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Refactor code for restoring files via shell commands 

Presently, restore_command uses a different code path than
archive_cleanup_command and recovery_end_command.  These code paths
are similar and can be easily combined, as long as it is possible to
identify if a command should:
- Issue a FATAL on signal.
- Exit immediately on SIGTERM.

While on it, this removes src/common/archive.c and its associated
header.  Since the introduction of c96de2c, BuildRestoreCommand() has
become a simple wrapper of replace_percent_placeholders() able to call
make_native_path().  This simplifies shell_restore.c as long as
RestoreArchivedFile() includes a call to make_native_path().

Author: Nathan Bossart
Reviewed-by: Andres Freund, Michael Paquier
Discussion: https://postgr.es/m/20221227192449.GA3672473@nathanxps13
This commit is contained in:
Michael Paquier 2023-01-18 11:15:48 +09:00
parent 2f31f405e1
commit 14bdb3f13d
8 changed files with 56 additions and 139 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

98
src/backend/access/transam/shell_restore.c
View File

@ -20,16 +20,16 @@
#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,
static bool ExecuteRecoveryCommand(const char *command,
const char *commandName,
bool failOnSignal,
bool exitOnSigterm,
uint32 wait_event_info,
const char *lastRestartPointFileName);
int fail_elevel);
/*
* Attempt to execute a shell-based restore command.
@ -40,25 +40,17 @@ bool
shell_restore(const char *file, const char *path,
const char *lastRestartPointFileName)
{
char *nativePath = pstrdup(path);
char *cmd;
int rc;
bool ret;
/* 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);
make_native_path(nativePath);
cmd = replace_percent_placeholders(recoveryRestoreCommand,
"restore_command", "frp", file,
lastRestartPointFileName,
nativePath);
pfree(nativePath);
/*
* Remember, we rollforward UNTIL the restore fails so failure here is
@ -84,17 +76,13 @@ shell_restore(const char *file, const char *path,
*
* 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);
ret = ExecuteRecoveryCommand(cmd, "restore_command",
true, /* failOnSignal */
true, /* exitOnSigterm */
WAIT_EVENT_RESTORE_COMMAND, DEBUG2);
pfree(cmd);
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);
return ret;
}
/*
@ -103,9 +91,14 @@ shell_restore(const char *file, const char *path,
void
shell_archive_cleanup(const char *lastRestartPointFileName)
{
ExecuteRecoveryCommand(archiveCleanupCommand, "archive_cleanup_command",
false, WAIT_EVENT_ARCHIVE_CLEANUP_COMMAND,
lastRestartPointFileName);
char *cmd;
cmd = replace_percent_placeholders(archiveCleanupCommand,
"archive_cleanup_command",
"r", lastRestartPointFileName);
(void) ExecuteRecoveryCommand(cmd, "archive_cleanup_command", false, false,
WAIT_EVENT_ARCHIVE_CLEANUP_COMMAND, WARNING);
pfree(cmd);
}
/*
@ -114,9 +107,14 @@ shell_archive_cleanup(const char *lastRestartPointFileName)
void
shell_recovery_end(const char *lastRestartPointFileName)
{
ExecuteRecoveryCommand(recoveryEndCommand, "recovery_end_command", true,
WAIT_EVENT_RECOVERY_END_COMMAND,
lastRestartPointFileName);
char *cmd;
cmd = replace_percent_placeholders(recoveryEndCommand,
"recovery_end_command",
"r", lastRestartPointFileName);
(void) ExecuteRecoveryCommand(cmd, "recovery_end_command", true, false,
WAIT_EVENT_RECOVERY_END_COMMAND, WARNING);
pfree(cmd);
}
/*
@ -125,26 +123,21 @@ shell_recovery_end(const char *lastRestartPointFileName)
* '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.
* error is thrown. Otherwise, 'fail_elevel' is used for the log message.
* If 'exitOnSigterm' is true and the command is killed by SIGTERM, we exit
* immediately.
*
* This is currently used for recovery_end_command and archive_cleanup_command.
* Returns whether the command succeeded.
*/
static void
static bool
ExecuteRecoveryCommand(const char *command, const char *commandName,
bool failOnSignal, uint32 wait_event_info,
const char *lastRestartPointFileName)
bool failOnSignal, bool exitOnSigterm,
uint32 wait_event_info, int fail_elevel)
{
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)));
@ -153,18 +146,19 @@ ExecuteRecoveryCommand(const char *command, const char *commandName,
*/
fflush(NULL);
pgstat_report_wait_start(wait_event_info);
rc = system(xlogRecoveryCmd);
rc = system(command);
pgstat_report_wait_end();
pfree(xlogRecoveryCmd);
if (rc != 0)
{
if (exitOnSigterm && wait_result_is_signal(rc, SIGTERM))
proc_exit(1);
/*
* 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,
ereport((failOnSignal && wait_result_is_any_signal(rc, true)) ? FATAL : fail_elevel,
/*------
translator: First %s represents a postgresql.conf parameter name like
"recovery_end_command", the 2nd is the value of that parameter, the
@ -172,4 +166,6 @@ ExecuteRecoveryCommand(const char *command, const char *commandName,
(errmsg("%s \"%s\": %s", commandName,
command, wait_result_to_str(rc))));
}
return (rc == 0);
}

1
src/backend/access/transam/xlogarchive.c
View File

@ -22,7 +22,6 @@
#include "access/xlog.h"
#include "access/xlog_internal.h"
#include "access/xlogarchive.h"
#include "common/archive.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "postmaster/startup.h"

1
src/common/Makefile
View File

@ -46,7 +46,6 @@ LIBS += $(PTHREAD_LIBS)
# If you add objects here, see also src/tools/msvc/Mkvcbuild.pm
OBJS_COMMON = \
archive.o \
base64.o \
checksum_helper.o \
compression.o \

60
src/common/archive.c
View File

@ -1,60 +0,0 @@
/*-------------------------------------------------------------------------
*
* archive.c
* Common WAL archive routines
*
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/common/archive.c
*
*-------------------------------------------------------------------------
*/
#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif
#include "common/archive.h"
#include "common/percentrepl.h"
/*
* BuildRestoreCommand
*
* Builds a restore command to retrieve a file from WAL archives, replacing
* the supported aliases with values supplied by the caller as defined by
* the GUC parameter restore_command: xlogpath for %p, xlogfname for %f and
* lastRestartPointFname for %r.
*
* The result is a palloc'd string for the restore command built. The
* caller is responsible for freeing it. If any of the required arguments
* is NULL and that the corresponding alias is found in the command given
* by the caller, then an error is thrown.
*/
char *
BuildRestoreCommand(const char *restoreCommand,
const char *xlogpath,
const char *xlogfname,
const char *lastRestartPointFname)
{
char *nativePath = NULL;
char *result;
if (xlogpath)
{
nativePath = pstrdup(xlogpath);
make_native_path(nativePath);
}
result = replace_percent_placeholders(restoreCommand, "restore_command", "frp",
xlogfname, lastRestartPointFname, nativePath);
if (nativePath)
pfree(nativePath);
return result;
}

1
src/common/meson.build
View File

@ -1,7 +1,6 @@
# Copyright (c) 2022-2023, PostgreSQL Global Development Group
common_sources = files(
'archive.c',
'base64.c',
'checksum_helper.c',
'compression.c',

11
src/fe_utils/archive.c
View File

@ -19,8 +19,8 @@
#include <sys/stat.h>
#include "access/xlog_internal.h"
#include "common/archive.h"
#include "common/logging.h"
#include "common/percentrepl.h"
#include "fe_utils/archive.h"
@ -41,13 +41,18 @@ RestoreArchivedFile(const char *path, const char *xlogfname,
{
char xlogpath[MAXPGPATH];
char *xlogRestoreCmd;
char *nativePath;
int rc;
struct stat stat_buf;
snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
xlogRestoreCmd = BuildRestoreCommand(restoreCommand, xlogpath,
xlogfname, NULL);
nativePath = pstrdup(xlogpath);
make_native_path(nativePath);
xlogRestoreCmd = replace_percent_placeholders(restoreCommand,
"restore_command", "fp",
xlogfname, nativePath);
pfree(nativePath);
/*
* Execute restore_command, which should copy the missing file from

21
src/include/common/archive.h
View File

@ -1,21 +0,0 @@
/*-------------------------------------------------------------------------
*
* archive.h
* Common WAL archive routines
*
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/common/archive.h
*
*-------------------------------------------------------------------------
*/
#ifndef ARCHIVE_H
#define ARCHIVE_H
extern char *BuildRestoreCommand(const char *restoreCommand,
const char *xlogpath, /* %p */
const char *xlogfname, /* %f */
const char *lastRestartPointFname); /* %r */
#endif /* ARCHIVE_H */

2
src/tools/msvc/Mkvcbuild.pm
View File

@ -133,7 +133,7 @@ sub mkvcbuild
}
our @pgcommonallfiles = qw(
archive.c base64.c checksum_helper.c compression.c
base64.c checksum_helper.c compression.c
config_info.c controldata_utils.c d2s.c encnames.c exec.c
f2s.c file_perm.c file_utils.c hashfn.c ip.c jsonapi.c
keywords.c kwlookup.c link-canary.c md5_common.c percentrepl.c