/*
* This file contains public functions for conversion between
- * client encoding and server internal encoding.
- * (currently mule internal code (mic) is used)
+ * client encoding and server (database) encoding.
+ *
* Tatsuo Ishii
*
- * $PostgreSQL: pgsql/src/backend/utils/mb/mbutils.c,v 1.82 2009/03/09 00:01:32 alvherre Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/mb/mbutils.c,v 1.83 2009/04/02 17:30:53 tgl Exp $
*/
#include "postgres.h"
#define MAX_CONVERSION_GROWTH 4
/*
- * We handle for actual FE and BE encoding setting encoding-identificator
- * and encoding-name too. It prevent searching and conversion from encoding
- * to encoding name in getdatabaseencoding() and other routines.
+ * We maintain a simple linked list caching the fmgr lookup info for the
+ * currently selected conversion functions, as well as any that have been
+ * selected previously in the current session. (We remember previous
+ * settings because we must be able to restore a previous setting during
+ * transaction rollback, without doing any fresh catalog accesses.)
+ *
+ * Since we'll never release this data, we just keep it in TopMemoryContext.
*/
-static pg_enc2name *ClientEncoding = &pg_enc2name_tbl[PG_SQL_ASCII];
-static pg_enc2name *DatabaseEncoding = &pg_enc2name_tbl[PG_SQL_ASCII];
+typedef struct ConvProcInfo
+{
+ int s_encoding; /* server and client encoding IDs */
+ int c_encoding;
+ FmgrInfo to_server_info; /* lookup info for conversion procs */
+ FmgrInfo to_client_info;
+} ConvProcInfo;
+
+static List *ConvProcList = NIL; /* List of ConvProcInfo */
/*
- * 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.
+ * These variables point to the currently active conversion functions,
+ * or are NULL when no conversion is needed.
*/
-static MemoryContext MbProcContext = NULL;
static FmgrInfo *ToServerConvProc = NULL;
static FmgrInfo *ToClientConvProc = NULL;
+/*
+ * These variables track the currently selected FE and BE encodings.
+ */
+static pg_enc2name *ClientEncoding = &pg_enc2name_tbl[PG_SQL_ASCII];
+static pg_enc2name *DatabaseEncoding = &pg_enc2name_tbl[PG_SQL_ASCII];
+
/*
* During backend startup we can't set client encoding because we (a)
* can't look up the conversion functions, and (b) may not know the database
SetClientEncoding(int encoding, bool doit)
{
int current_server_encoding;
- Oid to_server_proc,
- to_client_proc;
- FmgrInfo *to_server;
- FmgrInfo *to_client;
- MemoryContext oldcontext;
+ ListCell *lc;
if (!PG_VALID_FE_ENCODING(encoding))
return -1;
ClientEncoding = &pg_enc2name_tbl[encoding];
ToServerConvProc = NULL;
ToClientConvProc = NULL;
- if (MbProcContext)
- MemoryContextReset(MbProcContext);
}
return 0;
}
- /*
- * If we're not inside a transaction then we can't do catalog lookups, so
- * fail. After backend startup, this could only happen if we are
- * re-reading postgresql.conf due to SIGHUP --- so basically this just
- * constrains the ability to change client_encoding on the fly from
- * postgresql.conf. Which would probably be a stupid thing to do anyway.
- */
- if (!IsTransactionState())
- return -1;
+ if (IsTransactionState())
+ {
+ /*
+ * If we're in a live transaction, it's safe to access the catalogs,
+ * so look up the functions. We repeat the lookup even if the info
+ * is already cached, so that we can react to changes in the contents
+ * of pg_conversion.
+ */
+ Oid to_server_proc,
+ to_client_proc;
+ ConvProcInfo *convinfo;
+ MemoryContext oldcontext;
+
+ to_server_proc = FindDefaultConversionProc(encoding,
+ current_server_encoding);
+ if (!OidIsValid(to_server_proc))
+ return -1;
+ to_client_proc = FindDefaultConversionProc(current_server_encoding,
+ encoding);
+ if (!OidIsValid(to_client_proc))
+ return -1;
- /*
- * Look up the conversion functions.
- */
- to_server_proc = FindDefaultConversionProc(encoding,
- current_server_encoding);
- if (!OidIsValid(to_server_proc))
- return -1;
- to_client_proc = FindDefaultConversionProc(current_server_encoding,
- encoding);
- if (!OidIsValid(to_client_proc))
- return -1;
+ /*
+ * Done if not wanting to actually apply setting.
+ */
+ if (!doit)
+ return 0;
- /*
- * Done if not wanting to actually apply setting.
- */
- if (!doit)
- return 0;
+ /*
+ * Load the fmgr info into TopMemoryContext (could still fail here)
+ */
+ convinfo = (ConvProcInfo *) MemoryContextAlloc(TopMemoryContext,
+ sizeof(ConvProcInfo));
+ convinfo->s_encoding = current_server_encoding;
+ convinfo->c_encoding = encoding;
+ fmgr_info_cxt(to_server_proc, &convinfo->to_server_info,
+ TopMemoryContext);
+ fmgr_info_cxt(to_client_proc, &convinfo->to_client_info,
+ TopMemoryContext);
+
+ /* Attach new info to head of list */
+ oldcontext = MemoryContextSwitchTo(TopMemoryContext);
+ ConvProcList = lcons(convinfo, ConvProcList);
+ MemoryContextSwitchTo(oldcontext);
- /* Before loading the new fmgr info, remove the old info, if any */
- ToServerConvProc = NULL;
- ToClientConvProc = NULL;
- if (MbProcContext != NULL)
- {
- MemoryContextReset(MbProcContext);
+ /*
+ * Everything is okay, so apply the setting.
+ */
+ ClientEncoding = &pg_enc2name_tbl[encoding];
+ ToServerConvProc = &convinfo->to_server_info;
+ ToClientConvProc = &convinfo->to_client_info;
+
+ /*
+ * Remove any older entry for the same encoding pair (this is just
+ * to avoid memory leakage).
+ */
+ foreach(lc, ConvProcList)
+ {
+ ConvProcInfo *oldinfo = (ConvProcInfo *) lfirst(lc);
+
+ if (oldinfo == convinfo)
+ continue;
+ if (oldinfo->s_encoding == convinfo->s_encoding &&
+ oldinfo->c_encoding == convinfo->c_encoding)
+ {
+ ConvProcList = list_delete_ptr(ConvProcList, oldinfo);
+ pfree(oldinfo);
+ break; /* need not look further */
+ }
+ }
+
+ return 0; /* success */
}
else
{
/*
- * This is the first time through, so create the context. Make it a
- * child of TopMemoryContext so that these values survive across
- * transactions.
+ * If we're not in a live transaction, the only thing we can do
+ * is restore a previous setting using the cache. This covers all
+ * transaction-rollback cases. The only case it might not work for
+ * is trying to change client_encoding on the fly by editing
+ * postgresql.conf and SIGHUP'ing. Which would probably be a stupid
+ * thing to do anyway.
*/
- 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);
- fmgr_info(to_client_proc, to_client);
- MemoryContextSwitchTo(oldcontext);
+ foreach(lc, ConvProcList)
+ {
+ ConvProcInfo *oldinfo = (ConvProcInfo *) lfirst(lc);
- ClientEncoding = &pg_enc2name_tbl[encoding];
- ToServerConvProc = to_server;
- ToClientConvProc = to_client;
+ if (oldinfo->s_encoding == current_server_encoding &&
+ oldinfo->c_encoding == encoding)
+ {
+ if (doit)
+ {
+ ClientEncoding = &pg_enc2name_tbl[encoding];
+ ToServerConvProc = &oldinfo->to_server_info;
+ ToClientConvProc = &oldinfo->to_client_info;
+ }
+ return 0;
+ }
+ }
- return 0;
+ return -1; /* it's not cached, so fail */
+ }
}
/*
* Initialize client encoding if necessary.
- * called from InitPostgres() once during backend starting up.
+ * called from InitPostgres() once during backend startup.
*/
void
InitializeClientEncoding(void)
}
/*
- * returns the current client encoding */
+ * returns the current client encoding
+ */
int
pg_get_client_encoding(void)
{
/*
* Perform default encoding conversion using cached FmgrInfo. Since
* this function does not access database at all, it is safe to call
- * outside transactions. Explicit setting client encoding required
- * before calling this function. Otherwise no conversion is
- * performed.
-*/
+ * outside transactions. If the conversion has not been set up by
+ * SetClientEncoding(), no conversion is performed.
+ */
static char *
perform_default_encoding_conversion(const char *src, int len, bool is_client_to_server)
{
#endif
}
-void
-SetDefaultClientEncoding(void)
-{
- ClientEncoding = &pg_enc2name_tbl[GetDatabaseEncoding()];
-}
-
int
GetDatabaseEncoding(void)
{
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