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Simplify lock manager data structures by making a clear separation between

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the data defining the semantics of a lock method (ie, conflict resolution
table and ancillary data, which is all constant) and the hash tables
storing the current state.  The only thing we give up by this is the
ability to use separate hashtables for different lock methods, but there
is no need for that anyway.  Put some extra fields into the LockMethod
definition structs to clean up some other uglinesses, like hard-wired
tests for DEFAULT_LOCKMETHOD and USER_LOCKMETHOD.  This commit doesn't
do anything about the performance issues we were discussing, but it clears
away some of the underbrush that's in the way of fixing that.
REL8_2_STABLE
Tom Lane 20 years ago
parent 34848052d0
commit c599a247bb
12 changed files with 396 additions and 576 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 7
      contrib/userlock/user_locks.c
  2. 5
      src/backend/storage/ipc/ipci.c
  3. 27
      src/backend/storage/lmgr/README
  4. 5
      src/backend/storage/lmgr/deadlock.c
  5. 142
      src/backend/storage/lmgr/lmgr.c
  6. 596
      src/backend/storage/lmgr/lock.c
  7. 4
      src/backend/storage/lmgr/proc.c
  8. 5
      src/backend/utils/adt/lockfuncs.c
  9. 4
      src/backend/utils/cache/relcache.c
  10. 25
      src/include/storage/lmgr.h
  11. 119
      src/include/storage/lock.h
  12. 33
      src/tools/backend/index.html

7
contrib/userlock/user_locks.c
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@ -23,7 +23,8 @@
(locktag).locktag_field2 = (id1), \
(locktag).locktag_field3 = (id2), \
(locktag).locktag_field4 = 0, \
(locktag).locktag_type = LOCKTAG_USERLOCK)
(locktag).locktag_type = LOCKTAG_USERLOCK, \
(locktag).locktag_lockmethodid = USER_LOCKMETHOD)
int
@ -33,7 +34,7 @@ user_lock(uint32 id1, uint32 id2, LOCKMODE lockmode)
SET_LOCKTAG_USERLOCK(tag, id1, id2);
return (LockAcquire(USER_LOCKMETHOD, &tag, false,
return (LockAcquire(&tag, false,
lockmode, true, true) != LOCKACQUIRE_NOT_AVAIL);
}
@ -44,7 +45,7 @@ user_unlock(uint32 id1, uint32 id2, LOCKMODE lockmode)
SET_LOCKTAG_USERLOCK(tag, id1, id2);
return LockRelease(USER_LOCKMETHOD, &tag, lockmode, true);
return LockRelease(&tag, lockmode, true);
}
int

5
src/backend/storage/ipc/ipci.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/ipc/ipci.c,v 1.79 2005/10/15 02:49:25 momjian Exp $
* $PostgreSQL: pgsql/src/backend/storage/ipc/ipci.c,v 1.80 2005/12/09 01:22:03 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -25,7 +25,7 @@
#include "storage/bufmgr.h"
#include "storage/freespace.h"
#include "storage/ipc.h"
#include "storage/lmgr.h"
#include "storage/lock.h"
#include "storage/lwlock.h"
#include "storage/pg_sema.h"
#include "storage/pg_shmem.h"
@ -159,7 +159,6 @@ CreateSharedMemoryAndSemaphores(bool makePrivate, int port)
* Set up lock manager
*/
InitLocks();
InitLockTable();
/*
* Set up process table

27
src/backend/storage/lmgr/README
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@ -1,4 +1,4 @@
$PostgreSQL: pgsql/src/backend/storage/lmgr/README,v 1.17 2005/06/14 22:15:32 tgl Exp $
$PostgreSQL: pgsql/src/backend/storage/lmgr/README,v 1.18 2005/12/09 01:22:04 tgl Exp $
LOCKING OVERVIEW
@ -151,7 +151,7 @@ tag -
SHMEM offset of the LOCK object this PROCLOCK is for.
tag.proc
SHMEM offset of PROC of backend process that owns this PROCLOCK.
SHMEM offset of PGPROC of backend process that owns this PROCLOCK.
holdMask -
A bitmask for the lock types successfully acquired by this PROCLOCK.
@ -415,3 +415,26 @@ seems a safer approach than trying to allocate workspace on the fly; we
don't want to risk having the deadlock detector run out of memory, else
we really have no guarantees at all that deadlock will be detected.
USER LOCKS
User locks are handled totally on the application side as long term
cooperative locks which extend beyond the normal transaction boundaries.
Their purpose is to indicate to an application that someone is `working'
on an item. So it is possible to put an user lock on a tuple's oid,
retrieve the tuple, work on it for an hour and then update it and remove
the lock. While the lock is active other clients can still read and write
the tuple but they can be aware that it has been locked at the application
level by someone.
User locks and normal locks are completely orthogonal and they don't
interfere with each other.
User locks are always non blocking, therefore they are never acquired if
already held by another process. They must be released explicitly by the
application but they are released automatically when a backend terminates.
The lockmode parameter can have the same values as for normal locks although
probably only ExclusiveLock can have some practical use.
DZ - 22 Nov 1997

5
src/backend/storage/lmgr/deadlock.c
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@ -12,7 +12,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/lmgr/deadlock.c,v 1.36 2005/10/29 00:31:51 petere Exp $
* $PostgreSQL: pgsql/src/backend/storage/lmgr/deadlock.c,v 1.37 2005/12/09 01:22:04 tgl Exp $
*
* Interface:
*
@ -930,7 +930,8 @@ DeadLockReport(void)
appendStringInfo(&buf,
_("Process %d waits for %s on %s; blocked by process %d."),
info->pid,
GetLockmodeName(info->lockmode),
GetLockmodeName(info->locktag.locktag_lockmethodid,
info->lockmode),
buf2.data,
nextpid);
}

142
src/backend/storage/lmgr/lmgr.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/lmgr/lmgr.c,v 1.79 2005/10/15 02:49:26 momjian Exp $
* $PostgreSQL: pgsql/src/backend/storage/lmgr/lmgr.c,v 1.80 2005/12/09 01:22:04 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -18,96 +18,12 @@
#include "access/subtrans.h"
#include "access/transam.h"
#include "access/xact.h"
#include "catalog/catalog.h"
#include "miscadmin.h"
#include "storage/lmgr.h"
#include "storage/procarray.h"
#include "utils/inval.h"
/*
* This conflict table defines the semantics of the various lock modes.
*/
static const LOCKMASK LockConflicts[] = {
0,
/* AccessShareLock */
(1 << AccessExclusiveLock),
/* RowShareLock */
(1 << ExclusiveLock) | (1 << AccessExclusiveLock),
/* RowExclusiveLock */
(1 << ShareLock) | (1 << ShareRowExclusiveLock) |
(1 << ExclusiveLock) | (1 << AccessExclusiveLock),
/* ShareUpdateExclusiveLock */
(1 << ShareUpdateExclusiveLock) |
(1 << ShareLock) | (1 << ShareRowExclusiveLock) |
(1 << ExclusiveLock) | (1 << AccessExclusiveLock),
/* ShareLock */
(1 << RowExclusiveLock) | (1 << ShareUpdateExclusiveLock) |
(1 << ShareRowExclusiveLock) |
(1 << ExclusiveLock) | (1 << AccessExclusiveLock),
/* ShareRowExclusiveLock */
(1 << RowExclusiveLock) | (1 << ShareUpdateExclusiveLock) |
(1 << ShareLock) | (1 << ShareRowExclusiveLock) |
(1 << ExclusiveLock) | (1 << AccessExclusiveLock),
/* ExclusiveLock */
(1 << RowShareLock) |
(1 << RowExclusiveLock) | (1 << ShareUpdateExclusiveLock) |
(1 << ShareLock) | (1 << ShareRowExclusiveLock) |
(1 << ExclusiveLock) | (1 << AccessExclusiveLock),
/* AccessExclusiveLock */
(1 << AccessShareLock) | (1 << RowShareLock) |
(1 << RowExclusiveLock) | (1 << ShareUpdateExclusiveLock) |
(1 << ShareLock) | (1 << ShareRowExclusiveLock) |
(1 << ExclusiveLock) | (1 << AccessExclusiveLock)
};
static LOCKMETHODID LockTableId = INVALID_LOCKMETHOD;
/*
* Create the lock table described by LockConflicts
*/
void
InitLockTable(void)
{
LOCKMETHODID LongTermTableId;
/* there's no zero-th table */
NumLockMethods = 1;
/*
* Create the default lock method table
*/
/* number of lock modes is lengthof()-1 because of dummy zero */
LockTableId = LockMethodTableInit("LockTable",
LockConflicts,
lengthof(LockConflicts) - 1);
if (!LockMethodIsValid(LockTableId))
elog(ERROR, "could not initialize lock table");
Assert(LockTableId == DEFAULT_LOCKMETHOD);
#ifdef USER_LOCKS
/*
* Allocate another tableId for user locks (same shared hashtable though)
*/
LongTermTableId = LockMethodTableRename(LockTableId);
if (!LockMethodIsValid(LongTermTableId))
elog(ERROR, "could not rename user lock table");
Assert(LongTermTableId == USER_LOCKMETHOD);
#endif
}
/*
* RelationInitLockInfo
* Initializes the lock information in a relation descriptor.
@ -141,8 +57,7 @@ LockRelation(Relation relation, LOCKMODE lockmode)
relation->rd_lockInfo.lockRelId.dbId,
relation->rd_lockInfo.lockRelId.relId);
res = LockAcquire(LockTableId, &tag, relation->rd_istemp,
lockmode, false, false);
res = LockAcquire(&tag, relation->rd_istemp, lockmode, false, false);
/*
* Check to see if the relcache entry has been invalidated while we were
@ -178,8 +93,7 @@ ConditionalLockRelation(Relation relation, LOCKMODE lockmode)
relation->rd_lockInfo.lockRelId.dbId,
relation->rd_lockInfo.lockRelId.relId);
res = LockAcquire(LockTableId, &tag, relation->rd_istemp,
lockmode, false, true);
res = LockAcquire(&tag, relation->rd_istemp, lockmode, false, true);
if (res == LOCKACQUIRE_NOT_AVAIL)
return false;
@ -213,7 +127,7 @@ UnlockRelation(Relation relation, LOCKMODE lockmode)
relation->rd_lockInfo.lockRelId.dbId,
relation->rd_lockInfo.lockRelId.relId);
LockRelease(LockTableId, &tag, lockmode, false);
LockRelease(&tag, lockmode, false);
}
/*
@ -235,8 +149,7 @@ LockRelationForSession(LockRelId *relid, bool istemprel, LOCKMODE lockmode)
SET_LOCKTAG_RELATION(tag, relid->dbId, relid->relId);
(void) LockAcquire(LockTableId, &tag, istemprel,
lockmode, true, false);
(void) LockAcquire(&tag, istemprel, lockmode, true, false);
}
/*
@ -249,7 +162,7 @@ UnlockRelationForSession(LockRelId *relid, LOCKMODE lockmode)
SET_LOCKTAG_RELATION(tag, relid->dbId, relid->relId);
LockRelease(LockTableId, &tag, lockmode, true);
LockRelease(&tag, lockmode, true);
}
/*
@ -271,8 +184,7 @@ LockRelationForExtension(Relation relation, LOCKMODE lockmode)
relation->rd_lockInfo.lockRelId.dbId,
relation->rd_lockInfo.lockRelId.relId);
(void) LockAcquire(LockTableId, &tag, relation->rd_istemp,
lockmode, false, false);
(void) LockAcquire(&tag, relation->rd_istemp, lockmode, false, false);
}
/*
@ -287,7 +199,7 @@ UnlockRelationForExtension(Relation relation, LOCKMODE lockmode)
relation->rd_lockInfo.lockRelId.dbId,
relation->rd_lockInfo.lockRelId.relId);
LockRelease(LockTableId, &tag, lockmode, false);
LockRelease(&tag, lockmode, false);
}
/*
@ -306,8 +218,7 @@ LockPage(Relation relation, BlockNumber blkno, LOCKMODE lockmode)
relation->rd_lockInfo.lockRelId.relId,
blkno);
(void) LockAcquire(LockTableId, &tag, relation->rd_istemp,
lockmode, false, false);
(void) LockAcquire(&tag, relation->rd_istemp, lockmode, false, false);
}
/*
@ -326,7 +237,7 @@ ConditionalLockPage(Relation relation, BlockNumber blkno, LOCKMODE lockmode)
relation->rd_lockInfo.lockRelId.relId,
blkno);
return (LockAcquire(LockTableId, &tag, relation->rd_istemp,
return (LockAcquire(&tag, relation->rd_istemp,
lockmode, false, true) != LOCKACQUIRE_NOT_AVAIL);
}
@ -343,7 +254,7 @@ UnlockPage(Relation relation, BlockNumber blkno, LOCKMODE lockmode)
relation->rd_lockInfo.lockRelId.relId,
blkno);
LockRelease(LockTableId, &tag, lockmode, false);
LockRelease(&tag, lockmode, false);
}
/*
@ -364,8 +275,7 @@ LockTuple(Relation relation, ItemPointer tid, LOCKMODE lockmode)
ItemPointerGetBlockNumber(tid),
ItemPointerGetOffsetNumber(tid));
(void) LockAcquire(LockTableId, &tag, relation->rd_istemp,
lockmode, false, false);
(void) LockAcquire(&tag, relation->rd_istemp, lockmode, false, false);
}
/*
@ -385,7 +295,7 @@ ConditionalLockTuple(Relation relation, ItemPointer tid, LOCKMODE lockmode)
ItemPointerGetBlockNumber(tid),
ItemPointerGetOffsetNumber(tid));
return (LockAcquire(LockTableId, &tag, relation->rd_istemp,
return (LockAcquire(&tag, relation->rd_istemp,
lockmode, false, true) != LOCKACQUIRE_NOT_AVAIL);
}
@ -403,7 +313,7 @@ UnlockTuple(Relation relation, ItemPointer tid, LOCKMODE lockmode)
ItemPointerGetBlockNumber(tid),
ItemPointerGetOffsetNumber(tid));
LockRelease(LockTableId, &tag, lockmode, false);
LockRelease(&tag, lockmode, false);
}
/*
@ -420,8 +330,7 @@ XactLockTableInsert(TransactionId xid)
SET_LOCKTAG_TRANSACTION(tag, xid);
(void) LockAcquire(LockTableId, &tag, false,
ExclusiveLock, false, false);
(void) LockAcquire(&tag, false, ExclusiveLock, false, false);
}
/*
@ -439,7 +348,7 @@ XactLockTableDelete(TransactionId xid)
SET_LOCKTAG_TRANSACTION(tag, xid);
LockRelease(LockTableId, &tag, ExclusiveLock, false);
LockRelease(&tag, ExclusiveLock, false);
}
/*
@ -466,10 +375,9 @@ XactLockTableWait(TransactionId xid)
SET_LOCKTAG_TRANSACTION(tag, xid);
(void) LockAcquire(LockTableId, &tag, false,
ShareLock, false, false);
(void) LockAcquire(&tag, false, ShareLock, false, false);
LockRelease(LockTableId, &tag, ShareLock, false);
LockRelease(&tag, ShareLock, false);
if (!TransactionIdIsInProgress(xid))
break;
@ -502,11 +410,11 @@ ConditionalXactLockTableWait(TransactionId xid)
SET_LOCKTAG_TRANSACTION(tag, xid);
if (LockAcquire(LockTableId, &tag, false,
if (LockAcquire(&tag, false,
ShareLock, false, true) == LOCKACQUIRE_NOT_AVAIL)
return false;
LockRelease(LockTableId, &tag, ShareLock, false);
LockRelease(&tag, ShareLock, false);
if (!TransactionIdIsInProgress(xid))
break;
@ -545,8 +453,7 @@ LockDatabaseObject(Oid classid, Oid objid, uint16 objsubid,
objid,
objsubid);
(void) LockAcquire(LockTableId, &tag, false,
lockmode, false, false);
(void) LockAcquire(&tag, false, lockmode, false, false);
}
/*
@ -564,7 +471,7 @@ UnlockDatabaseObject(Oid classid, Oid objid, uint16 objsubid,
objid,
objsubid);
LockRelease(LockTableId, &tag, lockmode, false);
LockRelease(&tag, lockmode, false);
}
/*
@ -584,8 +491,7 @@ LockSharedObject(Oid classid, Oid objid, uint16 objsubid,
objid,
objsubid);
(void) LockAcquire(LockTableId, &tag, false,
lockmode, false, false);
(void) LockAcquire(&tag, false, lockmode, false, false);
}
/*
@ -603,5 +509,5 @@ UnlockSharedObject(Oid classid, Oid objid, uint16 objsubid,
objid,
objsubid);
LockRelease(LockTableId, &tag, lockmode, false);
LockRelease(&tag, lockmode, false);
}

596
src/backend/storage/lmgr/lock.c
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File diff suppressed because it is too large Load Diff

4
src/backend/storage/lmgr/proc.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/lmgr/proc.c,v 1.168 2005/11/22 18:17:21 momjian Exp $
* $PostgreSQL: pgsql/src/backend/storage/lmgr/proc.c,v 1.169 2005/12/09 01:22:04 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -630,7 +630,7 @@ ProcSleep(LockMethod lockMethodTable,
LOCK *lock,
PROCLOCK *proclock)
{
LWLockId masterLock = lockMethodTable->masterLock;
LWLockId masterLock = LockMgrLock;
PROC_QUEUE *waitQueue = &(lock->waitProcs);
LOCKMASK myHeldLocks = MyProc->heldLocks;
bool early_deadlock = false;

5
src/backend/utils/adt/lockfuncs.c
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@ -6,7 +6,7 @@
* Copyright (c) 2002-2005, PostgreSQL Global Development Group
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/lockfuncs.c,v 1.20 2005/10/15 02:49:28 momjian Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/lockfuncs.c,v 1.21 2005/12/09 01:22:04 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -256,7 +256,8 @@ pg_lock_status(PG_FUNCTION_ARGS)
else
nulls[10] = 'n';
values[11] = DirectFunctionCall1(textin,
CStringGetDatum(GetLockmodeName(mode)));
CStringGetDatum(GetLockmodeName(LOCK_LOCKMETHOD(*lock),
mode)));
values[12] = BoolGetDatum(granted);
tuple = heap_formtuple(funcctx->tuple_desc, values, nulls);

4
src/backend/utils/cache/relcache.c vendored
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.232 2005/11/22 18:17:24 momjian Exp $
* $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.233 2005/12/09 01:22:04 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -3362,7 +3362,7 @@ RelationIdIsInInitFile(Oid relationId)
* just after sending them. The unlink before ensures that a backend that's
* currently starting cannot read the now-obsolete init file and then miss
* the SI messages that will force it to update its relcache entries. (This
* works because the backend startup sequence gets into the PROC array before
* works because the backend startup sequence gets into the PGPROC array before
* trying to load the init file.) The unlink after is to synchronize with a
* backend that may currently be trying to write an init file based on data
* that we've just rendered invalid. Such a backend will see the SI messages,

25
src/include/storage/lmgr.h
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/storage/lmgr.h,v 1.52 2005/10/15 02:49:46 momjian Exp $
* $PostgreSQL: pgsql/src/include/storage/lmgr.h,v 1.53 2005/12/09 01:22:04 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -18,29 +18,6 @@
#include "utils/rel.h"
/* These are the valid values of type LOCKMODE: */
/* NoLock is not a lock mode, but a flag value meaning "don't get a lock" */
#define NoLock 0
#define AccessShareLock 1 /* SELECT */
#define RowShareLock 2 /* SELECT FOR UPDATE/FOR SHARE */
#define RowExclusiveLock 3 /* INSERT, UPDATE, DELETE */
#define ShareUpdateExclusiveLock 4 /* VACUUM (non-FULL) */
#define ShareLock 5 /* CREATE INDEX */
#define ShareRowExclusiveLock 6 /* like EXCLUSIVE MODE, but allows ROW
* SHARE */
#define ExclusiveLock 7 /* blocks ROW SHARE/SELECT...FOR
* UPDATE */
#define AccessExclusiveLock 8 /* ALTER TABLE, DROP TABLE, VACUUM
* FULL, and unqualified LOCK TABLE */
/*
* Note: all lock mode numbers must be less than lock.h's MAX_LOCKMODES,
* so increase that if you want to add more modes.
*/
extern void InitLockTable(void);
extern void RelationInitLockInfo(Relation relation);
/* Lock a relation */

119
src/include/storage/lock.h
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/storage/lock.h,v 1.91 2005/10/15 02:49:46 momjian Exp $
* $PostgreSQL: pgsql/src/include/storage/lock.h,v 1.92 2005/12/09 01:22:04 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -55,50 +55,68 @@ typedef int LOCKMODE;
#define LOCKBIT_ON(lockmode) (1 << (lockmode))
#define LOCKBIT_OFF(lockmode) (~(1 << (lockmode)))
/*
* There is normally only one lock method, the default one.
* If user locks are enabled, an additional lock method is present.
* Lock methods are identified by LOCKMETHODID. (Despite the declaration as
* uint16, we are constrained to 256 lockmethods by the layout of LOCKTAG.)
*/
typedef uint16 LOCKMETHODID;
/* MAX_LOCK_METHODS is the number of distinct lock control tables allowed */
#define MAX_LOCK_METHODS 3
#define INVALID_LOCKMETHOD 0
#define DEFAULT_LOCKMETHOD 1
#define USER_LOCKMETHOD 2
#define LockMethodIsValid(lockmethodid) ((lockmethodid) != INVALID_LOCKMETHOD)
extern int NumLockMethods;
/*
* This is the control structure for a lock table. It lives in shared
* memory. Currently, none of these fields change after startup. In addition
* to the LockMethodData, a lock table has a shared "lockHash" table holding
* per-locked-object lock information, and a shared "proclockHash" table
* holding per-lock-holder/waiter lock information.
* This data structure defines the locking semantics associated with a
* "lock method". The semantics specify the meaning of each lock mode
* (by defining which lock modes it conflicts with), and also whether locks
* of this method are transactional (ie, are released at transaction end).
* All of this data is constant and is kept in const tables.
*
* masterLock -- LWLock used to synchronize access to the table
* numLockModes -- number of lock modes (READ,WRITE,etc) that
* are defined in this lock method. Must be less than MAX_LOCKMODES.
*
* numLockModes -- number of lock types (READ,WRITE,etc) that
* are defined on this lock table
* transactional -- TRUE if locks are released automatically at xact end.
*
* conflictTab -- this is an array of bitmasks showing lock
* type conflicts. conflictTab[i] is a mask with the j-th bit
* turned on if lock types i and j conflict.
* mode conflicts. conflictTab[i] is a mask with the j-th bit
* turned on if lock modes i and j conflict. Lock modes are
* numbered 1..numLockModes; conflictTab[0] is unused.
*
* lockModeNames -- ID strings for debug printouts.
*
* trace_flag -- pointer to GUC trace flag for this lock method.
*/
typedef struct LockMethodData
{
LWLockId masterLock;
int numLockModes;
LOCKMASK conflictTab[MAX_LOCKMODES];
bool transactional;
const LOCKMASK *conflictTab;
const char * const *lockModeNames;
const bool *trace_flag;
} LockMethodData;
typedef LockMethodData *LockMethod;
typedef const LockMethodData *LockMethod;
/*
* Lock methods are identified by LOCKMETHODID. (Despite the declaration as
* uint16, we are constrained to 256 lockmethods by the layout of LOCKTAG.)
*/
typedef uint16 LOCKMETHODID;
/* These identify the known lock methods */
#define DEFAULT_LOCKMETHOD 1
#define USER_LOCKMETHOD 2
/*
* These are the valid values of type LOCKMODE for all the standard lock
* methods (both DEFAULT and USER).
*/
/* NoLock is not a lock mode, but a flag value meaning "don't get a lock" */
#define NoLock 0
#define AccessShareLock 1 /* SELECT */
#define RowShareLock 2 /* SELECT FOR UPDATE/FOR SHARE */
#define RowExclusiveLock 3 /* INSERT, UPDATE, DELETE */
#define ShareUpdateExclusiveLock 4 /* VACUUM (non-FULL) */
#define ShareLock 5 /* CREATE INDEX */
#define ShareRowExclusiveLock 6 /* like EXCLUSIVE MODE, but allows ROW
* SHARE */
#define ExclusiveLock 7 /* blocks ROW SHARE/SELECT...FOR
* UPDATE */
#define AccessExclusiveLock 8 /* ALTER TABLE, DROP TABLE, VACUUM
* FULL, and unqualified LOCK TABLE */
/*
@ -138,9 +156,7 @@ typedef enum LockTagType
* to widen Oid, BlockNumber, or TransactionId to more than 32 bits.
*
* We include lockmethodid in the locktag so that a single hash table in
* shared memory can store locks of different lockmethods. For largely
* historical reasons, it's passed to the lock.c routines as a separate
* argument and then stored into the locktag.
* shared memory can store locks of different lockmethods.
*/
typedef struct LOCKTAG
{
@ -162,42 +178,48 @@ typedef struct LOCKTAG
(locktag).locktag_field2 = (reloid), \
(locktag).locktag_field3 = 0, \
(locktag).locktag_field4 = 0, \
(locktag).locktag_type = LOCKTAG_RELATION)
(locktag).locktag_type = LOCKTAG_RELATION, \
(locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
#define SET_LOCKTAG_RELATION_EXTEND(locktag,dboid,reloid) \
((locktag).locktag_field1 = (dboid), \
(locktag).locktag_field2 = (reloid), \
(locktag).locktag_field3 = 0, \
(locktag).locktag_field4 = 0, \
(locktag).locktag_type = LOCKTAG_RELATION_EXTEND)
(locktag).locktag_type = LOCKTAG_RELATION_EXTEND, \
(locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
#define SET_LOCKTAG_PAGE(locktag,dboid,reloid,blocknum) \
((locktag).locktag_field1 = (dboid), \
(locktag).locktag_field2 = (reloid), \
(locktag).locktag_field3 = (blocknum), \
(locktag).locktag_field4 = 0, \
(locktag).locktag_type = LOCKTAG_PAGE)
(locktag).locktag_type = LOCKTAG_PAGE, \
(locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
#define SET_LOCKTAG_TUPLE(locktag,dboid,reloid,blocknum,offnum) \
((locktag).locktag_field1 = (dboid), \
(locktag).locktag_field2 = (reloid), \
(locktag).locktag_field3 = (blocknum), \
(locktag).locktag_field4 = (offnum), \
(locktag).locktag_type = LOCKTAG_TUPLE)
(locktag).locktag_type = LOCKTAG_TUPLE, \
(locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
#define SET_LOCKTAG_TRANSACTION(locktag,xid) \
((locktag).locktag_field1 = (xid), \
(locktag).locktag_field2 = 0, \
(locktag).locktag_field3 = 0, \
(locktag).locktag_field4 = 0, \
(locktag).locktag_type = LOCKTAG_TRANSACTION)
(locktag).locktag_type = LOCKTAG_TRANSACTION, \
(locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
#define SET_LOCKTAG_OBJECT(locktag,dboid,classoid,objoid,objsubid) \
((locktag).locktag_field1 = (dboid), \
(locktag).locktag_field2 = (classoid), \
(locktag).locktag_field3 = (objoid), \
(locktag).locktag_field4 = (objsubid), \
(locktag).locktag_type = LOCKTAG_OBJECT)
(locktag).locktag_type = LOCKTAG_OBJECT, \
(locktag).locktag_lockmethodid = DEFAULT_LOCKMETHOD)
/*
@ -366,18 +388,13 @@ typedef enum
* function prototypes
*/
extern void InitLocks(void);
extern LockMethod GetLocksMethodTable(LOCK *lock);
extern LOCKMETHODID LockMethodTableInit(const char *tabName,
const LOCKMASK *conflictsP,
int numModes);
extern LOCKMETHODID LockMethodTableRename(LOCKMETHODID lockmethodid);
extern LockAcquireResult LockAcquire(LOCKMETHODID lockmethodid,
LOCKTAG *locktag,
extern LockMethod GetLocksMethodTable(const LOCK *lock);
extern LockAcquireResult LockAcquire(const LOCKTAG *locktag,
bool isTempObject,
LOCKMODE lockmode,
bool sessionLock,
bool dontWait);
extern bool LockRelease(LOCKMETHODID lockmethodid, LOCKTAG *locktag,
extern bool LockRelease(const LOCKTAG *locktag,
LOCKMODE lockmode, bool sessionLock);
extern void LockReleaseAll(LOCKMETHODID lockmethodid, bool allLocks);
extern void LockReleaseCurrentOwner(void);
@ -399,7 +416,7 @@ extern void RememberSimpleDeadLock(PGPROC *proc1,
PGPROC *proc2);
extern void InitDeadLockChecking(void);
extern LockData *GetLockStatusData(void);
extern const char *GetLockmodeName(LOCKMODE mode);
extern const char *GetLockmodeName(LOCKMETHODID lockmethodid, LOCKMODE mode);
extern void lock_twophase_recover(TransactionId xid, uint16 info,
void *recdata, uint32 len);

33
src/tools/backend/index.html
Unescape View File

@ -128,31 +128,16 @@ Block</a> - data/index buffer cache block</li>
addresses using table name and block number( <a
href="../../include/storage/buf_internals.h">BufferTag</a>)</li>
<li>MultiLevelLockTable (ctl) - control structure for each locking
method. Currently, only multi-level locking is used(<a
href="../../include/storage/lock.h">LOCKMETHODCTL</a>).</li>
<li>MultiLevelLockTable (lock hash) - the <a
<li>Lock Manager Tables (lock hash) - the <a
href="../../include/storage/lock.h">LOCK</a> structure, looked up
using relation, database object ids(<a
href="../../include/storage/lock.h">LOCKTAG)</a>. The lock table
structure contains the lock modes(read/write or shared/exclusive)
and circular linked list of backends (<a
href="../../include/storage/proc.h">PROC</a> structure pointers)
waiting on the lock.</li>
<li>MultiLevelLockTable (xid hash) - lookup of LOCK structure
address using transaction id, LOCK address. It is used to quickly
check if the current transaction already has any locks on a table,
rather than having to search through all the held locks. It also
stores the modes (read/write) of the locks held by the current
transaction. The returned <a
href="../../include/storage/lock.h">XIDLookupEnt</a> structure also
contains a pointer to the backend's PROC.lockQueue.</li>
<li><a href="../../include/storage/proc.h">Proc Header</a> -
information about each backend, including locks held/waiting,
indexed by process id</li>
using a <a href="../../include/storage/lock.h">LOCKTAG</a>.
A LOCK structure exists for each lockable object that is currently
locked by any backend. Also, there is a subsidiary <a
href="../../include/storage/lock.h">PROCLOCK</a> structure for each
backend currently interested in a given LOCK</li>
<li><a href="../../include/storage/proc.h">PGPROC Structures</a> -
information about each backend, including locks held/waiting</li>
</ul>
<p>Each data structure is created by calling <a

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