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3a694bb0a1
Essentially, we shoehorn in a lockable-object-type field by taking a byte away from the lockmethodid, which can surely fit in one byte instead of two. This allows less artificial definitions of all the other fields of LOCKTAG; we can get rid of the special pg_xactlock pseudo-relation, and also support locks on individual tuples and general database objects (including shared objects). None of those possibilities are actually exploited just yet, however. I removed pg_xactlock from pg_class, but did not force initdb for that change. At this point, relkind 's' (SPECIAL) is unused and could be removed entirely.
80 lines
1.5 KiB
C
80 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 = (id1), \
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(locktag).locktag_field2 = (id2), \
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(locktag).locktag_field3 = MyDatabaseId, \
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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, InvalidTransactionId,
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lockmode, true);
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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, InvalidTransactionId, lockmode);
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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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return LockReleaseAll(USER_LOCKMETHOD, true);
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}
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