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Fix pg_recvlogical upon signal termination

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When pg_recvlogical needs to abort on a signal like SIGINT/SIGTERM, it
is expected to exit cleanly as the code documents.  However, the code
forgot to clean up the state of the connection before leaving.  This
would cause the tool to emit messages like "unexpected termination of
replication stream" error, which is meant for really unexpected
termination or a crash.

The code is refactored to apply the same termination abort operations for
signals, end LSN and keepalive cases, registering a "reason" for the
termination with a message printed under --verbose adapted to the reason
used.

This is arguably a bug, but this has been this way since the tool exists
and the signal termination can now become slower depending on the change
being decoded when the signal is received.

Reported-by: Andres Freund
Author: Bharath Rupireddy
Reviewed-by: Andres Freund, Kyotaro Horiguchi, Cary Huang, Michael
Paquier
Discussion: https://postgr.es/m/20221019213953.htdtzikf4f45ywil@awork3.anarazel.de
This commit is contained in:
Michael Paquier 2023-07-20 10:22:46 +09:00
parent ab29a7a9c6
commit 47556a0013
2 changed files with 44 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

55
src/bin/pg_basebackup/pg_recvlogical.c
View File

@ -32,6 +32,14 @@
/* Time to sleep between reconnection attempts */
#define RECONNECT_SLEEP_TIME 5
typedef enum
{
STREAM_STOP_NONE,
STREAM_STOP_END_OF_WAL,
STREAM_STOP_KEEPALIVE,
STREAM_STOP_SIGNAL
} StreamStopReason;
/* Global Options */
static char *outfile = NULL;
static int verbose = 0;
@ -55,6 +63,7 @@ static const char *plugin = "test_decoding";
/* Global State */
static int outfd = -1;
static volatile sig_atomic_t time_to_abort = false;
static volatile sig_atomic_t stop_reason = STREAM_STOP_NONE;
static volatile sig_atomic_t output_reopen = false;
static bool output_isfile;
static TimestampTz output_last_fsync = -1;
@ -66,7 +75,8 @@ static void usage(void);
static void StreamLogicalLog(void);
static bool flushAndSendFeedback(PGconn *conn, TimestampTz *now);
static void prepareToTerminate(PGconn *conn, XLogRecPtr endpos,
bool keepalive, XLogRecPtr lsn);
StreamStopReason reason,
XLogRecPtr lsn);
static void
usage(void)
@ -207,9 +217,11 @@ StreamLogicalLog(void)
TimestampTz last_status = -1;
int i;
PQExpBuffer query;
XLogRecPtr cur_record_lsn;
output_written_lsn = InvalidXLogRecPtr;
output_fsync_lsn = InvalidXLogRecPtr;
cur_record_lsn = InvalidXLogRecPtr;
/*
* Connect in replication mode to the server
@ -275,7 +287,8 @@ StreamLogicalLog(void)
int bytes_written;
TimestampTz now;
int hdr_len;
XLogRecPtr cur_record_lsn = InvalidXLogRecPtr;
cur_record_lsn = InvalidXLogRecPtr;
if (copybuf != NULL)
{
@ -487,7 +500,7 @@ StreamLogicalLog(void)
if (endposReached)
{
prepareToTerminate(conn, endpos, true, InvalidXLogRecPtr);
stop_reason = STREAM_STOP_KEEPALIVE;
time_to_abort = true;
break;
}
@ -527,7 +540,7 @@ StreamLogicalLog(void)
*/
if (!flushAndSendFeedback(conn, &now))
goto error;
prepareToTerminate(conn, endpos, false, cur_record_lsn);
stop_reason = STREAM_STOP_END_OF_WAL;
time_to_abort = true;
break;
}
@ -572,12 +585,16 @@ StreamLogicalLog(void)
/* endpos was exactly the record we just processed, we're done */
if (!flushAndSendFeedback(conn, &now))
goto error;
prepareToTerminate(conn, endpos, false, cur_record_lsn);
stop_reason = STREAM_STOP_END_OF_WAL;
time_to_abort = true;
break;
}
}
/* Clean up connection state if stream has been aborted */
if (time_to_abort)
prepareToTerminate(conn, endpos, stop_reason, cur_record_lsn);
res = PQgetResult(conn);
if (PQresultStatus(res) == PGRES_COPY_OUT)
{
@ -656,6 +673,7 @@ error:
static void
sigexit_handler(SIGNAL_ARGS)
{
stop_reason = STREAM_STOP_SIGNAL;
time_to_abort = true;
}
@ -1021,18 +1039,31 @@ flushAndSendFeedback(PGconn *conn, TimestampTz *now)
* retry on failure.
*/
static void
prepareToTerminate(PGconn *conn, XLogRecPtr endpos, bool keepalive, XLogRecPtr lsn)
prepareToTerminate(PGconn *conn, XLogRecPtr endpos, StreamStopReason reason,
XLogRecPtr lsn)
{
(void) PQputCopyEnd(conn, NULL);
(void) PQflush(conn);
if (verbose)
{
if (keepalive)
pg_log_info("end position %X/%X reached by keepalive",
LSN_FORMAT_ARGS(endpos));
else
pg_log_info("end position %X/%X reached by WAL record at %X/%X",
LSN_FORMAT_ARGS(endpos), LSN_FORMAT_ARGS(lsn));
switch (reason)
{
case STREAM_STOP_SIGNAL:
pg_log_info("received interrupt signal, exiting");
break;
case STREAM_STOP_KEEPALIVE:
pg_log_info("end position %X/%X reached by keepalive",
LSN_FORMAT_ARGS(endpos));
break;
case STREAM_STOP_END_OF_WAL:
Assert(!XLogRecPtrIsInvalid(lsn));
pg_log_info("end position %X/%X reached by WAL record at %X/%X",
LSN_FORMAT_ARGS(endpos), LSN_FORMAT_ARGS(lsn));
break;
case STREAM_STOP_NONE:
Assert(false);
break;
}
}
}

1
src/tools/pgindent/typedefs.list
View File

@ -2639,6 +2639,7 @@ Step
StopList
StrategyNumber
StreamCtl
StreamStopReason
String
StringInfo
StringInfoData