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Add some assertions in syncrep.c

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A couple of routines assume that the LWLock SyncRepLock needs to be
taken, so add a couple of assertions to be sure of that.  Also, when
waiting for a given LSN at transaction commit, the code implied that the
syncrep queue cleanup happens while holding interrupts, but the code
never checked after that.

Author: Michael Paquier
Reviewed-by: Fujii Masao, Kyotaro Horiguchi, Dongming Liu
Discussion: https://postgr.es/m/a0806273-8bbb-43b3-bbe1-c45a58f6ae21.lingce.ldm@alibaba-inc.com
This commit is contained in:
Michael Paquier 2019-11-01 22:51:05 +09:00
parent 20345197ff
commit e174f699c4
1 changed files with 15 additions and 1 deletions
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16
src/backend/replication/syncrep.c
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@ -149,6 +149,13 @@ SyncRepWaitForLSN(XLogRecPtr lsn, bool commit)
const char *old_status;
int mode;
/*
* This should be called while holding interrupts during a transaction
* commit to prevent the follow-up shared memory queue cleanups to be
* influenced by external interruptions.
*/
Assert(InterruptHoldoffCount > 0);
/* Cap the level for anything other than commit to remote flush only. */
if (commit)
mode = SyncRepWaitMode;
@ -516,6 +523,8 @@ SyncRepReleaseWaiters(void)
/*
* Calculate the synced Write, Flush and Apply positions among sync standbys.
*
* The caller must hold SyncRepLock.
*
* Return false if the number of sync standbys is less than
* synchronous_standby_names specifies. Otherwise return true and
* store the positions into *writePtr, *flushPtr and *applyPtr.
@ -529,6 +538,8 @@ SyncRepGetSyncRecPtr(XLogRecPtr *writePtr, XLogRecPtr *flushPtr,
{
List *sync_standbys;
Assert(LWLockHeldByMe(SyncRepLock));
*writePtr = InvalidXLogRecPtr;
*flushPtr = InvalidXLogRecPtr;
*applyPtr = InvalidXLogRecPtr;
@ -688,6 +699,8 @@ cmp_lsn(const void *a, const void *b)
List *
SyncRepGetSyncStandbys(bool *am_sync)
{
Assert(LWLockHeldByMe(SyncRepLock));
/* Set default result */
if (am_sync != NULL)
*am_sync = false;
@ -992,7 +1005,7 @@ SyncRepGetStandbyPriority(void)
* Pass all = true to wake whole queue; otherwise, just wake up to
* the walsender's LSN.
*
* Must hold SyncRepLock.
* The caller must hold SyncRepLock in exclusive mode.
*/
static int
SyncRepWakeQueue(bool all, int mode)
@ -1003,6 +1016,7 @@ SyncRepWakeQueue(bool all, int mode)
int numprocs = 0;
Assert(mode >= 0 && mode < NUM_SYNC_REP_WAIT_MODE);
Assert(LWLockHeldByMeInMode(SyncRepLock, LW_EXCLUSIVE));
Assert(SyncRepQueueIsOrderedByLSN(mode));
proc = (PGPROC *) SHMQueueNext(&(WalSndCtl->SyncRepQueue[mode]),