Retry in FileRead and FileWrite if Windows returns ERROR_NO_SYSTEM_RESOURCES.

Also add a retry for Unixen returning EINTR, which hasn't been reported
as an issue but at least theoretically could be.  Patch by Qingqing Zhou,
some minor adjustments by me.

diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index 2ab1497..f54e164 100644 (file)
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/storage/file/fd.c,v 1.122 2005/11/22 18:17:20 momjian Exp $
+ *       $PostgreSQL: pgsql/src/backend/storage/file/fd.c,v 1.123 2005/12/01 20:24:18 tgl Exp $
  *
  * NOTES:
  *
@@ -1009,11 +1009,41 @@ FileRead(File file, char *buffer, int amount)
        if (returnCode < 0)
                return returnCode;
 
+retry:
        returnCode = read(VfdCache[file].fd, buffer, amount);
-       if (returnCode > 0)
+
+       if (returnCode >= 0)
                VfdCache[file].seekPos += returnCode;
        else
+       {
+               /*
+                * Windows may run out of kernel buffers and return "Insufficient
+                * system resources" error.  Wait a bit and retry to solve it.
+                *
+                * It is rumored that EINTR is also possible on some Unix filesystems,
+                * in which case immediate retry is indicated.
+                */
+#ifdef WIN32
+               DWORD error = GetLastError();
+
+               switch (error)
+               {
+                       case ERROR_NO_SYSTEM_RESOURCES:
+                               pg_usleep(1000L);
+                               errno = EINTR;
+                               break;
+                       default:
+                               _dosmaperr(error);
+                               break;
+               }
+#endif
+               /* OK to retry if interrupted */
+               if (errno == EINTR)
+                       goto retry;
+
+               /* Trouble, so assume we don't know the file position anymore */
                VfdCache[file].seekPos = FileUnknownPos;
+       }
 
        return returnCode;
 }
@@ -1033,6 +1063,7 @@ FileWrite(File file, char *buffer, int amount)
        if (returnCode < 0)
                return returnCode;
 
+retry:
        errno = 0;
        returnCode = write(VfdCache[file].fd, buffer, amount);
 
@@ -1040,10 +1071,34 @@ FileWrite(File file, char *buffer, int amount)
        if (returnCode != amount && errno == 0)
                errno = ENOSPC;
 
-       if (returnCode > 0)
+       if (returnCode >= 0)
                VfdCache[file].seekPos += returnCode;
        else
+       {
+               /*
+                * See comments in FileRead()
+                */
+#ifdef WIN32
+               DWORD error = GetLastError();
+
+               switch (error)
+               {
+                       case ERROR_NO_SYSTEM_RESOURCES:
+                               pg_usleep(1000L);
+                               errno = EINTR;
+                               break;
+                       default:
+                               _dosmaperr(error);
+                               break;
+               }
+#endif
+               /* OK to retry if interrupted */
+               if (errno == EINTR)
+                       goto retry;
+
+               /* Trouble, so assume we don't know the file position anymore */
                VfdCache[file].seekPos = FileUnknownPos;
+       }
 
        return returnCode;
 }