mirror of
https://github.com/postgres/postgres.git
synced 2025-07-05 07:21:24 +03:00
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 named shell_restore.c. The code is split into three functions: - shell_restore(), that attempts the execution of a shell-based restore_command. - shell_archive_cleanup(), for archive_cleanup_command. - shell_recovery_end(), for recovery_end_command. This introduces no functional changes, with failure patterns and logs generated in consequence being the same as before (one case actually generates one less DEBUG2 message "could not restore" when a restore command succeeds but the follow-up stat() to check the size fails, but that only matters with a elevel high enough). This is preparatory work for allowing recovery modules, a facility similar to archive modules, with callbacks shaped similarly to the functions introduced here. Author: Nathan Bossart Reviewed-by: Andres Freund, Michael Paquier Discussion: https://postgr.es/m/20221227192449.GA3672473@nathanxps13
This commit is contained in:
Michael Paquier
175
src/backend/access/transam/shell_restore.c
Normal file
175
src/backend/access/transam/shell_restore.c
Normal file
@ -0,0 +1,175 @@
|
||||
/*-------------------------------------------------------------------------
|
||||
*
|
||||
* shell_restore.c
|
||||
* Recovery functions for a user-specified shell command.
|
||||
*
|
||||
* These recovery functions use a user-specified shell command (e.g. based
|
||||
* on the GUC restore_command).
|
||||
*
|
||||
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
|
||||
* Portions Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
* src/backend/access/transam/shell_restore.c
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
|
||||
#include "postgres.h"
|
||||
|
||||
#include <signal.h>
|
||||
|
||||
#include "access/xlogarchive.h"
|
||||
#include "access/xlogrecovery.h"
|
||||
#include "common/archive.h"
|
||||
#include "common/percentrepl.h"
|
||||
#include "storage/ipc.h"
|
||||
#include "utils/wait_event.h"
|
||||
|
||||
static void ExecuteRecoveryCommand(const char *command,
|
||||
const char *commandName,
|
||||
bool failOnSignal,
|
||||
uint32 wait_event_info,
|
||||
const char *lastRestartPointFileName);
|
||||
|
||||
/*
|
||||
* Attempt to execute a shell-based restore command.
|
||||
*
|
||||
* Returns true if the command has succeeded, false otherwise.
|
||||
*/
|
||||
bool
|
||||
shell_restore(const char *file, const char *path,
|
||||
const char *lastRestartPointFileName)
|
||||
{
|
||||
char *cmd;
|
||||
int rc;
|
||||
|
||||
/* Build the restore command to execute */
|
||||
cmd = BuildRestoreCommand(recoveryRestoreCommand, path, file,
|
||||
lastRestartPointFileName);
|
||||
|
||||
ereport(DEBUG3,
|
||||
(errmsg_internal("executing restore command \"%s\"", cmd)));
|
||||
|
||||
/*
|
||||
* Copy xlog from archival storage to XLOGDIR
|
||||
*/
|
||||
fflush(NULL);
|
||||
pgstat_report_wait_start(WAIT_EVENT_RESTORE_COMMAND);
|
||||
rc = system(cmd);
|
||||
pgstat_report_wait_end();
|
||||
|
||||
pfree(cmd);
|
||||
|
||||
/*
|
||||
* Remember, we rollforward UNTIL the restore fails so failure here is
|
||||
* just part of the process... that makes it difficult to determine
|
||||
* whether the restore failed because there isn't an archive to restore,
|
||||
* or because the administrator has specified the restore program
|
||||
* incorrectly. We have to assume the former.
|
||||
*
|
||||
* However, if the failure was due to any sort of signal, it's best to
|
||||
* punt and abort recovery. (If we "return false" here, upper levels will
|
||||
* assume that recovery is complete and start up the database!) It's
|
||||
* essential to abort on child SIGINT and SIGQUIT, because per spec
|
||||
* system() ignores SIGINT and SIGQUIT while waiting; if we see one of
|
||||
* those it's a good bet we should have gotten it too.
|
||||
*
|
||||
* On SIGTERM, assume we have received a fast shutdown request, and exit
|
||||
* cleanly. It's pure chance whether we receive the SIGTERM first, or the
|
||||
* child process. If we receive it first, the signal handler will call
|
||||
* proc_exit, otherwise we do it here. If we or the child process received
|
||||
* SIGTERM for any other reason than a fast shutdown request, postmaster
|
||||
* will perform an immediate shutdown when it sees us exiting
|
||||
* unexpectedly.
|
||||
*
|
||||
* We treat hard shell errors such as "command not found" as fatal, too.
|
||||
*/
|
||||
if (rc != 0)
|
||||
{
|
||||
if (wait_result_is_signal(rc, SIGTERM))
|
||||
proc_exit(1);
|
||||
|
||||
ereport(wait_result_is_any_signal(rc, true) ? FATAL : DEBUG2,
|
||||
(errmsg("could not restore file \"%s\" from archive: %s",
|
||||
file, wait_result_to_str(rc))));
|
||||
}
|
||||
|
||||
return (rc == 0);
|
||||
}
|
||||
|
||||
/*
|
||||
* Attempt to execute a shell-based archive cleanup command.
|
||||
*/
|
||||
void
|
||||
shell_archive_cleanup(const char *lastRestartPointFileName)
|
||||
{
|
||||
ExecuteRecoveryCommand(archiveCleanupCommand, "archive_cleanup_command",
|
||||
false, WAIT_EVENT_ARCHIVE_CLEANUP_COMMAND,
|
||||
lastRestartPointFileName);
|
||||
}
|
||||
|
||||
/*
|
||||
* Attempt to execute a shell-based end-of-recovery command.
|
||||
*/
|
||||
void
|
||||
shell_recovery_end(const char *lastRestartPointFileName)
|
||||
{
|
||||
ExecuteRecoveryCommand(recoveryEndCommand, "recovery_end_command", true,
|
||||
WAIT_EVENT_RECOVERY_END_COMMAND,
|
||||
lastRestartPointFileName);
|
||||
}
|
||||
|
||||
/*
|
||||
* Attempt to execute an external shell command during recovery.
|
||||
*
|
||||
* 'command' is the shell command to be executed, 'commandName' is a
|
||||
* human-readable name describing the command emitted in the logs. If
|
||||
* 'failOnSignal' is true and the command is killed by a signal, a FATAL
|
||||
* error is thrown. Otherwise a WARNING is emitted.
|
||||
*
|
||||
* This is currently used for recovery_end_command and archive_cleanup_command.
|
||||
*/
|
||||
static void
|
||||
ExecuteRecoveryCommand(const char *command, const char *commandName,
|
||||
bool failOnSignal, uint32 wait_event_info,
|
||||
const char *lastRestartPointFileName)
|
||||
{
|
||||
char *xlogRecoveryCmd;
|
||||
int rc;
|
||||
|
||||
Assert(command && commandName);
|
||||
|
||||
/*
|
||||
* construct the command to be executed
|
||||
*/
|
||||
xlogRecoveryCmd = replace_percent_placeholders(command, commandName, "r",
|
||||
lastRestartPointFileName);
|
||||
|
||||
ereport(DEBUG3,
|
||||
(errmsg_internal("executing %s \"%s\"", commandName, command)));
|
||||
|
||||
/*
|
||||
* execute the constructed command
|
||||
*/
|
||||
fflush(NULL);
|
||||
pgstat_report_wait_start(wait_event_info);
|
||||
rc = system(xlogRecoveryCmd);
|
||||
pgstat_report_wait_end();
|
||||
|
||||
pfree(xlogRecoveryCmd);
|
||||
|
||||
if (rc != 0)
|
||||
{
|
||||
/*
|
||||
* If the failure was due to any sort of signal, it's best to punt and
|
||||
* abort recovery. See comments in shell_restore().
|
||||
*/
|
||||
ereport((failOnSignal && wait_result_is_any_signal(rc, true)) ? FATAL : WARNING,
|
||||
/*------
|
||||
translator: First %s represents a postgresql.conf parameter name like
|
||||
"recovery_end_command", the 2nd is the value of that parameter, the
|
||||
third an already translated error message. */
|
||||
(errmsg("%s \"%s\": %s", commandName,
|
||||
command, wait_result_to_str(rc))));
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user