postgresql/contrib/pg_archivecleanup/pg_archivecleanup.c
Alvaro Herrera b2e431a4db Implement dry-run mode for pg_archivecleanup
In dry-run mode, just the name of the file to be removed is printed to
stdout; this is so the user can easily plug it into another program
through a pipe.  If debug mode is also specified, a more verbose message
is printed to stderr.

Author: Gabriele Bartolini
Reviewer: Josh Kupershmidt
2012-02-01 14:18:12 -03:00

342 lines
9.1 KiB
C

/*
* contrib/pg_archivecleanup/pg_archivecleanup.c
*
* pg_archivecleanup.c
*
* Production-ready example of an archive_cleanup_command
* used to clean an archive when using standby_mode = on in 9.0
* or for standalone use for any version of PostgreSQL 8.0+.
*
* Original author: Simon Riggs simon@2ndquadrant.com
* Current maintainer: Simon Riggs
*/
#include "postgres_fe.h"
#include <ctype.h>
#include <dirent.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <signal.h>
#ifndef WIN32
#include <sys/time.h>
#include <unistd.h>
#ifdef HAVE_GETOPT_H
#include <getopt.h>
#endif
#else /* WIN32 */
extern int getopt(int argc, char *const argv[], const char *optstring);
#endif /* ! WIN32 */
extern char *optarg;
extern int optind;
const char *progname;
/* Options and defaults */
bool debug = false; /* are we debugging? */
bool dryrun = false; /* are we performing a dry-run operation? */
char *archiveLocation; /* where to find the archive? */
char *restartWALFileName; /* the file from which we can restart restore */
char WALFilePath[MAXPGPATH]; /* the file path including archive */
char exclusiveCleanupFileName[MAXPGPATH]; /* the oldest file we
* want to remain in
* archive */
/* =====================================================================
*
* Customizable section
*
* =====================================================================
*
* Currently, this section assumes that the Archive is a locally
* accessible directory. If you want to make other assumptions,
* such as using a vendor-specific archive and access API, these
* routines are the ones you'll need to change. You're
* enouraged to submit any changes to pgsql-hackers@postgresql.org
* or personally to the current maintainer. Those changes may be
* folded in to later versions of this program.
*/
#define XLOG_DATA_FNAME_LEN 24
/* Reworked from access/xlog_internal.h */
#define XLogFileName(fname, tli, log, seg) \
snprintf(fname, XLOG_DATA_FNAME_LEN + 1, "%08X%08X%08X", tli, log, seg)
#define XLOG_BACKUP_FNAME_LEN 40
/*
* Initialize allows customized commands into the archive cleanup program.
*
* You may wish to add code to check for tape libraries, etc..
*/
static void
Initialize(void)
{
/*
* This code assumes that archiveLocation is a directory, so we use stat
* to test if it's accessible.
*/
struct stat stat_buf;
if (stat(archiveLocation, &stat_buf) != 0 ||
!S_ISDIR(stat_buf.st_mode))
{
fprintf(stderr, "%s: archive location \"%s\" does not exist\n",
progname, archiveLocation);
exit(2);
}
}
static void
CleanupPriorWALFiles(void)
{
int rc;
DIR *xldir;
struct dirent *xlde;
if ((xldir = opendir(archiveLocation)) != NULL)
{
while ((xlde = readdir(xldir)) != NULL)
{
/*
* We ignore the timeline part of the XLOG segment identifiers in
* deciding whether a segment is still needed. This ensures that
* we won't prematurely remove a segment from a parent timeline.
* We could probably be a little more proactive about removing
* segments of non-parent timelines, but that would be a whole lot
* more complicated.
*
* We use the alphanumeric sorting property of the filenames to
* decide which ones are earlier than the exclusiveCleanupFileName
* file. Note that this means files are not removed in the order
* they were originally written, in case this worries you.
*/
if (strlen(xlde->d_name) == XLOG_DATA_FNAME_LEN &&
strspn(xlde->d_name, "0123456789ABCDEF") == XLOG_DATA_FNAME_LEN &&
strcmp(xlde->d_name + 8, exclusiveCleanupFileName + 8) < 0)
{
snprintf(WALFilePath, MAXPGPATH, "%s/%s",
archiveLocation, xlde->d_name);
if (dryrun)
{
/*
* Prints the name of the file to be removed and skips the
* actual removal. The regular printout is so that the
* user can pipe the output into some other program.
*/
printf("%s\n", WALFilePath);
if (debug)
fprintf(stderr,
"%s: file \"%s\" would be removed\n",
progname, WALFilePath);
continue;
}
if (debug)
fprintf(stderr, "%s: removing file \"%s\"\n",
progname, WALFilePath);
rc = unlink(WALFilePath);
if (rc != 0)
{
fprintf(stderr, "%s: ERROR: could not remove file \"%s\": %s\n",
progname, WALFilePath, strerror(errno));
break;
}
}
}
closedir(xldir);
}
else
fprintf(stderr, "%s: could not open archive location \"%s\": %s\n",
progname, archiveLocation, strerror(errno));
}
/*
* SetWALFileNameForCleanup()
*
* Set the earliest WAL filename that we want to keep on the archive
* and decide whether we need_cleanup
*/
static void
SetWALFileNameForCleanup(void)
{
bool fnameOK = false;
/*
* If restartWALFileName is a WAL file name then just use it directly. If
* restartWALFileName is a .backup filename, make sure we use the prefix
* of the filename, otherwise we will remove wrong files since
* 000000010000000000000010.00000020.backup is after
* 000000010000000000000010.
*/
if (strlen(restartWALFileName) == XLOG_DATA_FNAME_LEN &&
strspn(restartWALFileName, "0123456789ABCDEF") == XLOG_DATA_FNAME_LEN)
{
strcpy(exclusiveCleanupFileName, restartWALFileName);
fnameOK = true;
}
else if (strlen(restartWALFileName) == XLOG_BACKUP_FNAME_LEN)
{
int args;
uint32 tli = 1,
log = 0,
seg = 0,
offset = 0;
args = sscanf(restartWALFileName, "%08X%08X%08X.%08X.backup", &tli, &log, &seg, &offset);
if (args == 4)
{
fnameOK = true;
/*
* Use just the prefix of the filename, ignore everything after
* first period
*/
XLogFileName(exclusiveCleanupFileName, tli, log, seg);
}
}
if (!fnameOK)
{
fprintf(stderr, "%s: invalid filename input\n", progname);
fprintf(stderr, "Try \"%s --help\" for more information.\n", progname);
exit(2);
}
}
/* =====================================================================
* End of Customizable section
* =====================================================================
*/
static void
usage(void)
{
printf("%s removes older WAL files from PostgreSQL archives.\n\n", progname);
printf("Usage:\n");
printf(" %s [OPTION]... ARCHIVELOCATION OLDESTKEPTWALFILE\n", progname);
printf("\nOptions:\n");
printf(" -d generates debug output (verbose mode)\n");
printf(" -n shows the names of the files that would have been removed (dry-run)\n");
printf(" --help show this help, then exit\n");
printf(" --version output version information, then exit\n");
printf("\n"
"For use as archive_cleanup_command in recovery.conf when standby_mode = on:\n"
" archive_cleanup_command = 'pg_archivecleanup [OPTION]... ARCHIVELOCATION %%r'\n"
"e.g.\n"
" archive_cleanup_command = 'pg_archivecleanup /mnt/server/archiverdir %%r'\n");
printf("\n"
"Or for use as a standalone archive cleaner:\n"
"e.g.\n"
" pg_archivecleanup /mnt/server/archiverdir 000000010000000000000010.00000020.backup\n");
printf("\nReport bugs to <pgsql-bugs@postgresql.org>.\n");
}
/*------------ MAIN ----------------------------------------*/
int
main(int argc, char **argv)
{
int c;
progname = get_progname(argv[0]);
if (argc > 1)
{
if (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") == 0)
{
usage();
exit(0);
}
if (strcmp(argv[1], "--version") == 0 || strcmp(argv[1], "-V") == 0)
{
puts("pg_archivecleanup (PostgreSQL) " PG_VERSION);
exit(0);
}
}
while ((c = getopt(argc, argv, "dn")) != -1)
{
switch (c)
{
case 'd': /* Debug mode */
debug = true;
break;
case 'n': /* Dry-Run mode */
dryrun = true;
break;
default:
fprintf(stderr, "Try \"%s --help\" for more information.\n", progname);
exit(2);
break;
}
}
/*
* We will go to the archiveLocation to check restartWALFileName.
* restartWALFileName may not exist anymore, which would not be an error,
* so we separate the archiveLocation and restartWALFileName so we can
* check separately whether archiveLocation exists, if not that is an
* error
*/
if (optind < argc)
{
archiveLocation = argv[optind];
optind++;
}
else
{
fprintf(stderr, "%s: must specify archive location\n", progname);
fprintf(stderr, "Try \"%s --help\" for more information.\n", progname);
exit(2);
}
if (optind < argc)
{
restartWALFileName = argv[optind];
optind++;
}
else
{
fprintf(stderr, "%s: must specify restartfilename\n", progname);
fprintf(stderr, "Try \"%s --help\" for more information.\n", progname);
exit(2);
}
if (optind < argc)
{
fprintf(stderr, "%s: too many parameters\n", progname);
fprintf(stderr, "Try \"%s --help\" for more information.\n", progname);
exit(2);
}
/*
* Check archive exists and other initialization if required.
*/
Initialize();
/*
* Check filename is a valid name, then process to find cut-off
*/
SetWALFileNameForCleanup();
if (debug)
{
snprintf(WALFilePath, MAXPGPATH, "%s/%s",
archiveLocation, exclusiveCleanupFileName);
fprintf(stderr, "%s: keep WAL file \"%s\" and later\n",
progname, WALFilePath);
}
/*
* Remove WAL files older than cut-off
*/
CleanupPriorWALFiles();
exit(0);
}