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(table or index) before trying to open its relcache entry. This fixes race conditions in which someone else commits a change to the relation's catalog entries while we are in process of doing relcache load. Problems of that ilk have been reported sporadically for years, but it was not really practical to fix until recently --- for instance, the recent addition of WAL-log support for in-place updates helped. Along the way, remove pg_am.amconcurrent: all AMs are now expected to support concurrent update.
83 lines
1.5 KiB
C
83 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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PG_MODULE_MAGIC;
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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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(locktag).locktag_lockmethodid = USER_LOCKMETHOD)
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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(&tag, 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(&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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