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Rationalize GetWalRcv{Write,Flush}RecPtr().

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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
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24
src/backend/replication/walreceiverfuncs.c
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@ -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);