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Add -F option to pg_receivexlog, for specifying fsync interval.

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This allows us to specify the maximum time to issue fsync to ensure
the received WAL file is safely flushed to disk. Without this,
pg_receivexlog always flushes WAL file only when it's closed and
which can cause WAL data to be lost at the event of a crash.

Furuya Osamu, heavily modified by me.
This commit is contained in:
Fujii Masao 2014-08-08 16:50:54 +09:00
parent 1add956ac7
commit 3dad73e71f
5 changed files with 195 additions and 70 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
doc/src/sgml/ref/pg_receivexlog.sgml
View File

@ -105,6 +105,21 @@ PostgreSQL documentation
</listitem>
</varlistentry>
<varlistentry>
<term><option>-F <replaceable class="parameter">interval</replaceable></option></term>
<term><option>--fsync-interval=<replaceable class="parameter">interval</replaceable></option></term>
<listitem>
<para>
Specifies the maximum time to issue sync commands to ensure the
received WAL file is safely flushed to disk, in seconds. The default
value is zero, which disables issuing fsyncs except when WAL file is
closed. If <literal>-1</literal> is specified, WAL file is flushed as
soon as possible, that is, as soon as there are WAL data which has
not been flushed yet.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-v</option></term>
<term><option>--verbose</option></term>

2
src/bin/pg_basebackup/pg_basebackup.c
View File

@ -371,7 +371,7 @@ LogStreamerMain(logstreamer_param *param)
if (!ReceiveXlogStream(param->bgconn, param->startptr, param->timeline,
param->sysidentifier, param->xlogdir,
reached_end_position, standby_message_timeout,
NULL))
NULL, 0))
/*
* Any errors will already have been reported in the function process,

18
src/bin/pg_basebackup/pg_receivexlog.c
View File

@ -36,6 +36,7 @@ static char *basedir = NULL;
static int verbose = 0;
static int noloop = 0;
static int standby_message_timeout = 10 * 1000; /* 10 sec = default */
static int fsync_interval = 0; /* 0 = default */
static volatile bool time_to_abort = false;
@ -62,6 +63,8 @@ usage(void)
printf(_("\nOptions:\n"));
printf(_(" -D, --directory=DIR receive transaction log files into this directory\n"));
printf(_(" -n, --no-loop do not loop on connection lost\n"));
printf(_(" -F --fsync-interval=INTERVAL\n"
" frequency of syncs to transaction log files (in seconds)\n"));
printf(_(" -v, --verbose output verbose messages\n"));
printf(_(" -V, --version output version information, then exit\n"));
printf(_(" -?, --help show this help, then exit\n"));
@ -330,7 +333,8 @@ StreamLog(void)
starttli);
ReceiveXlogStream(conn, startpos, starttli, NULL, basedir,
stop_streaming, standby_message_timeout, ".partial");
stop_streaming, standby_message_timeout, ".partial",
fsync_interval);
PQfinish(conn);
}
@ -360,6 +364,7 @@ main(int argc, char **argv)
{"port", required_argument, NULL, 'p'},
{"username", required_argument, NULL, 'U'},
{"no-loop", no_argument, NULL, 'n'},
{"fsync-interval", required_argument, NULL, 'F'},
{"no-password", no_argument, NULL, 'w'},
{"password", no_argument, NULL, 'W'},
{"status-interval", required_argument, NULL, 's'},
@ -389,7 +394,7 @@ main(int argc, char **argv)
}
}
while ((c = getopt_long(argc, argv, "D:d:h:p:U:s:nwWv",
while ((c = getopt_long(argc, argv, "D:d:h:p:U:s:nF:wWv",
long_options, &option_index)) != -1)
{
switch (c)
@ -436,6 +441,15 @@ main(int argc, char **argv)
case 'n':
noloop = 1;
break;
case 'F':
fsync_interval = atoi(optarg) * 1000;
if (fsync_interval < -1000)
{
fprintf(stderr, _("%s: invalid fsync interval \"%s\"\n"),
progname, optarg);
exit(1);
}
break;
case 'v':
verbose++;
break;

175
src/bin/pg_basebackup/receivelog.c
View File

@ -31,12 +31,14 @@ static char current_walfile_name[MAXPGPATH] = "";
static bool reportFlushPosition = false;
static XLogRecPtr lastFlushPosition = InvalidXLogRecPtr;
static int64 last_fsync = -1; /* timestamp of last WAL file flush */
static bool still_sending = true; /* feedback still needs to be sent? */
static PGresult *HandleCopyStream(PGconn *conn, XLogRecPtr startpos,
uint32 timeline, char *basedir,
stream_stop_callback stream_stop, int standby_message_timeout,
char *partial_suffix, XLogRecPtr *stoppos);
char *partial_suffix, XLogRecPtr *stoppos,
int fsync_interval);
static int CopyStreamPoll(PGconn *conn, long timeout_ms);
static int CopyStreamReceive(PGconn *conn, long timeout, char **buffer);
static bool ProcessKeepaliveMsg(PGconn *conn, char *copybuf, int len,
@ -48,6 +50,13 @@ static bool ProcessXLogDataMsg(PGconn *conn, char *copybuf, int len,
static PGresult *HandleEndOfCopyStream(PGconn *conn, char *copybuf,
XLogRecPtr blockpos, char *basedir, char *partial_suffix,
XLogRecPtr *stoppos);
static bool CheckCopyStreamStop(PGconn *conn, XLogRecPtr blockpos,
uint32 timeline, char *basedir,
stream_stop_callback stream_stop,
char *partial_suffix, XLogRecPtr *stoppos);
static long CalculateCopyStreamSleeptime(int64 now, int standby_message_timeout,
int64 last_status, int fsync_interval,
XLogRecPtr blockpos);
static bool ReadEndOfStreamingResult(PGresult *res, XLogRecPtr *startpos,
uint32 *timeline);
@ -200,6 +209,7 @@ close_walfile(char *basedir, char *partial_suffix, XLogRecPtr pos)
progname, current_walfile_name, partial_suffix);
lastFlushPosition = pos;
last_fsync = feGetCurrentTimestamp();
return true;
}
@ -430,13 +440,17 @@ CheckServerVersionForStreaming(PGconn *conn)
* allows you to tell the difference between partial and completed files,
* so that you can continue later where you left.
*
* fsync_interval controls how often we flush to the received WAL file,
* in milliseconds.
*
* Note: The log position *must* be at a log segment start!
*/
bool
ReceiveXlogStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
char *sysidentifier, char *basedir,
stream_stop_callback stream_stop,
int standby_message_timeout, char *partial_suffix)
int standby_message_timeout, char *partial_suffix,
int fsync_interval)
{
char query[128];
char slotcmd[128];
@ -581,7 +595,7 @@ ReceiveXlogStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
/* Stream the WAL */
res = HandleCopyStream(conn, startpos, timeline, basedir, stream_stop,
standby_message_timeout, partial_suffix,
&stoppos);
&stoppos, fsync_interval);
if (res == NULL)
goto error;
@ -746,7 +760,7 @@ static PGresult *
HandleCopyStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
char *basedir, stream_stop_callback stream_stop,
int standby_message_timeout, char *partial_suffix,
XLogRecPtr *stoppos)
XLogRecPtr *stoppos, int fsync_interval)
{
char *copybuf = NULL;
int64 last_status = -1;
@ -763,26 +777,36 @@ HandleCopyStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
/*
* Check if we should continue streaming, or abort at this point.
*/
if (still_sending && stream_stop(blockpos, timeline, false))
if (!CheckCopyStreamStop(conn, blockpos, timeline, basedir,
stream_stop, partial_suffix, stoppos))
goto error;
now = feGetCurrentTimestamp();
/*
* If fsync_interval has elapsed since last WAL flush and we've written
* some WAL data, flush them to disk.
*/
if (lastFlushPosition < blockpos &&
walfile != -1 &&
((fsync_interval > 0 &&
feTimestampDifferenceExceeds(last_fsync, now, fsync_interval)) ||
fsync_interval < 0))
{
if (!close_walfile(basedir, partial_suffix, blockpos))
if (fsync(walfile) != 0)
{
/* Potential error message is written by close_walfile */
fprintf(stderr, _("%s: could not fsync file \"%s\": %s\n"),
progname, current_walfile_name, strerror(errno));
goto error;
}
if (PQputCopyEnd(conn, NULL) <= 0 || PQflush(conn))
{
fprintf(stderr, _("%s: could not send copy-end packet: %s"),
progname, PQerrorMessage(conn));
goto error;
}
still_sending = false;
lastFlushPosition = blockpos;
last_fsync = now;
}
/*
* Potentially send a status message to the master
*/
now = feGetCurrentTimestamp();
if (still_sending && standby_message_timeout > 0 &&
feTimestampDifferenceExceeds(last_status, now,
standby_message_timeout))
@ -794,34 +818,14 @@ HandleCopyStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
}
/*
* Compute how long send/receive loops should sleep
* Calculate how long send/receive loops should sleep
*/
if (standby_message_timeout && still_sending)
{
int64 targettime;
long secs;
int usecs;
targettime = last_status + (standby_message_timeout - 1) * ((int64) 1000);
feTimestampDifference(now,
targettime,
&secs,
&usecs);
/* Always sleep at least 1 sec */
if (secs <= 0)
{
secs = 1;
usecs = 0;
}
sleeptime = secs * 1000 + usecs / 1000;
}
else
sleeptime = -1;
sleeptime = CalculateCopyStreamSleeptime(now, standby_message_timeout,
last_status, fsync_interval, blockpos);
r = CopyStreamReceive(conn, sleeptime, &copybuf);
if (r == 0)
continue;
while (r != 0)
{
if (r == -1)
goto error;
if (r == -2)
@ -846,6 +850,13 @@ HandleCopyStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
if (!ProcessXLogDataMsg(conn, copybuf, r, &blockpos,
timeline, basedir, stream_stop, partial_suffix))
goto error;
/*
* Check if we should continue streaming, or abort at this point.
*/
if (!CheckCopyStreamStop(conn, blockpos, timeline, basedir,
stream_stop, partial_suffix, stoppos))
goto error;
}
else
{
@ -853,6 +864,13 @@ HandleCopyStream(PGconn *conn, XLogRecPtr startpos, uint32 timeline,
progname, copybuf[0]);
goto error;
}
/*
* Process the received data, and any subsequent data we
* can read without blocking.
*/
r = CopyStreamReceive(conn, 0, &copybuf);
}
}
error:
@ -1193,3 +1211,80 @@ HandleEndOfCopyStream(PGconn *conn, char *copybuf,
*stoppos = blockpos;
return res;
}
/*
* Check if we should continue streaming, or abort at this point.
*/
static bool
CheckCopyStreamStop(PGconn *conn, XLogRecPtr blockpos, uint32 timeline,
char *basedir, stream_stop_callback stream_stop,
char *partial_suffix, XLogRecPtr *stoppos)
{
if (still_sending && stream_stop(blockpos, timeline, false))
{
if (!close_walfile(basedir, partial_suffix, blockpos))
{
/* Potential error message is written by close_walfile */
return false;
}
if (PQputCopyEnd(conn, NULL) <= 0 || PQflush(conn))
{
fprintf(stderr, _("%s: could not send copy-end packet: %s"),
progname, PQerrorMessage(conn));
return false;
}
still_sending = false;
}
return true;
}
/*
* Calculate how long send/receive loops should sleep
*/
static long
CalculateCopyStreamSleeptime(int64 now, int standby_message_timeout,
int64 last_status, int fsync_interval, XLogRecPtr blockpos)
{
int64 targettime = 0;
int64 status_targettime = 0;
int64 fsync_targettime = 0;
long sleeptime;
if (standby_message_timeout && still_sending)
status_targettime = last_status +
(standby_message_timeout - 1) * ((int64) 1000);
if (fsync_interval > 0 && lastFlushPosition < blockpos)
fsync_targettime = last_fsync +
(fsync_interval - 1) * ((int64) 1000);
if ((status_targettime < fsync_targettime && status_targettime > 0) ||
fsync_targettime == 0)
targettime = status_targettime;
else
targettime = fsync_targettime;
if (targettime > 0)
{
long secs;
int usecs;
feTimestampDifference(now,
targettime,
&secs,
&usecs);
/* Always sleep at least 1 sec */
if (secs <= 0)
{
secs = 1;
usecs = 0;
}
sleeptime = secs * 1000 + usecs / 1000;
}
else
sleeptime = -1;
return sleeptime;
}

3
src/bin/pg_basebackup/receivelog.h
View File

@ -16,4 +16,5 @@ extern bool ReceiveXlogStream(PGconn *conn,
char *basedir,
stream_stop_callback stream_stop,
int standby_message_timeout,
char *partial_suffix);
char *partial_suffix,
int fsync_interval);