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Use pg_pwrite() in more places.

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This removes some lseek() system calls.

Author: Thomas Munro
Reviewed-by: Andres Freund
Discussion: https://postgr.es/m/CA%2BhUKGJ%2BoHhnvqjn3%3DHro7xu-YDR8FPr0FL6LF35kHRX%3D_bUzg%40mail.gmail.com
This commit is contained in:
Thomas Munro
2020-02-11 17:22:37 +13:00
parent 2102ba4b58
commit 701a51fd4e
4 changed files with 7 additions and 40 deletions
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28
src/backend/replication/walreceiver.c
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@@ -85,14 +85,13 @@ WalReceiverFunctionsType *WalReceiverFunctions = NULL;
#define NAPTIME_PER_CYCLE 100 /* max sleep time between cycles (100ms) */
/*
* These variables are used similarly to openLogFile/SegNo/Off,
* These variables are used similarly to openLogFile/SegNo,
* but for walreceiver to write the XLOG. recvFileTLI is the TimeLineID
* corresponding the filename of recvFile.
*/
static int recvFile = -1;
static TimeLineID recvFileTLI = 0;
static XLogSegNo recvSegNo = 0;
static uint32 recvOff = 0;
/*
* Flags set by interrupt handlers of walreceiver for later service in the
@@ -945,7 +944,6 @@ XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
use_existent = true;
recvFile = XLogFileInit(recvSegNo, &use_existent, true);
recvFileTLI = ThisTimeLineID;
recvOff = 0;
}
/* Calculate the start offset of the received logs */
@@ -956,29 +954,10 @@ XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
else
segbytes = nbytes;
/* Need to seek in the file? */
if (recvOff != startoff)
{
if (lseek(recvFile, (off_t) startoff, SEEK_SET) < 0)
{
char xlogfname[MAXFNAMELEN];
int save_errno = errno;
XLogFileName(xlogfname, recvFileTLI, recvSegNo, wal_segment_size);
errno = save_errno;
ereport(PANIC,
(errcode_for_file_access(),
errmsg("could not seek in log segment %s to offset %u: %m",
xlogfname, startoff)));
}
recvOff = startoff;
}
/* OK to write the logs */
errno = 0;
byteswritten = write(recvFile, buf, segbytes);
byteswritten = pg_pwrite(recvFile, buf, segbytes, (off_t) startoff);
if (byteswritten <= 0)
{
char xlogfname[MAXFNAMELEN];
@@ -995,13 +974,12 @@ XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
(errcode_for_file_access(),
errmsg("could not write to log segment %s "
"at offset %u, length %lu: %m",
xlogfname, recvOff, (unsigned long) segbytes)));
xlogfname, startoff, (unsigned long) segbytes)));
}
/* Update state for write */
recptr += byteswritten;
recvOff += byteswritten;
nbytes -= byteswritten;
buf += byteswritten;