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Commit316c4c5

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Clean up some problems in error recovery --- elog() was pretty broken
for the case of errors in backend startup, and proc_exit's method forcoping with errors during proc_exit was *completely* busted. Fixed perdiscussions on pghackers around 11/6/99.
1 parentbb203c7 commit316c4c5

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3 files changed

+66
-70
lines changed

3 files changed

+66
-70
lines changed

‎src/backend/storage/ipc/ipc.c‎

Lines changed: 35 additions & 59 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
/*-------------------------------------------------------------------------
1+
/*-------------------------------------------------------------------------
22
*
33
* ipc.c
44
* POSTGRES inter-process communication definitions.
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/ipc.c,v 1.42 1999/11/06 19:46:57 momjian Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/ipc.c,v 1.43 1999/11/22 02:06:31 tgl Exp $
1111
*
1212
* NOTES
1313
*
@@ -28,8 +28,8 @@
2828
#include<sys/file.h>
2929
#include<errno.h>
3030

31-
3231
#include"postgres.h"
32+
3333
#include"storage/ipc.h"
3434
#include"storage/s_lock.h"
3535
/* In Ultrix, sem.h and shm.h must be included AFTER ipc.h */
@@ -43,6 +43,13 @@
4343
#include<sys/ipc.h>
4444
#endif
4545

46+
/*
47+
* This flag is set during proc_exit() to change elog()'s behavior,
48+
* so that an elog() from an on_proc_exit routine cannot get us out
49+
* of the exit procedure. We do NOT want to go back to the idle loop...
50+
*/
51+
boolproc_exit_inprogress= false;
52+
4653
staticintUsePrivateMemory=0;
4754

4855
staticvoidIpcMemoryDetach(intstatus,char*shmaddr);
@@ -70,7 +77,8 @@ typedef struct _PrivateMemStruct
7077
char*memptr;
7178
}PrivateMem;
7279

73-
PrivateMemIpcPrivateMem[16];
80+
staticPrivateMemIpcPrivateMem[16];
81+
7482

7583
staticint
7684
PrivateMemoryCreate(IpcMemoryKeymemKey,
@@ -105,45 +113,34 @@ PrivateMemoryAttach(IpcMemoryId memid)
105113
*-cim 2/6/90
106114
* ----------------------------------------------------------------
107115
*/
108-
staticintproc_exit_inprogress=0;
109-
110116
void
111117
proc_exit(intcode)
112118
{
113-
inti;
114-
115-
TPRINTF(TRACE_VERBOSE,"proc_exit(%d) [#%d]",code,proc_exit_inprogress);
116-
117119
/*
118-
*If proc_exit is called too many times something bad is happening, so
119-
*exit immediately. This is crafted in two if's for a reason.
120+
*Once we set this flag, we are committed to exit. Any elog() will
121+
*NOT send control back to the main loop, but right back here.
120122
*/
123+
proc_exit_inprogress= true;
121124

122-
if (++proc_exit_inprogress==9)
123-
elog(ERROR,"infinite recursion in proc_exit");
124-
if (proc_exit_inprogress >=9)
125-
gotoexit;
126-
127-
/* ----------------
128-
*if proc_exit_inprocess > 1, then it means that we
129-
*are being invoked from within an on_exit() handler
130-
*and so we return immediately to avoid recursion.
131-
* ----------------
132-
*/
133-
if (proc_exit_inprogress>1)
134-
return;
125+
TPRINTF(TRACE_VERBOSE,"proc_exit(%d)",code);
135126

136127
/* do our shared memory exits first */
137128
shmem_exit(code);
138129

139130
/* ----------------
140131
*call all the callbacks registered before calling exit().
132+
*
133+
*Note that since we decrement on_proc_exit_index each time,
134+
*if a callback calls elog(ERROR) or elog(FATAL) then it won't
135+
*be invoked again when control comes back here (nor will the
136+
*previously-completed callbacks). So, an infinite loop
137+
*should not be possible.
141138
* ----------------
142139
*/
143-
for (i=on_proc_exit_index-1;i >=0;--i)
144-
(*on_proc_exit_list[i].function) (code,on_proc_exit_list[i].arg);
140+
while (--on_proc_exit_index >=0)
141+
(*on_proc_exit_list[on_proc_exit_index].function) (code,
142+
on_proc_exit_list[on_proc_exit_index].arg);
145143

146-
exit:
147144
TPRINTF(TRACE_VERBOSE,"exit(%d)",code);
148145
exit(code);
149146
}
@@ -154,44 +151,23 @@ proc_exit(int code)
154151
* semaphores after a backend dies horribly
155152
* ------------------
156153
*/
157-
staticintshmem_exit_inprogress=0;
158-
159154
void
160155
shmem_exit(intcode)
161156
{
162-
inti;
163-
164-
TPRINTF(TRACE_VERBOSE,"shmem_exit(%d) [#%d]",
165-
code,shmem_exit_inprogress);
166-
167-
/*
168-
* If shmem_exit is called too many times something bad is happenig,
169-
* so exit immediately.
170-
*/
171-
if (shmem_exit_inprogress>9)
172-
{
173-
elog(ERROR,"infinite recursion in shmem_exit");
174-
exit(-1);
175-
}
176-
177-
/* ----------------
178-
*if shmem_exit_inprocess is true, then it means that we
179-
*are being invoked from within an on_exit() handler
180-
*and so we return immediately to avoid recursion.
181-
* ----------------
182-
*/
183-
if (shmem_exit_inprogress++)
184-
return;
157+
TPRINTF(TRACE_VERBOSE,"shmem_exit(%d)",code);
185158

186159
/* ----------------
187-
*call all the callbacks registered before calling exit().
160+
*call all the registered callbacks.
161+
*
162+
*As with proc_exit(), we remove each callback from the list
163+
*before calling it, to avoid infinite loop in case of error.
188164
* ----------------
189165
*/
190-
for (i=on_shmem_exit_index-1;i >=0;--i)
191-
(*on_shmem_exit_list[i].function) (code,on_shmem_exit_list[i].arg);
166+
while (--on_shmem_exit_index >=0)
167+
(*on_shmem_exit_list[on_shmem_exit_index].function) (code,
168+
on_shmem_exit_list[on_shmem_exit_index].arg);
192169

193170
on_shmem_exit_index=0;
194-
shmem_exit_inprogress=0;
195171
}
196172

197173
/* ----------------------------------------------------------------
@@ -202,7 +178,7 @@ shmem_exit(int code)
202178
* ----------------------------------------------------------------
203179
*/
204180
int
205-
on_proc_exit(void (*function) (),caddr_targ)
181+
on_proc_exit(void (*function) (),caddr_targ)
206182
{
207183
if (on_proc_exit_index >=MAX_ON_EXITS)
208184
return-1;
@@ -223,7 +199,7 @@ int
223199
* ----------------------------------------------------------------
224200
*/
225201
int
226-
on_shmem_exit(void (*function) (),caddr_targ)
202+
on_shmem_exit(void (*function) (),caddr_targ)
227203
{
228204
if (on_shmem_exit_index >=MAX_ON_EXITS)
229205
return-1;

‎src/backend/utils/error/elog.c‎

Lines changed: 28 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/utils/error/elog.c,v 1.51 1999/11/1606:13:36 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/utils/error/elog.c,v 1.52 1999/11/22 02:06:31 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -30,6 +30,7 @@
3030
#include"libpq/libpq.h"
3131
#include"libpq/pqformat.h"
3232
#include"miscadmin.h"
33+
#include"storage/ipc.h"
3334
#include"storage/proc.h"
3435
#include"tcop/tcopprot.h"
3536
#include"utils/trace.h"
@@ -371,21 +372,38 @@ elog(int lev, const char *fmt, ...)
371372
*/
372373
if (lev==ERROR||lev==FATAL)
373374
{
374-
if (InError)
375+
/*
376+
* If we have not yet entered the main backend loop (ie, we are in
377+
* the postmaster or in backend startup), then go directly to
378+
* proc_exit. The same is true if anyone tries to report an error
379+
* after proc_exit has begun to run. (It's proc_exit's responsibility
380+
* to see that this doesn't turn into infinite recursion!) But in
381+
* the latter case, we exit with nonzero exit code to indicate that
382+
* something's pretty wrong.
383+
*/
384+
if (proc_exit_inprogress|| !Warn_restart_ready)
375385
{
376-
/* error reported during error recovery; don't loop forever */
377-
elog(REALLYFATAL,"elog: error during error recovery, giving up!");
386+
fflush(stdout);
387+
fflush(stderr);
388+
ProcReleaseSpins(NULL);/* get rid of spinlocks we hold */
389+
ProcReleaseLocks();/* get rid of real locks we hold */
390+
/* XXX shouldn't proc_exit be doing the above?? */
391+
proc_exit((int)proc_exit_inprogress);
378392
}
393+
/*
394+
* Guard against infinite loop from elog() during error recovery.
395+
*/
396+
if (InError)
397+
elog(REALLYFATAL,"elog: error during error recovery, giving up!");
379398
InError= true;
399+
/*
400+
* Otherwise we can return to the main loop in postgres.c.
401+
* In the FATAL case, postgres.c will call proc_exit, but not
402+
* till after completing a standard transaction-abort sequence.
403+
*/
380404
ProcReleaseSpins(NULL);/* get rid of spinlocks we hold */
381-
if (!Warn_restart_ready)
382-
{
383-
/* error reported before there is a main loop to return to */
384-
elog(REALLYFATAL,"elog: error in postmaster or backend startup, giving up!");
385-
}
386405
if (lev==FATAL)
387406
ExitAfterAbort= true;
388-
/* exit to main loop */
389407
siglongjmp(Warn_restart,1);
390408
}
391409

‎src/include/storage/ipc.h‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
*
77
* Copyright (c) 1994, Regents of the University of California
88
*
9-
* $Id: ipc.h,v 1.36 1999/10/06 21:58:17 vadim Exp $
9+
* $Id: ipc.h,v 1.37 1999/11/22 02:06:30 tgl Exp $
1010
*
1111
* NOTES
1212
* This file is very architecture-specific.This stuff should actually
@@ -71,6 +71,8 @@ typedef int IpcMemoryId;
7171

7272

7373
/* ipc.c */
74+
externboolproc_exit_inprogress;
75+
7476
externvoidproc_exit(intcode);
7577
externvoidshmem_exit(intcode);
7678
externinton_shmem_exit(void (*function) (),caddr_targ);

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