database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-08-28 18:48:04 +03:00
Code Activity

Rationalize GetWalRcv{Write,Flush}RecPtr().

Browse Source 
GetWalRcvWriteRecPtr() previously reported the latest *flushed*
location.  Adopt the conventional terminology used elsewhere in the tree
by renaming it to GetWalRcvFlushRecPtr(), and likewise for some related
variables that used the term "received".

Add a new definition of GetWalRcvWriteRecPtr(), which returns the latest
*written* value.  This will allow later patches to use the value for
non-data-integrity purposes, without having to wait for the flush
pointer to advance.

Reviewed-by: Alvaro Herrera <alvherre@2ndquadrant.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CA%2BhUKGJ4VJN8ttxScUFM8dOKX0BrBiboo5uz1cq%3DAovOddfHpA%40mail.gmail.com
This commit is contained in:
Thomas Munro
2020-04-08 23:45:09 +12:00
parent 83fd4532a7
commit d140f2f3e2
7 changed files with 55 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
src/backend/replication/README
View File

@@ -54,7 +54,7 @@ and WalRcvData->slotname, and initializes the starting point in
WalRcvData->receiveStart.
As walreceiver receives WAL from the master server, and writes and flushes
it to disk (in pg_wal), it updates WalRcvData->receivedUpto and signals
it to disk (in pg_wal), it updates WalRcvData->flushedUpto and signals
the startup process to know how far WAL replay can advance.
Walreceiver sends information about replication progress to the master server

15
src/backend/replication/walreceiver.c
View File

@@ -12,7 +12,7 @@
* in the primary server), and then keeps receiving XLOG records and
* writing them to the disk as long as the connection is alive. As XLOG
* records are received and flushed to disk, it updates the
* WalRcv->receivedUpto variable in shared memory, to inform the startup
* WalRcv->flushedUpto variable in shared memory, to inform the startup
* process of how far it can proceed with XLOG replay.
*
* A WAL receiver cannot directly load GUC parameters used when establishing
@@ -261,6 +261,8 @@ WalReceiverMain(void)
SpinLockRelease(&walrcv->mutex);
pg_atomic_init_u64(&WalRcv->writtenUpto, 0);
/* Arrange to clean up at walreceiver exit */
on_shmem_exit(WalRcvDie, 0);
@@ -984,6 +986,9 @@ XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
LogstreamResult.Write = recptr;
}
/* Update shared-memory status */
pg_atomic_write_u64(&WalRcv->writtenUpto, LogstreamResult.Write);
}
/*
@@ -1005,10 +1010,10 @@ XLogWalRcvFlush(bool dying)
/* Update shared-memory status */
SpinLockAcquire(&walrcv->mutex);
if (walrcv->receivedUpto < LogstreamResult.Flush)
if (walrcv->flushedUpto < LogstreamResult.Flush)
{
walrcv->latestChunkStart = walrcv->receivedUpto;
walrcv->receivedUpto = LogstreamResult.Flush;
walrcv->latestChunkStart = walrcv->flushedUpto;
walrcv->flushedUpto = LogstreamResult.Flush;
walrcv->receivedTLI = ThisTimeLineID;
}
SpinLockRelease(&walrcv->mutex);
@@ -1361,7 +1366,7 @@ pg_stat_get_wal_receiver(PG_FUNCTION_ARGS)
state = WalRcv->walRcvState;
receive_start_lsn = WalRcv->receiveStart;
receive_start_tli = WalRcv->receiveStartTLI;
received_lsn = WalRcv->receivedUpto;
received_lsn = WalRcv->flushedUpto;
received_tli = WalRcv->receivedTLI;
last_send_time = WalRcv->lastMsgSendTime;
last_receipt_time = WalRcv->lastMsgReceiptTime;

24
src/backend/replication/walreceiverfuncs.c
View File

@@ -282,11 +282,11 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
/*
* If this is the first startup of walreceiver (on this timeline),
* initialize receivedUpto and latestChunkStart to the starting point.
* initialize flushedUpto and latestChunkStart to the starting point.
*/
if (walrcv->receiveStart == 0 || walrcv->receivedTLI != tli)
{
walrcv->receivedUpto = recptr;
walrcv->flushedUpto = recptr;
walrcv->receivedTLI = tli;
walrcv->latestChunkStart = recptr;
}
@@ -304,7 +304,7 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
}
/*
* Returns the last+1 byte position that walreceiver has written.
* Returns the last+1 byte position that walreceiver has flushed.
*
* Optionally, returns the previous chunk start, that is the first byte
* written in the most recent walreceiver flush cycle. Callers not
@@ -312,13 +312,13 @@ RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr, const char *conninfo,
* receiveTLI.
*/
XLogRecPtr
GetWalRcvWriteRecPtr(XLogRecPtr *latestChunkStart, TimeLineID *receiveTLI)
GetWalRcvFlushRecPtr(XLogRecPtr *latestChunkStart, TimeLineID *receiveTLI)
{
WalRcvData *walrcv = WalRcv;
XLogRecPtr recptr;
SpinLockAcquire(&walrcv->mutex);
recptr = walrcv->receivedUpto;
recptr = walrcv->flushedUpto;
if (latestChunkStart)
*latestChunkStart = walrcv->latestChunkStart;
if (receiveTLI)
@@ -328,6 +328,18 @@ GetWalRcvWriteRecPtr(XLogRecPtr *latestChunkStart, TimeLineID *receiveTLI)
return recptr;
}
/*
* Returns the last+1 byte position that walreceiver has written.
* This returns a recently written value without taking a lock.
*/
XLogRecPtr
GetWalRcvWriteRecPtr(void)
{
WalRcvData *walrcv = WalRcv;
return pg_atomic_read_u64(&walrcv->writtenUpto);
}
/*
* Returns the replication apply delay in ms or -1
* if the apply delay info is not available
@@ -345,7 +357,7 @@ GetReplicationApplyDelay(void)
TimestampTz chunkReplayStartTime;
SpinLockAcquire(&walrcv->mutex);
receivePtr = walrcv->receivedUpto;
receivePtr = walrcv->flushedUpto;
SpinLockRelease(&walrcv->mutex);
replayPtr = GetXLogReplayRecPtr(NULL);

2
src/backend/replication/walsender.c
View File

@@ -2949,7 +2949,7 @@ GetStandbyFlushRecPtr(void)
* has streamed, but hasn't been replayed yet.
*/
receivePtr = GetWalRcvWriteRecPtr(NULL, &receiveTLI);
receivePtr = GetWalRcvFlushRecPtr(NULL, &receiveTLI);
replayPtr = GetXLogReplayRecPtr(&replayTLI);
ThisTimeLineID = replayTLI;