mbutils was previously doing some allocations, including invoking

fmgr_info(), in the TopMemoryContext. I couldn't see that the code
actually leaked, but in general I think it's fragile to assume that
pfree'ing an FmgrInfo along with its fn_extra field is enough to
reclaim all the resources allocated by fmgr_info().  I changed the
code to do its allocations in a new child context of
TopMemoryContext, MbProcContext. When we want to release the
allocations we can just reset the context, which is cleaner.

diff --git a/src/backend/utils/mb/mbutils.c b/src/backend/utils/mb/mbutils.c
index 3313439eb71ed7233b0b8912511ea22cf19de1c9..dc43b049c6ee326ee1fcca5a5c54884fb2256262 100644 (file)
--- a/src/backend/utils/mb/mbutils.c
+++ b/src/backend/utils/mb/mbutils.c
@@ -4,17 +4,17 @@
  * (currently mule internal code (mic) is used)
  * Tatsuo Ishii
  *
- * $PostgreSQL: pgsql/src/backend/utils/mb/mbutils.c,v 1.54 2006/01/11 08:43:12 neilc Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/mb/mbutils.c,v 1.55 2006/01/12 22:04:02 neilc Exp $
  */
 #include "postgres.h"
 
 #include "access/xact.h"
+#include "catalog/namespace.h"
 #include "miscadmin.h"
 #include "mb/pg_wchar.h"
 #include "utils/builtins.h"
 #include "utils/memutils.h"
 #include "utils/syscache.h"
-#include "catalog/namespace.h"
 
 /*
  * We handle for actual FE and BE encoding setting encoding-identificator
@@ -25,10 +25,12 @@ static pg_enc2name *ClientEncoding = &pg_enc2name_tbl[PG_SQL_ASCII];
 static pg_enc2name *DatabaseEncoding = &pg_enc2name_tbl[PG_SQL_ASCII];
 
 /*
- * Caches for conversion function info. Note that these values are
- * allocated in TopMemoryContext so that they survive across
- * transactions. See SetClientEncoding() for more details.
+ * Caches for conversion function info. These values are allocated in
+ * MbProcContext. That context is a child of TopMemoryContext,
+ * which allows these values to survive across transactions. See
+ * SetClientEncoding() for more details.
  */
+static MemoryContext MbProcContext = NULL;
 static FmgrInfo *ToServerConvProc = NULL;
 static FmgrInfo *ToClientConvProc = NULL;
 
@@ -86,22 +88,10 @@ SetClientEncoding(int encoding, bool doit)
                if (doit)
                {
                        ClientEncoding = &pg_enc2name_tbl[encoding];
-
-                       if (ToServerConvProc != NULL)
-                       {
-                               if (ToServerConvProc->fn_extra)
-                                       pfree(ToServerConvProc->fn_extra);
-                               pfree(ToServerConvProc);
-                       }
                        ToServerConvProc = NULL;
-
-                       if (ToClientConvProc != NULL)
-                       {
-                               if (ToClientConvProc->fn_extra)
-                                       pfree(ToClientConvProc->fn_extra);
-                               pfree(ToClientConvProc);
-                       }
                        ToClientConvProc = NULL;
+                       if (MbProcContext)
+                               MemoryContextReset(MbProcContext);
                }
                return 0;
        }
@@ -134,11 +124,29 @@ SetClientEncoding(int encoding, bool doit)
        if (!doit)
                return 0;
 
-       /*
-        * load the fmgr info into TopMemoryContext so that it survives outside
-        * transaction.
-        */
-       oldcontext = MemoryContextSwitchTo(TopMemoryContext);
+       /* Before loading the new fmgr info, remove the old info, if any */
+       ToServerConvProc = NULL;
+       ToClientConvProc = NULL;
+       if (MbProcContext != NULL)
+       {
+               MemoryContextReset(MbProcContext);
+       }
+       else
+       {
+               /*
+                * This is the first time through, so create the context. Make
+                * it a child of TopMemoryContext so that these values survive
+                * across transactions.
+                */
+               MbProcContext = AllocSetContextCreate(TopMemoryContext,
+                                                                                         "MbProcContext",
+                                                                                         ALLOCSET_SMALL_MINSIZE,
+                                                                                         ALLOCSET_SMALL_INITSIZE,
+                                                                                         ALLOCSET_SMALL_MAXSIZE);
+       }
+
+       /* Load the fmgr info into MbProcContext */
+       oldcontext = MemoryContextSwitchTo(MbProcContext);
        to_server = palloc(sizeof(FmgrInfo));
        to_client = palloc(sizeof(FmgrInfo));
        fmgr_info(to_server_proc, to_server);
@@ -146,21 +154,7 @@ SetClientEncoding(int encoding, bool doit)
        MemoryContextSwitchTo(oldcontext);
 
        ClientEncoding = &pg_enc2name_tbl[encoding];
-
-       if (ToServerConvProc != NULL)
-       {
-               if (ToServerConvProc->fn_extra)
-                       pfree(ToServerConvProc->fn_extra);
-               pfree(ToServerConvProc);
-       }
        ToServerConvProc = to_server;
-
-       if (ToClientConvProc != NULL)
-       {
-               if (ToClientConvProc->fn_extra)
-                       pfree(ToClientConvProc->fn_extra);
-               pfree(ToClientConvProc);
-       }
        ToClientConvProc = to_client;
 
        return 0;