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Fix SetClientEncoding() to maintain a cache of previously selected encoding

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conversion functions.  This allows transaction rollback to revert to a
previous client_encoding setting without doing fresh catalog lookups.
I believe that this explains and fixes the recent report of "failed to commit
client_encoding" failures.

This bug is present in 8.3.x, but it doesn't seem prudent to back-patch
the fix, at least not till it's had some time for field testing in HEAD.

In passing, remove SetDefaultClientEncoding(), which was used nowhere.
REL8_5_ALPHA1_BRANCH
Tom Lane 17 years ago
parent 33e7eac37c
commit c26ffb1ead
2 changed files with 127 additions and 86 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 210
      src/backend/utils/mb/mbutils.c
  2. 3
      src/include/mb/pg_wchar.h

210
src/backend/utils/mb/mbutils.c
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@ -1,10 +1,10 @@
/*
* 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"
@ -28,23 +28,37 @@
#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
@ -70,11 +84,7 @@ int
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;
@ -101,79 +111,117 @@ SetClientEncoding(int encoding, bool doit)
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)
@ -196,7 +244,8 @@ InitializeClientEncoding(void)
}
/*
* returns the current client encoding */
* returns the current client encoding
*/
int
pg_get_client_encoding(void)
{
@ -511,10 +560,9 @@ pg_server_to_client(const char *s, int len)
/*
* 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)
{
@ -919,12 +967,6 @@ pg_bind_textdomain_codeset(const char *domainname, int encoding)
#endif
}
void
SetDefaultClientEncoding(void)
{
ClientEncoding = &pg_enc2name_tbl[GetDatabaseEncoding()];
}
int
GetDatabaseEncoding(void)
{

3
src/include/mb/pg_wchar.h
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@ -6,7 +6,7 @@
* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/mb/pg_wchar.h,v 1.87 2009/03/09 00:01:32 alvherre Exp $
* $PostgreSQL: pgsql/src/include/mb/pg_wchar.h,v 1.88 2009/04/02 17:30:53 tgl Exp $
*
* NOTES
* This is used both by the backend and by libpq, but should not be
@ -383,7 +383,6 @@ extern size_t wchar2char(char *to, const wchar_t *from, size_t tolen);
extern size_t char2wchar(wchar_t *to, size_t tolen, const char *from, size_t fromlen);
#endif
extern void SetDefaultClientEncoding(void);
extern int SetClientEncoding(int encoding, bool doit);
extern void InitializeClientEncoding(void);
extern int pg_get_client_encoding(void);

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