From a933ee38bbb8dffbc48a3363a94ff6f2a9f7964d Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 16 Nov 2000 22:30:52 +0000
Subject: Change SearchSysCache coding conventions so that a reference count is
 maintained for each cache entry.  A cache entry will not be freed until the
 matching ReleaseSysCache call has been executed.  This eliminates worries
 about cache entries getting dropped while still in use.  See my posting to
 pg-hackers of even date for more info.

---
 src/backend/commands/async.c | 35 ++++++++++++++++++-----------------
 1 file changed, 18 insertions(+), 17 deletions(-)

(limited to 'src/backend/commands/async.c')

diff --git a/src/backend/commands/async.c b/src/backend/commands/async.c
index 6611f134727..77f7776f6d9 100644
--- a/src/backend/commands/async.c
+++ b/src/backend/commands/async.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/async.c,v 1.70 2000/10/03 03:11:13 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/async.c,v 1.71 2000/11/16 22:30:18 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -193,9 +193,7 @@ void
 Async_Listen(char *relname, int pid)
 {
 	Relation	lRel;
-	TupleDesc	tdesc;
-	HeapTuple	tuple,
-				newtup;
+	HeapTuple	tuple;
 	Datum		values[Natts_pg_listener];
 	char		nulls[Natts_pg_listener];
 	int			i;
@@ -205,13 +203,12 @@ Async_Listen(char *relname, int pid)
 		elog(DEBUG, "Async_Listen: %s", relname);
 
 	lRel = heap_openr(ListenerRelationName, AccessExclusiveLock);
-	tdesc = RelationGetDescr(lRel);
 
 	/* Detect whether we are already listening on this relname */
-	tuple = SearchSysCacheTuple(LISTENREL, Int32GetDatum(pid),
-								PointerGetDatum(relname),
-								0, 0);
-	if (tuple != NULL)
+	if (SearchSysCacheExists(LISTENREL,
+							 Int32GetDatum(pid),
+							 PointerGetDatum(relname),
+							 0, 0))
 	{
 		/* No need to scan the rest of the table */
 		heap_close(lRel, AccessExclusiveLock);
@@ -235,18 +232,18 @@ Async_Listen(char *relname, int pid)
 	values[i++] = (Datum) 0;	/* no notifies pending */
 
 	tupDesc = lRel->rd_att;
-	newtup = heap_formtuple(tupDesc, values, nulls);
-	heap_insert(lRel, newtup);
+	tuple = heap_formtuple(tupDesc, values, nulls);
+	heap_insert(lRel, tuple);
 	if (RelationGetForm(lRel)->relhasindex)
 	{
 		Relation	idescs[Num_pg_listener_indices];
 
 		CatalogOpenIndices(Num_pg_listener_indices, Name_pg_listener_indices, idescs);
-		CatalogIndexInsert(idescs, Num_pg_listener_indices, lRel, newtup);
+		CatalogIndexInsert(idescs, Num_pg_listener_indices, lRel, tuple);
 		CatalogCloseIndices(Num_pg_listener_indices, idescs);
 	}
 
-	heap_freetuple(newtup);
+	heap_freetuple(tuple);
 
 	heap_close(lRel, AccessExclusiveLock);
 
@@ -296,11 +293,15 @@ Async_Unlisten(char *relname, int pid)
 
 	lRel = heap_openr(ListenerRelationName, AccessExclusiveLock);
 	/* Note we assume there can be only one matching tuple. */
-	lTuple = SearchSysCacheTuple(LISTENREL, Int32GetDatum(pid),
-								PointerGetDatum(relname),
-								0, 0);
-	if (lTuple != NULL)
+	lTuple = SearchSysCache(LISTENREL,
+							Int32GetDatum(pid),
+							PointerGetDatum(relname),
+							0, 0);
+	if (HeapTupleIsValid(lTuple))
+	{
 		heap_delete(lRel, &lTuple->t_self, NULL);
+		ReleaseSysCache(lTuple);
+	}
 	heap_close(lRel, AccessExclusiveLock);
 
 	/*
-- 
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