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Commit5764f61

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Use dlist/dclist instead of PROC_QUEUE / SHM_QUEUE for heavyweight locks
Part of a series to remove SHM_QUEUE. ilist.h style lists are more widely usedand have an easier to use interface.As PROC_QUEUE is now unused, remove it.Reviewed-by: Thomas Munro <thomas.munro@gmail.com> (in an older version)Discussion:https://postgr.es/m/20221120055930.t6kl3tyivzhlrzu2@awork3.anarazel.deDiscussion:https://postgr.es/m/20200211042229.msv23badgqljrdg2@alap3.anarazel.de
1 parent51384cc commit5764f61

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7 files changed

+183
-339
lines changed

7 files changed

+183
-339
lines changed

‎src/backend/access/transam/twophase.c‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -461,7 +461,7 @@ MarkAsPreparingGuts(GlobalTransaction gxact, TransactionId xid, const char *gid,
461461
/* Initialize the PGPROC entry */
462462
MemSet(proc,0,sizeof(PGPROC));
463463
proc->pgprocno=gxact->pgprocno;
464-
SHMQueueElemInit(&(proc->links));
464+
dlist_node_init(&proc->links);
465465
proc->waitStatus=PROC_WAIT_STATUS_OK;
466466
if (LocalTransactionIdIsValid(MyProc->lxid))
467467
{
@@ -491,7 +491,7 @@ MarkAsPreparingGuts(GlobalTransaction gxact, TransactionId xid, const char *gid,
491491
proc->waitProcLock=NULL;
492492
pg_atomic_init_u64(&proc->waitStart,0);
493493
for (i=0;i<NUM_LOCK_PARTITIONS;i++)
494-
SHMQueueInit(&(proc->myProcLocks[i]));
494+
dlist_init(&proc->myProcLocks[i]);
495495
/* subxid data must be filled later by GXactLoadSubxactData */
496496
proc->subxidStatus.overflowed= false;
497497
proc->subxidStatus.count=0;

‎src/backend/storage/lmgr/deadlock.c‎

Lines changed: 35 additions & 52 deletions
Original file line numberDiff line numberDiff line change
@@ -216,9 +216,6 @@ InitDeadLockChecking(void)
216216
DeadLockState
217217
DeadLockCheck(PGPROC*proc)
218218
{
219-
inti,
220-
j;
221-
222219
/* Initialize to "no constraints" */
223220
nCurConstraints=0;
224221
nPossibleConstraints=0;
@@ -246,26 +243,23 @@ DeadLockCheck(PGPROC *proc)
246243
}
247244

248245
/* Apply any needed rearrangements of wait queues */
249-
for (i=0;i<nWaitOrders;i++)
246+
for (inti=0;i<nWaitOrders;i++)
250247
{
251248
LOCK*lock=waitOrders[i].lock;
252249
PGPROC**procs=waitOrders[i].procs;
253250
intnProcs=waitOrders[i].nProcs;
254-
PROC_QUEUE*waitQueue=&(lock->waitProcs);
251+
dclist_head*waitQueue=&lock->waitProcs;
255252

256-
Assert(nProcs==waitQueue->size);
253+
Assert(nProcs==dclist_count(waitQueue));
257254

258255
#ifdefDEBUG_DEADLOCK
259256
PrintLockQueue(lock,"DeadLockCheck:");
260257
#endif
261258

262259
/* Reset the queue and re-add procs in the desired order */
263-
ProcQueueInit(waitQueue);
264-
for (j=0;j<nProcs;j++)
265-
{
266-
SHMQueueInsertBefore(&(waitQueue->links),&(procs[j]->links));
267-
waitQueue->size++;
268-
}
260+
dclist_init(waitQueue);
261+
for (intj=0;j<nProcs;j++)
262+
dclist_push_tail(waitQueue,&procs[j]->links);
269263

270264
#ifdefDEBUG_DEADLOCK
271265
PrintLockQueue(lock,"rearranged to:");
@@ -544,11 +538,8 @@ FindLockCycleRecurseMember(PGPROC *checkProc,
544538
{
545539
PGPROC*proc;
546540
LOCK*lock=checkProc->waitLock;
547-
PROCLOCK*proclock;
548-
SHM_QUEUE*procLocks;
541+
dlist_iterproclock_iter;
549542
LockMethodlockMethodTable;
550-
PROC_QUEUE*waitQueue;
551-
intqueue_size;
552543
intconflictMask;
553544
inti;
554545
intnumLockModes,
@@ -571,13 +562,9 @@ FindLockCycleRecurseMember(PGPROC *checkProc,
571562
* Scan for procs that already hold conflicting locks. These are "hard"
572563
* edges in the waits-for graph.
573564
*/
574-
procLocks=&(lock->procLocks);
575-
576-
proclock= (PROCLOCK*)SHMQueueNext(procLocks,procLocks,
577-
offsetof(PROCLOCK,lockLink));
578-
579-
while (proclock)
565+
dlist_foreach(proclock_iter,&lock->procLocks)
580566
{
567+
PROCLOCK*proclock=dlist_container(PROCLOCK,lockLink,proclock_iter.cur);
581568
PGPROC*leader;
582569

583570
proc=proclock->tag.myProc;
@@ -636,9 +623,6 @@ FindLockCycleRecurseMember(PGPROC *checkProc,
636623
}
637624
}
638625
}
639-
640-
proclock= (PROCLOCK*)SHMQueueNext(procLocks,&proclock->lockLink,
641-
offsetof(PROCLOCK,lockLink));
642626
}
643627

644628
/*
@@ -660,8 +644,7 @@ FindLockCycleRecurseMember(PGPROC *checkProc,
660644
{
661645
/* Use the given hypothetical wait queue order */
662646
PGPROC**procs=waitOrders[i].procs;
663-
664-
queue_size=waitOrders[i].nProcs;
647+
intqueue_size=waitOrders[i].nProcs;
665648

666649
for (i=0;i<queue_size;i++)
667650
{
@@ -711,9 +694,11 @@ FindLockCycleRecurseMember(PGPROC *checkProc,
711694
else
712695
{
713696
PGPROC*lastGroupMember=NULL;
697+
dlist_iterproc_iter;
698+
dclist_head*waitQueue;
714699

715700
/* Use the true lock wait queue order */
716-
waitQueue=&(lock->waitProcs);
701+
waitQueue=&lock->waitProcs;
717702

718703
/*
719704
* Find the last member of the lock group that is present in the wait
@@ -726,26 +711,25 @@ FindLockCycleRecurseMember(PGPROC *checkProc,
726711
lastGroupMember=checkProc;
727712
else
728713
{
729-
proc= (PGPROC*)waitQueue->links.next;
730-
queue_size=waitQueue->size;
731-
while (queue_size-->0)
714+
dclist_foreach(proc_iter,waitQueue)
732715
{
716+
proc=dlist_container(PGPROC,links,proc_iter.cur);
717+
733718
if (proc->lockGroupLeader==checkProcLeader)
734719
lastGroupMember=proc;
735-
proc= (PGPROC*)proc->links.next;
736720
}
737721
Assert(lastGroupMember!=NULL);
738722
}
739723

740724
/*
741725
* OK, now rescan (or scan) the queue to identify the soft conflicts.
742726
*/
743-
queue_size=waitQueue->size;
744-
proc= (PGPROC*)waitQueue->links.next;
745-
while (queue_size-->0)
727+
dclist_foreach(proc_iter,waitQueue)
746728
{
747729
PGPROC*leader;
748730

731+
proc=dlist_container(PGPROC,links,proc_iter.cur);
732+
749733
leader=proc->lockGroupLeader==NULL ?proc :
750734
proc->lockGroupLeader;
751735

@@ -779,8 +763,6 @@ FindLockCycleRecurseMember(PGPROC *checkProc,
779763
return true;
780764
}
781765
}
782-
783-
proc= (PGPROC*)proc->links.next;
784766
}
785767
}
786768

@@ -832,8 +814,8 @@ ExpandConstraints(EDGE *constraints,
832814
/* No, so allocate a new list */
833815
waitOrders[nWaitOrders].lock=lock;
834816
waitOrders[nWaitOrders].procs=waitOrderProcs+nWaitOrderProcs;
835-
waitOrders[nWaitOrders].nProcs=lock->waitProcs.size;
836-
nWaitOrderProcs+=lock->waitProcs.size;
817+
waitOrders[nWaitOrders].nProcs=dclist_count(&lock->waitProcs);
818+
nWaitOrderProcs+=dclist_count(&lock->waitProcs);
837819
Assert(nWaitOrderProcs <=MaxBackends);
838820

839821
/*
@@ -880,23 +862,25 @@ TopoSort(LOCK *lock,
880862
intnConstraints,
881863
PGPROC**ordering)/* output argument */
882864
{
883-
PROC_QUEUE*waitQueue=&(lock->waitProcs);
884-
intqueue_size=waitQueue->size;
865+
dclist_head*waitQueue=&lock->waitProcs;
866+
intqueue_size=dclist_count(waitQueue);
885867
PGPROC*proc;
886868
inti,
887869
j,
888870
jj,
889871
k,
890872
kk,
891873
last;
874+
dlist_iterproc_iter;
892875

893876
/* First, fill topoProcs[] array with the procs in their current order */
894-
proc=(PGPROC*)waitQueue->links.next;
895-
for (i=0;i<queue_size;i++)
877+
i=0;
878+
dclist_foreach(proc_iter,waitQueue)
896879
{
897-
topoProcs[i]=proc;
898-
proc=(PGPROC*)proc->links.next;
880+
proc=dlist_container(PGPROC,links,proc_iter.cur);
881+
topoProcs[i++]=proc;
899882
}
883+
Assert(i==queue_size);
900884

901885
/*
902886
* Scan the constraints, and for each proc in the array, generate a count
@@ -1066,17 +1050,16 @@ TopoSort(LOCK *lock,
10661050
staticvoid
10671051
PrintLockQueue(LOCK*lock,constchar*info)
10681052
{
1069-
PROC_QUEUE*waitQueue=&(lock->waitProcs);
1070-
intqueue_size=waitQueue->size;
1071-
PGPROC*proc;
1072-
inti;
1053+
dclist_head*waitQueue=&lock->waitProcs;
1054+
dlist_iterproc_iter;
10731055

10741056
printf("%s lock %p queue ",info,lock);
1075-
proc= (PGPROC*)waitQueue->links.next;
1076-
for (i=0;i<queue_size;i++)
1057+
1058+
dclist_foreach(proc_iter,waitQueue)
10771059
{
1060+
PGPROC*proc=dlist_container(PGPROC,links,proc_iter.cur);
1061+
10781062
printf(" %d",proc->pid);
1079-
proc= (PGPROC*)proc->links.next;
10801063
}
10811064
printf("\n");
10821065
fflush(stdout);

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