Fix Windows setitimer() emulation to not depend on delivering an APC

to the main thread.  This allows removal of WaitForSingleObjectEx() calls
from the main thread, thereby allowing us to re-enable Qingqing Zhou's
CHECK_FOR_INTERRUPTS performance improvement.  Qingqing, Magnus, et al.

diff --git a/src/backend/port/win32/signal.c b/src/backend/port/win32/signal.c
index fa7d8cf..3204c9c 100644 (file)
--- a/src/backend/port/win32/signal.c
+++ b/src/backend/port/win32/signal.c
@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/port/win32/signal.c,v 1.13 2005/10/21 21:43:45 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/port/win32/signal.c,v 1.14 2005/10/25 15:15:16 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -90,16 +90,6 @@ pgwin32_signal_initialize(void)
 }
 
 /*
- * Support routine for CHECK_FOR_INTERRUPTS() macro
- */
-void
-pgwin32_check_queued_signals(void)
-{
-       if (WaitForSingleObjectEx(pgwin32_signal_event, 0, TRUE) == WAIT_OBJECT_0)
-               pgwin32_dispatch_queued_signals();
-}
-
-/*
  * Dispatch all signals currently queued and not blocked
  * Blocked signals are ignored, and will be fired at the time of
  * the sigsetmask() call.

diff --git a/src/backend/port/win32/socket.c b/src/backend/port/win32/socket.c
index 808977a..b4bd121 100644 (file)
--- a/src/backend/port/win32/socket.c
+++ b/src/backend/port/win32/socket.c
@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/port/win32/socket.c,v 1.9 2005/10/15 02:49:23 momjian Exp $
+ *       $PostgreSQL: pgsql/src/backend/port/win32/socket.c,v 1.10 2005/10/25 15:15:16 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -93,7 +93,7 @@ TranslateSocketError(void)
 static int
 pgwin32_poll_signals(void)
 {
-       if (WaitForSingleObjectEx(pgwin32_signal_event, 0, TRUE) == WAIT_OBJECT_0)
+       if (UNBLOCKED_SIGNAL_QUEUE())
        {
                pgwin32_dispatch_queued_signals();
                errno = EINTR;

diff --git a/src/backend/port/win32/timer.c b/src/backend/port/win32/timer.c
index c31c7bc..b6c0b40 100644 (file)
--- a/src/backend/port/win32/timer.c
+++ b/src/backend/port/win32/timer.c
@@ -3,10 +3,15 @@
  * timer.c
  *       Microsoft Windows Win32 Timer Implementation
  *
+ *    Limitations of this implementation:
+ *
+ *    - Does not support interval timer (value->it_interval)
+ *    - Only supports ITIMER_REAL
+ *
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/port/win32/timer.c,v 1.5 2004/12/31 22:00:37 pgsql Exp $
+ *       $PostgreSQL: pgsql/src/backend/port/win32/timer.c,v 1.6 2005/10/25 15:15:16 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -16,56 +21,98 @@
 #include "libpq/pqsignal.h"
 
 
-static HANDLE timerHandle = INVALID_HANDLE_VALUE;
+/* Communication area for inter-thread communication */
+typedef struct timerCA {
+       struct itimerval value;
+       HANDLE event;
+       CRITICAL_SECTION crit_sec;
+} timerCA;
+
+static timerCA timerCommArea;
+static HANDLE timerThreadHandle = INVALID_HANDLE_VALUE;
 
-static VOID CALLBACK
-timer_completion(LPVOID arg, DWORD timeLow, DWORD timeHigh)
+
+/* Timer management thread */
+static DWORD WINAPI
+pg_timer_thread(LPVOID param)
 {
-       pg_queue_signal(SIGALRM);
-}
+       DWORD waittime;
+
+       Assert(param == NULL);
 
+       waittime = INFINITE;
+
+       for (;;)
+       {
+               int r;
+
+               r = WaitForSingleObjectEx(timerCommArea.event, waittime, FALSE);
+               if (r == WAIT_OBJECT_0)
+               {
+                       /* Event signalled from main thread, change the timer */
+                       EnterCriticalSection(&timerCommArea.crit_sec);
+                       if (timerCommArea.value.it_value.tv_sec == 0 &&
+                               timerCommArea.value.it_value.tv_usec == 0)
+                               waittime = INFINITE; /* Cancel the interrupt */
+                       else
+                               waittime = timerCommArea.value.it_value.tv_usec / 10 + timerCommArea.value.it_value.tv_sec * 1000;
+                       ResetEvent(timerCommArea.event);
+                       LeaveCriticalSection(&timerCommArea.crit_sec);
+               }
+               else if (r == WAIT_TIMEOUT)
+               {
+                       /* Timeout expired, signal SIGALRM and turn it off */
+                       pg_queue_signal(SIGALRM);
+                       waittime = INFINITE;
+               }
+               else
+               {
+                       /* Should never happen */
+                       Assert(false);
+               }
+       }
+
+       return 0;
+}
 
 /*
- * Limitations of this implementation:
- *
- * - Does not support setting ovalue
- * - Does not support interval timer (value->it_interval)
- * - Only supports ITIMER_REAL
+ * Win32 setitimer emulation by creating a persistent thread
+ * to handle the timer setting and notification upon timeout.
  */
 int
 setitimer(int which, const struct itimerval * value, struct itimerval * ovalue)
 {
-       LARGE_INTEGER dueTime;
-
-       Assert(ovalue == NULL);
        Assert(value != NULL);
        Assert(value->it_interval.tv_sec == 0 && value->it_interval.tv_usec == 0);
        Assert(which == ITIMER_REAL);
 
-       if (timerHandle == INVALID_HANDLE_VALUE)
+       if (timerThreadHandle == INVALID_HANDLE_VALUE)
        {
-               /* First call in this backend, create new timer object */
-               timerHandle = CreateWaitableTimer(NULL, TRUE, NULL);
-               if (timerHandle == NULL)
+               /* First call in this backend, create event and the timer thread */
+               timerCommArea.event = CreateEvent(NULL, TRUE, FALSE, NULL);
+               if (timerCommArea.event == NULL)
                        ereport(FATAL,
-                                       (errmsg_internal("failed to create waitable timer: %i", (int) GetLastError())));
-       }
+                                       (errmsg_internal("failed to create timer event: %d",
+                                                                        (int) GetLastError())));
 
-       if (value->it_value.tv_sec == 0 &&
-               value->it_value.tv_usec == 0)
-       {
-               /* Turn timer off */
-               CancelWaitableTimer(timerHandle);
-               return 0;
-       }
+               MemSet(&timerCommArea.value, 0, sizeof(struct itimerval));
+
+               InitializeCriticalSection(&timerCommArea.crit_sec);
 
-       /* Negative time to SetWaitableTimer means relative time */
-       dueTime.QuadPart = -(value->it_value.tv_usec * 10 + value->it_value.tv_sec * 10000000L);
+               timerThreadHandle = CreateThread(NULL, 0, pg_timer_thread, NULL, 0, NULL);
+               if (timerThreadHandle == INVALID_HANDLE_VALUE)
+                       ereport(FATAL,
+                                       (errmsg_internal("failed to create timer thread: %d",
+                                                                        (int) GetLastError())));
+       }
 
-       /* Turn timer on, or change timer */
-       if (!SetWaitableTimer(timerHandle, &dueTime, 0, timer_completion, NULL, FALSE))
-               ereport(FATAL,
-                               (errmsg_internal("failed to set waitable timer: %i", (int) GetLastError())));
+       /* Request the timer thread to change settings */
+       EnterCriticalSection(&timerCommArea.crit_sec);
+       if (ovalue)
+               *ovalue = timerCommArea.value;
+       timerCommArea.value = *value;
+       LeaveCriticalSection(&timerCommArea.crit_sec);
+       SetEvent(timerCommArea.event);
 
        return 0;
 }

diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h
index f82fffe..fc13891 100644 (file)
--- a/src/include/miscadmin.h
+++ b/src/include/miscadmin.h
@@ -13,7 +13,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/miscadmin.h,v 1.182 2005/10/22 17:09:48 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/miscadmin.h,v 1.183 2005/10/25 15:15:16 tgl Exp $
  *
  * NOTES
  *       some of the information in this file should be moved to other files.
@@ -88,7 +88,8 @@ do { \
 
 #define CHECK_FOR_INTERRUPTS() \
 do { \
-       pgwin32_check_queued_signals(); \
+       if (UNBLOCKED_SIGNAL_QUEUE()) \
+               pgwin32_dispatch_queued_signals(); \
        if (InterruptPending) \
                ProcessInterrupts(); \
 } while(0)

diff --git a/src/include/port/win32.h b/src/include/port/win32.h
index 9d1a6da..5bf6ce2 100644 (file)
--- a/src/include/port/win32.h
+++ b/src/include/port/win32.h
@@ -1,4 +1,4 @@
-/* $PostgreSQL: pgsql/src/include/port/win32.h,v 1.48 2005/10/21 21:43:46 tgl Exp $ */
+/* $PostgreSQL: pgsql/src/include/port/win32.h,v 1.49 2005/10/25 15:15:16 tgl Exp $ */
 
 /* undefine and redefine after #include */
 #undef mkdir
@@ -224,7 +224,6 @@ extern HANDLE pgwin32_initial_signal_pipe;
 
 void           pgwin32_signal_initialize(void);
 HANDLE         pgwin32_create_signal_listener(pid_t pid);
-void           pgwin32_check_queued_signals(void);
 void           pgwin32_dispatch_queued_signals(void);
 void           pg_queue_signal(int signum);