*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.542 2007/09/26 22:36:30 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.543 2007/10/26 21:50:10 mha Exp $
*
* NOTES
*
#ifdef EXEC_BACKEND
#ifdef WIN32
-static void win32_AddChild(pid_t pid, HANDLE handle);
-static void win32_RemoveChild(pid_t pid);
static pid_t win32_waitpid(int *exitstatus);
-static DWORD WINAPI win32_sigchld_waiter(LPVOID param);
+static void WINAPI pgwin32_deadchild_callback(PVOID lpParameter, BOOLEAN TimerOrWaitFired);
-static pid_t *win32_childPIDArray;
-static HANDLE *win32_childHNDArray;
-static unsigned long win32_numChildren = 0;
+static HANDLE win32ChildQueue;
+
+typedef struct
+{
+ HANDLE waitHandle;
+ HANDLE procHandle;
+ DWORD procId;
+} win32_deadchild_waitinfo;
HANDLE PostmasterHandle;
#endif
#ifdef WIN32
/*
- * Initialize the child pid/HANDLE arrays for signal handling.
+ * Initialize I/O completion port used to deliver list of dead children.
*/
- win32_childPIDArray = (pid_t *)
- malloc(mul_size(NUM_BACKENDARRAY_ELEMS, sizeof(pid_t)));
- win32_childHNDArray = (HANDLE *)
- malloc(mul_size(NUM_BACKENDARRAY_ELEMS, sizeof(HANDLE)));
- if (!win32_childPIDArray || !win32_childHNDArray)
+ win32ChildQueue = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 1);
+ if (win32ChildQueue == NULL)
ereport(FATAL,
- (errcode(ERRCODE_OUT_OF_MEMORY),
- errmsg("out of memory")));
+ (errmsg("could not create I/O completion port for child queue")));
/*
* Set up a handle that child processes can use to check whether the
#define LOOPHEADER() (exitstatus = status.w_status)
#else /* WIN32 */
#define LOOPTEST() ((pid = win32_waitpid(&exitstatus)) > 0)
- /*
- * We need to do this here, and not in CleanupBackend, since this is
- * to be called on all children when we are done with them. Could move
- * to LogChildExit, but that seems like asking for future trouble...
- */
-#define LOOPHEADER() (win32_RemoveChild(pid))
+#define LOOPHEADER()
#endif /* WIN32 */
#endif /* HAVE_WAITPID */
int i;
int j;
char cmdLine[MAXPGPATH * 2];
- HANDLE childHandleCopy;
- HANDLE waiterThread;
HANDLE paramHandle;
BackendParameters *param;
SECURITY_ATTRIBUTES sa;
char paramHandleStr[32];
+ win32_deadchild_waitinfo *childinfo;
/* Make sure caller set up argv properly */
Assert(argc >= 3);
Assert(strncmp(argv[1], "--fork", 6) == 0);
Assert(argv[2] == NULL);
- /* Verify that there is room in the child list */
- if (win32_numChildren >= NUM_BACKENDARRAY_ELEMS)
- {
- elog(LOG, "no room for child entry in backend list");
- /* Report same error as for a fork failure on Unix */
- errno = EAGAIN;
- return -1;
- }
-
/* Set up shared memory for parameter passing */
ZeroMemory(&sa, sizeof(sa));
sa.nLength = sizeof(sa);
return -1;
}
- if (!IsUnderPostmaster)
- {
- /* We are the Postmaster creating a child... */
- win32_AddChild(pi.dwProcessId, pi.hProcess);
- }
-
- /* Set up the thread to handle the SIGCHLD for this process */
- if (DuplicateHandle(GetCurrentProcess(),
- pi.hProcess,
- GetCurrentProcess(),
- &childHandleCopy,
- 0,
- FALSE,
- DUPLICATE_SAME_ACCESS) == 0)
+ /*
+ * Queue a waiter for to signal when this child dies. The wait will be handled automatically
+ * by an operating system thread pool.
+ *
+ * Note: use malloc instead of palloc, since it needs to be thread-safe. Struct will be
+ * free():d from the callback function that runs on a different thread.
+ */
+ childinfo = malloc(sizeof(win32_deadchild_waitinfo));
+ if (!childinfo)
ereport(FATAL,
- (errmsg_internal("could not duplicate child handle: error code %d",
+ (errcode(ERRCODE_OUT_OF_MEMORY),
+ errmsg("out of memory")));
+
+ childinfo->procHandle = pi.hProcess;
+ childinfo->procId = pi.dwProcessId;
+
+ if (!RegisterWaitForSingleObject(&childinfo->waitHandle,
+ pi.hProcess,
+ pgwin32_deadchild_callback,
+ childinfo,
+ INFINITE,
+ WT_EXECUTEONLYONCE | WT_EXECUTEINWAITTHREAD))
+ ereport(FATAL,
+ (errmsg_internal("could not register process for wait: error code %d",
(int) GetLastError())));
- waiterThread = CreateThread(NULL, 64 * 1024, win32_sigchld_waiter,
- (LPVOID) childHandleCopy, 0, NULL);
- if (!waiterThread)
- ereport(FATAL,
- (errmsg_internal("could not create sigchld waiter thread: error code %d",
- (int) GetLastError())));
- CloseHandle(waiterThread);
+ /* Don't close pi.hProcess here - the wait thread needs access to it */
- if (IsUnderPostmaster)
- CloseHandle(pi.hProcess);
CloseHandle(pi.hThread);
return pi.dwProcessId;
#ifdef WIN32
-/*
- * Note: The following three functions must not be interrupted (eg. by
- * signals). As the Postgres Win32 signalling architecture (currently)
- * requires polling, or APC checking functions which aren't used here, this
- * is not an issue.
- *
- * We keep two separate arrays, instead of a single array of pid/HANDLE
- * structs, to avoid having to re-create a handle array for
- * WaitForMultipleObjects on each call to win32_waitpid.
- */
-
-static void
-win32_AddChild(pid_t pid, HANDLE handle)
-{
- Assert(win32_childPIDArray && win32_childHNDArray);
- if (win32_numChildren < NUM_BACKENDARRAY_ELEMS)
- {
- win32_childPIDArray[win32_numChildren] = pid;
- win32_childHNDArray[win32_numChildren] = handle;
- ++win32_numChildren;
- }
- else
- ereport(FATAL,
- (errmsg_internal("no room for child entry with pid %lu",
- (unsigned long) pid)));
-}
-
-static void
-win32_RemoveChild(pid_t pid)
-{
- int i;
-
- Assert(win32_childPIDArray && win32_childHNDArray);
-
- for (i = 0; i < win32_numChildren; i++)
- {
- if (win32_childPIDArray[i] == pid)
- {
- CloseHandle(win32_childHNDArray[i]);
-
- /* Swap last entry into the "removed" one */
- --win32_numChildren;
- win32_childPIDArray[i] = win32_childPIDArray[win32_numChildren];
- win32_childHNDArray[i] = win32_childHNDArray[win32_numChildren];
- return;
- }
- }
-
- ereport(WARNING,
- (errmsg_internal("could not find child entry with pid %lu",
- (unsigned long) pid)));
-}
-
static pid_t
win32_waitpid(int *exitstatus)
{
+ DWORD dwd;
+ ULONG_PTR key;
+ OVERLAPPED* ovl;
+
/*
- * Note: Do NOT use WaitForMultipleObjectsEx, as we don't want to run
- * queued APCs here.
+ * Check if there are any dead children. If there are, return the pid of the first one that died.
*/
- int index;
- DWORD exitCode;
- DWORD ret;
- unsigned long offset;
-
- Assert(win32_childPIDArray && win32_childHNDArray);
- elog(DEBUG3, "waiting on %lu children", win32_numChildren);
-
- for (offset = 0; offset < win32_numChildren; offset += MAXIMUM_WAIT_OBJECTS)
+ if (GetQueuedCompletionStatus(win32ChildQueue, &dwd, &key, &ovl, 0))
{
- unsigned long num = Min(MAXIMUM_WAIT_OBJECTS, win32_numChildren - offset);
-
- ret = WaitForMultipleObjects(num, &win32_childHNDArray[offset], FALSE, 0);
- switch (ret)
- {
- case WAIT_FAILED:
- ereport(LOG,
- (errmsg_internal("failed to wait on %lu of %lu children: error code %d",
- num, win32_numChildren, (int) GetLastError())));
- return -1;
-
- case WAIT_TIMEOUT:
- /* No children (in this chunk) have finished */
- break;
-
- default:
-
- /*
- * Get the exit code, and return the PID of, the respective
- * process
- */
- index = offset + ret - WAIT_OBJECT_0;
- Assert(index >= 0 && index < win32_numChildren);
- if (!GetExitCodeProcess(win32_childHNDArray[index], &exitCode))
- {
- /*
- * If we get this far, this should never happen, but, then
- * again... No choice other than to assume a catastrophic
- * failure.
- */
- ereport(FATAL,
- (errmsg_internal("failed to get exit code for child %lu",
- (unsigned long) win32_childPIDArray[index])));
- }
- *exitstatus = (int) exitCode;
- return win32_childPIDArray[index];
- }
+ *exitstatus = (int)key;
+ return dwd;
}
- /* No children have finished */
return -1;
}
/*
- * Note! Code below executes on separate threads, one for
- * each child process created
+ * Note! Code below executes on a thread pool! All operations must
+ * be thread safe! Note that elog() and friends must *not* be used.
*/
-static DWORD WINAPI
-win32_sigchld_waiter(LPVOID param)
+static void WINAPI
+pgwin32_deadchild_callback(PVOID lpParameter, BOOLEAN TimerOrWaitFired)
{
- HANDLE procHandle = (HANDLE) param;
+ win32_deadchild_waitinfo *childinfo = (win32_deadchild_waitinfo *)lpParameter;
+ DWORD exitcode;
- DWORD r = WaitForSingleObject(procHandle, INFINITE);
+ if (TimerOrWaitFired)
+ return; /* timeout. Should never happen, since we use INFINITE as timeout value. */
- if (r == WAIT_OBJECT_0)
- pg_queue_signal(SIGCHLD);
- else
- write_stderr("could not wait on child process handle: error code %d\n",
- (int) GetLastError());
- CloseHandle(procHandle);
- return 0;
+ /* Remove handle from wait - required even though it's set to wait only once */
+ UnregisterWaitEx(childinfo->waitHandle, NULL);
+
+ if (!GetExitCodeProcess(childinfo->procHandle, &exitcode))
+ {
+ /*
+ * Should never happen. Inform user and set a fixed exitcode.
+ */
+ write_stderr("could not read exitcode for process\n");
+ exitcode = 255;
+ }
+
+ if (!PostQueuedCompletionStatus(win32ChildQueue, childinfo->procId, (ULONG_PTR)exitcode, NULL))
+ write_stderr("could not post child completion status\n");
+
+ /* Handle is per-process, so we close it here instead of in the originating thread */
+ CloseHandle(childinfo->procHandle);
+
+ /* Free struct that was allocated before the call to RegisterWaitForSingleObject() */
+ free(childinfo);
+
+ /* Queue SIGCHLD signal */
+ pg_queue_signal(SIGCHLD);
}
#endif /* WIN32 */
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