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8563ccae2c
it is sufficient to track whether a backend holds a lock or not, and store information about transaction vs. session locks only in the inside-the-backend LocalLockTable. Since there can now be but one PROCLOCK per lock per backend, LockCountMyLocks() is no longer needed, thus eliminating some O(N^2) behavior when a backend holds many locks. Also simplify the LockAcquire/LockRelease API by passing just a 'sessionLock' boolean instead of a transaction ID. The previous API was designed with the idea that per-transaction lock holding would be important for subtransactions, but now that we have subtransactions we know that this is unwanted. While at it, add an 'isTempObject' parameter to LockAcquire to indicate whether the lock is being taken on a temp table. This is not used just yet, but will be needed shortly for two-phase commit.
82 lines
1.5 KiB
C
82 lines
1.5 KiB
C
/*
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* user_locks.c --
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*
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* This loadable module provides support for user-level long-term
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* cooperative locks.
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*
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* Copyright (C) 1999, Massimo Dal Zotto <dz@cs.unitn.it>
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*
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* This software is distributed under the GNU General Public License
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* either version 2, or (at your option) any later version.
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*/
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#include "postgres.h"
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#include "miscadmin.h"
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#include "storage/lmgr.h"
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#include "storage/proc.h"
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#include "user_locks.h"
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#define SET_LOCKTAG_USERLOCK(locktag,id1,id2) \
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((locktag).locktag_field1 = MyDatabaseId, \
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(locktag).locktag_field2 = (id1), \
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(locktag).locktag_field3 = (id2), \
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(locktag).locktag_field4 = 0, \
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(locktag).locktag_type = LOCKTAG_USERLOCK)
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int
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user_lock(uint32 id1, uint32 id2, LOCKMODE lockmode)
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{
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LOCKTAG tag;
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SET_LOCKTAG_USERLOCK(tag, id1, id2);
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return (LockAcquire(USER_LOCKMETHOD, &tag, false,
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lockmode, true, true) != LOCKACQUIRE_NOT_AVAIL);
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}
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int
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user_unlock(uint32 id1, uint32 id2, LOCKMODE lockmode)
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{
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LOCKTAG tag;
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SET_LOCKTAG_USERLOCK(tag, id1, id2);
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return LockRelease(USER_LOCKMETHOD, &tag, lockmode, true);
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}
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int
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user_write_lock(uint32 id1, uint32 id2)
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{
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return user_lock(id1, id2, ExclusiveLock);
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}
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int
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user_write_unlock(uint32 id1, uint32 id2)
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{
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return user_unlock(id1, id2, ExclusiveLock);
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}
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int
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user_write_lock_oid(Oid oid)
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{
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return user_lock(0, oid, ExclusiveLock);
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}
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int
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user_write_unlock_oid(Oid oid)
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{
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return user_unlock(0, oid, ExclusiveLock);
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}
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int
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user_unlock_all(void)
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{
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LockReleaseAll(USER_LOCKMETHOD, true);
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return true;
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}
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