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Commit8e5ac74

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Some refinement for the "fast path" lock patch.
1. In GetLockStatusData, avoid initializing instance before we've ensuredthat the array is large enough. Otherwise, if repalloc moves the blockaround, we're hosed.2. Add the word "Relation" to the name of some identifiers, to avoidassuming that the fast-path mechanism will only ever apply to relations(though these particular parts certainly will). Some of the macroscould possibly use similar treatment, but the names are getting awfullylong already.3. Add a missing word to comment in AtPrepare_Locks().
1 parentcdd6123 commit8e5ac74

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1 file changed

+42
-37
lines changed
  • src/backend/storage/lmgr

1 file changed

+42
-37
lines changed

‎src/backend/storage/lmgr/lock.c

Lines changed: 42 additions & 37 deletions
Original file line numberDiff line numberDiff line change
@@ -155,11 +155,11 @@ static intFastPathLocalUseCount = 0;
155155
#defineFastPathStrongMode(mode)((mode) > ShareUpdateExclusiveLock)
156156
#defineFastPathRelevantMode(mode)((mode) != ShareUpdateExclusiveLock)
157157

158-
staticboolFastPathGrantLock(Oidrelid,LOCKMODElockmode);
159-
staticboolFastPathUnGrantLock(Oidrelid,LOCKMODElockmode);
160-
staticboolFastPathTransferLocks(LockMethodlockMethodTable,
158+
staticboolFastPathGrantRelationLock(Oidrelid,LOCKMODElockmode);
159+
staticboolFastPathUnGrantRelationLock(Oidrelid,LOCKMODElockmode);
160+
staticboolFastPathTransferRelationLocks(LockMethodlockMethodTable,
161161
constLOCKTAG*locktag,uint32hashcode);
162-
staticPROCLOCK*FastPathGetLockEntry(LOCALLOCK*locallock);
162+
staticPROCLOCK*FastPathGetRelationLockEntry(LOCALLOCK*locallock);
163163

164164
/*
165165
* To make the fast-path lock mechanism work, we must have some way of
@@ -186,9 +186,9 @@ typedef struct
186186
{
187187
slock_tmutex;
188188
uint32count[FAST_PATH_STRONG_LOCK_HASH_PARTITIONS];
189-
}FastPathStrongLockData;
189+
}FastPathStrongRelationLockData;
190190

191-
FastPathStrongLockData*FastPathStrongLocks;
191+
FastPathStrongRelationLockData*FastPathStrongRelationLocks;
192192

193193
#ifndefLOCK_DEBUG
194194
staticboolDummy_trace= false;
@@ -415,10 +415,11 @@ InitLocks(void)
415415
/*
416416
* Allocate fast-path structures.
417417
*/
418-
FastPathStrongLocks=ShmemInitStruct("Fast Path Strong Lock Data",
419-
sizeof(FastPathStrongLockData),&found);
418+
FastPathStrongRelationLocks=
419+
ShmemInitStruct("Fast Path Strong Relation Lock Data",
420+
sizeof(FastPathStrongRelationLockData),&found);
420421
if (!found)
421-
SpinLockInit(&FastPathStrongLocks->mutex);
422+
SpinLockInit(&FastPathStrongRelationLocks->mutex);
422423

423424
/*
424425
* Allocate non-shared hash table for LOCALLOCK structs. This stores lock
@@ -720,10 +721,11 @@ LockAcquireExtended(const LOCKTAG *locktag,
720721
* yet to begin to transfer fast-path locks.
721722
*/
722723
LWLockAcquire(MyProc->backendLock,LW_EXCLUSIVE);
723-
if (FastPathStrongLocks->count[fasthashcode]!=0)
724+
if (FastPathStrongRelationLocks->count[fasthashcode]!=0)
724725
acquired= false;
725726
else
726-
acquired=FastPathGrantLock(locktag->locktag_field2,lockmode);
727+
acquired=FastPathGrantRelationLock(locktag->locktag_field2,
728+
lockmode);
727729
LWLockRelease(MyProc->backendLock);
728730
if (acquired)
729731
{
@@ -742,11 +744,12 @@ LockAcquireExtended(const LOCKTAG *locktag,
742744
* instruction here, on architectures where that is supported.
743745
*/
744746
Assert(locallock->holdsStrongLockCount== FALSE);
745-
SpinLockAcquire(&FastPathStrongLocks->mutex);
746-
FastPathStrongLocks->count[fasthashcode]++;
747+
SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
748+
FastPathStrongRelationLocks->count[fasthashcode]++;
747749
locallock->holdsStrongLockCount= TRUE;
748-
SpinLockRelease(&FastPathStrongLocks->mutex);
749-
if (!FastPathTransferLocks(lockMethodTable,locktag,hashcode))
750+
SpinLockRelease(&FastPathStrongRelationLocks->mutex);
751+
if (!FastPathTransferRelationLocks(lockMethodTable,locktag,
752+
hashcode))
750753
{
751754
if (reportMemoryError)
752755
ereport(ERROR,
@@ -1099,11 +1102,11 @@ RemoveLocalLock(LOCALLOCK *locallock)
10991102
uint32fasthashcode;
11001103
fasthashcode=FastPathStrongLockHashPartition(locallock->hashcode);
11011104

1102-
SpinLockAcquire(&FastPathStrongLocks->mutex);
1103-
Assert(FastPathStrongLocks->count[fasthashcode]>0);
1104-
FastPathStrongLocks->count[fasthashcode]--;
1105+
SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
1106+
Assert(FastPathStrongRelationLocks->count[fasthashcode]>0);
1107+
FastPathStrongRelationLocks->count[fasthashcode]--;
11051108
locallock->holdsStrongLockCount= FALSE;
1106-
SpinLockRelease(&FastPathStrongLocks->mutex);
1109+
SpinLockRelease(&FastPathStrongRelationLocks->mutex);
11071110
}
11081111
if (!hash_search(LockMethodLocalHash,
11091112
(void*)&(locallock->tag),
@@ -1642,7 +1645,8 @@ LockRelease(const LOCKTAG *locktag, LOCKMODE lockmode, bool sessionLock)
16421645
* it here. Another backend may have moved it to the main table.
16431646
*/
16441647
LWLockAcquire(MyProc->backendLock,LW_EXCLUSIVE);
1645-
released=FastPathUnGrantLock(locktag->locktag_field2,lockmode);
1648+
released=FastPathUnGrantRelationLock(locktag->locktag_field2,
1649+
lockmode);
16461650
LWLockRelease(MyProc->backendLock);
16471651
if (released)
16481652
{
@@ -1825,7 +1829,7 @@ LockReleaseAll(LOCKMETHODID lockmethodid, bool allLocks)
18251829

18261830
/* Attempt fast-path release. */
18271831
relid=locallock->tag.lock.locktag_field2;
1828-
if (FastPathUnGrantLock(relid,lockmode))
1832+
if (FastPathUnGrantRelationLock(relid,lockmode))
18291833
{
18301834
RemoveLocalLock(locallock);
18311835
continue;
@@ -2117,11 +2121,11 @@ LockReassignCurrentOwner(void)
21172121
}
21182122

21192123
/*
2120-
*FastPathGrantLock
2124+
*FastPathGrantRelationLock
21212125
*Grant lock using per-backend fast-path array, if there is space.
21222126
*/
21232127
staticbool
2124-
FastPathGrantLock(Oidrelid,LOCKMODElockmode)
2128+
FastPathGrantRelationLock(Oidrelid,LOCKMODElockmode)
21252129
{
21262130
uint32f;
21272131
uint32unused_slot=FP_LOCK_SLOTS_PER_BACKEND;
@@ -2153,12 +2157,12 @@ FastPathGrantLock(Oid relid, LOCKMODE lockmode)
21532157
}
21542158

21552159
/*
2156-
*FastPathUnGrantLock
2160+
*FastPathUnGrantRelationLock
21572161
*Release fast-path lock, if present. Update backend-private local
21582162
*use count, while we're at it.
21592163
*/
21602164
staticbool
2161-
FastPathUnGrantLock(Oidrelid,LOCKMODElockmode)
2165+
FastPathUnGrantRelationLock(Oidrelid,LOCKMODElockmode)
21622166
{
21632167
uint32f;
21642168
boolresult= false;
@@ -2180,12 +2184,12 @@ FastPathUnGrantLock(Oid relid, LOCKMODE lockmode)
21802184
}
21812185

21822186
/*
2183-
*FastPathTransferLocks
2187+
*FastPathTransferRelationLocks
21842188
*Transfer locks matching the given lock tag from per-backend fast-path
21852189
*arrays to the shared hash table.
21862190
*/
21872191
staticbool
2188-
FastPathTransferLocks(LockMethodlockMethodTable,constLOCKTAG*locktag,
2192+
FastPathTransferRelationLocks(LockMethodlockMethodTable,constLOCKTAG*locktag,
21892193
uint32hashcode)
21902194
{
21912195
LWLockIdpartitionLock=LockHashPartitionLock(hashcode);
@@ -2267,7 +2271,7 @@ FastPathTransferLocks(LockMethod lockMethodTable, const LOCKTAG *locktag,
22672271
* transferring it to the primary lock table if necessary.
22682272
*/
22692273
staticPROCLOCK*
2270-
FastPathGetLockEntry(LOCALLOCK*locallock)
2274+
FastPathGetRelationLockEntry(LOCALLOCK*locallock)
22712275
{
22722276
LockMethodlockMethodTable=LockMethods[DEFAULT_LOCKMETHOD];
22732277
LOCKTAG*locktag=&locallock->tag.lock;
@@ -2650,9 +2654,9 @@ LockRefindAndRelease(LockMethod lockMethodTable, PGPROC *proc,
26502654
&&FastPathTag(&lock->tag)&&FastPathStrongMode(lockmode))
26512655
{
26522656
uint32fasthashcode=FastPathStrongLockHashPartition(hashcode);
2653-
SpinLockAcquire(&FastPathStrongLocks->mutex);
2654-
FastPathStrongLocks->count[fasthashcode]--;
2655-
SpinLockRelease(&FastPathStrongLocks->mutex);
2657+
SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
2658+
FastPathStrongRelationLocks->count[fasthashcode]--;
2659+
SpinLockRelease(&FastPathStrongRelationLocks->mutex);
26562660
}
26572661
}
26582662

@@ -2715,11 +2719,11 @@ AtPrepare_Locks(void)
27152719
/*
27162720
* If the local lock was taken via the fast-path, we need to move it
27172721
* to the primary lock table, or just get a pointer to the existing
2718-
* primary lock table if by chance it's already been transferred.
2722+
* primary lock tableentryif by chance it's already been transferred.
27192723
*/
27202724
if (locallock->proclock==NULL)
27212725
{
2722-
locallock->proclock=FastPathGetLockEntry(locallock);
2726+
locallock->proclock=FastPathGetRelationLockEntry(locallock);
27232727
locallock->lock=locallock->proclock->tag.myLock;
27242728
}
27252729

@@ -3010,7 +3014,7 @@ GetLockStatusData(void)
30103014

30113015
for (f=0;f<FP_LOCK_SLOTS_PER_BACKEND;++f)
30123016
{
3013-
LockInstanceData*instance=&data->locks[el];
3017+
LockInstanceData*instance;
30143018
uint32lockbits=FAST_PATH_GET_BITS(proc,f);
30153019

30163020
/* Skip unallocated slots. */
@@ -3024,6 +3028,7 @@ GetLockStatusData(void)
30243028
repalloc(data->locks,sizeof(LockInstanceData)*els);
30253029
}
30263030

3031+
instance=&data->locks[el];
30273032
SET_LOCKTAG_RELATION(instance->locktag,proc->databaseId,
30283033
proc->fpRelId[f]);
30293034
instance->holdMask=lockbits <<FAST_PATH_LOCKNUMBER_OFFSET;
@@ -3455,9 +3460,9 @@ lock_twophase_recover(TransactionId xid, uint16 info,
34553460
if (FastPathTag(&lock->tag)&&FastPathStrongMode(lockmode))
34563461
{
34573462
uint32fasthashcode=FastPathStrongLockHashPartition(hashcode);
3458-
SpinLockAcquire(&FastPathStrongLocks->mutex);
3459-
FastPathStrongLocks->count[fasthashcode]++;
3460-
SpinLockRelease(&FastPathStrongLocks->mutex);
3463+
SpinLockAcquire(&FastPathStrongRelationLocks->mutex);
3464+
FastPathStrongRelationLocks->count[fasthashcode]++;
3465+
SpinLockRelease(&FastPathStrongRelationLocks->mutex);
34613466
}
34623467

34633468
LWLockRelease(partitionLock);

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