From f91feba8776eb66008cdb73b3a8c0c7c08cc54d9 Mon Sep 17 00:00:00 2001
From: Stephen Frost <sfrost@snowman.net>
Date: Fri, 8 May 2015 19:25:30 -0400
Subject: [PATCH] Modify pg_stat_get_activity to build a tuplestore
This updates pg_stat_get_activity() to build a tuplestore for its
results instead of using the old-style multiple-call method. This
simplifies the function, though that wasn't the primary motivation for
the change, which is that we may turn it into a helper function which
can filter the results (or not) much more easily.
---
src/backend/utils/adt/pgstatfuncs.c | 194 ++++++++++------------------
1 file changed, 67 insertions(+), 127 deletions(-)
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index bbe94c34a15..2b3778b03ad 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -524,137 +524,75 @@ pg_stat_get_backend_idset(PG_FUNCTION_ARGS)
}
}
+/*
+ * Returns activity of PG backends.
+ */
Datum
pg_stat_get_activity(PG_FUNCTION_ARGS)
{
- FuncCallContext *funcctx;
-
- if (SRF_IS_FIRSTCALL())
- {
- MemoryContext oldcontext;
- TupleDesc tupdesc;
-
- funcctx = SRF_FIRSTCALL_INIT();
-
- oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
-
- tupdesc = CreateTemplateTupleDesc(22, false);
- TupleDescInitEntry(tupdesc, (AttrNumber) 1, "datid",
- OIDOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 2, "pid",
- INT4OID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 3, "usesysid",
- OIDOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 4, "application_name",
- TEXTOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 5, "state",
- TEXTOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 6, "query",
- TEXTOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 7, "waiting",
- BOOLOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 8, "act_start",
- TIMESTAMPTZOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 9, "query_start",
- TIMESTAMPTZOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 10, "backend_start",
- TIMESTAMPTZOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 11, "state_change",
- TIMESTAMPTZOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 12, "client_addr",
- INETOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 13, "client_hostname",
- TEXTOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 14, "client_port",
- INT4OID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 15, "backend_xid",
- XIDOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 16, "backend_xmin",
- XIDOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 17, "ssl",
- BOOLOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 18, "sslversion",
- TEXTOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 19, "sslcipher",
- TEXTOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 20, "sslbits",
- INT4OID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 21, "sslcompression",
- BOOLOID, -1, 0);
- TupleDescInitEntry(tupdesc, (AttrNumber) 22, "sslclientdn",
- TEXTOID, -1, 0);
-
- funcctx->tuple_desc = BlessTupleDesc(tupdesc);
-
- funcctx->user_fctx = palloc0(sizeof(int));
- if (PG_ARGISNULL(0))
- {
- /* Get all backends */
- funcctx->max_calls = pgstat_fetch_stat_numbackends();
- }
- else
- {
- /*
- * Get one backend - locate by pid.
- *
- * We lookup the backend early, so we can return zero rows if it
- * doesn't exist, instead of returning a single row full of NULLs.
- */
- int pid = PG_GETARG_INT32(0);
- int i;
- int n = pgstat_fetch_stat_numbackends();
-
- for (i = 1; i <= n; i++)
- {
- PgBackendStatus *be = pgstat_fetch_stat_beentry(i);
-
- if (be)
- {
- if (be->st_procpid == pid)
- {
- *(int *) (funcctx->user_fctx) = i;
- break;
- }
- }
- }
-
- if (*(int *) (funcctx->user_fctx) == 0)
- /* Pid not found, return zero rows */
- funcctx->max_calls = 0;
- else
- funcctx->max_calls = 1;
- }
-
- MemoryContextSwitchTo(oldcontext);
- }
-
- /* stuff done on every call of the function */
- funcctx = SRF_PERCALL_SETUP();
-
- if (funcctx->call_cntr < funcctx->max_calls)
+#define PG_STAT_GET_ACTIVITY_COLS 22
+ int num_backends = pgstat_fetch_stat_numbackends();
+ int curr_backend;
+ int pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
+ ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+ TupleDesc tupdesc;
+ Tuplestorestate *tupstore;
+ MemoryContext per_query_ctx;
+ MemoryContext oldcontext;
+
+ /* 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);
+
+ /* 1-based index */
+ for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
{
/* for each row */
- Datum values[22];
- bool nulls[22];
- HeapTuple tuple;
+ Datum values[PG_STAT_GET_ACTIVITY_COLS];
+ bool nulls[PG_STAT_GET_ACTIVITY_COLS];
LocalPgBackendStatus *local_beentry;
PgBackendStatus *beentry;
MemSet(values, 0, sizeof(values));
MemSet(nulls, 0, sizeof(nulls));
- if (*(int *) (funcctx->user_fctx) > 0)
- {
- /* Get specific pid slot */
- local_beentry = pgstat_fetch_stat_local_beentry(*(int *) (funcctx->user_fctx));
- beentry = &local_beentry->backendStatus;
- }
- else
+ if (pid != -1)
{
- /* Get the next one in the list */
- local_beentry = pgstat_fetch_stat_local_beentry(funcctx->call_cntr + 1); /* 1-based index */
- beentry = &local_beentry->backendStatus;
+ /* Skip any which are not the one we're looking for. */
+ PgBackendStatus *be = pgstat_fetch_stat_beentry(curr_backend);
+
+ if (!be || be->st_procpid != pid)
+ continue;
+
}
+
+ /* Get the next one in the list */
+ local_beentry = pgstat_fetch_stat_local_beentry(curr_backend);
+ if (!local_beentry)
+ continue;
+
+ beentry = &local_beentry->backendStatus;
if (!beentry)
{
int i;
@@ -665,8 +603,8 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
nulls[5] = false;
values[5] = CStringGetTextDatum("<backend information not available>");
- tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
- SRF_RETURN_NEXT(funcctx, HeapTupleGetDatum(tuple));
+ tuplestore_putvalues(tupstore, tupdesc, values, nulls);
+ continue;
}
/* Values available to all callers */
@@ -839,15 +777,17 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
nulls[13] = true;
}
- tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
+ tuplestore_putvalues(tupstore, tupdesc, values, nulls);
- SRF_RETURN_NEXT(funcctx, HeapTupleGetDatum(tuple));
- }
- else
- {
- /* nothing left */
- SRF_RETURN_DONE(funcctx);
+ /* If only a single backend was requested, and we found it, break. */
+ if (pid != -1)
+ break;
}
+
+ /* clean up and return the tuplestore */
+ tuplestore_donestoring(tupstore);
+
+ return (Datum) 0;
}
--
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