Report missing wait event for timeline history file.

TimelineHistoryRead and TimelineHistoryWrite wait events are reported
during waiting for a read and write of a timeline history file, respectively.
However, previously, TimelineHistoryRead wait event was not reported
while readTimeLineHistory() was reading a timeline history file. Also
TimelineHistoryWrite was not reported while writeTimeLineHistory() was
writing one line with the details of the timeline split, at the end.
This commit fixes these issues.

Back-patch to v10 where wait events for a timeline history file was added.

Author: Masahiro Ikeda
Reviewed-by: Michael Paquier, Fujii Masao
Discussion: https://postgr.es/m/d11b0c910b63684424e06772eb844ab5@oss.nttdata.com

diff --git a/src/backend/access/transam/timeline.c b/src/backend/access/transam/timeline.c
index de57d699af1b882dd79e50a6f312aacbccf6d88d..e6a29d9a9b7f0dc2c4cb79ea795cb55816ee2222 100644 (file)
--- a/src/backend/access/transam/timeline.c
+++ b/src/backend/access/transam/timeline.c
@@ -78,7 +78,6 @@ readTimeLineHistory(TimeLineID targetTLI)
    List       *result;
    char        path[MAXPGPATH];
    char        histfname[MAXFNAMELEN];
-   char        fline[MAXPGPATH];
    FILE       *fd;
    TimeLineHistoryEntry *entry;
    TimeLineID  lasttli = 0;
@@ -123,15 +122,30 @@ readTimeLineHistory(TimeLineID targetTLI)
     * Parse the file...
     */
    prevend = InvalidXLogRecPtr;
-   while (fgets(fline, sizeof(fline), fd) != NULL)
+   for (;;)
    {
-       /* skip leading whitespace and check for # comment */
+       char        fline[MAXPGPATH];
+       char       *res;
        char       *ptr;
        TimeLineID  tli;
        uint32      switchpoint_hi;
        uint32      switchpoint_lo;
        int         nfields;
 
+       pgstat_report_wait_start(WAIT_EVENT_TIMELINE_HISTORY_READ);
+       res = fgets(fline, sizeof(fline), fd);
+       pgstat_report_wait_end();
+       if (res == NULL)
+       {
+           if (ferror(fd))
+               ereport(ERROR,
+                       (errcode_for_file_access(),
+                        errmsg("could not read file \"%s\": %m", path)));
+
+           break;
+       }
+
+       /* skip leading whitespace and check for # comment */
        for (ptr = fline; *ptr; ptr++)
        {
            if (!isspace((unsigned char) *ptr))
@@ -393,6 +407,7 @@ writeTimeLineHistory(TimeLineID newTLI, TimeLineID parentTLI,
 
    nbytes = strlen(buffer);
    errno = 0;
+   pgstat_report_wait_start(WAIT_EVENT_TIMELINE_HISTORY_WRITE);
    if ((int) write(fd, buffer, nbytes) != nbytes)
    {
        int         save_errno = errno;
@@ -408,6 +423,7 @@ writeTimeLineHistory(TimeLineID newTLI, TimeLineID parentTLI,
                (errcode_for_file_access(),
                 errmsg("could not write to file \"%s\": %m", tmppath)));
    }
+   pgstat_report_wait_end();
 
    pgstat_report_wait_start(WAIT_EVENT_TIMELINE_HISTORY_SYNC);
    if (pg_fsync(fd) != 0)