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Use pg_pwrite() in more places. 

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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7
contrib/pg_stat_statements/pg_stat_statements.c
View File

@ -1868,12 +1868,9 @@ qtext_store(const char *query, int query_len,
if (fd < 0)
goto error;
if (lseek(fd, off, SEEK_SET) != off)
if (pg_pwrite(fd, query, query_len, off) != query_len)
goto error;
if (write(fd, query, query_len) != query_len)
goto error;
if (write(fd, "\0", 1) != 1)
if (pg_pwrite(fd, "\0", 1, off + query_len) != 1)
goto error;
CloseTransientFile(fd);

9
src/backend/access/heap/rewriteheap.c
View File

@ -1156,13 +1156,6 @@ heap_xlog_logical_rewrite(XLogReaderState *r)
path, (uint32) xlrec->offset)));
pgstat_report_wait_end();
/* now seek to the position we want to write our data to */
if (lseek(fd, xlrec->offset, SEEK_SET) != xlrec->offset)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not seek to end of file \"%s\": %m",
path)));
data = XLogRecGetData(r) + sizeof(*xlrec);
len = xlrec->num_mappings * sizeof(LogicalRewriteMappingData);
@ -1170,7 +1163,7 @@ heap_xlog_logical_rewrite(XLogReaderState *r)
/* write out tail end of mapping file (again) */
errno = 0;
pgstat_report_wait_start(WAIT_EVENT_LOGICAL_REWRITE_MAPPING_WRITE);
if (write(fd, data, len) != len)
if (pg_pwrite(fd, data, len, xlrec->offset) != len)
{
/* if write didn't set errno, assume problem is no disk space */
if (errno == 0)

28
src/backend/replication/walreceiver.c
View File

@ -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;

3
src/backend/utils/init/miscinit.c
View File

@ -1333,8 +1333,7 @@ AddToDataDirLockFile(int target_line, const char *str)
len = strlen(destbuffer);
errno = 0;
pgstat_report_wait_start(WAIT_EVENT_LOCK_FILE_ADDTODATADIR_WRITE);
if (lseek(fd, (off_t) 0, SEEK_SET) != 0 ||
(int) write(fd, destbuffer, len) != len)
if (pg_pwrite(fd, destbuffer, len, 0) != len)
{
pgstat_report_wait_end();
/* if write didn't set errno, assume problem is no disk space */