[PATCH] "could not reattach to shared memory" on Windows

Hello,

This patch using VirtualAlloc()/VirtualFree() to avoid failing in
reattach to shared memory.

Can this be added to CommitFest ?


Recent threads in pgsql-bugs are
  http://archives.postgresql.org/pgsql-bugs/2009-07/msg00036.php

This fix is almost same as previous patch. debug code is deleted.
  http://archives.postgresql.org/pgsql-bugs/2009-07/msg00078.php

Regards,

--
Tsutomu Yamada
SRA OSS, Inc. Japan

Index: src/backend/port/win32_shmem.c
===================================================================
RCS file: /mnt/prj/pg/cvsmirror/pg/pgsql/src/backend/port/win32_shmem.c,v
retrieving revision 1.11
diff -c -r1.11 win32_shmem.c
*** src/backend/port/win32_shmem.c    11 Jun 2009 14:49:00 -0000    1.11
--- src/backend/port/win32_shmem.c    14 Jul 2009 10:11:44 -0000
***************
*** 18,23 ****
--- 18,24 ----

  unsigned long UsedShmemSegID = 0;
  void       *UsedShmemSegAddr = NULL;
+ static Size UsedShmemSegSize = 0;

  static void pgwin32_SharedMemoryDelete(int status, Datum shmId);

***************
*** 233,238 ****
--- 234,240 ----

      /* Save info for possible future use */
      UsedShmemSegAddr = memAddress;
+     UsedShmemSegSize = size;
      UsedShmemSegID = (unsigned long) hmap2;

      return hdr;
***************
*** 257,262 ****
--- 259,273 ----
      Assert(UsedShmemSegAddr != NULL);
      Assert(IsUnderPostmaster);

+     /* release memory region
+      * that reserved by parant process
+      */
+     if (VirtualFree(UsedShmemSegAddr, 0, MEM_RELEASE) == 0)
+     {
+         elog(LOG, "failed to release reserved memory region (addr=%p): %lu",
+              UsedShmemSegAddr, GetLastError());
+     }
+
      hdr = (PGShmemHeader *) MapViewOfFileEx((HANDLE) UsedShmemSegID, FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, 0,
UsedShmemSegAddr);
      if (!hdr)
          elog(FATAL, "could not reattach to shared memory (key=%d, addr=%p): %lu",
***************
*** 302,304 ****
--- 313,335 ----
      if (!CloseHandle((HANDLE) DatumGetInt32(shmId)))
          elog(LOG, "could not close handle to shared memory: %lu", GetLastError());
  }
+
+ /*
+  * pgwin32_ReserveSharedMemory(HANDLE pChild)
+  * Reserve shared memory area,
+  * BEFORE child process allocates memory for DLL and/or others.
+  */
+ void
+ pgwin32_ReserveSharedMemory(HANDLE pChild)
+ {
+     void *memAddress;
+
+     Assert(UsedShmemSegAddr != NULL);
+     Assert(UsedShmemSegSize != 0);
+     memAddress = VirtualAllocEx(pChild, UsedShmemSegAddr, UsedShmemSegSize,
+                                 MEM_RESERVE, PAGE_READWRITE);
+     if (memAddress == NULL) {
+         elog(LOG, "could not reserve shared memory region (addr=%p): %lu",
+              UsedShmemSegAddr, GetLastError());
+     }
+ }
Index: src/backend/postmaster/postmaster.c
===================================================================
RCS file: /mnt/prj/pg/cvsmirror/pg/pgsql/src/backend/postmaster/postmaster.c,v
retrieving revision 1.584
diff -c -r1.584 postmaster.c
*** src/backend/postmaster/postmaster.c    8 Jul 2009 18:55:35 -0000    1.584
--- src/backend/postmaster/postmaster.c    13 Jul 2009 08:40:36 -0000
***************
*** 3643,3648 ****
--- 3643,3655 ----
          elog(LOG, "could not close handle to backend parameter file: error code %d",
               (int) GetLastError());

+     {
+         /* reserve shared memory area before ResumeThread() */
+         /* XXX: if it fail ? */
+         extern void pgwin32_ReserveSharedMemory(HANDLE);
+         pgwin32_ReserveSharedMemory(pi.hProcess);
+     }
+
      /*
       * Now that the backend variables are written out, we start the child
       * thread so it can start initializing while we set up the rest of the