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Remove superfluous 'pgprocno' field from PGPROC
It was always just the index of the PGPROC entry from the beginning of the proc array. Introduce a macro to compute it from the pointer instead. Reviewed-by: Andres Freund Discussion: https://www.postgresql.org/message-id/8171f1aa-496f-46a6-afc3-c46fe7a9b407@iki.fi
1 parent 4989ce7 commit 28f3915

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14 files changed

+46
-43
lines changed

14 files changed

+46
-43
lines changed

‎src/backend/access/transam/clog.c

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -425,6 +425,7 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
425425
{
426426
volatile PROC_HDR *procglobal = ProcGlobal;
427427
PGPROC *proc = MyProc;
428+
int pgprocno = MyProcNumber;
428429
uint32 nextidx;
429430
uint32 wakeidx;
430431

@@ -458,7 +459,7 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
458459
* less efficiently.
459460
*/
460461
if (nextidx != INVALID_PGPROCNO &&
461-
ProcGlobal->allProcs[nextidx].clogGroupMemberPage != proc->clogGroupMemberPage)
462+
GetPGProcByNumber(nextidx)->clogGroupMemberPage != proc->clogGroupMemberPage)
462463
{
463464
/*
464465
* Ensure that this proc is not a member of any clog group that
@@ -473,7 +474,7 @@ TransactionGroupUpdateXidStatus(TransactionId xid, XidStatus status,
473474

474475
if (pg_atomic_compare_exchange_u32(&procglobal->clogGroupFirst,
475476
&nextidx,
476-
(uint32) proc->pgprocno))
477+
(uint32) pgprocno))
477478
break;
478479
}
479480

‎src/backend/access/transam/twophase.c

Lines changed: 5 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -284,7 +284,7 @@ TwoPhaseShmemInit(void)
284284
TwoPhaseState->freeGXacts = &gxacts[i];
285285

286286
/* associate it with a PGPROC assigned by InitProcGlobal */
287-
gxacts[i].pgprocno = PreparedXactProcs[i].pgprocno;
287+
gxacts[i].pgprocno = GetNumberFromPGProc(&PreparedXactProcs[i]);
288288

289289
/*
290290
* Assign a unique ID for each dummy proc, so that the range of
@@ -461,7 +461,6 @@ MarkAsPreparingGuts(GlobalTransaction gxact, TransactionId xid, const char *gid,
461461

462462
/* Initialize the PGPROC entry */
463463
MemSet(proc, 0, sizeof(PGPROC));
464-
proc->pgprocno = gxact->pgprocno;
465464
dlist_node_init(&proc->links);
466465
proc->waitStatus = PROC_WAIT_STATUS_OK;
467466
if (LocalTransactionIdIsValid(MyProc->lxid))
@@ -780,7 +779,7 @@ pg_prepared_xact(PG_FUNCTION_ARGS)
780779
while (status->array != NULL && status->currIdx < status->ngxacts)
781780
{
782781
GlobalTransaction gxact = &status->array[status->currIdx++];
783-
PGPROC *proc = &ProcGlobal->allProcs[gxact->pgprocno];
782+
PGPROC *proc = GetPGProcByNumber(gxact->pgprocno);
784783
Datum values[5] = {0};
785784
bool nulls[5] = {0};
786785
HeapTuple tuple;
@@ -935,7 +934,7 @@ TwoPhaseGetDummyProc(TransactionId xid, bool lock_held)
935934
{
936935
GlobalTransaction gxact = TwoPhaseGetGXact(xid, lock_held);
937936

938-
return &ProcGlobal->allProcs[gxact->pgprocno];
937+
return GetPGProcByNumber(gxact->pgprocno);
939938
}
940939

941940
/************************************************************************/
@@ -1080,7 +1079,7 @@ save_state_data(const void *data, uint32 len)
10801079
void
10811080
StartPrepare(GlobalTransaction gxact)
10821081
{
1083-
PGPROC *proc = &ProcGlobal->allProcs[gxact->pgprocno];
1082+
PGPROC *proc = GetPGProcByNumber(gxact->pgprocno);
10841083
TransactionId xid = gxact->xid;
10851084
TwoPhaseFileHeader hdr;
10861085
TransactionId *children;
@@ -1539,7 +1538,7 @@ FinishPreparedTransaction(const char *gid, bool isCommit)
15391538
* try to commit the same GID at once.
15401539
*/
15411540
gxact = LockGXact(gid, GetUserId());
1542-
proc = &ProcGlobal->allProcs[gxact->pgprocno];
1541+
proc = GetPGProcByNumber(gxact->pgprocno);
15431542
xid = gxact->xid;
15441543

15451544
/*

‎src/backend/access/transam/xlog.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1379,7 +1379,7 @@ WALInsertLockAcquire(void)
13791379
static int lockToTry = -1;
13801380

13811381
if (lockToTry == -1)
1382-
lockToTry = MyProc->pgprocno % NUM_XLOGINSERT_LOCKS;
1382+
lockToTry = MyProcNumber % NUM_XLOGINSERT_LOCKS;
13831383
MyLockNo = lockToTry;
13841384

13851385
/*

‎src/backend/postmaster/bgwriter.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -326,7 +326,7 @@ BackgroundWriterMain(void)
326326
if (rc == WL_TIMEOUT && can_hibernate && prev_hibernate)
327327
{
328328
/* Ask for notification at next buffer allocation */
329-
StrategyNotifyBgWriter(MyProc->pgprocno);
329+
StrategyNotifyBgWriter(MyProcNumber);
330330
/* Sleep ... */
331331
(void) WaitLatch(MyLatch,
332332
WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH,

‎src/backend/postmaster/pgarch.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -242,7 +242,7 @@ PgArchiverMain(void)
242242
* Advertise our pgprocno so that backends can use our latch to wake us up
243243
* while we're sleeping.
244244
*/
245-
PgArch->pgprocno = MyProc->pgprocno;
245+
PgArch->pgprocno = MyProcNumber;
246246

247247
/* Create workspace for pgarch_readyXlog() */
248248
arch_files = palloc(sizeof(struct arch_files_state));

‎src/backend/postmaster/walsummarizer.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -248,7 +248,7 @@ WalSummarizerMain(void)
248248
/* Advertise ourselves. */
249249
on_shmem_exit(WalSummarizerShutdown, (Datum) 0);
250250
LWLockAcquire(WALSummarizerLock, LW_EXCLUSIVE);
251-
WalSummarizerCtl->summarizer_pgprocno = MyProc->pgprocno;
251+
WalSummarizerCtl->summarizer_pgprocno = MyProcNumber;
252252
LWLockRelease(WALSummarizerLock);
253253

254254
/* Create and switch to a memory context that we can reset on error. */

‎src/backend/storage/buffer/bufmgr.c

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -4780,7 +4780,7 @@ UnlockBuffers(void)
47804780
* got a cancel/die interrupt before getting the signal.
47814781
*/
47824782
if ((buf_state & BM_PIN_COUNT_WAITER) != 0 &&
4783-
buf->wait_backend_pgprocno == MyProc->pgprocno)
4783+
buf->wait_backend_pgprocno == MyProcNumber)
47844784
buf_state &= ~BM_PIN_COUNT_WAITER;
47854785

47864786
UnlockBufHdr(buf, buf_state);
@@ -4930,7 +4930,7 @@ LockBufferForCleanup(Buffer buffer)
49304930
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
49314931
elog(ERROR, "multiple backends attempting to wait for pincount 1");
49324932
}
4933-
bufHdr->wait_backend_pgprocno = MyProc->pgprocno;
4933+
bufHdr->wait_backend_pgprocno = MyProcNumber;
49344934
PinCountWaitBuf = bufHdr;
49354935
buf_state |= BM_PIN_COUNT_WAITER;
49364936
UnlockBufHdr(bufHdr, buf_state);
@@ -4994,7 +4994,7 @@ LockBufferForCleanup(Buffer buffer)
49944994
*/
49954995
buf_state = LockBufHdr(bufHdr);
49964996
if ((buf_state & BM_PIN_COUNT_WAITER) != 0 &&
4997-
bufHdr->wait_backend_pgprocno == MyProc->pgprocno)
4997+
bufHdr->wait_backend_pgprocno == MyProcNumber)
49984998
buf_state &= ~BM_PIN_COUNT_WAITER;
49994999
UnlockBufHdr(bufHdr, buf_state);
50005000

‎src/backend/storage/ipc/procarray.c

Lines changed: 8 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -468,6 +468,7 @@ CreateSharedProcArray(void)
468468
void
469469
ProcArrayAdd(PGPROC *proc)
470470
{
471+
int pgprocno = GetNumberFromPGProc(proc);
471472
ProcArrayStruct *arrayP = procArray;
472473
int index;
473474
int movecount;
@@ -499,13 +500,13 @@ ProcArrayAdd(PGPROC *proc)
499500
*/
500501
for (index = 0; index < arrayP->numProcs; index++)
501502
{
502-
int procno PG_USED_FOR_ASSERTS_ONLY = arrayP->pgprocnos[index];
503+
int this_procno = arrayP->pgprocnos[index];
503504

504-
Assert(procno >= 0 && procno < (arrayP->maxProcs + NUM_AUXILIARY_PROCS));
505-
Assert(allProcs[procno].pgxactoff == index);
505+
Assert(this_procno >= 0 && this_procno < (arrayP->maxProcs + NUM_AUXILIARY_PROCS));
506+
Assert(allProcs[this_procno].pgxactoff == index);
506507

507508
/* If we have found our right position in the array, break */
508-
if (arrayP->pgprocnos[index] > proc->pgprocno)
509+
if (this_procno > pgprocno)
509510
break;
510511
}
511512

@@ -523,7 +524,7 @@ ProcArrayAdd(PGPROC *proc)
523524
&ProcGlobal->statusFlags[index],
524525
movecount * sizeof(*ProcGlobal->statusFlags));
525526

526-
arrayP->pgprocnos[index] = proc->pgprocno;
527+
arrayP->pgprocnos[index] = GetNumberFromPGProc(proc);
527528
proc->pgxactoff = index;
528529
ProcGlobal->xids[index] = proc->xid;
529530
ProcGlobal->subxidStates[index] = proc->subxidStatus;
@@ -791,6 +792,7 @@ ProcArrayEndTransactionInternal(PGPROC *proc, TransactionId latestXid)
791792
static void
792793
ProcArrayGroupClearXid(PGPROC *proc, TransactionId latestXid)
793794
{
795+
int pgprocno = GetNumberFromPGProc(proc);
794796
PROC_HDR *procglobal = ProcGlobal;
795797
uint32 nextidx;
796798
uint32 wakeidx;
@@ -808,7 +810,7 @@ ProcArrayGroupClearXid(PGPROC *proc, TransactionId latestXid)
808810

809811
if (pg_atomic_compare_exchange_u32(&procglobal->procArrayGroupFirst,
810812
&nextidx,
811-
(uint32) proc->pgprocno))
813+
(uint32) pgprocno))
812814
break;
813815
}
814816

‎src/backend/storage/lmgr/condition_variable.c

Lines changed: 6 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -57,7 +57,7 @@ ConditionVariableInit(ConditionVariable *cv)
5757
void
5858
ConditionVariablePrepareToSleep(ConditionVariable *cv)
5959
{
60-
int pgprocno = MyProc->pgprocno;
60+
int pgprocno = MyProcNumber;
6161

6262
/*
6363
* If some other sleep is already prepared, cancel it; this is necessary
@@ -181,10 +181,10 @@ ConditionVariableTimedSleep(ConditionVariable *cv, long timeout,
181181
* guarantee not to return spuriously, we'll avoid this obvious case.
182182
*/
183183
SpinLockAcquire(&cv->mutex);
184-
if (!proclist_contains(&cv->wakeup, MyProc->pgprocno, cvWaitLink))
184+
if (!proclist_contains(&cv->wakeup, MyProcNumber, cvWaitLink))
185185
{
186186
done = true;
187-
proclist_push_tail(&cv->wakeup, MyProc->pgprocno, cvWaitLink);
187+
proclist_push_tail(&cv->wakeup, MyProcNumber, cvWaitLink);
188188
}
189189
SpinLockRelease(&cv->mutex);
190190

@@ -236,8 +236,8 @@ ConditionVariableCancelSleep(void)
236236
return false;
237237

238238
SpinLockAcquire(&cv->mutex);
239-
if (proclist_contains(&cv->wakeup, MyProc->pgprocno, cvWaitLink))
240-
proclist_delete(&cv->wakeup, MyProc->pgprocno, cvWaitLink);
239+
if (proclist_contains(&cv->wakeup, MyProcNumber, cvWaitLink))
240+
proclist_delete(&cv->wakeup, MyProcNumber, cvWaitLink);
241241
else
242242
signaled = true;
243243
SpinLockRelease(&cv->mutex);
@@ -281,7 +281,7 @@ ConditionVariableSignal(ConditionVariable *cv)
281281
void
282282
ConditionVariableBroadcast(ConditionVariable *cv)
283283
{
284-
int pgprocno = MyProc->pgprocno;
284+
int pgprocno = MyProcNumber;
285285
PGPROC *proc = NULL;
286286
bool have_sentinel = false;
287287

‎src/backend/storage/lmgr/lwlock.c

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1056,9 +1056,9 @@ LWLockQueueSelf(LWLock *lock, LWLockMode mode)
10561056

10571057
/* LW_WAIT_UNTIL_FREE waiters are always at the front of the queue */
10581058
if (mode == LW_WAIT_UNTIL_FREE)
1059-
proclist_push_head(&lock->waiters, MyProc->pgprocno, lwWaitLink);
1059+
proclist_push_head(&lock->waiters, MyProcNumber, lwWaitLink);
10601060
else
1061-
proclist_push_tail(&lock->waiters, MyProc->pgprocno, lwWaitLink);
1061+
proclist_push_tail(&lock->waiters, MyProcNumber, lwWaitLink);
10621062

10631063
/* Can release the mutex now */
10641064
LWLockWaitListUnlock(lock);
@@ -1097,7 +1097,7 @@ LWLockDequeueSelf(LWLock *lock)
10971097
*/
10981098
on_waitlist = MyProc->lwWaiting == LW_WS_WAITING;
10991099
if (on_waitlist)
1100-
proclist_delete(&lock->waiters, MyProc->pgprocno, lwWaitLink);
1100+
proclist_delete(&lock->waiters, MyProcNumber, lwWaitLink);
11011101

11021102
if (proclist_is_empty(&lock->waiters) &&
11031103
(pg_atomic_read_u32(&lock->state) & LW_FLAG_HAS_WAITERS) != 0)

‎src/backend/storage/lmgr/predicate.c

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1830,7 +1830,7 @@ GetSerializableTransactionSnapshotInt(Snapshot snapshot,
18301830
sxact->finishedBefore = InvalidTransactionId;
18311831
sxact->xmin = snapshot->xmin;
18321832
sxact->pid = MyProcPid;
1833-
sxact->pgprocno = MyProc->pgprocno;
1833+
sxact->pgprocno = MyProcNumber;
18341834
dlist_init(&sxact->predicateLocks);
18351835
dlist_node_init(&sxact->finishedLink);
18361836
sxact->flags = 0;

‎src/backend/storage/lmgr/proc.c

Lines changed: 9 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -65,6 +65,7 @@ bool log_lock_waits = false;
6565

6666
/* Pointer to this process's PGPROC struct, if any */
6767
PGPROC *MyProc = NULL;
68+
int MyProcNumber = INVALID_PGPROCNO;
6869

6970
/*
7071
* This spinlock protects the freelist of recycled PGPROC structures.
@@ -228,7 +229,6 @@ InitProcGlobal(void)
228229
InitSharedLatch(&(proc->procLatch));
229230
LWLockInitialize(&(proc->fpInfoLock), LWTRANCHE_LOCK_FASTPATH);
230231
}
231-
proc->pgprocno = i;
232232

233233
/*
234234
* Newly created PGPROCs for normal backends, autovacuum and bgworkers
@@ -353,6 +353,7 @@ InitProcess(void)
353353
(errcode(ERRCODE_TOO_MANY_CONNECTIONS),
354354
errmsg("sorry, too many clients already")));
355355
}
356+
MyProcNumber = GetNumberFromPGProc(MyProc);
356357

357358
/*
358359
* Cross-check that the PGPROC is of the type we expect; if this were not
@@ -566,6 +567,8 @@ InitAuxiliaryProcess(void)
566567

567568
SpinLockRelease(ProcStructLock);
568569

570+
MyProcNumber = GetNumberFromPGProc(MyProc);
571+
569572
/*
570573
* Initialize all fields of MyProc, except for those previously
571574
* initialized by InitProcGlobal.
@@ -907,6 +910,7 @@ ProcKill(int code, Datum arg)
907910

908911
proc = MyProc;
909912
MyProc = NULL;
913+
MyProcNumber = INVALID_PGPROCNO;
910914
DisownLatch(&proc->procLatch);
911915

912916
procgloballist = proc->procgloballist;
@@ -978,6 +982,7 @@ AuxiliaryProcKill(int code, Datum arg)
978982

979983
proc = MyProc;
980984
MyProc = NULL;
985+
MyProcNumber = INVALID_PGPROCNO;
981986
DisownLatch(&proc->procLatch);
982987

983988
SpinLockAcquire(ProcStructLock);
@@ -1903,10 +1908,9 @@ BecomeLockGroupMember(PGPROC *leader, int pid)
19031908

19041909
/*
19051910
* Get lock protecting the group fields. Note LockHashPartitionLockByProc
1906-
* accesses leader->pgprocno in a PGPROC that might be free. This is safe
1907-
* because all PGPROCs' pgprocno fields are set during shared memory
1908-
* initialization and never change thereafter; so we will acquire the
1909-
* correct lock even if the leader PGPROC is in process of being recycled.
1911+
* calculates the proc number based on the PGPROC slot without looking at
1912+
* its contents, so we will acquire the correct lock even if the leader
1913+
* PGPROC is in process of being recycled.
19101914
*/
19111915
leader_lwlock = LockHashPartitionLockByProc(leader);
19121916
LWLockAcquire(leader_lwlock, LW_EXCLUSIVE);

‎src/include/storage/lock.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -540,7 +540,7 @@ typedef enum
540540
* used for a given lock group is determined by the group leader's pgprocno.
541541
*/
542542
#define LockHashPartitionLockByProc(leader_pgproc) \
543-
LockHashPartitionLock((leader_pgproc)->pgprocno)
543+
LockHashPartitionLock(GetNumberFromPGProc(leader_pgproc))
544544

545545
/*
546546
* function prototypes

‎src/include/storage/proc.h

Lines changed: 3 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -194,11 +194,6 @@ struct PGPROC
194194
int pgxactoff; /* offset into various ProcGlobal->arrays with
195195
* data mirrored from this PGPROC */
196196

197-
int pgprocno; /* Number of this PGPROC in
198-
* ProcGlobal->allProcs array. This is set
199-
* once by InitProcGlobal().
200-
* ProcGlobal->allProcs[n].pgprocno == n */
201-
202197
/* These fields are zero while a backend is still starting up: */
203198
BackendId backendId; /* This backend's backend ID (if assigned) */
204199
Oid databaseId; /* OID of database this backend is using */
@@ -307,6 +302,7 @@ struct PGPROC
307302

308303

309304
extern PGDLLIMPORT PGPROC *MyProc;
305+
extern PGDLLIMPORT int MyProcNumber; /* same as GetNumberFromPGProc(MyProc) */
310306

311307
/*
312308
* There is one ProcGlobal struct for the whole database cluster.
@@ -410,8 +406,9 @@ extern PGDLLIMPORT PROC_HDR *ProcGlobal;
410406

411407
extern PGDLLIMPORT PGPROC *PreparedXactProcs;
412408

413-
/* Accessor for PGPROC given a pgprocno. */
409+
/* Accessor for PGPROC given a pgprocno, and vice versa. */
414410
#define GetPGProcByNumber(n) (&ProcGlobal->allProcs[(n)])
411+
#define GetNumberFromPGProc(proc) ((proc) - &ProcGlobal->allProcs[0])
415412

416413
/*
417414
* We set aside some extra PGPROC structures for auxiliary processes,

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