Improve comments.

tglsfdc · tglsfdc · commit 8b53eaf90ce8 · 2000-10-19T23:06:24.000Z
diff --git a/src/backend/utils/cache/temprel.c b/src/backend/utils/cache/temprel.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/cache/Attic/temprel.c,v 1.28 2000/10/11 21:28:19 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/cache/Attic/temprel.c,v 1.29 2000/10/19 23:06:24 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -91,24 +91,37 @@ create_temp_relation(const char *relname, HeapTuple pg_class_tuple)
 void
 remove_all_temp_relations(void)
 {
+	/* skip xact start overhead if nothing to do */
+	if (temp_rels == NIL)
+		return;
+
 	AbortOutOfAnyTransaction();
 	StartTransactionCommand();
 
+	/*
+	 * The way this works is that each time through the loop, we delete
+	 * the frontmost entry.  The DROP will call remove_temp_rel_by_relid()
+	 * as a side effect, thereby removing the entry in the temp_rels list.
+	 * So this is not an infinite loop, even though it looks like one.
+	 */
 	while (temp_rels != NIL)
 	{
-		char		relname[NAMEDATALEN];
 		TempTable  *temp_rel = (TempTable *) lfirst(temp_rels);
 
 		if (temp_rel->relkind != RELKIND_INDEX)
 		{
+			char		relname[NAMEDATALEN];
+
 			/* safe from deallocation */
 			strcpy(relname, temp_rel->user_relname);
 			heap_drop_with_catalog(relname, allowSystemTableMods);
 		}
 		else
 			index_drop(temp_rel->relid);
+		/* advance cmd counter to make catalog changes visible */
 		CommandCounterIncrement();
 	}
+
 	CommitTransactionCommand();
 }
 

Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,7 @@`
`8`	`8`	`*`
`9`	`9`	`*`
`10`	`10`	`* IDENTIFICATION`
`11`		`- * $Header: /cvsroot/pgsql/src/backend/utils/cache/Attic/temprel.c,v 1.28 2000/10/11 21:28:19 momjian Exp $`
	`11`	`+ * $Header: /cvsroot/pgsql/src/backend/utils/cache/Attic/temprel.c,v 1.29 2000/10/19 23:06:24 tgl Exp $`
`12`	`12`	`*`
`13`	`13`	`*-------------------------------------------------------------------------`
`14`	`14`	`*/`
`@@ -91,24 +91,37 @@ create_temp_relation(const char *relname, HeapTuple pg_class_tuple)`
`91`	`91`	`void`
`92`	`92`	`remove_all_temp_relations(void)`
`93`	`93`	`{`
	`94`	`+ /* skip xact start overhead if nothing to do */`
	`95`	`+ if (temp_rels == NIL)`
	`96`	`+ return;`
	`97`	`+`
`94`	`98`	`AbortOutOfAnyTransaction();`
`95`	`99`	`StartTransactionCommand();`
`96`	`100`
	`101`	`+ /*`
	`102`	`+ * The way this works is that each time through the loop, we delete`
	`103`	`+ * the frontmost entry. The DROP will call remove_temp_rel_by_relid()`
	`104`	`+ * as a side effect, thereby removing the entry in the temp_rels list.`
	`105`	`+ * So this is not an infinite loop, even though it looks like one.`
	`106`	`+ */`
`97`	`107`	`while (temp_rels != NIL)`
`98`	`108`	`{`
`99`		`- char relname[NAMEDATALEN];`
`100`	`109`	`TempTable temp_rel = (TempTable ) lfirst(temp_rels);`
`101`	`110`
`102`	`111`	`if (temp_rel->relkind != RELKIND_INDEX)`
`103`	`112`	`{`
	`113`	`+ char relname[NAMEDATALEN];`
	`114`	`+`
`104`	`115`	`/* safe from deallocation */`
`105`	`116`	`strcpy(relname, temp_rel->user_relname);`
`106`	`117`	`heap_drop_with_catalog(relname, allowSystemTableMods);`
`107`	`118`	`}`
`108`	`119`	`else`
`109`	`120`	`index_drop(temp_rel->relid);`
	`121`	`+ /* advance cmd counter to make catalog changes visible */`
`110`	`122`	`CommandCounterIncrement();`
`111`	`123`	`}`
	`124`	`+`
`112`	`125`	`CommitTransactionCommand();`
`113`	`126`	`}`
`114`	`127`