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Put the logic to decide which synchronous standby is active into a function.

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This avoids duplicating the code.

Michael Paquier, reviewed by Simon Riggs and me
This commit is contained in:
Heikki Linnakangas
2014-12-12 13:39:36 +02:00
parent 7afc2336cd
commit b1332e98c4
3 changed files with 79 additions and 65 deletions
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52
src/backend/replication/walsender.c
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@@ -2741,9 +2741,7 @@ pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
Tuplestorestate *tupstore;
MemoryContext per_query_ctx;
MemoryContext oldcontext;
int *sync_priority;
int priority = 0;
int sync_standby = -1;
WalSnd *sync_standby;
int i;
/* check to see if caller supports us returning a tuplestore */
@@ -2772,38 +2770,10 @@ pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
MemoryContextSwitchTo(oldcontext);
/*
* Get the priorities of sync standbys all in one go, to minimise lock
* acquisitions and to allow us to evaluate who is the current sync
* standby. This code must match the code in SyncRepReleaseWaiters().
* Get the currently active synchronous standby.
*/
sync_priority = palloc(sizeof(int) * max_wal_senders);
LWLockAcquire(SyncRepLock, LW_SHARED);
for (i = 0; i < max_wal_senders; i++)
{
/* use volatile pointer to prevent code rearrangement */
volatile WalSnd *walsnd = &WalSndCtl->walsnds[i];
if (walsnd->pid != 0)
{
/*
* Treat a standby such as a pg_basebackup background process
* which always returns an invalid flush location, as an
* asynchronous standby.
*/
sync_priority[i] = XLogRecPtrIsInvalid(walsnd->flush) ?
0 : walsnd->sync_standby_priority;
if (walsnd->state == WALSNDSTATE_STREAMING &&
walsnd->sync_standby_priority > 0 &&
(priority == 0 ||
priority > walsnd->sync_standby_priority) &&
!XLogRecPtrIsInvalid(walsnd->flush))
{
priority = walsnd->sync_standby_priority;
sync_standby = i;
}
}
}
sync_standby = SyncRepGetSynchronousStandby();
LWLockRelease(SyncRepLock);
for (i = 0; i < max_wal_senders; i++)
@@ -2814,6 +2784,7 @@ pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
XLogRecPtr write;
XLogRecPtr flush;
XLogRecPtr apply;
int priority;
WalSndState state;
Datum values[PG_STAT_GET_WAL_SENDERS_COLS];
bool nulls[PG_STAT_GET_WAL_SENDERS_COLS];
@@ -2827,6 +2798,7 @@ pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
write = walsnd->write;
flush = walsnd->flush;
apply = walsnd->apply;
priority = walsnd->sync_standby_priority;
SpinLockRelease(&walsnd->mutex);
memset(nulls, 0, sizeof(nulls));
@@ -2857,15 +2829,22 @@ pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
nulls[5] = true;
values[5] = LSNGetDatum(apply);
values[6] = Int32GetDatum(sync_priority[i]);
/*
* Treat a standby such as a pg_basebackup background process
* which always returns an invalid flush location, as an
* asynchronous standby.
*/
priority = XLogRecPtrIsInvalid(walsnd->flush) ? 0 : priority;
values[6] = Int32GetDatum(priority);
/*
* More easily understood version of standby state. This is purely
* informational, not different from priority.
*/
if (sync_priority[i] == 0)
if (priority == 0)
values[7] = CStringGetTextDatum("async");
else if (i == sync_standby)
else if (walsnd == sync_standby)
values[7] = CStringGetTextDatum("sync");
else
values[7] = CStringGetTextDatum("potential");
@@ -2873,7 +2852,6 @@ pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
tuplestore_putvalues(tupstore, tupdesc, values, nulls);
}
pfree(sync_priority);
/* clean up and return the tuplestore */
tuplestore_donestoring(tupstore);