Remove XLogFileInit() ability to unlink a pre-existing file.

Only initdb used it.  initdb refuses to operate on a non-empty directory
and generally does not cope with pre-existing files of other kinds.
Hence, use the opportunity to simplify.

Discussion: https://postgr.es/m/20210202151416.GB3304930@rfd.leadboat.com

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 073dabc96dc45ae170d9b8998f70d4167edfc419..1a31788071cf47a05aff2404eb50fd64c19a30b0 100644 (file)
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -2424,7 +2424,7 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible)
    bool        ispartialpage;
    bool        last_iteration;
    bool        finishing_seg;
-   bool        use_existent;
+   bool        added;
    int         curridx;
    int         npages;
    int         startidx;
@@ -2490,8 +2490,7 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible)
                            wal_segment_size);
 
            /* create/use new log file */
-           use_existent = true;
-           openLogFile = XLogFileInit(openLogSegNo, &use_existent);
+           openLogFile = XLogFileInit(openLogSegNo, &added);
            ReserveExternalFD();
        }
 
@@ -3260,9 +3259,7 @@ XLogNeedsFlush(XLogRecPtr record)
  *
  * logsegno: identify segment to be created/opened.
  *
- * *use_existent: if true, OK to use a pre-existing file (else, any
- * pre-existing file will be deleted).  On return, false iff this call added
- * some segment on disk.
+ * *added: on return, true if this call raised the number of extant segments.
  *
  * Returns FD of opened file.
  *
@@ -3272,7 +3269,7 @@ XLogNeedsFlush(XLogRecPtr record)
  * in a critical section.
  */
 int
-XLogFileInit(XLogSegNo logsegno, bool *use_existent)
+XLogFileInit(XLogSegNo logsegno, bool *added)
 {
    char        path[MAXPGPATH];
    char        tmppath[MAXPGPATH];
@@ -3287,19 +3284,17 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent)
    /*
     * Try to use existent file (checkpoint maker may have created it already)
     */
-   if (*use_existent)
+   *added = false;
+   fd = BasicOpenFile(path, O_RDWR | PG_BINARY | get_sync_bit(sync_method));
+   if (fd < 0)
    {
-       fd = BasicOpenFile(path, O_RDWR | PG_BINARY | get_sync_bit(sync_method));
-       if (fd < 0)
-       {
-           if (errno != ENOENT)
-               ereport(ERROR,
-                       (errcode_for_file_access(),
-                        errmsg("could not open file \"%s\": %m", path)));
-       }
-       else
-           return fd;
+       if (errno != ENOENT)
+           ereport(ERROR,
+                   (errcode_for_file_access(),
+                    errmsg("could not open file \"%s\": %m", path)));
    }
+   else
+       return fd;
 
    /*
     * Initialize an empty (all zeroes) segment.  NOTE: it is possible that
@@ -3412,12 +3407,9 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent)
                 errmsg("could not close file \"%s\": %m", tmppath)));
 
    /*
-    * Now move the segment into place with its final name.
-    *
-    * If caller didn't want to use a pre-existing file, get rid of any
-    * pre-existing file.  Otherwise, cope with possibility that someone else
-    * has created the file while we were filling ours: if so, use ours to
-    * pre-create a future log segment.
+    * Now move the segment into place with its final name.  Cope with
+    * possibility that someone else has created the file while we were
+    * filling ours: if so, use ours to pre-create a future log segment.
     */
    installed_segno = logsegno;
 
@@ -3431,9 +3423,8 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent)
     * CheckPointSegments.
     */
    max_segno = logsegno + CheckPointSegments;
-   if (InstallXLogFileSegment(&installed_segno, tmppath,
-                              *use_existent, max_segno))
-       *use_existent = false;
+   if (InstallXLogFileSegment(&installed_segno, tmppath, true, max_segno))
+       *added = true;
    else
    {
        /*
@@ -3918,7 +3909,7 @@ PreallocXlogFiles(XLogRecPtr endptr)
 {
    XLogSegNo   _logSegNo;
    int         lf;
-   bool        use_existent;
+   bool        added;
    uint64      offset;
 
    XLByteToPrevSeg(endptr, _logSegNo, wal_segment_size);
@@ -3926,10 +3917,9 @@ PreallocXlogFiles(XLogRecPtr endptr)
    if (offset >= (uint32) (0.75 * wal_segment_size))
    {
        _logSegNo++;
-       use_existent = true;
-       lf = XLogFileInit(_logSegNo, &use_existent);
+       lf = XLogFileInit(_logSegNo, &added);
        close(lf);
-       if (!use_existent)
+       if (added)
            CheckpointStats.ckpt_segs_added++;
    }
 }
@@ -5224,7 +5214,7 @@ BootStrapXLOG(void)
    XLogLongPageHeader longpage;
    XLogRecord *record;
    char       *recptr;
-   bool        use_existent;
+   bool        added;
    uint64      sysidentifier;
    struct timeval tv;
    pg_crc32c   crc;
@@ -5321,8 +5311,7 @@ BootStrapXLOG(void)
    record->xl_crc = crc;
 
    /* Create first XLOG segment file */
-   use_existent = false;
-   openLogFile = XLogFileInit(1, &use_existent);
+   openLogFile = XLogFileInit(1, &added);
 
    /*
     * We needn't bother with Reserve/ReleaseExternalFD here, since we'll
@@ -5628,10 +5617,10 @@ exitArchiveRecovery(TimeLineID endTLI, XLogRecPtr endOfLog)
         * The switch happened at a segment boundary, so just create the next
         * segment on the new timeline.
         */
-       bool        use_existent = true;
+       bool        added;
        int         fd;
 
-       fd = XLogFileInit(startLogSegNo, &use_existent);
+       fd = XLogFileInit(startLogSegNo, &added);
 
        if (close(fd) != 0)
        {

diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index b00066ed2a71f7ca0f89abc17a11795368cd37c0..eadff8f908fe60a82270fe2ab8e5ff927f696e80 100644 (file)
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -885,7 +885,7 @@ XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
 
        if (recvFile < 0 || !XLByteInSeg(recptr, recvSegNo, wal_segment_size))
        {
-           bool        use_existent;
+           bool        added;
 
            /*
             * fsync() and close current file before we switch to next one. We
@@ -923,8 +923,7 @@ XLogWalRcvWrite(char *buf, Size nbytes, XLogRecPtr recptr)
 
            /* Create/use new log file */
            XLByteToSeg(recptr, recvSegNo, wal_segment_size);
-           use_existent = true;
-           recvFile = XLogFileInit(recvSegNo, &use_existent);
+           recvFile = XLogFileInit(recvSegNo, &added);
            recvFileTLI = ThisTimeLineID;
        }
 

diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index a1756490bf86ef2cfac003349e945001931e66ba..d8b8f59c4bd79a16e4d3d6de037dfd511fa52e5b 100644 (file)
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -296,7 +296,7 @@ extern XLogRecPtr XLogInsertRecord(struct XLogRecData *rdata,
 extern void XLogFlush(XLogRecPtr RecPtr);
 extern bool XLogBackgroundFlush(void);
 extern bool XLogNeedsFlush(XLogRecPtr RecPtr);
-extern int XLogFileInit(XLogSegNo segno, bool *use_existent);
+extern int XLogFileInit(XLogSegNo segno, bool *added);
 extern int XLogFileOpen(XLogSegNo segno);
 
 extern void CheckXLogRemoved(XLogSegNo segno, TimeLineID tli);