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Clean up backend-exit-time cleanup behavior. Use on_shmem_exit callbacks

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to ensure that we have released buffer refcounts and so forth, rather than
putting ad-hoc operations before (some of the calls to) proc_exit.  Add
commentary to discourage future hackers from repeating that mistake.
This commit is contained in:
Tom Lane
2000-12-18 00:44:50 +00:00
parent 8c8ed4f456
commit a626b78c89
14 changed files with 255 additions and 139 deletions
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100
src/backend/tcop/postgres.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.194 2000/12/03 10:27:27 vadim Exp $
* $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.195 2000/12/18 00:44:47 tgl Exp $
*
* NOTES
* this is the "main" module of the postgres backend and
@ -61,7 +61,6 @@
#include "utils/guc.h"
#include "utils/memutils.h"
#include "utils/ps_status.h"
#include "utils/temprel.h"
#ifdef MULTIBYTE
#include "mb/pg_wchar.h"
#endif
@ -95,7 +94,7 @@ DLLIMPORT sigjmp_buf Warn_restart;
bool Warn_restart_ready = false;
bool InError = false;
bool ExitAfterAbort = false;
bool ProcDiePending = false;
static bool EchoQuery = false; /* default don't echo */
char pg_pathname[MAXPGPATH];
@ -921,7 +920,8 @@ finish_xact_command(void)
void
handle_warn(SIGNAL_ARGS)
{
if (StopIfError)
/* Don't joggle the elbow of a critical section */
if (CritSectionCount > 0)
{
QueryCancel = true;
return;
@ -958,13 +958,15 @@ die(SIGNAL_ARGS)
{
PG_SETMASK(&BlockSig);
ExitAfterAbort = true;
if (StopIfError)
/* Don't joggle the elbow of a critical section */
if (CritSectionCount > 0)
{
QueryCancel = true;
ProcDiePending = true;
return;
}
if (InError) /* If ERROR/FATAL is in progress... */
/* Don't joggle the elbow of proc_exit, either */
if (proc_exit_inprogress)
return;
elog(FATAL, "The system is shutting down");
}
@ -1096,6 +1098,8 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha
MemoryContextInit();
}
SetProcessingMode(InitProcessing);
/*
* Set default values for command-line options.
*/
@ -1109,8 +1113,6 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha
}
StatFp = stderr;
SetProcessingMode(InitProcessing);
/* Check for PGDATESTYLE environment variable */
set_default_datestyle();
@ -1428,11 +1430,16 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha
break;
}
/*
* Post-processing for command line options.
*
* XXX It'd be nice if libpq were already running here, so we could do
* elog(NOTICE) instead of just writing on stderr...
*/
if (Show_query_stats &&
(Show_parser_stats || Show_planner_stats || Show_executor_stats))
{
elog(NOTICE, "Query statistics are disabled because parser, planner, or executor statistics are on.");
fprintf(stderr, "Query statistics are disabled because parser, planner, or executor statistics are on.\n");
Show_query_stats = false;
}
@ -1528,7 +1535,13 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha
XLOGPathInit();
BaseInit();
/*
* Start up xlog for standalone backend, and register to have it
* closed down at exit.
*/
StartupXLOG();
on_shmem_exit(ShutdownXLOG, 0);
}
/*
@ -1602,20 +1615,17 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha
remote_host, username, DBName);
/*
* general initialization
* General initialization.
*
* NOTE: if you are tempted to add code in this vicinity, consider
* putting it inside InitPostgres() instead. In particular, anything
* that involves database access should be there, not here.
*/
if (DebugLvl > 1)
elog(DEBUG, "InitPostgres");
InitPostgres(DBName, username);
#ifdef MULTIBYTE
/* set default client encoding */
if (DebugLvl > 1)
elog(DEBUG, "set_default_client_encoding");
set_default_client_encoding();
#endif
on_shmem_exit(remove_all_temp_relations, 0);
SetProcessingMode(NormalProcessing);
/*
* Send this backend's cancellation info to the frontend.
@ -1636,17 +1646,9 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha
if (!IsUnderPostmaster)
{
puts("\nPOSTGRES backend interactive interface ");
puts("$Revision: 1.194 $ $Date: 2000/12/03 10:27:27 $\n");
puts("$Revision: 1.195 $ $Date: 2000/12/18 00:44:47 $\n");
}
/*
* Initialize the deferred trigger manager
*/
if (DeferredTriggerInit() != 0)
goto normalexit;
SetProcessingMode(NormalProcessing);
/*
* Create the memory context we will use in the main loop.
*
@ -1671,6 +1673,10 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha
if (sigsetjmp(Warn_restart, 1) != 0)
{
/*
* NOTE: if you are tempted to add more code in this if-block,
* consider the probability that it should be in AbortTransaction()
* instead.
*
* Make sure we are in a valid memory context during recovery.
*
* We use ErrorContext in hopes that it will have some free space
@ -1678,19 +1684,22 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha
*/
MemoryContextSwitchTo(ErrorContext);
/* Do the recovery */
if (DebugLvl >= 1)
elog(DEBUG, "AbortCurrentTransaction");
AbortCurrentTransaction();
if (ExitAfterAbort)
goto errorexit;
/*
* If we recovered successfully, return to normal top-level context
* and clear ErrorContext for next time.
* Now return to normal top-level context and clear ErrorContext
* for next time.
*/
MemoryContextSwitchTo(TopMemoryContext);
MemoryContextResetAndDeleteChildren(ErrorContext);
/*
* Clear flag to indicate that we got out of error recovery mode
* successfully. (Flag was set in elog.c before longjmp().)
*/
InError = false;
}
@ -1775,7 +1784,7 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha
if (HandleFunctionRequest() == EOF)
{
/* lost frontend connection during F message input */
goto normalexit;
proc_exit(0);
}
/* commit the function-invocation transaction */
@ -1830,7 +1839,14 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha
*/
case 'X':
case EOF:
goto normalexit;
/*
* NOTE: if you are tempted to add more code here, DON'T!
* Whatever you had in mind to do should be set up as
* an on_proc_exit or on_shmem_exit callback, instead.
* Otherwise it will fail to be called during other
* backend-shutdown scenarios.
*/
proc_exit(0);
default:
elog(ERROR, "unknown frontend message was received");
@ -1845,16 +1861,8 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha
#endif
} /* end of input-reading loop */
normalexit:
ExitAfterAbort = true; /* ensure we will exit if elog during abort */
AbortOutOfAnyTransaction();
if (!IsUnderPostmaster)
ShutdownXLOG();
errorexit:
pq_close();
ProcReleaseLocks(); /* Just to be sure... */
proc_exit(0);
/* can't get here because the above loop never exits */
Assert(false);
return 1; /* keep compiler quiet */
}