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Commitc26ffb1

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Fix SetClientEncoding() to maintain a cache of previously selected encoding
conversion functions. This allows transaction rollback to revert to aprevious client_encoding setting without doing fresh catalog lookups.I believe that this explains and fixes the recent report of "failed to commitclient_encoding" failures.This bug is present in 8.3.x, but it doesn't seem prudent to back-patchthe fix, at least not till it's had some time for field testing in HEAD.In passing, remove SetDefaultClientEncoding(), which was used nowhere.
1 parent33e7eac commitc26ffb1

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2 files changed

+127
-86
lines changed

2 files changed

+127
-86
lines changed

‎src/backend/utils/mb/mbutils.c‎

Lines changed: 126 additions & 84 deletions
Original file line numberDiff line numberDiff line change
@@ -1,10 +1,10 @@
11
/*
22
* This file contains public functions for conversion between
3-
* client encoding and serverinternal encoding.
4-
* (currently mule internal code (mic) is used)
3+
* client encoding and server(database) encoding.
4+
*
55
* Tatsuo Ishii
66
*
7-
* $PostgreSQL: pgsql/src/backend/utils/mb/mbutils.c,v 1.82 2009/03/09 00:01:32 alvherre Exp $
7+
* $PostgreSQL: pgsql/src/backend/utils/mb/mbutils.c,v 1.83 2009/04/02 17:30:53 tgl Exp $
88
*/
99
#include"postgres.h"
1010

@@ -28,23 +28,37 @@
2828
#defineMAX_CONVERSION_GROWTH 4
2929

3030
/*
31-
* We handle for actual FE and BE encoding setting encoding-identificator
32-
* and encoding-name too. It prevent searching and conversion from encoding
33-
* to encoding name in getdatabaseencoding() and other routines.
31+
* We maintain a simple linked list caching the fmgr lookup info for the
32+
* currently selected conversion functions, as well as any that have been
33+
* selected previously in the current session. (We remember previous
34+
* settings because we must be able to restore a previous setting during
35+
* transaction rollback, without doing any fresh catalog accesses.)
36+
*
37+
* Since we'll never release this data, we just keep it in TopMemoryContext.
3438
*/
35-
staticpg_enc2name*ClientEncoding=&pg_enc2name_tbl[PG_SQL_ASCII];
36-
staticpg_enc2name*DatabaseEncoding=&pg_enc2name_tbl[PG_SQL_ASCII];
39+
typedefstructConvProcInfo
40+
{
41+
ints_encoding;/* server and client encoding IDs */
42+
intc_encoding;
43+
FmgrInfoto_server_info;/* lookup info for conversion procs */
44+
FmgrInfoto_client_info;
45+
}ConvProcInfo;
46+
47+
staticList*ConvProcList=NIL;/* List of ConvProcInfo */
3748

3849
/*
39-
* Caches for conversion function info. These values are allocated in
40-
* MbProcContext. That context is a child of TopMemoryContext,
41-
* which allows these values to survive across transactions. See
42-
* SetClientEncoding() for more details.
50+
* These variables point to the currently active conversion functions,
51+
* or are NULL when no conversion is needed.
4352
*/
44-
staticMemoryContextMbProcContext=NULL;
4553
staticFmgrInfo*ToServerConvProc=NULL;
4654
staticFmgrInfo*ToClientConvProc=NULL;
4755

56+
/*
57+
* These variables track the currently selected FE and BE encodings.
58+
*/
59+
staticpg_enc2name*ClientEncoding=&pg_enc2name_tbl[PG_SQL_ASCII];
60+
staticpg_enc2name*DatabaseEncoding=&pg_enc2name_tbl[PG_SQL_ASCII];
61+
4862
/*
4963
* During backend startup we can't set client encoding because we (a)
5064
* can't look up the conversion functions, and (b) may not know the database
@@ -70,11 +84,7 @@ int
7084
SetClientEncoding(intencoding,booldoit)
7185
{
7286
intcurrent_server_encoding;
73-
Oidto_server_proc,
74-
to_client_proc;
75-
FmgrInfo*to_server;
76-
FmgrInfo*to_client;
77-
MemoryContextoldcontext;
87+
ListCell*lc;
7888

7989
if (!PG_VALID_FE_ENCODING(encoding))
8090
return-1;
@@ -101,79 +111,117 @@ SetClientEncoding(int encoding, bool doit)
101111
ClientEncoding=&pg_enc2name_tbl[encoding];
102112
ToServerConvProc=NULL;
103113
ToClientConvProc=NULL;
104-
if (MbProcContext)
105-
MemoryContextReset(MbProcContext);
106114
}
107115
return0;
108116
}
109117

110-
/*
111-
* If we're not inside a transaction then we can't do catalog lookups, so
112-
* fail. After backend startup, this could only happen if we are
113-
* re-reading postgresql.conf due to SIGHUP --- so basically this just
114-
* constrains the ability to change client_encoding on the fly from
115-
* postgresql.conf. Which would probably be a stupid thing to do anyway.
116-
*/
117-
if (!IsTransactionState())
118-
return-1;
118+
if (IsTransactionState())
119+
{
120+
/*
121+
* If we're in a live transaction, it's safe to access the catalogs,
122+
* so look up the functions. We repeat the lookup even if the info
123+
* is already cached, so that we can react to changes in the contents
124+
* of pg_conversion.
125+
*/
126+
Oidto_server_proc,
127+
to_client_proc;
128+
ConvProcInfo*convinfo;
129+
MemoryContextoldcontext;
130+
131+
to_server_proc=FindDefaultConversionProc(encoding,
132+
current_server_encoding);
133+
if (!OidIsValid(to_server_proc))
134+
return-1;
135+
to_client_proc=FindDefaultConversionProc(current_server_encoding,
136+
encoding);
137+
if (!OidIsValid(to_client_proc))
138+
return-1;
119139

120-
/*
121-
* Look up the conversion functions.
122-
*/
123-
to_server_proc=FindDefaultConversionProc(encoding,
124-
current_server_encoding);
125-
if (!OidIsValid(to_server_proc))
126-
return-1;
127-
to_client_proc=FindDefaultConversionProc(current_server_encoding,
128-
encoding);
129-
if (!OidIsValid(to_client_proc))
130-
return-1;
140+
/*
141+
* Done if not wanting to actually apply setting.
142+
*/
143+
if (!doit)
144+
return0;
131145

132-
/*
133-
* Done if not wanting to actually apply setting.
134-
*/
135-
if (!doit)
136-
return0;
146+
/*
147+
* Load the fmgr info into TopMemoryContext (could still fail here)
148+
*/
149+
convinfo= (ConvProcInfo*)MemoryContextAlloc(TopMemoryContext,
150+
sizeof(ConvProcInfo));
151+
convinfo->s_encoding=current_server_encoding;
152+
convinfo->c_encoding=encoding;
153+
fmgr_info_cxt(to_server_proc,&convinfo->to_server_info,
154+
TopMemoryContext);
155+
fmgr_info_cxt(to_client_proc,&convinfo->to_client_info,
156+
TopMemoryContext);
157+
158+
/* Attach new info to head of list */
159+
oldcontext=MemoryContextSwitchTo(TopMemoryContext);
160+
ConvProcList=lcons(convinfo,ConvProcList);
161+
MemoryContextSwitchTo(oldcontext);
137162

138-
/* Before loading the new fmgr info, remove the old info, if any */
139-
ToServerConvProc=NULL;
140-
ToClientConvProc=NULL;
141-
if (MbProcContext!=NULL)
142-
{
143-
MemoryContextReset(MbProcContext);
163+
/*
164+
* Everything is okay, so apply the setting.
165+
*/
166+
ClientEncoding=&pg_enc2name_tbl[encoding];
167+
ToServerConvProc=&convinfo->to_server_info;
168+
ToClientConvProc=&convinfo->to_client_info;
169+
170+
/*
171+
* Remove any older entry for the same encoding pair (this is just
172+
* to avoid memory leakage).
173+
*/
174+
foreach(lc,ConvProcList)
175+
{
176+
ConvProcInfo*oldinfo= (ConvProcInfo*)lfirst(lc);
177+
178+
if (oldinfo==convinfo)
179+
continue;
180+
if (oldinfo->s_encoding==convinfo->s_encoding&&
181+
oldinfo->c_encoding==convinfo->c_encoding)
182+
{
183+
ConvProcList=list_delete_ptr(ConvProcList,oldinfo);
184+
pfree(oldinfo);
185+
break;/* need not look further */
186+
}
187+
}
188+
189+
return0;/* success */
144190
}
145191
else
146192
{
147193
/*
148-
* This is the first time through, so create the context. Make it a
149-
* child of TopMemoryContext so that these values survive across
150-
* transactions.
194+
* If we're not in a live transaction, the only thing we can do
195+
* is restore a previous setting using the cache. This covers all
196+
* transaction-rollback cases. The only case it might not work for
197+
* is trying to change client_encoding on the fly by editing
198+
* postgresql.conf and SIGHUP'ing. Which would probably be a stupid
199+
* thing to do anyway.
151200
*/
152-
MbProcContext=AllocSetContextCreate(TopMemoryContext,
153-
"MbProcContext",
154-
ALLOCSET_SMALL_MINSIZE,
155-
ALLOCSET_SMALL_INITSIZE,
156-
ALLOCSET_SMALL_MAXSIZE);
157-
}
158-
159-
/* Load the fmgr info into MbProcContext */
160-
oldcontext=MemoryContextSwitchTo(MbProcContext);
161-
to_server=palloc(sizeof(FmgrInfo));
162-
to_client=palloc(sizeof(FmgrInfo));
163-
fmgr_info(to_server_proc,to_server);
164-
fmgr_info(to_client_proc,to_client);
165-
MemoryContextSwitchTo(oldcontext);
201+
foreach(lc,ConvProcList)
202+
{
203+
ConvProcInfo*oldinfo= (ConvProcInfo*)lfirst(lc);
166204

167-
ClientEncoding=&pg_enc2name_tbl[encoding];
168-
ToServerConvProc=to_server;
169-
ToClientConvProc=to_client;
205+
if (oldinfo->s_encoding==current_server_encoding&&
206+
oldinfo->c_encoding==encoding)
207+
{
208+
if (doit)
209+
{
210+
ClientEncoding=&pg_enc2name_tbl[encoding];
211+
ToServerConvProc=&oldinfo->to_server_info;
212+
ToClientConvProc=&oldinfo->to_client_info;
213+
}
214+
return0;
215+
}
216+
}
170217

171-
return0;
218+
return-1;/* it's not cached, so fail */
219+
}
172220
}
173221

174222
/*
175223
* Initialize client encoding if necessary.
176-
*called from InitPostgres() once during backendstarting up.
224+
*called from InitPostgres() once during backendstartup.
177225
*/
178226
void
179227
InitializeClientEncoding(void)
@@ -196,7 +244,8 @@ InitializeClientEncoding(void)
196244
}
197245

198246
/*
199-
* returns the current client encoding */
247+
* returns the current client encoding
248+
*/
200249
int
201250
pg_get_client_encoding(void)
202251
{
@@ -511,10 +560,9 @@ pg_server_to_client(const char *s, int len)
511560
/*
512561
*Perform default encoding conversion using cached FmgrInfo. Since
513562
*this function does not access database at all, it is safe to call
514-
*outside transactions. Explicit setting client encoding required
515-
*before calling this function. Otherwise no conversion is
516-
*performed.
517-
*/
563+
*outside transactions. If the conversion has not been set up by
564+
*SetClientEncoding(), no conversion is performed.
565+
*/
518566
staticchar*
519567
perform_default_encoding_conversion(constchar*src,intlen,boolis_client_to_server)
520568
{
@@ -919,12 +967,6 @@ pg_bind_textdomain_codeset(const char *domainname, int encoding)
919967
#endif
920968
}
921969

922-
void
923-
SetDefaultClientEncoding(void)
924-
{
925-
ClientEncoding=&pg_enc2name_tbl[GetDatabaseEncoding()];
926-
}
927-
928970
int
929971
GetDatabaseEncoding(void)
930972
{

‎src/include/mb/pg_wchar.h‎

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
9-
* $PostgreSQL: pgsql/src/include/mb/pg_wchar.h,v 1.87 2009/03/09 00:01:32 alvherre Exp $
9+
* $PostgreSQL: pgsql/src/include/mb/pg_wchar.h,v 1.88 2009/04/02 17:30:53 tgl Exp $
1010
*
1111
*NOTES
1212
*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);
383383
externsize_tchar2wchar(wchar_t*to,size_ttolen,constchar*from,size_tfromlen);
384384
#endif
385385

386-
externvoidSetDefaultClientEncoding(void);
387386
externintSetClientEncoding(intencoding,booldoit);
388387
externvoidInitializeClientEncoding(void);
389388
externintpg_get_client_encoding(void);

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