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

diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 6f82a671ee72dc56d17336b0a65fa3c19f73e8f8..e0dbeebde3d8aba20e3a9a6bb6f2fa9147df2d2b 100644 (file)
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -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);

diff --git a/src/backend/access/heap/rewriteheap.c b/src/backend/access/heap/rewriteheap.c
index 5869922ff838e3c5418277d6f8435787211bb4f2..9c29bc0e0f00e0bf039399d9eea32ff73c9f0dad 100644 (file)
--- a/src/backend/access/heap/rewriteheap.c
+++ b/src/backend/access/heap/rewriteheap.c
@@ -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)

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index a5e85d32f31e4916ab8415d3b620e8d167dd9873..2ab15c3cbb690822721c5728e1037502dec23218 100644 (file)
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -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;
 

diff --git a/src/backend/utils/init/miscinit.c b/src/backend/utils/init/miscinit.c
index c4b29469862471d52ff18dc213c017c514a19853..c7c9bef617ede10594d667592546cd5b3d89066b 100644 (file)
--- a/src/backend/utils/init/miscinit.c
+++ b/src/backend/utils/init/miscinit.c
@@ -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 */