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Remove all use of ThisTimeLineID global variable outside of xlog.c

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All such code deals with this global variable in one of three ways.
Sometimes the same functions use it in more than one of these ways
at the same time.

First, sometimes it's an implicit argument to one or more functions
being called in xlog.c or elsewhere, and must be set to the
appropriate value before calling those functions lest they
misbehave. In those cases, it is now passed as an explicit argument
instead.

Second, sometimes it's used to obtain the current timeline after
the end of recovery, i.e. the timeline to which WAL is being
written and flushed. Such code now calls GetWALInsertionTimeLine()
or relies on the new out parameter added to GetFlushRecPtr().

Third, sometimes it's used during recovery to store the current
replay timeline. That can change, so such code must generally
update the value before each use. It can still do that, but must
now use a local variable instead.

The net effect of these changes is to reduce by a fair amount the
amount of code that is directly accessing this global variable.
That's good, because history has shown that we don't always think
clearly about which timeline ID it's supposed to contain at any
given point in time, or indeed, whether it has been or needs to
be initialized at any given point in the code.

Patch by me, reviewed and tested by Michael Paquier, Amul Sul, and
Álvaro Herrera.

Discussion: https://postgr.es/m/CA+TgmobfAAqhfWa1kaFBBFvX+5CjM=7TE=n4r4Q1o2bjbGYBpA@mail.gmail.com
This commit is contained in:
Robert Haas
2021-11-05 12:50:01 -04:00
parent caf1f675b8
commit e997a0c642
13 changed files with 169 additions and 132 deletions
Download Patch File Download Diff File Expand all files Collapse all files

54
src/backend/replication/walreceiver.c
View File

@@ -122,10 +122,12 @@ static StringInfoData incoming_message;
static void WalRcvFetchTimeLineHistoryFiles(TimeLineID first, TimeLineID last);
static void WalRcvWaitForStartPosition(XLogRecPtr *startpoint, TimeLineID *startpointTLI);
static void WalRcvDie(int code, Datum arg);
static void XLogWalRcvProcessMsg(unsigned char type, char *buf, Size len);
static void XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr);
static void XLogWalRcvFlush(bool dying);
static void XLogWalRcvClose(XLogRecPtr recptr);
static void XLogWalRcvProcessMsg(unsigned char type, char *buf, Size len,
TimeLineID tli);
static void XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr,
TimeLineID tli);
static void XLogWalRcvFlush(bool dying, TimeLineID tli);
static void XLogWalRcvClose(XLogRecPtr recptr, TimeLineID tli);
static void XLogWalRcvSendReply(bool force, bool requestReply);
static void XLogWalRcvSendHSFeedback(bool immed);
static void ProcessWalSndrMessage(XLogRecPtr walEnd, TimestampTz sendTime);
@@ -255,7 +257,7 @@ WalReceiverMain(void)
pg_atomic_write_u64(&WalRcv->writtenUpto, 0);
/* Arrange to clean up at walreceiver exit */
on_shmem_exit(WalRcvDie, 0);
on_shmem_exit(WalRcvDie, PointerGetDatum(&startpointTLI));
/* Properly accept or ignore signals the postmaster might send us */
pqsignal(SIGHUP, SignalHandlerForConfigReload); /* set flag to read config
@@ -394,7 +396,6 @@ WalReceiverMain(void)
options.startpoint = startpoint;
options.slotname = slotname[0] != '\0' ? slotname : NULL;
options.proto.physical.startpointTLI = startpointTLI;
ThisTimeLineID = startpointTLI;
if (walrcv_startstreaming(wrconn, &options))
{
if (first_stream)
@@ -462,7 +463,8 @@ WalReceiverMain(void)
*/
last_recv_timestamp = GetCurrentTimestamp();
ping_sent = false;
XLogWalRcvProcessMsg(buf[0], &buf[1], len - 1);
XLogWalRcvProcessMsg(buf[0], &buf[1], len - 1,
startpointTLI);
}
else if (len == 0)
break;
@@ -487,7 +489,7 @@ WalReceiverMain(void)
* let the startup process and primary server know about
* them.
*/
XLogWalRcvFlush(false);
XLogWalRcvFlush(false, startpointTLI);
}
/* Check if we need to exit the streaming loop. */
@@ -608,7 +610,7 @@ WalReceiverMain(void)
{
char xlogfname[MAXFNAMELEN];
XLogWalRcvFlush(false);
XLogWalRcvFlush(false, startpointTLI);
XLogFileName(xlogfname, recvFileTLI, recvSegNo, wal_segment_size);
if (close(recvFile) != 0)
ereport(PANIC,
@@ -776,9 +778,12 @@ static void
WalRcvDie(int code, Datum arg)
{
WalRcvData *walrcv = WalRcv;
TimeLineID *startpointTLI_p = (TimeLineID *) DatumGetPointer(arg);
Assert(*startpointTLI_p != 0);
/* Ensure that all WAL records received are flushed to disk */
XLogWalRcvFlush(true);
XLogWalRcvFlush(true, *startpointTLI_p);
/* Mark ourselves inactive in shared memory */
SpinLockAcquire(&walrcv->mutex);
@@ -808,7 +813,7 @@ WalRcvDie(int code, Datum arg)
* Accept the message from XLOG stream, and process it.
*/
static void
XLogWalRcvProcessMsg(unsigned char type, char *buf, Size len)
XLogWalRcvProcessMsg(unsigned char type, char *buf, Size len, TimeLineID tli)
{
int hdrlen;
XLogRecPtr dataStart;
@@ -838,7 +843,7 @@ XLogWalRcvProcessMsg(unsigned char type, char *buf, Size len)
buf += hdrlen;
len -= hdrlen;
XLogWalRcvWrite(buf, len, dataStart);
XLogWalRcvWrite(buf, len, dataStart, tli);
break;
}
case 'k': /* Keepalive */
@@ -875,25 +880,27 @@ XLogWalRcvProcessMsg(unsigned char type, char *buf, Size len)
* Write XLOG data to disk.
*/
static void
XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr, TimeLineID tli)
{
int startoff;
int byteswritten;
Assert(tli != 0);
while (nbytes > 0)
{
int segbytes;
/* Close the current segment if it's completed */
if (recvFile >= 0 && !XLByteInSeg(recptr, recvSegNo, wal_segment_size))
XLogWalRcvClose(recptr);
XLogWalRcvClose(recptr, tli);
if (recvFile < 0)
{
/* Create/use new log file */
XLByteToSeg(recptr, recvSegNo, wal_segment_size);
recvFile = XLogFileInit(recvSegNo);
recvFileTLI = ThisTimeLineID;
recvFile = XLogFileInit(recvSegNo, tli);
recvFileTLI = tli;
}
/* Calculate the start offset of the received logs */
@@ -946,7 +953,7 @@ XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
* segment is received and written.
*/
if (recvFile >= 0 && !XLByteInSeg(recptr, recvSegNo, wal_segment_size))
XLogWalRcvClose(recptr);
XLogWalRcvClose(recptr, tli);
}
/*
@@ -956,13 +963,15 @@ XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
* an error, so we skip sending a reply in that case.
*/
static void
XLogWalRcvFlush(bool dying)
XLogWalRcvFlush(bool dying, TimeLineID tli)
{
Assert(tli != 0);
if (LogstreamResult.Flush < LogstreamResult.Write)
{
WalRcvData *walrcv = WalRcv;
issue_xlog_fsync(recvFile, recvSegNo);
issue_xlog_fsync(recvFile, recvSegNo, tli);
LogstreamResult.Flush = LogstreamResult.Write;
@@ -972,7 +981,7 @@ XLogWalRcvFlush(bool dying)
{
walrcv->latestChunkStart = walrcv->flushedUpto;
walrcv->flushedUpto = LogstreamResult.Flush;
walrcv->receivedTLI = ThisTimeLineID;
walrcv->receivedTLI = tli;
}
SpinLockRelease(&walrcv->mutex);
@@ -1009,17 +1018,18 @@ XLogWalRcvFlush(bool dying)
* Create an archive notification file since the segment is known completed.
*/
static void
XLogWalRcvClose(XLogRecPtr recptr)
XLogWalRcvClose(XLogRecPtr recptr, TimeLineID tli)
{
char xlogfname[MAXFNAMELEN];
Assert(recvFile >= 0 && !XLByteInSeg(recptr, recvSegNo, wal_segment_size));
Assert(tli != 0);
/*
* fsync() and close current file before we switch to next one. We would
* otherwise have to reopen this file to fsync it later
*/
XLogWalRcvFlush(false);
XLogWalRcvFlush(false, tli);
XLogFileName(xlogfname, recvFileTLI, recvSegNo, wal_segment_size);