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mhagandermhagander
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Prevent shutdown in normal mode if online backup is running, and
have pg_ctl warn about this. Cancel running online backups (by renaming the backup_label file, thus rendering the backup useless) when shutting down in fast mode. Laurenz Albe
1 parent cf23b75 commit c979a1f

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+115
-14
lines changed

6 files changed

+115
-14
lines changed

‎doc/src/sgml/ref/pg_ctl-ref.sgml

Lines changed: 5 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
<!--
2-
$PostgreSQL: pgsql/doc/src/sgml/ref/pg_ctl-ref.sgml,v 1.44 2007/11/10 21:48:51 momjian Exp $
2+
$PostgreSQL: pgsql/doc/src/sgml/ref/pg_ctl-ref.sgml,v 1.45 2008/04/23 13:44:58 mha Exp $
33
PostgreSQL documentation
44
-->
55

@@ -133,9 +133,10 @@ PostgreSQL documentation
133133
In <option>stop</option> mode, the server that is running in
134134
the specified data directory is shut down. Three different
135135
shutdown methods can be selected with the <option>-m</option>
136-
option: <quote>Smart</quote> mode waits for all the clients to
137-
disconnect. This is the default. <quote>Fast</quote> mode does
138-
not wait for clients to disconnect. All active transactions are
136+
option: <quote>Smart</quote> mode waits for online backup mode
137+
to finish and all the clients to disconnect. This is the default.
138+
<quote>Fast</quote> mode does not wait for clients to disconnect and
139+
will terminate an online backup in progress. All active transactions are
139140
rolled back and clients are forcibly disconnected, then the
140141
server is shut down. <quote>Immediate</quote> mode will abort
141142
all server processes without a clean shutdown. This will lead to

‎doc/src/sgml/runtime.sgml

Lines changed: 5 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.414 2008/04/17 20:56:41 momjian Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.415 2008/04/23 13:44:58 mha Exp $ -->
22

33
<chapter Id="runtime">
44
<title>Operating System Environment</title>
@@ -1307,6 +1307,7 @@ sysctl -w vm.overcommit_memory=2
13071307
<listitem>
13081308
<para>
13091309
After receiving <systemitem>SIGTERM</systemitem>, the server
1310+
waits until online backup mode is no longer active. It then
13101311
disallows new connections, but lets existing sessions end their
13111312
work normally. It shuts down only after all of the sessions
13121313
terminate normally. This is the <firstterm>Smart
@@ -1322,7 +1323,9 @@ sysctl -w vm.overcommit_memory=2
13221323
The server disallows new connections and sends all existing
13231324
server processes <systemitem>SIGTERM</systemitem>, which will cause them
13241325
to abort their current transactions and exit promptly. It then
1325-
waits for the server processes to exit and finally shuts down. This is the
1326+
waits for the server processes to exit and finally shuts down.
1327+
If the server is in online backup mode, backup mode will be
1328+
terminated, rendering the backup useless. This is the
13261329
<firstterm>Fast Shutdown</firstterm>.
13271330
</para>
13281331
</listitem>

‎src/backend/access/transam/xlog.c

Lines changed: 51 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.298 2008/04/21 00:26:44 tgl Exp $
10+
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.299 2008/04/23 13:44:58 mha Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -6577,6 +6577,7 @@ pg_start_backup_callback(int code, Datum arg)
65776577
* create a backup history file in pg_xlog (whence it will immediately be
65786578
* archived). The backup history file contains the same info found in
65796579
* the label file, plus the backup-end time and WAL location.
6580+
* Note: different from CancelBackup which just cancels online backup mode.
65806581
*/
65816582
Datum
65826583
pg_stop_backup(PG_FUNCTION_ARGS)
@@ -7063,3 +7064,52 @@ rm_redo_error_callback(void *arg)
70637064

70647065
pfree(buf.data);
70657066
}
7067+
7068+
/*
7069+
* BackupInProgress: check if online backup mode is active
7070+
*
7071+
* This is done by checking for existence of the "backup_label" file.
7072+
*/
7073+
bool
7074+
BackupInProgress(void)
7075+
{
7076+
struct stat stat_buf;
7077+
7078+
return (stat(BACKUP_LABEL_FILE, &stat_buf) == 0);
7079+
}
7080+
7081+
/*
7082+
* CancelBackup: rename the "backup_label" file to cancel backup mode
7083+
*
7084+
* If the "backup_label" file exists, it will be renamed to "backup_label.old".
7085+
* Note that this will render an online backup in progress useless.
7086+
* To correctly finish an online backup, pg_stop_backup must be called.
7087+
*/
7088+
void
7089+
CancelBackup(void)
7090+
{
7091+
struct stat stat_buf;
7092+
7093+
/* if the file is not there, return */
7094+
if (stat(BACKUP_LABEL_FILE, &stat_buf) < 0)
7095+
return;
7096+
7097+
/* remove leftover file from previously cancelled backup if it exists */
7098+
unlink(BACKUP_LABEL_OLD);
7099+
7100+
if (rename(BACKUP_LABEL_FILE, BACKUP_LABEL_OLD) == 0)
7101+
{
7102+
ereport(LOG,
7103+
(errmsg("online backup mode cancelled"),
7104+
errdetail("\"%s\" renamed to \"%s\"",
7105+
BACKUP_LABEL_FILE, BACKUP_LABEL_OLD)));
7106+
}
7107+
else
7108+
{
7109+
ereport(WARNING,
7110+
(errcode_for_file_access(),
7111+
errmsg("could not rename \"%s\" to \"%s\", backup mode not cancelled: %m",
7112+
BACKUP_LABEL_FILE, BACKUP_LABEL_OLD)));
7113+
}
7114+
}
7115+

‎src/backend/postmaster/postmaster.c

Lines changed: 32 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -37,7 +37,7 @@
3737
*
3838
*
3939
* IDENTIFICATION
40-
* $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.554 2008/03/31 02:43:14 tgl Exp $
40+
* $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.555 2008/04/23 13:44:59 mha Exp $
4141
*
4242
* NOTES
4343
*
@@ -253,6 +253,7 @@ typedef enum
253253
PM_INIT, /* postmaster starting */
254254
PM_STARTUP, /* waiting for startup subprocess */
255255
PM_RUN, /* normal "database is alive" state */
256+
PM_WAIT_BACKUP, /* waiting for online backup mode to end */
256257
PM_WAIT_BACKENDS, /* waiting for live backends to exit */
257258
PM_SHUTDOWN, /* waiting for bgwriter to do shutdown ckpt */
258259
PM_SHUTDOWN_2, /* waiting for archiver to finish */
@@ -1724,8 +1725,12 @@ processCancelRequest(Port *port, void *pkt)
17241725
static enum CAC_state
17251726
canAcceptConnections(void)
17261727
{
1727-
/* Can't start backends when in startup/shutdown/recovery state. */
1728-
if (pmState != PM_RUN)
1728+
/*
1729+
* Can't start backends when in startup/shutdown/recovery state.
1730+
* In state PM_WAIT_BACKUP we must allow connections so that
1731+
* a superuser can end online backup mode.
1732+
*/
1733+
if ((pmState != PM_RUN) && (pmState != PM_WAIT_BACKUP))
17291734
{
17301735
if (Shutdown > NoShutdown)
17311736
return CAC_SHUTDOWN; /* shutdown is pending */
@@ -1965,11 +1970,12 @@ pmdie(SIGNAL_ARGS)
19651970
/* and the walwriter too */
19661971
if (WalWriterPID != 0)
19671972
signal_child(WalWriterPID, SIGTERM);
1968-
pmState = PM_WAIT_BACKENDS;
1973+
pmState = PM_WAIT_BACKUP;
19691974
}
19701975

19711976
/*
1972-
* Now wait for backends to exit. If there are none,
1977+
* Now wait for online backup mode to end and
1978+
* backends to exit. If that is already the case,
19731979
* PostmasterStateMachine will take the next step.
19741980
*/
19751981
PostmasterStateMachine();
@@ -2011,6 +2017,13 @@ pmdie(SIGNAL_ARGS)
20112017
* PostmasterStateMachine will take the next step.
20122018
*/
20132019
PostmasterStateMachine();
2020+
2021+
/*
2022+
* Terminate backup mode to avoid recovery after a
2023+
* clean fast shutdown.
2024+
*/
2025+
CancelBackup();
2026+
20142027
break;
20152028

20162029
case SIGQUIT:
@@ -2552,6 +2565,20 @@ LogChildExit(int lev, const char *procname, int pid, int exitstatus)
25522565
static void
25532566
PostmasterStateMachine(void)
25542567
{
2568+
if (pmState == PM_WAIT_BACKUP)
2569+
{
2570+
/*
2571+
* PM_WAIT_BACKUP state ends when online backup mode is no longer
2572+
* active. In this state canAcceptConnections() will still allow
2573+
* client connections, which is necessary because a superuser
2574+
* has to call pg_stop_backup() to end online backup mode.
2575+
*/
2576+
if (!BackupInProgress())
2577+
{
2578+
pmState = PM_WAIT_BACKENDS;
2579+
}
2580+
}
2581+
25552582
/*
25562583
* If we are in a state-machine state that implies waiting for backends to
25572584
* exit, see if they're all gone, and change state if so.

‎src/bin/pg_ctl/pg_ctl.c

Lines changed: 17 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -4,7 +4,7 @@
44
*
55
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
66
*
7-
* $PostgreSQL: pgsql/src/bin/pg_ctl/pg_ctl.c,v 1.96 2008/02/29 23:31:20 adunstan Exp $
7+
* $PostgreSQL: pgsql/src/bin/pg_ctl/pg_ctl.c,v 1.97 2008/04/23 13:44:59 mha Exp $
88
*
99
*-------------------------------------------------------------------------
1010
*/
@@ -144,6 +144,7 @@ static char def_postopts_file[MAXPGPATH];
144144
static char postopts_file[MAXPGPATH];
145145
static char pid_file[MAXPGPATH];
146146
static char conf_file[MAXPGPATH];
147+
static char backup_file[MAXPGPATH];
147148

148149
#if defined(HAVE_GETRLIMIT) && defined(RLIMIT_CORE)
149150
static void unlimit_core_size(void);
@@ -731,6 +732,7 @@ do_stop(void)
731732
{
732733
int cnt;
733734
pgpid_t pid;
735+
struct stat statbuf;
734736

735737
pid = get_pgpid();
736738

@@ -763,6 +765,12 @@ do_stop(void)
763765
}
764766
else
765767
{
768+
if ((shutdown_mode == SMART_MODE) && (stat(backup_file, &statbuf) == 0))
769+
{
770+
print_msg(_("WARNING: online backup mode is active; must be ended\n"
771+
" with pg_stop_backup() for shutdown to complete\n\n"));
772+
}
773+
766774
print_msg(_("waiting for server to shut down..."));
767775

768776
for (cnt = 0; cnt < wait_seconds; cnt++)
@@ -799,6 +807,7 @@ do_restart(void)
799807
{
800808
int cnt;
801809
pgpid_t pid;
810+
struct stat statbuf;
802811

803812
pid = get_pgpid();
804813

@@ -833,6 +842,12 @@ do_restart(void)
833842
exit(1);
834843
}
835844

845+
if ((shutdown_mode == SMART_MODE) && (stat(backup_file, &statbuf) == 0))
846+
{
847+
print_msg(_("WARNING: online backup mode is active; must be ended\n"
848+
" with pg_stop_backup() for shutdown to complete\n\n"));
849+
}
850+
836851
print_msg(_("waiting for server to shut down..."));
837852

838853
/* always wait for restart */
@@ -1883,6 +1898,7 @@ main(int argc, char **argv)
18831898
snprintf(postopts_file, MAXPGPATH, "%s/postmaster.opts", pg_data);
18841899
snprintf(pid_file, MAXPGPATH, "%s/postmaster.pid", pg_data);
18851900
snprintf(conf_file, MAXPGPATH, "%s/postgresql.conf", pg_data);
1901+
snprintf(backup_file, MAXPGPATH, "%s/backup_label", pg_data);
18861902
}
18871903

18881904
switch (ctl_command)

‎src/include/miscadmin.h

Lines changed: 5 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -13,7 +13,7 @@
1313
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
1414
* Portions Copyright (c) 1994, Regents of the University of California
1515
*
16-
* $PostgreSQL: pgsql/src/include/miscadmin.h,v 1.201 2008/02/20 22:46:24 tgl Exp $
16+
* $PostgreSQL: pgsql/src/include/miscadmin.h,v 1.202 2008/04/23 13:44:59 mha Exp $
1717
*
1818
* NOTES
1919
* some of the information in this file should be moved to other files.
@@ -330,4 +330,8 @@ extern void ValidatePgVersion(const char *path);
330330
extern void process_shared_preload_libraries(void);
331331
extern void process_local_preload_libraries(void);
332332

333+
/* in access/transam/xlog.c */
334+
extern bool BackupInProgress(void);
335+
extern void CancelBackup(void);
336+
333337
#endif /* MISCADMIN_H */

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