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Try to reduce confusion about what is a lock method identifier, a lock

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method control structure, or a table of control structures.

. Use type LOCKMASK where an int is not a counter.

. Get rid of INVALID_TABLEID, use INVALID_LOCKMETHOD instead.

. Use INVALID_LOCKMETHOD instead of (LOCKMETHOD) NULL, because
  LOCKMETHOD is not a pointer.

. Define and use macro LockMethodIsValid.

. Rename LOCKMETHOD to LOCKMETHODID.

. Remove global variable LongTermTableId in lmgr.c, because it is
  never used.

. Make LockTableId static in lmgr.c, because it is used nowhere else.
  Why not remove it and use DEFAULT_LOCKMETHOD?

. Rename the lock method control structure from LOCKMETHODTABLE to
  LockMethodData.  Introduce a pointer type named LockMethod.

. Remove elog(FATAL) after InitLockTable() call in
  CreateSharedMemoryAndSemaphores(), because if something goes wrong,
  there is elog(FATAL) in LockMethodTableInit(), and if this doesn't
  help, an elog(ERROR) in InitLockTable() is promoted to FATAL.

. Make InitLockTable() void, because its only caller does not use its
  return value any more.

. Rename variables in lock.c to avoid statements like
        LockMethodTable[NumLockMethods] = lockMethodTable;
        lockMethodTable = LockMethodTable[lockmethod];

. Change LOCKMETHODID type to uint16 to fit into struct LOCKTAG.

. Remove static variables BITS_OFF and BITS_ON from lock.c, because
  I agree to this doubt:
 * XXX is a fetch from a static array really faster than a shift?

. Define and use macros LOCKBIT_ON/OFF.


Manfred Koizar
This commit is contained in:
Bruce Momjian
2003-12-01 21:59:25 +00:00
parent e2ac58c7bd
commit e7ca867485
8 changed files with 153 additions and 181 deletions
Download Patch File Download Diff File Expand all files Collapse all files

211
src/backend/storage/lmgr/lock.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.129 2003/11/29 19:51:56 pgsql Exp $
* $PostgreSQL: pgsql/src/backend/storage/lmgr/lock.c,v 1.130 2003/12/01 21:59:25 momjian Exp $
*
* NOTES
* Outside modules can create a lock table and acquire/release
@@ -46,7 +46,7 @@ int max_locks_per_xact; /* set by guc.c */
#define NLOCKENTS(maxBackends) (max_locks_per_xact * (maxBackends))
static int WaitOnLock(LOCKMETHOD lockmethod, LOCKMODE lockmode,
static int WaitOnLock(LOCKMETHODID lockmethodid, LOCKMODE lockmode,
LOCK *lock, PROCLOCK *proclock);
static void LockCountMyLocks(SHMEM_OFFSET lockOffset, PGPROC *proc,
int *myHolding);
@@ -111,7 +111,7 @@ LOCK_PRINT(const char *where, const LOCK *lock, LOCKMODE type)
"req(%d,%d,%d,%d,%d,%d,%d)=%d "
"grant(%d,%d,%d,%d,%d,%d,%d)=%d wait(%d) type(%s)",
where, MAKE_OFFSET(lock),
lock->tag.lockmethod, lock->tag.relId, lock->tag.dbId,
lock->tag.lockmethodid, lock->tag.relId, lock->tag.dbId,
lock->tag.objId.blkno, lock->grantMask,
lock->requested[1], lock->requested[2], lock->requested[3],
lock->requested[4], lock->requested[5], lock->requested[6],
@@ -150,19 +150,9 @@ PROCLOCK_PRINT(const char *where, const PROCLOCK *proclockP)
/*
* These are to simplify/speed up some bit arithmetic.
*
* XXX is a fetch from a static array really faster than a shift?
* Wouldn't bet on it...
* map from lock method id to the lock table structure
*/
static LOCKMASK BITS_OFF[MAX_LOCKMODES];
static LOCKMASK BITS_ON[MAX_LOCKMODES];
/*
* map from lockmethod to the lock table structure
*/
static LOCKMETHODTABLE *LockMethodTable[MAX_LOCK_METHODS];
static LockMethod LockMethods[MAX_LOCK_METHODS];
static int NumLockMethods;
@@ -173,28 +163,20 @@ static int NumLockMethods;
void
InitLocks(void)
{
int i;
int bit;
bit = 1;
for (i = 0; i < MAX_LOCKMODES; i++, bit <<= 1)
{
BITS_ON[i] = bit;
BITS_OFF[i] = ~bit;
}
/* NOP */
}
/*
* Fetch the lock method table associated with a given lock
*/
LOCKMETHODTABLE *
LockMethod
GetLocksMethodTable(LOCK *lock)
{
LOCKMETHOD lockmethod = LOCK_LOCKMETHOD(*lock);
LOCKMETHODID lockmethodid = LOCK_LOCKMETHOD(*lock);
Assert(lockmethod > 0 && lockmethod < NumLockMethods);
return LockMethodTable[lockmethod];
Assert(0 < lockmethodid && lockmethodid < NumLockMethods);
return LockMethods[lockmethodid];
}
@@ -205,7 +187,7 @@ GetLocksMethodTable(LOCK *lock)
* Notes: just copying. Should only be called once.
*/
static void
LockMethodInit(LOCKMETHODTABLE *lockMethodTable,
LockMethodInit(LockMethod lockMethodTable,
LOCKMASK *conflictsP,
int numModes)
{
@@ -226,13 +208,13 @@ LockMethodInit(LOCKMETHODTABLE *lockMethodTable,
* by the postmaster are inherited by each backend, so they must be in
* TopMemoryContext.
*/
LOCKMETHOD
LOCKMETHODID
LockMethodTableInit(char *tabName,
LOCKMASK *conflictsP,
int numModes,
int maxBackends)
{
LOCKMETHODTABLE *lockMethodTable;
LockMethod newLockMethod;
char *shmemName;
HASHCTL info;
int hash_flags;
@@ -254,10 +236,10 @@ LockMethodTableInit(char *tabName,
/* each lock table has a header in shared memory */
sprintf(shmemName, "%s (lock method table)", tabName);
lockMethodTable = (LOCKMETHODTABLE *)
ShmemInitStruct(shmemName, sizeof(LOCKMETHODTABLE), &found);
newLockMethod = (LockMethod)
ShmemInitStruct(shmemName, sizeof(LockMethodData), &found);
if (!lockMethodTable)
if (!newLockMethod)
elog(FATAL, "could not initialize lock table \"%s\"", tabName);
/*
@@ -275,15 +257,15 @@ LockMethodTableInit(char *tabName,
*/
if (!found)
{
MemSet(lockMethodTable, 0, sizeof(LOCKMETHODTABLE));
lockMethodTable->masterLock = LockMgrLock;
lockMethodTable->lockmethod = NumLockMethods;
MemSet(newLockMethod, 0, sizeof(LockMethodData));
newLockMethod->masterLock = LockMgrLock;
newLockMethod->lockmethodid = NumLockMethods;
}
/*
* other modules refer to the lock table by a lockmethod ID
*/
LockMethodTable[NumLockMethods] = lockMethodTable;
LockMethods[NumLockMethods] = newLockMethod;
NumLockMethods++;
Assert(NumLockMethods <= MAX_LOCK_METHODS);
@@ -297,15 +279,15 @@ LockMethodTableInit(char *tabName,
hash_flags = (HASH_ELEM | HASH_FUNCTION);
sprintf(shmemName, "%s (lock hash)", tabName);
lockMethodTable->lockHash = ShmemInitHash(shmemName,
init_table_size,
max_table_size,
&info,
hash_flags);
newLockMethod->lockHash = ShmemInitHash(shmemName,
init_table_size,
max_table_size,
&info,
hash_flags);
if (!lockMethodTable->lockHash)
if (!newLockMethod->lockHash)
elog(FATAL, "could not initialize lock table \"%s\"", tabName);
Assert(lockMethodTable->lockHash->hash == tag_hash);
Assert(newLockMethod->lockHash->hash == tag_hash);
/*
* allocate a hash table for PROCLOCK structs. This is used to store
@@ -317,23 +299,23 @@ LockMethodTableInit(char *tabName,
hash_flags = (HASH_ELEM | HASH_FUNCTION);
sprintf(shmemName, "%s (proclock hash)", tabName);
lockMethodTable->proclockHash = ShmemInitHash(shmemName,
init_table_size,
max_table_size,
&info,
hash_flags);
newLockMethod->proclockHash = ShmemInitHash(shmemName,
init_table_size,
max_table_size,
&info,
hash_flags);
if (!lockMethodTable->proclockHash)
if (!newLockMethod->proclockHash)
elog(FATAL, "could not initialize lock table \"%s\"", tabName);
/* init data structures */
LockMethodInit(lockMethodTable, conflictsP, numModes);
LockMethodInit(newLockMethod, conflictsP, numModes);
LWLockRelease(LockMgrLock);
pfree(shmemName);
return lockMethodTable->lockmethod;
return newLockMethod->lockmethodid;
}
/*
@@ -349,22 +331,22 @@ LockMethodTableInit(char *tabName,
* short term and long term locks, yet store them all in one hashtable.
*/
LOCKMETHOD
LockMethodTableRename(LOCKMETHOD lockmethod)
LOCKMETHODID
LockMethodTableRename(LOCKMETHODID lockmethodid)
{
LOCKMETHOD newLockMethod;
LOCKMETHODID newLockMethodId;
if (NumLockMethods >= MAX_LOCK_METHODS)
return INVALID_LOCKMETHOD;
if (LockMethodTable[lockmethod] == INVALID_LOCKMETHOD)
if (LockMethods[lockmethodid] == INVALID_LOCKMETHOD)
return INVALID_LOCKMETHOD;
/* other modules refer to the lock table by a lockmethod ID */
newLockMethod = NumLockMethods;
newLockMethodId = NumLockMethods;
NumLockMethods++;
LockMethodTable[newLockMethod] = LockMethodTable[lockmethod];
return newLockMethod;
LockMethods[newLockMethodId] = LockMethods[lockmethodid];
return newLockMethodId;
}
/*
@@ -412,7 +394,7 @@ LockMethodTableRename(LOCKMETHOD lockmethod)
*
* normal lock user lock
*
* lockmethod 1 2
* lockmethodid 1 2
* tag.dbId database oid database oid
* tag.relId rel oid or 0 0
* tag.objId block id lock id2
@@ -429,7 +411,7 @@ LockMethodTableRename(LOCKMETHOD lockmethod)
*/
bool
LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag,
LockAcquire(LOCKMETHODID lockmethodid, LOCKTAG *locktag,
TransactionId xid, LOCKMODE lockmode, bool dontWait)
{
PROCLOCK *proclock;
@@ -438,25 +420,25 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag,
bool found;
LOCK *lock;
LWLockId masterLock;
LOCKMETHODTABLE *lockMethodTable;
LockMethod lockMethodTable;
int status;
int myHolding[MAX_LOCKMODES];
int i;
#ifdef LOCK_DEBUG
if (lockmethod == USER_LOCKMETHOD && Trace_userlocks)
if (lockmethodid == USER_LOCKMETHOD && Trace_userlocks)
elog(LOG, "LockAcquire: user lock [%u] %s",
locktag->objId.blkno, lock_mode_names[lockmode]);
#endif
/* ???????? This must be changed when short term locks will be used */
locktag->lockmethod = lockmethod;
locktag->lockmethodid = lockmethodid;
Assert(lockmethod < NumLockMethods);
lockMethodTable = LockMethodTable[lockmethod];
Assert(lockmethodid < NumLockMethods);
lockMethodTable = LockMethods[lockmethodid];
if (!lockMethodTable)
{
elog(WARNING, "bad lock table id: %d", lockmethod);
elog(WARNING, "bad lock table id: %d", lockmethodid);
return FALSE;
}
@@ -666,15 +648,12 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag,
* Construct bitmask of locks this process holds on this object.
*/
{
int heldLocks = 0;
int tmpMask;
LOCKMASK heldLocks = 0;
for (i = 1, tmpMask = 2;
i <= lockMethodTable->numLockModes;
i++, tmpMask <<= 1)
for (i = 1; i <= lockMethodTable->numLockModes; i++)
{
if (myHolding[i] > 0)
heldLocks |= tmpMask;
heldLocks |= LOCKBIT_ON(i);
}
MyProc->heldLocks = heldLocks;
}
@@ -682,7 +661,7 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag,
/*
* Sleep till someone wakes me up.
*/
status = WaitOnLock(lockmethod, lockmode, lock, proclock);
status = WaitOnLock(lockmethodid, lockmode, lock, proclock);
/*
* NOTE: do not do any material change of state between here and
@@ -729,7 +708,7 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag,
* known. If NULL is passed then these values will be computed internally.
*/
int
LockCheckConflicts(LOCKMETHODTABLE *lockMethodTable,
LockCheckConflicts(LockMethod lockMethodTable,
LOCKMODE lockmode,
LOCK *lock,
PROCLOCK *proclock,
@@ -737,9 +716,8 @@ LockCheckConflicts(LOCKMETHODTABLE *lockMethodTable,
int *myHolding) /* myHolding[] array or NULL */
{
int numLockModes = lockMethodTable->numLockModes;
int bitmask;
int i,
tmpMask;
LOCKMASK bitmask;
int i;
int localHolding[MAX_LOCKMODES];
/*
@@ -772,11 +750,10 @@ LockCheckConflicts(LOCKMETHODTABLE *lockMethodTable,
/* Compute mask of lock types held by other processes */
bitmask = 0;
tmpMask = 2;
for (i = 1; i <= numLockModes; i++, tmpMask <<= 1)
for (i = 1; i <= numLockModes; i++)
{
if (lock->granted[i] != myHolding[i])
bitmask |= tmpMask;
bitmask |= LOCKBIT_ON(i);
}
/*
@@ -842,9 +819,9 @@ GrantLock(LOCK *lock, PROCLOCK *proclock, LOCKMODE lockmode)
{
lock->nGranted++;
lock->granted[lockmode]++;
lock->grantMask |= BITS_ON[lockmode];
lock->grantMask |= LOCKBIT_ON(lockmode);
if (lock->granted[lockmode] == lock->requested[lockmode])
lock->waitMask &= BITS_OFF[lockmode];
lock->waitMask &= LOCKBIT_OFF(lockmode);
LOCK_PRINT("GrantLock", lock, lockmode);
Assert((lock->nGranted > 0) && (lock->granted[lockmode] > 0));
Assert(lock->nGranted <= lock->nRequested);
@@ -862,14 +839,14 @@ GrantLock(LOCK *lock, PROCLOCK *proclock, LOCKMODE lockmode)
* The locktable's masterLock must be held at entry.
*/
static int
WaitOnLock(LOCKMETHOD lockmethod, LOCKMODE lockmode,
WaitOnLock(LOCKMETHODID lockmethodid, LOCKMODE lockmode,
LOCK *lock, PROCLOCK *proclock)
{
LOCKMETHODTABLE *lockMethodTable = LockMethodTable[lockmethod];
LockMethod lockMethodTable = LockMethods[lockmethodid];
char *new_status,
*old_status;
Assert(lockmethod < NumLockMethods);
Assert(lockmethodid < NumLockMethods);
LOCK_PRINT("WaitOnLock: sleeping on lock", lock, lockmode);
@@ -957,7 +934,7 @@ RemoveFromWaitQueue(PGPROC *proc)
waitLock->requested[lockmode]--;
/* don't forget to clear waitMask bit if appropriate */
if (waitLock->granted[lockmode] == waitLock->requested[lockmode])
waitLock->waitMask &= BITS_OFF[lockmode];
waitLock->waitMask &= LOCKBIT_OFF(lockmode);
/* Clean up the proc's own state */
proc->waitLock = NULL;
@@ -968,7 +945,7 @@ RemoveFromWaitQueue(PGPROC *proc)
}
/*
* LockRelease -- look up 'locktag' in lock table 'lockmethod' and
* LockRelease -- look up 'locktag' in lock table 'lockmethodid' and
* release one 'lockmode' lock on it.
*
* Side Effects: find any waiting processes that are now wakable,
@@ -978,27 +955,27 @@ RemoveFromWaitQueue(PGPROC *proc)
* come along and request the lock.)
*/
bool
LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag,
LockRelease(LOCKMETHODID lockmethodid, LOCKTAG *locktag,
TransactionId xid, LOCKMODE lockmode)
{
LOCK *lock;
LWLockId masterLock;
LOCKMETHODTABLE *lockMethodTable;
LockMethod lockMethodTable;
PROCLOCK *proclock;
PROCLOCKTAG proclocktag;
HTAB *proclockTable;
bool wakeupNeeded = false;
#ifdef LOCK_DEBUG
if (lockmethod == USER_LOCKMETHOD && Trace_userlocks)
if (lockmethodid == USER_LOCKMETHOD && Trace_userlocks)
elog(LOG, "LockRelease: user lock tag [%u] %d", locktag->objId.blkno, lockmode);
#endif
/* ???????? This must be changed when short term locks will be used */
locktag->lockmethod = lockmethod;
locktag->lockmethodid = lockmethodid;
Assert(lockmethod < NumLockMethods);
lockMethodTable = LockMethodTable[lockmethod];
Assert(lockmethodid < NumLockMethods);
lockMethodTable = LockMethods[lockmethodid];
if (!lockMethodTable)
{
elog(WARNING, "lockMethodTable is null in LockRelease");
@@ -1045,7 +1022,7 @@ LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag,
{
LWLockRelease(masterLock);
#ifdef USER_LOCKS
if (lockmethod == USER_LOCKMETHOD)
if (lockmethodid == USER_LOCKMETHOD)
elog(WARNING, "no lock with this tag");
else
#endif
@@ -1083,7 +1060,7 @@ LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag,
if (lock->granted[lockmode] == 0)
{
/* change the conflict mask. No more of this lock type. */
lock->grantMask &= BITS_OFF[lockmode];
lock->grantMask &= LOCKBIT_OFF(lockmode);
}
LOCK_PRINT("LockRelease: updated", lock, lockmode);
@@ -1173,29 +1150,29 @@ LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag,
* specified XID are released.
*/
bool
LockReleaseAll(LOCKMETHOD lockmethod, PGPROC *proc,
LockReleaseAll(LOCKMETHODID lockmethodid, PGPROC *proc,
bool allxids, TransactionId xid)
{
SHM_QUEUE *procHolders = &(proc->procHolders);
PROCLOCK *proclock;
PROCLOCK *nextHolder;
LWLockId masterLock;
LOCKMETHODTABLE *lockMethodTable;
LockMethod lockMethodTable;
int i,
numLockModes;
LOCK *lock;
#ifdef LOCK_DEBUG
if (lockmethod == USER_LOCKMETHOD ? Trace_userlocks : Trace_locks)
if (lockmethodid == USER_LOCKMETHOD ? Trace_userlocks : Trace_locks)
elog(LOG, "LockReleaseAll: lockmethod=%d, pid=%d",
lockmethod, proc->pid);
lockmethodid, proc->pid);
#endif
Assert(lockmethod < NumLockMethods);
lockMethodTable = LockMethodTable[lockmethod];
Assert(lockmethodid < NumLockMethods);
lockMethodTable = LockMethods[lockmethodid];
if (!lockMethodTable)
{
elog(WARNING, "bad lock method: %d", lockmethod);
elog(WARNING, "bad lock method: %d", lockmethodid);
return FALSE;
}
@@ -1220,7 +1197,7 @@ LockReleaseAll(LOCKMETHOD lockmethod, PGPROC *proc,
lock = (LOCK *) MAKE_PTR(proclock->tag.lock);
/* Ignore items that are not of the lockmethod to be removed */
if (LOCK_LOCKMETHOD(*lock) != lockmethod)
if (LOCK_LOCKMETHOD(*lock) != lockmethodid)
goto next_item;
/* If not allxids, ignore items that are of the wrong xid */
@@ -1249,7 +1226,7 @@ LockReleaseAll(LOCKMETHOD lockmethod, PGPROC *proc,
lock->granted[i] -= proclock->holding[i];
Assert(lock->requested[i] >= 0 && lock->granted[i] >= 0);
if (lock->granted[i] == 0)
lock->grantMask &= BITS_OFF[i];
lock->grantMask &= LOCKBIT_OFF(i);
/*
* Read comments in LockRelease
@@ -1331,7 +1308,7 @@ next_item:
LWLockRelease(masterLock);
#ifdef LOCK_DEBUG
if (lockmethod == USER_LOCKMETHOD ? Trace_userlocks : Trace_locks)
if (lockmethodid == USER_LOCKMETHOD ? Trace_userlocks : Trace_locks)
elog(LOG, "LockReleaseAll done");
#endif
@@ -1346,7 +1323,7 @@ LockShmemSize(int maxBackends)
size += MAXALIGN(sizeof(PROC_HDR)); /* ProcGlobal */
size += maxBackends * MAXALIGN(sizeof(PGPROC)); /* each MyProc */
size += MAX_LOCK_METHODS * MAXALIGN(sizeof(LOCKMETHODTABLE)); /* each lockMethodTable */
size += MAX_LOCK_METHODS * MAXALIGN(sizeof(LockMethodData)); /* each lock method */
/* lockHash table */
size += hash_estimate_size(max_table_size, sizeof(LOCK));
@@ -1390,7 +1367,7 @@ GetLockStatusData(void)
LWLockAcquire(LockMgrLock, LW_EXCLUSIVE);
proclockTable = LockMethodTable[DEFAULT_LOCKMETHOD]->proclockHash;
proclockTable = LockMethods[DEFAULT_LOCKMETHOD]->proclockHash;
data->nelements = i = proclockTable->hctl->nentries;
@@ -1446,8 +1423,8 @@ DumpLocks(void)
SHM_QUEUE *procHolders;
PROCLOCK *proclock;
LOCK *lock;
int lockmethod = DEFAULT_LOCKMETHOD;
LOCKMETHODTABLE *lockMethodTable;
int lockmethodid = DEFAULT_LOCKMETHOD;
LockMethod lockMethodTable;
proc = MyProc;
if (proc == NULL)
@@ -1455,8 +1432,8 @@ DumpLocks(void)
procHolders = &proc->procHolders;
Assert(lockmethod < NumLockMethods);
lockMethodTable = LockMethodTable[lockmethod];
Assert(lockmethodid < NumLockMethods);
lockMethodTable = LockMethods[lockmethodid];
if (!lockMethodTable)
return;
@@ -1489,8 +1466,8 @@ DumpAllLocks(void)
PGPROC *proc;
PROCLOCK *proclock;
LOCK *lock;
int lockmethod = DEFAULT_LOCKMETHOD;
LOCKMETHODTABLE *lockMethodTable;
int lockmethodid = DEFAULT_LOCKMETHOD;
LockMethod lockMethodTable;
HTAB *proclockTable;
HASH_SEQ_STATUS status;
@@ -1498,8 +1475,8 @@ DumpAllLocks(void)
if (proc == NULL)
return;
Assert(lockmethod < NumLockMethods);
lockMethodTable = LockMethodTable[lockmethod];
Assert(lockmethodid < NumLockMethods);
lockMethodTable = LockMethods[lockmethodid];
if (!lockMethodTable)
return;