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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 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
@@ -23,7 +23,6 @@
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#include "access/xlog_internal.h"
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#include "access/xlogarchive.h"
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#include "common/archive.h"
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#include "common/percentrepl.h"
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#include "miscadmin.h"
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#include "pgstat.h"
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#include "postmaster/startup.h"
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@@ -57,9 +56,8 @@ RestoreArchivedFile(char *path, const char *xlogfname,
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bool cleanupEnabled)
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{
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char xlogpath[MAXPGPATH];
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char *xlogRestoreCmd;
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char lastRestartPointFname[MAXPGPATH];
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int rc;
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bool ret;
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struct stat stat_buf;
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XLogSegNo restartSegNo;
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XLogRecPtr restartRedoPtr;
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@@ -150,15 +148,6 @@ RestoreArchivedFile(char *path, const char *xlogfname,
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else
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XLogFileName(lastRestartPointFname, 0, 0L, wal_segment_size);
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/* Build the restore command to execute */
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xlogRestoreCmd = BuildRestoreCommand(recoveryRestoreCommand,
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xlogpath, xlogfname,
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lastRestartPointFname);
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ereport(DEBUG3,
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(errmsg_internal("executing restore command \"%s\"",
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xlogRestoreCmd)));
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/*
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* Check signals before restore command and reset afterwards.
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*/
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@@ -167,15 +156,11 @@ RestoreArchivedFile(char *path, const char *xlogfname,
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/*
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* Copy xlog from archival storage to XLOGDIR
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*/
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fflush(NULL);
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pgstat_report_wait_start(WAIT_EVENT_RESTORE_COMMAND);
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rc = system(xlogRestoreCmd);
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pgstat_report_wait_end();
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ret = shell_restore(xlogfname, xlogpath, lastRestartPointFname);
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PostRestoreCommand();
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pfree(xlogRestoreCmd);
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if (rc == 0)
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if (ret)
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{
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/*
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* command apparently succeeded, but let's make sure the file is
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@@ -231,37 +216,6 @@ RestoreArchivedFile(char *path, const char *xlogfname,
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}
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}
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/*
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* 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 (wait_result_is_signal(rc, SIGTERM))
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proc_exit(1);
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ereport(wait_result_is_any_signal(rc, true) ? FATAL : DEBUG2,
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(errmsg("could not restore file \"%s\" from archive: %s",
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xlogfname, wait_result_to_str(rc))));
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not_available:
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/*
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@@ -275,74 +229,6 @@ not_available:
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return false;
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}
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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
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* 'failOnSignal' is true and the command is killed by a signal, a FATAL
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* error is thrown. Otherwise a WARNING is emitted.
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*
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* This is currently used for recovery_end_command and archive_cleanup_command.
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*/
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void
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ExecuteRecoveryCommand(const char *command, const char *commandName,
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bool failOnSignal, uint32 wait_event_info)
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{
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char *xlogRecoveryCmd;
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char lastRestartPointFname[MAXPGPATH];
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int rc;
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XLogSegNo restartSegNo;
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XLogRecPtr restartRedoPtr;
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TimeLineID restartTli;
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Assert(command && commandName);
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/*
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* Calculate the archive file cutoff point for use during log shipping
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* replication. All files earlier than this point can be deleted from the
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* archive, though there is no requirement to do so.
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*/
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GetOldestRestartPoint(&restartRedoPtr, &restartTli);
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XLByteToSeg(restartRedoPtr, restartSegNo, wal_segment_size);
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XLogFileName(lastRestartPointFname, restartTli, restartSegNo,
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wal_segment_size);
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/*
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* construct the command to be executed
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*/
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xlogRecoveryCmd = replace_percent_placeholders(command, commandName, "r", lastRestartPointFname);
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ereport(DEBUG3,
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(errmsg_internal("executing %s \"%s\"", commandName, command)));
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/*
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* execute the constructed command
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*/
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fflush(NULL);
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pgstat_report_wait_start(wait_event_info);
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rc = system(xlogRecoveryCmd);
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pgstat_report_wait_end();
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pfree(xlogRecoveryCmd);
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if (rc != 0)
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{
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/*
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* If the failure was due to any sort of signal, it's best to punt and
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* abort recovery. See comments in RestoreArchivedFile().
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*/
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ereport((failOnSignal && wait_result_is_any_signal(rc, true)) ? FATAL : WARNING,
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/*------
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translator: First %s represents a postgresql.conf parameter name like
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"recovery_end_command", the 2nd is the value of that parameter, the
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third an already translated error message. */
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(errmsg("%s \"%s\": %s", commandName,
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command, wait_result_to_str(rc))));
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}
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}
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/*
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* A file was restored from the archive under a temporary filename (path),
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* and now we want to keep it. Rename it under the permanent filename in
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