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Commit9a740f8

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Refactor code in charge of running shell-based recovery commands
The code specific to the execution of archive_cleanup_command,recovery_end_command and restore_command is moved to a new file namedshell_restore.c. The code is split into three functions:- shell_restore(), that attempts the execution of a shell-basedrestore_command.- shell_archive_cleanup(), for archive_cleanup_command.- shell_recovery_end(), for recovery_end_command.This introduces no functional changes, with failure patterns and logsgenerated in consequence being the same as before (one case actuallygenerates one less DEBUG2 message "could not restore" when a restorecommand succeeds but the follow-up stat() to check the size fails, butthat only matters with a elevel high enough).This is preparatory work for allowing recovery modules, a facilitysimilar to archive modules, with callbacks shaped similarly to thefunctions introduced here.Author: Nathan BossartReviewed-by: Andres Freund, Michael PaquierDiscussion:https://postgr.es/m/20221227192449.GA3672473@nathanxps13
1 parent02d3448 commit9a740f8

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6 files changed

+214
-127
lines changed

6 files changed

+214
-127
lines changed

‎src/backend/access/transam/Makefile

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -19,6 +19,7 @@ OBJS = \
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multixact.o\
2020
parallel.o\
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rmgr.o\
22+
shell_restore.o\
2223
slru.o\
2324
subtrans.o\
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timeline.o\

‎src/backend/access/transam/meson.build

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -7,6 +7,7 @@ backend_sources += files(
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'multixact.c',
88
'parallel.c',
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'rmgr.c',
10+
'shell_restore.c',
1011
'slru.c',
1112
'subtrans.c',
1213
'timeline.c',
Lines changed: 175 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,175 @@
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/*-------------------------------------------------------------------------
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*
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* shell_restore.c
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*Recovery functions for a user-specified shell command.
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*
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* These recovery functions use a user-specified shell command (e.g. based
7+
* on the GUC restore_command).
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*
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* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
10+
* Portions Copyright (c) 1994, Regents of the University of California
11+
*
12+
* src/backend/access/transam/shell_restore.c
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*
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*-------------------------------------------------------------------------
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*/
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#include"postgres.h"
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#include<signal.h>
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21+
#include"access/xlogarchive.h"
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#include"access/xlogrecovery.h"
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#include"common/archive.h"
24+
#include"common/percentrepl.h"
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#include"storage/ipc.h"
26+
#include"utils/wait_event.h"
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28+
staticvoidExecuteRecoveryCommand(constchar*command,
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constchar*commandName,
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boolfailOnSignal,
31+
uint32wait_event_info,
32+
constchar*lastRestartPointFileName);
33+
34+
/*
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* Attempt to execute a shell-based restore command.
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*
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* Returns true if the command has succeeded, false otherwise.
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*/
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bool
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shell_restore(constchar*file,constchar*path,
41+
constchar*lastRestartPointFileName)
42+
{
43+
char*cmd;
44+
intrc;
45+
46+
/* Build the restore command to execute */
47+
cmd=BuildRestoreCommand(recoveryRestoreCommand,path,file,
48+
lastRestartPointFileName);
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50+
ereport(DEBUG3,
51+
(errmsg_internal("executing restore command \"%s\"",cmd)));
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/*
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* Copy xlog from archival storage to XLOGDIR
55+
*/
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fflush(NULL);
57+
pgstat_report_wait_start(WAIT_EVENT_RESTORE_COMMAND);
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rc=system(cmd);
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pgstat_report_wait_end();
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61+
pfree(cmd);
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/*
64+
* Remember, we rollforward UNTIL the restore fails so failure here is
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* just part of the process... that makes it difficult to determine
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* whether the restore failed because there isn't an archive to restore,
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* or because the administrator has specified the restore program
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* incorrectly. We have to assume the former.
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*
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* However, if the failure was due to any sort of signal, it's best to
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* punt and abort recovery. (If we "return false" here, upper levels will
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* assume that recovery is complete and start up the database!) It's
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* essential to abort on child SIGINT and SIGQUIT, because per spec
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* system() ignores SIGINT and SIGQUIT while waiting; if we see one of
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* those it's a good bet we should have gotten it too.
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*
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* On SIGTERM, assume we have received a fast shutdown request, and exit
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* cleanly. It's pure chance whether we receive the SIGTERM first, or the
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* child process. If we receive it first, the signal handler will call
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* proc_exit, otherwise we do it here. If we or the child process received
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* SIGTERM for any other reason than a fast shutdown request, postmaster
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* will perform an immediate shutdown when it sees us exiting
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* unexpectedly.
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*
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* We treat hard shell errors such as "command not found" as fatal, too.
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*/
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if (rc!=0)
88+
{
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if (wait_result_is_signal(rc,SIGTERM))
90+
proc_exit(1);
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92+
ereport(wait_result_is_any_signal(rc, true) ?FATAL :DEBUG2,
93+
(errmsg("could not restore file \"%s\" from archive: %s",
94+
file,wait_result_to_str(rc))));
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}
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return (rc==0);
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}
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/*
101+
* Attempt to execute a shell-based archive cleanup command.
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*/
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void
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shell_archive_cleanup(constchar*lastRestartPointFileName)
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{
106+
ExecuteRecoveryCommand(archiveCleanupCommand,"archive_cleanup_command",
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false,WAIT_EVENT_ARCHIVE_CLEANUP_COMMAND,
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lastRestartPointFileName);
109+
}
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/*
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* Attempt to execute a shell-based end-of-recovery command.
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*/
114+
void
115+
shell_recovery_end(constchar*lastRestartPointFileName)
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{
117+
ExecuteRecoveryCommand(recoveryEndCommand,"recovery_end_command", true,
118+
WAIT_EVENT_RECOVERY_END_COMMAND,
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lastRestartPointFileName);
120+
}
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/*
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* Attempt to execute an external shell command during recovery.
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*
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* 'command' is the shell command to be executed, 'commandName' is a
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* human-readable name describing the command emitted in the logs. If
127+
* 'failOnSignal' is true and the command is killed by a signal, a FATAL
128+
* error is thrown. Otherwise a WARNING is emitted.
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*
130+
* This is currently used for recovery_end_command and archive_cleanup_command.
131+
*/
132+
staticvoid
133+
ExecuteRecoveryCommand(constchar*command,constchar*commandName,
134+
boolfailOnSignal,uint32wait_event_info,
135+
constchar*lastRestartPointFileName)
136+
{
137+
char*xlogRecoveryCmd;
138+
intrc;
139+
140+
Assert(command&&commandName);
141+
142+
/*
143+
* construct the command to be executed
144+
*/
145+
xlogRecoveryCmd=replace_percent_placeholders(command,commandName,"r",
146+
lastRestartPointFileName);
147+
148+
ereport(DEBUG3,
149+
(errmsg_internal("executing %s \"%s\"",commandName,command)));
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151+
/*
152+
* execute the constructed command
153+
*/
154+
fflush(NULL);
155+
pgstat_report_wait_start(wait_event_info);
156+
rc=system(xlogRecoveryCmd);
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pgstat_report_wait_end();
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159+
pfree(xlogRecoveryCmd);
160+
161+
if (rc!=0)
162+
{
163+
/*
164+
* If the failure was due to any sort of signal, it's best to punt and
165+
* abort recovery. See comments in shell_restore().
166+
*/
167+
ereport((failOnSignal&&wait_result_is_any_signal(rc, true)) ?FATAL :WARNING,
168+
/*------
169+
translator: First %s represents a postgresql.conf parameter name like
170+
"recovery_end_command", the 2nd is the value of that parameter, the
171+
third an already translated error message. */
172+
(errmsg("%s \"%s\": %s",commandName,
173+
command,wait_result_to_str(rc))));
174+
}
175+
}

‎src/backend/access/transam/xlog.c

Lines changed: 29 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -692,6 +692,7 @@ static char *GetXLogBuffer(XLogRecPtr ptr, TimeLineID tli);
692692
staticXLogRecPtrXLogBytePosToRecPtr(uint64bytepos);
693693
staticXLogRecPtrXLogBytePosToEndRecPtr(uint64bytepos);
694694
staticuint64XLogRecPtrToBytePos(XLogRecPtrptr);
695+
staticvoidGetOldestRestartPointFileName(char*fname);
695696

696697
staticvoidWALInsertLockAcquire(void);
697698
staticvoidWALInsertLockAcquireExclusive(void);
@@ -4887,10 +4888,12 @@ CleanupAfterArchiveRecovery(TimeLineID EndOfLogTLI, XLogRecPtr EndOfLog,
48874888
* Execute the recovery_end_command, if any.
48884889
*/
48894890
if (recoveryEndCommand&&strcmp(recoveryEndCommand,"")!=0)
4890-
ExecuteRecoveryCommand(recoveryEndCommand,
4891-
"recovery_end_command",
4892-
true,
4893-
WAIT_EVENT_RECOVERY_END_COMMAND);
4891+
{
4892+
charlastRestartPointFname[MAXFNAMELEN];
4893+
4894+
GetOldestRestartPointFileName(lastRestartPointFname);
4895+
shell_recovery_end(lastRestartPointFname);
4896+
}
48944897

48954898
/*
48964899
* We switched to a new timeline. Clean up segments on the old timeline.
@@ -7307,10 +7310,12 @@ CreateRestartPoint(int flags)
73077310
* Finally, execute archive_cleanup_command, if any.
73087311
*/
73097312
if (archiveCleanupCommand&&strcmp(archiveCleanupCommand,"")!=0)
7310-
ExecuteRecoveryCommand(archiveCleanupCommand,
7311-
"archive_cleanup_command",
7312-
false,
7313-
WAIT_EVENT_ARCHIVE_CLEANUP_COMMAND);
7313+
{
7314+
charlastRestartPointFname[MAXFNAMELEN];
7315+
7316+
GetOldestRestartPointFileName(lastRestartPointFname);
7317+
shell_archive_cleanup(lastRestartPointFname);
7318+
}
73147319

73157320
return true;
73167321
}
@@ -8884,6 +8889,22 @@ GetOldestRestartPoint(XLogRecPtr *oldrecptr, TimeLineID *oldtli)
88848889
LWLockRelease(ControlFileLock);
88858890
}
88868891

8892+
/*
8893+
* Returns the WAL file name for the last checkpoint or restartpoint. This is
8894+
* the oldest WAL file that we still need if we have to restart recovery.
8895+
*/
8896+
staticvoid
8897+
GetOldestRestartPointFileName(char*fname)
8898+
{
8899+
XLogRecPtrrestartRedoPtr;
8900+
TimeLineIDrestartTli;
8901+
XLogSegNorestartSegNo;
8902+
8903+
GetOldestRestartPoint(&restartRedoPtr,&restartTli);
8904+
XLByteToSeg(restartRedoPtr,restartSegNo,wal_segment_size);
8905+
XLogFileName(fname,restartTli,restartSegNo,wal_segment_size);
8906+
}
8907+
88878908
/* Thin wrapper around ShutdownWalRcv(). */
88888909
void
88898910
XLogShutdownWalRcv(void)

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