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New system view pg_stat_replication displays activity of wal sender processes.

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Itagaki Takahiro and Simon Riggs.
This commit is contained in:
Itagaki Takahiro
2011-01-07 20:35:38 +09:00
parent 46d28820b6
commit a755ea33ae
5 changed files with 95 additions and 1 deletions
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74
src/backend/replication/walsender.c
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@@ -37,6 +37,7 @@
#include <signal.h>
#include <unistd.h>
#include "funcapi.h"
#include "access/xlog_internal.h"
#include "catalog/pg_type.h"
#include "libpq/libpq.h"
@@ -49,6 +50,7 @@
#include "storage/ipc.h"
#include "storage/pmsignal.h"
#include "tcop/tcopprot.h"
#include "utils/builtins.h"
#include "utils/guc.h"
#include "utils/memutils.h"
#include "utils/ps_status.h"
@@ -942,6 +944,78 @@ WalSndWakeup(void)
SetLatch(&WalSndCtl->walsnds[i].latch);
}
/*
* Returns activity of walsenders, including pids and xlog locations sent to
* standby servers.
*/
Datum
pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
{
#define PG_STAT_GET_WAL_SENDERS_COLS 2
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
TupleDesc tupdesc;
Tuplestorestate *tupstore;
MemoryContext per_query_ctx;
MemoryContext oldcontext;
int i;
/* check to see if caller supports us returning a tuplestore */
if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("set-valued function called in context that cannot accept a set")));
if (!(rsinfo->allowedModes & SFRM_Materialize))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("materialize mode required, but it is not " \
"allowed in this context")));
/* Build a tuple descriptor for our result type */
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
oldcontext = MemoryContextSwitchTo(per_query_ctx);
tupstore = tuplestore_begin_heap(true, false, work_mem);
rsinfo->returnMode = SFRM_Materialize;
rsinfo->setResult = tupstore;
rsinfo->setDesc = tupdesc;
MemoryContextSwitchTo(oldcontext);
for (i = 0; i < max_wal_senders; i++)
{
/* use volatile pointer to prevent code rearrangement */
volatile WalSnd *walsnd = &WalSndCtl->walsnds[i];
char sent_location[MAXFNAMELEN];
XLogRecPtr sentPtr;
Datum values[PG_STAT_GET_WAL_SENDERS_COLS];
bool nulls[PG_STAT_GET_WAL_SENDERS_COLS];
if (walsnd->pid == 0)
continue;
SpinLockAcquire(&walsnd->mutex);
sentPtr = walsnd->sentPtr;
SpinLockRelease(&walsnd->mutex);
snprintf(sent_location, sizeof(sent_location), "%X/%X",
sentPtr.xlogid, sentPtr.xrecoff);
memset(nulls, 0, sizeof(nulls));
values[0] = Int32GetDatum(walsnd->pid);
values[1] = CStringGetTextDatum(sent_location);
tuplestore_putvalues(tupstore, tupdesc, values, nulls);
}
/* clean up and return the tuplestore */
tuplestore_donestoring(tupstore);
return (Datum) 0;
}
/*
* This isn't currently used for anything. Monitoring tools might be
* interested in the future, and we'll need something like this in the