Re: [GENERAL] Removing pgsql_tmp files

Alvaro Herrera <alvherre@commandprompt.com> writes:
> Excerpts from Tom Lane's message of lun nov 08 22:29:28 -0300 2010:
>> I think we need to re-order the operations there to ensure that the
>> unlink will still happen if the ereport gets interrupted.

> Would it work to put the removal inside a PG_CATCH block?

Well, that still begs the question of what to do exactly.  After some
thought I believe the attached is the best fix.

            regards, tom lane

diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index d9ab5e1ea2452131c2778acca6ad913ad4b333af..fd5ec7805fdcaedf73c3fa6aaa1a35970cf8e6db 100644
*** a/src/backend/storage/file/fd.c
--- b/src/backend/storage/file/fd.c
*************** void
*** 1032,1038 ****
  FileClose(File file)
  {
      Vfd           *vfdP;
-     struct stat filestats;

      Assert(FileIsValid(file));

--- 1032,1037 ----
*************** FileClose(File file)
*** 1055,1069 ****
      }

      /*
!      * Delete the file if it was temporary
       */
      if (vfdP->fdstate & FD_TEMPORARY)
      {
!         /* reset flag so that die() interrupt won't cause problems */
          vfdP->fdstate &= ~FD_TEMPORARY;
          if (log_temp_files >= 0)
          {
!             if (stat(vfdP->fileName, &filestats) == 0)
              {
                  if ((filestats.st_size / 1024) >= log_temp_files)
                      ereport(LOG,
--- 1054,1089 ----
      }

      /*
!      * Delete the file if it was temporary, and make a log entry if wanted
       */
      if (vfdP->fdstate & FD_TEMPORARY)
      {
!         /*
!          * If we get an error, as could happen within the ereport/elog calls,
!          * we'll come right back here during transaction abort.  Reset the
!          * flag to ensure that we can't get into an infinite loop.  This code
!          * is arranged to ensure that the worst-case consequence is failing
!          * to emit log message(s), not failing to attempt the unlink.
!          */
          vfdP->fdstate &= ~FD_TEMPORARY;
+
          if (log_temp_files >= 0)
          {
!             struct stat filestats;
!             int        stat_errno;
!
!             /* first try the stat() */
!             if (stat(vfdP->fileName, &filestats))
!                 stat_errno = errno;
!             else
!                 stat_errno = 0;
!
!             /* in any case do the unlink */
!             if (unlink(vfdP->fileName))
!                 elog(LOG, "could not unlink file \"%s\": %m", vfdP->fileName);
!
!             /* and last report the stat results */
!             if (stat_errno == 0)
              {
                  if ((filestats.st_size / 1024) >= log_temp_files)
                      ereport(LOG,
*************** FileClose(File file)
*** 1072,1081 ****
                                      (unsigned long) filestats.st_size)));
              }
              else
                  elog(LOG, "could not stat file \"%s\": %m", vfdP->fileName);
          }
-         if (unlink(vfdP->fileName))
-             elog(LOG, "could not unlink file \"%s\": %m", vfdP->fileName);
      }

      /* Unregister it from the resource owner */
--- 1092,1108 ----
                                      (unsigned long) filestats.st_size)));
              }
              else
+             {
+                 errno = stat_errno;
                  elog(LOG, "could not stat file \"%s\": %m", vfdP->fileName);
+             }
+         }
+         else
+         {
+             /* easy case, just do the unlink */
+             if (unlink(vfdP->fileName))
+                 elog(LOG, "could not unlink file \"%s\": %m", vfdP->fileName);
          }
      }

      /* Unregister it from the resource owner */