greenplumn xlogarchive 源码
greenplumn xlogarchive 代码
文件路径：/src/backend/access/transam/xlogarchive.c
/*-------------------------------------------------------------------------
*
* xlogarchive.c
* Functions for archiving WAL files and restoring from the archive.
*
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/backend/access/transam/xlogarchive.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <sys/stat.h>
#include <sys/wait.h>
#include <signal.h>
#include <unistd.h>
#include "access/xlog.h"
#include "access/xlog_internal.h"
#include "miscadmin.h"
#include "postmaster/startup.h"
#include "replication/walsender.h"
#include "storage/fd.h"
#include "storage/ipc.h"
#include "storage/lwlock.h"
#include "storage/pmsignal.h"
/*
* GPDB specific imports:
*/
#include "cdb/cdbvars.h"
#include "utils/builtins.h"
/*
* Attempt to retrieve the specified file from off-line archival storage.
* If successful, fill "path" with its complete path (note that this will be
* a temp file name that doesn't follow the normal naming convention), and
* return true.
*
* If not successful, fill "path" with the name of the normal on-line file
* (which may or may not actually exist, but we'll try to use it), and return
* false.
*
* For fixed-size files, the caller may pass the expected size as an
* additional crosscheck on successful recovery. If the file size is not
* known, set expectedSize = 0.
*
* When 'cleanupEnabled' is false, refrain from deleting any old WAL segments
* in the archive. This is used when fetching the initial checkpoint record,
* when we are not yet sure how far back we need the WAL.
*/
bool
RestoreArchivedFile(char *path, const char *xlogfname,
const char *recovername, off_t expectedSize,
bool cleanupEnabled)
{
char xlogpath[MAXPGPATH];
char xlogRestoreCmd[MAXPGPATH];
char lastRestartPointFname[MAXPGPATH];
char *dp;
char *endp;
const char *sp;
int rc;
struct stat stat_buf;
XLogSegNo restartSegNo;
XLogRecPtr restartRedoPtr;
TimeLineID restartTli;
char contentid[12]; /* sign, 10 digits and '\0' */
/* In standby mode, restore_command might not be supplied */
if (recoveryRestoreCommand == NULL || strcmp(recoveryRestoreCommand, "") == 0)
goto not_available;
/*
* When doing archive recovery, we always prefer an archived log file even
* if a file of the same name exists in XLOGDIR. The reason is that the
* file in XLOGDIR could be an old, un-filled or partly-filled version
* that was copied and restored as part of backing up $PGDATA.
*
* We could try to optimize this slightly by checking the local copy
* lastchange timestamp against the archived copy, but we have no API to
* do this, nor can we guarantee that the lastchange timestamp was
* preserved correctly when we copied to archive. Our aim is robustness,
* so we elect not to do this.
*
* If we cannot obtain the log file from the archive, however, we will try
* to use the XLOGDIR file if it exists. This is so that we can make use
* of log segments that weren't yet transferred to the archive.
*
* Notice that we don't actually overwrite any files when we copy back
* from archive because the restore_command may inadvertently restore
* inappropriate xlogs, or they may be corrupt, so we may wish to fallback
* to the segments remaining in current XLOGDIR later. The
* copy-from-archive filename is always the same, ensuring that we don't
* run out of disk space on long recoveries.
*/
snprintf(xlogpath, MAXPGPATH, XLOGDIR "/%s", recovername);
/*
* Make sure there is no existing file named recovername.
*/
if (stat(xlogpath, &stat_buf) != 0)
{
if (errno != ENOENT)
ereport(FATAL,
(errcode_for_file_access(),
errmsg("could not stat file \"%s\": %m",
xlogpath)));
}
else
{
if (unlink(xlogpath) != 0)
ereport(FATAL,
(errcode_for_file_access(),
errmsg("could not remove file \"%s\": %m",
xlogpath)));
}
/*
* Calculate the archive file cutoff point for use during log shipping
* replication. All files earlier than this point can be deleted from the
* archive, though there is no requirement to do so.
*
* If cleanup is not enabled, initialise this with the filename of
* InvalidXLogRecPtr, which will prevent the deletion of any WAL files
* from the archive because of the alphabetic sorting property of WAL
* filenames.
*
* Once we have successfully located the redo pointer of the checkpoint
* from which we start recovery we never request a file prior to the redo
* pointer of the last restartpoint. When redo begins we know that we have
* successfully located it, so there is no need for additional status
* flags to signify the point when we can begin deleting WAL files from
* the archive.
*/
if (cleanupEnabled)
{
GetOldestRestartPoint(&restartRedoPtr, &restartTli);
XLByteToSeg(restartRedoPtr, restartSegNo, wal_segment_size);
XLogFileName(lastRestartPointFname, restartTli, restartSegNo,
wal_segment_size);
/* we shouldn't need anything earlier than last restart point */
Assert(strcmp(lastRestartPointFname, xlogfname) <= 0);
}
else
XLogFileName(lastRestartPointFname, 0, 0L, wal_segment_size);
/*
* construct the command to be executed
*/
dp = xlogRestoreCmd;
endp = xlogRestoreCmd + MAXPGPATH - 1;
*endp = '\0';
for (sp = recoveryRestoreCommand; *sp; sp++)
{
if (*sp == '%')
{
switch (sp[1])
{
case 'p':
/* %p: relative path of target file */
sp++;
StrNCpy(dp, xlogpath, endp - dp);
make_native_path(dp);
dp += strlen(dp);
break;
case 'f':
/* %f: filename of desired file */
sp++;
StrNCpy(dp, xlogfname, endp - dp);
dp += strlen(dp);
break;
case 'r':
/* %r: filename of last restartpoint */
sp++;
StrNCpy(dp, lastRestartPointFname, endp - dp);
dp += strlen(dp);
break;
case 'c':
/* GPDB: %c: contentId of segment */
Assert(GpIdentity.segindex != UNINITIALIZED_GP_IDENTITY_VALUE);
sp++;
pg_ltoa(GpIdentity.segindex, contentid);
StrNCpy(dp, contentid, endp - dp);
dp += strlen(dp);
break;
case '%':
/* convert %% to a single % */
sp++;
if (dp < endp)
*dp++ = *sp;
break;
default:
/* otherwise treat the % as not special */
if (dp < endp)
*dp++ = *sp;
break;
}
}
else
{
if (dp < endp)
*dp++ = *sp;
}
}
*dp = '\0';
ereport(DEBUG3,
(errmsg_internal("executing restore command \"%s\"",
xlogRestoreCmd)));
/*
* Check signals before restore command and reset afterwards.
*/
PreRestoreCommand();
/*
* Copy xlog from archival storage to XLOGDIR
*/
rc = system(xlogRestoreCmd);
PostRestoreCommand();
if (rc == 0)
{
/*
* command apparently succeeded, but let's make sure the file is
* really there now and has the correct size.
*/
if (stat(xlogpath, &stat_buf) == 0)
{
if (expectedSize > 0 && stat_buf.st_size != expectedSize)
{
int elevel;
/*
* If we find a partial file in standby mode, we assume it's
* because it's just being copied to the archive, and keep
* trying.
*
* Otherwise treat a wrong-sized file as FATAL to ensure the
* DBA would notice it, but is that too strong? We could try
* to plow ahead with a local copy of the file ... but the
* problem is that there probably isn't one, and we'd
* incorrectly conclude we've reached the end of WAL and we're
* done recovering ...
*/
if (StandbyMode && stat_buf.st_size < expectedSize)
elevel = DEBUG1;
else
elevel = FATAL;
ereport(elevel,
(errmsg("archive file \"%s\" has wrong size: %lu instead of %lu",
xlogfname,
(unsigned long) stat_buf.st_size,
(unsigned long) expectedSize)));
return false;
}
else
{
ereport(LOG,
(errmsg("restored log file \"%s\" from archive",
xlogfname)));
strcpy(path, xlogpath);
return true;
}
}
else
{
/* stat failed */
if (errno != ENOENT)
ereport(FATAL,
(errcode_for_file_access(),
errmsg("could not stat file \"%s\": %m",
xlogpath)));
}
}
/*
* 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 (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",
xlogfname, wait_result_to_str(rc))));
not_available:
/*
* if an archived file is not available, there might still be a version of
* this file in XLOGDIR, so return that as the filename to open.
*
* In many recovery scenarios we expect this to fail also, but if so that
* just means we've reached the end of WAL.
*/
snprintf(path, MAXPGPATH, XLOGDIR "/%s", xlogfname);
return false;
}
/*
* 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.
*/
void
ExecuteRecoveryCommand(const char *command, const char *commandName, bool failOnSignal)
{
char xlogRecoveryCmd[MAXPGPATH];
char lastRestartPointFname[MAXPGPATH];
char *dp;
char *endp;
const char *sp;
int rc;
char contentid[12]; /* sign, 10 digits and '\0' */
XLogSegNo restartSegNo;
XLogRecPtr restartRedoPtr;
TimeLineID restartTli;
Assert(command && commandName);
/*
* Calculate the archive file cutoff point for use during log shipping
* replication. All files earlier than this point can be deleted from the
* archive, though there is no requirement to do so.
*/
GetOldestRestartPoint(&restartRedoPtr, &restartTli);
XLByteToSeg(restartRedoPtr, restartSegNo, wal_segment_size);
XLogFileName(lastRestartPointFname, restartTli, restartSegNo,
wal_segment_size);
/*
* construct the command to be executed
*/
dp = xlogRecoveryCmd;
endp = xlogRecoveryCmd + MAXPGPATH - 1;
*endp = '\0';
for (sp = command; *sp; sp++)
{
if (*sp == '%')
{
switch (sp[1])
{
case 'r':
/* %r: filename of last restartpoint */
sp++;
StrNCpy(dp, lastRestartPointFname, endp - dp);
dp += strlen(dp);
break;
case 'c':
/* GPDB: %c: contentId of segment */
Assert(GpIdentity.segindex != UNINITIALIZED_GP_IDENTITY_VALUE);
sp++;
pg_ltoa(GpIdentity.segindex, contentid);
StrNCpy(dp, contentid, endp - dp);
dp += strlen(dp);
break;
case '%':
/* convert %% to a single % */
sp++;
if (dp < endp)
*dp++ = *sp;
break;
default:
/* otherwise treat the % as not special */
if (dp < endp)
*dp++ = *sp;
break;
}
}
else
{
if (dp < endp)
*dp++ = *sp;
}
}
*dp = '\0';
ereport(DEBUG3,
(errmsg_internal("executing %s \"%s\"", commandName, command)));
/*
* execute the constructed command
*/
rc = system(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 RestoreArchivedFile().
*/
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))));
}
}
/*
* A file was restored from the archive under a temporary filename (path),
* and now we want to keep it. Rename it under the permanent filename in
* pg_wal (xlogfname), replacing any existing file with the same name.
*/
void
KeepFileRestoredFromArchive(const char *path, const char *xlogfname)
{
char xlogfpath[MAXPGPATH];
bool reload = false;
struct stat statbuf;
snprintf(xlogfpath, MAXPGPATH, XLOGDIR "/%s", xlogfname);
if (stat(xlogfpath, &statbuf) == 0)
{
char oldpath[MAXPGPATH];
#ifdef WIN32
static unsigned int deletedcounter = 1;
/*
* On Windows, if another process (e.g a walsender process) holds the
* file open in FILE_SHARE_DELETE mode, unlink will succeed, but the
* file will still show up in directory listing until the last handle
* is closed, and we cannot rename the new file in its place until
* that. To avoid that problem, rename the old file to a temporary
* name first. Use a counter to create a unique filename, because the
* same file might be restored from the archive multiple times, and a
* walsender could still be holding onto an old deleted version of it.
*/
snprintf(oldpath, MAXPGPATH, "%s.deleted%u",
xlogfpath, deletedcounter++);
if (rename(xlogfpath, oldpath) != 0)
{
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not rename file \"%s\" to \"%s\": %m",
xlogfpath, oldpath)));
}
#else
/* same-size buffers, so this never truncates */
strlcpy(oldpath, xlogfpath, MAXPGPATH);
#endif
if (unlink(oldpath) != 0)
ereport(FATAL,
(errcode_for_file_access(),
errmsg("could not remove file \"%s\": %m",
xlogfpath)));
reload = true;
}
durable_rename(path, xlogfpath, ERROR);
/*
* Create .done file forcibly to prevent the restored segment from being
* archived again later.
*/
if (XLogArchiveMode != ARCHIVE_MODE_ALWAYS)
XLogArchiveForceDone(xlogfname);
else
XLogArchiveNotify(xlogfname);
/*
* If the existing file was replaced, since walsenders might have it open,
* request them to reload a currently-open segment. This is only required
* for WAL segments, walsenders don't hold other files open, but there's
* no harm in doing this too often, and we don't know what kind of a file
* we're dealing with here.
*/
if (reload)
WalSndRqstFileReload();
/*
* Signal walsender that new WAL has arrived. Again, this isn't necessary
* if we restored something other than a WAL segment, but it does no harm
* either.
*/
WalSndWakeup();
}
/*
* XLogArchiveNotify
*
* Create an archive notification file
*
* The name of the notification file is the message that will be picked up
* by the archiver, e.g. we write 0000000100000001000000C6.ready
* and the archiver then knows to archive XLOGDIR/0000000100000001000000C6,
* then when complete, rename it to 0000000100000001000000C6.done
*/
void
XLogArchiveNotify(const char *xlog)
{
char archiveStatusPath[MAXPGPATH];
FILE *fd;
/* insert an otherwise empty file called <XLOG>.ready */
StatusFilePath(archiveStatusPath, xlog, ".ready");
fd = AllocateFile(archiveStatusPath, "w");
if (fd == NULL)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not create archive status file \"%s\": %m",
archiveStatusPath)));
return;
}
if (FreeFile(fd))
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not write archive status file \"%s\": %m",
archiveStatusPath)));
return;
}
/* Notify archiver that it's got something to do */
if (IsUnderPostmaster)
SendPostmasterSignal(PMSIGNAL_WAKEN_ARCHIVER);
}
/*
* Convenience routine to notify using segment number representation of filename
*/
void
XLogArchiveNotifySeg(XLogSegNo segno)
{
char xlog[MAXFNAMELEN];
XLogFileName(xlog, ThisTimeLineID, segno, wal_segment_size);
XLogArchiveNotify(xlog);
}
/*
* XLogArchiveForceDone
*
* Emit notification forcibly that an XLOG segment file has been successfully
* archived, by creating <XLOG>.done regardless of whether <XLOG>.ready
* exists or not.
*/
void
XLogArchiveForceDone(const char *xlog)
{
char archiveReady[MAXPGPATH];
char archiveDone[MAXPGPATH];
struct stat stat_buf;
FILE *fd;
/* Exit if already known done */
StatusFilePath(archiveDone, xlog, ".done");
if (stat(archiveDone, &stat_buf) == 0)
return;
/* If .ready exists, rename it to .done */
StatusFilePath(archiveReady, xlog, ".ready");
if (stat(archiveReady, &stat_buf) == 0)
{
(void) durable_rename(archiveReady, archiveDone, WARNING);
return;
}
/* insert an otherwise empty file called <XLOG>.done */
fd = AllocateFile(archiveDone, "w");
if (fd == NULL)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not create archive status file \"%s\": %m",
archiveDone)));
return;
}
if (FreeFile(fd))
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not write archive status file \"%s\": %m",
archiveDone)));
return;
}
}
/*
* XLogArchiveCheckDone
*
* This is called when we are ready to delete or recycle an old XLOG segment
* file or backup history file. If it is okay to delete it then return true.
* If it is not time to delete it, make sure a .ready file exists, and return
* false.
*
* If <XLOG>.done exists, then return true; else if <XLOG>.ready exists,
* then return false; else create <XLOG>.ready and return false.
*
* The reason we do things this way is so that if the original attempt to
* create <XLOG>.ready fails, we'll retry during subsequent checkpoints.
*/
bool
XLogArchiveCheckDone(const char *xlog)
{
char archiveStatusPath[MAXPGPATH];
struct stat stat_buf;
bool inRecovery = RecoveryInProgress();
/*
* The file is always deletable if archive_mode is "off". On standbys
* archiving is disabled if archive_mode is "on", and enabled with
* "always". On a primary, archiving is enabled if archive_mode is "on"
* or "always".
*/
if (!((XLogArchivingActive() && !inRecovery) ||
(XLogArchivingAlways() && inRecovery)))
return true;
/* First check for .done --- this means archiver is done with it */
StatusFilePath(archiveStatusPath, xlog, ".done");
if (stat(archiveStatusPath, &stat_buf) == 0)
return true;
/* check for .ready --- this means archiver is still busy with it */
StatusFilePath(archiveStatusPath, xlog, ".ready");
if (stat(archiveStatusPath, &stat_buf) == 0)
return false;
/* Race condition --- maybe archiver just finished, so recheck */
StatusFilePath(archiveStatusPath, xlog, ".done");
if (stat(archiveStatusPath, &stat_buf) == 0)
return true;
/* Retry creation of the .ready file */
XLogArchiveNotify(xlog);
return false;
}
/*
* XLogArchiveIsBusy
*
* Check to see if an XLOG segment file is still unarchived.
* This is almost but not quite the inverse of XLogArchiveCheckDone: in
* the first place we aren't chartered to recreate the .ready file, and
* in the second place we should consider that if the file is already gone
* then it's not busy. (This check is needed to handle the race condition
* that a checkpoint already deleted the no-longer-needed file.)
*/
bool
XLogArchiveIsBusy(const char *xlog)
{
char archiveStatusPath[MAXPGPATH];
struct stat stat_buf;
/* First check for .done --- this means archiver is done with it */
StatusFilePath(archiveStatusPath, xlog, ".done");
if (stat(archiveStatusPath, &stat_buf) == 0)
return false;
/* check for .ready --- this means archiver is still busy with it */
StatusFilePath(archiveStatusPath, xlog, ".ready");
if (stat(archiveStatusPath, &stat_buf) == 0)
return true;
/* Race condition --- maybe archiver just finished, so recheck */
StatusFilePath(archiveStatusPath, xlog, ".done");
if (stat(archiveStatusPath, &stat_buf) == 0)
return false;
/*
* Check to see if the WAL file has been removed by checkpoint, which
* implies it has already been archived, and explains why we can't see a
* status file for it.
*/
snprintf(archiveStatusPath, MAXPGPATH, XLOGDIR "/%s", xlog);
if (stat(archiveStatusPath, &stat_buf) != 0 &&
errno == ENOENT)
return false;
return true;
}
/*
* XLogArchiveIsReadyOrDone
*
* Check to see if an XLOG segment file has a .ready or .done file.
* This is similar to XLogArchiveIsBusy(), but returns true if the file
* is already archived or is about to be archived.
*
* This is currently only used at recovery. During normal operation this
* would be racy: the file might get removed or marked with .ready as we're
* checking it, or immediately after we return.
*/
bool
XLogArchiveIsReadyOrDone(const char *xlog)
{
char archiveStatusPath[MAXPGPATH];
struct stat stat_buf;
/* First check for .done --- this means archiver is done with it */
StatusFilePath(archiveStatusPath, xlog, ".done");
if (stat(archiveStatusPath, &stat_buf) == 0)
return true;
/* check for .ready --- this means archiver is still busy with it */
StatusFilePath(archiveStatusPath, xlog, ".ready");
if (stat(archiveStatusPath, &stat_buf) == 0)
return true;
/* Race condition --- maybe archiver just finished, so recheck */
StatusFilePath(archiveStatusPath, xlog, ".done");
if (stat(archiveStatusPath, &stat_buf) == 0)
return true;
return false;
}
/*
* XLogArchiveIsReady
*
* Check to see if an XLOG segment file has an archive notification (.ready)
* file.
*/
bool
XLogArchiveIsReady(const char *xlog)
{
char archiveStatusPath[MAXPGPATH];
struct stat stat_buf;
StatusFilePath(archiveStatusPath, xlog, ".ready");
if (stat(archiveStatusPath, &stat_buf) == 0)
return true;
return false;
}
/*
* XLogArchiveCleanup
*
* Cleanup archive notification file(s) for a particular xlog segment
*/
void
XLogArchiveCleanup(const char *xlog)
{
char archiveStatusPath[MAXPGPATH];
/* Remove the .done file */
StatusFilePath(archiveStatusPath, xlog, ".done");
unlink(archiveStatusPath);
/* should we complain about failure? */
/* Remove the .ready file if present --- normally it shouldn't be */
StatusFilePath(archiveStatusPath, xlog, ".ready");
unlink(archiveStatusPath);
/* should we complain about failure? */
}
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