(LockMethodProcLockHash,
|
|
(void *) &proclocktag,
|
|
proclock_hashcode,
|
|
HASH_ENTER_NULL,
|
|
&found);
|
|
if (!proclock)
|
|
{
|
|
/* Ooops, not enough shmem for the proclock */
|
|
if (lock->nRequested == 0)
|
|
{
|
|
/*
|
|
* There are no other requestors of this lock, so garbage-collect
|
|
* the lock object. We *must* do this to avoid a permanent leak
|
|
* of shared memory, because there won't be anything to cause
|
|
* anyone to release the lock object later.
|
|
*/
|
|
Assert(SHMQueueEmpty(&(lock->procLocks)));
|
|
if (!hash_search_with_hash_value(LockMethodLockHash,
|
|
(void *) &(lock->tag),
|
|
hashcode,
|
|
HASH_REMOVE,
|
|
NULL))
|
|
elog(PANIC, "lock table corrupted");
|
|
}
|
|
LWLockRelease(partitionLock);
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_OUT_OF_MEMORY),
|
|
errmsg("out of shared memory"),
|
|
errhint("You might need to increase max_locks_per_transaction.")));
|
|
}
|
|
|
|
/*
|
|
* If new, initialize the new entry
|
|
*/
|
|
if (!found)
|
|
{
|
|
proclock->holdMask = 0;
|
|
proclock->releaseMask = 0;
|
|
/* Add proclock to appropriate lists */
|
|
SHMQueueInsertBefore(&lock->procLocks, &proclock->lockLink);
|
|
SHMQueueInsertBefore(&(proc->myProcLocks[partition]),
|
|
&proclock->procLink);
|
|
PROCLOCK_PRINT("lock_twophase_recover: new", proclock);
|
|
}
|
|
else
|
|
{
|
|
PROCLOCK_PRINT("lock_twophase_recover: found", proclock);
|
|
Assert((proclock->holdMask & ~lock->grantMask) == 0);
|
|
}
|
|
|
|
/*
|
|
* lock->nRequested and lock->requested[] count the total number of
|
|
* requests, whether granted or waiting, so increment those immediately.
|
|
*/
|
|
lock->nRequested++;
|
|
lock->requested[lockmode]++;
|
|
Assert((lock->nRequested > 0) && (lock->requested[lockmode] > 0));
|
|
|
|
/*
|
|
* We shouldn't already hold the desired lock.
|
|
*/
|
|
if (proclock->holdMask & LOCKBIT_ON(lockmode))
|
|
elog(ERROR, "lock %s on object %u/%u/%u is already held",
|
|
lockMethodTable->lockModeNames[lockmode],
|
|
lock->tag.locktag_field1, lock->tag.locktag_field2,
|
|
lock->tag.locktag_field3);
|
|
|
|
/*
|
|
* We ignore any possible conflicts and just grant ourselves the lock.
|
|
* Not only because we don't bother, but also to avoid deadlocks when
|
|
* switching from standby to normal mode. See function comment.
|
|
*/
|
|
GrantLock(lock, proclock, lockmode);
|
|
|
|
LWLockRelease(partitionLock);
|
|
}
|
|
|
|
/*
|
|
* Re-acquire a lock belonging to a transaction that was prepared, when
|
|
* when starting up into hot standby mode.
|
|
*/
|
|
void
|
|
lock_twophase_standby_recover(TransactionId xid, uint16 info,
|
|
void *recdata, uint32 len)
|
|
{
|
|
TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
|
|
LOCKTAG *locktag;
|
|
LOCKMODE lockmode;
|
|
LOCKMETHODID lockmethodid;
|
|
|
|
Assert(len == sizeof(TwoPhaseLockRecord));
|
|
locktag = &rec->locktag;
|
|
lockmode = rec->lockmode;
|
|
lockmethodid = locktag->locktag_lockmethodid;
|
|
|
|
if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
|
|
elog(ERROR, "unrecognized lock method: %d", lockmethodid);
|
|
|
|
if (lockmode == AccessExclusiveLock &&
|
|
locktag->locktag_type == LOCKTAG_RELATION)
|
|
{
|
|
StandbyAcquireAccessExclusiveLock(xid,
|
|
locktag->locktag_field1 /* dboid */,
|
|
locktag->locktag_field2 /* reloid */);
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
* 2PC processing routine for COMMIT PREPARED case.
|
|
*
|
|
* Find and release the lock indicated by the 2PC record.
|
|
*/
|
|
void
|
|
lock_twophase_postcommit(TransactionId xid, uint16 info,
|
|
void *recdata, uint32 len)
|
|
{
|
|
TwoPhaseLockRecord *rec = (TwoPhaseLockRecord *) recdata;
|
|
PGPROC *proc = TwoPhaseGetDummyProc(xid);
|
|
LOCKTAG *locktag;
|
|
LOCKMODE lockmode;
|
|
LOCKMETHODID lockmethodid;
|
|
LOCK *lock;
|
|
PROCLOCK *proclock;
|
|
PROCLOCKTAG proclocktag;
|
|
uint32 hashcode;
|
|
uint32 proclock_hashcode;
|
|
LWLockId partitionLock;
|
|
LockMethod lockMethodTable;
|
|
bool wakeupNeeded;
|
|
|
|
Assert(len == sizeof(TwoPhaseLockRecord));
|
|
locktag = &rec->locktag;
|
|
lockmode = rec->lockmode;
|
|
lockmethodid = locktag->locktag_lockmethodid;
|
|
|
|
if (lockmethodid <= 0 || lockmethodid >= lengthof(LockMethods))
|
|
elog(ERROR, "unrecognized lock method: %d", lockmethodid);
|
|
lockMethodTable = LockMethods[lockmethodid];
|
|
|
|
hashcode = LockTagHashCode(locktag);
|
|
partitionLock = LockHashPartitionLock(hashcode);
|
|
|
|
LWLockAcquire(partitionLock, LW_EXCLUSIVE);
|
|
|
|
/*
|
|
* Re-find the lock object (it had better be there).
|
|
*/
|
|
lock = (LOCK *) hash_search_with_hash_value(LockMethodLockHash,
|
|
(void *) locktag,
|
|
hashcode,
|
|
HASH_FIND,
|
|
NULL);
|
|
if (!lock)
|
|
elog(PANIC, "failed to re-find shared lock object");
|
|
|
|
/*
|
|
* Re-find the proclock object (ditto).
|
|
*/
|
|
proclocktag.myLock = lock;
|
|
proclocktag.myProc = proc;
|
|
|
|
proclock_hashcode = ProcLockHashCode(&proclocktag, hashcode);
|
|
|
|
proclock = (PROCLOCK *) hash_search_with_hash_value(LockMethodProcLockHash,
|
|
(void *) &proclocktag,
|
|
proclock_hashcode,
|
|
HASH_FIND,
|
|
NULL);
|
|
if (!proclock)
|
|
elog(PANIC, "failed to re-find shared proclock object");
|
|
|
|
/*
|
|
* Double-check that we are actually holding a lock of the type we want to
|
|
* release.
|
|
*/
|
|
if (!(proclock->holdMask & LOCKBIT_ON(lockmode)))
|
|
{
|
|
PROCLOCK_PRINT("lock_twophase_postcommit: WRONGTYPE", proclock);
|
|
LWLockRelease(partitionLock);
|
|
elog(WARNING, "you don't own a lock of type %s",
|
|
lockMethodTable->lockModeNames[lockmode]);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Do the releasing. CleanUpLock will waken any now-wakable waiters.
|
|
*/
|
|
wakeupNeeded = UnGrantLock(lock, lockmode, proclock, lockMethodTable);
|
|
|
|
CleanUpLock(lock, proclock,
|
|
lockMethodTable, hashcode,
|
|
wakeupNeeded);
|
|
|
|
LWLockRelease(partitionLock);
|
|
}
|
|
|
|
/*
|
|
* 2PC processing routine for ROLLBACK PREPARED case.
|
|
*
|
|
* This is actually just the same as the COMMIT case.
|
|
*/
|
|
void
|
|
lock_twophase_postabort(TransactionId xid, uint16 info,
|
|
void *recdata, uint32 len)
|
|
{
|
|
lock_twophase_postcommit(xid, info, recdata, len);
|
|
}
|