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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.
1 parent b835472 commit 25777f6

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5 files changed

+87
-50
lines changed

5 files changed

+87
-50
lines changed

‎src/backend/port/win32/signal.c

Lines changed: 1 addition & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
77
*
88
* IDENTIFICATION
9-
* $PostgreSQL: pgsql/src/backend/port/win32/signal.c,v 1.13 2005/10/21 21:43:45 tgl Exp $
9+
* $PostgreSQL: pgsql/src/backend/port/win32/signal.c,v 1.14 2005/10/25 15:15:16 tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -89,16 +89,6 @@ pgwin32_signal_initialize(void)
8989
(errmsg_internal("failed to set console control handler")));
9090
}
9191

92-
/*
93-
* Support routine for CHECK_FOR_INTERRUPTS() macro
94-
*/
95-
void
96-
pgwin32_check_queued_signals(void)
97-
{
98-
if (WaitForSingleObjectEx(pgwin32_signal_event, 0, TRUE) == WAIT_OBJECT_0)
99-
pgwin32_dispatch_queued_signals();
100-
}
101-
10292
/*
10393
* Dispatch all signals currently queued and not blocked
10494
* Blocked signals are ignored, and will be fired at the time of

‎src/backend/port/win32/socket.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
77
*
88
* IDENTIFICATION
9-
* $PostgreSQL: pgsql/src/backend/port/win32/socket.c,v 1.9 2005/10/15 02:49:23 momjian Exp $
9+
* $PostgreSQL: pgsql/src/backend/port/win32/socket.c,v 1.10 2005/10/25 15:15:16 tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -93,7 +93,7 @@ TranslateSocketError(void)
9393
static int
9494
pgwin32_poll_signals(void)
9595
{
96-
if (WaitForSingleObjectEx(pgwin32_signal_event, 0, TRUE) == WAIT_OBJECT_0)
96+
if (UNBLOCKED_SIGNAL_QUEUE())
9797
{
9898
pgwin32_dispatch_queued_signals();
9999
errno = EINTR;

‎src/backend/port/win32/timer.c

Lines changed: 80 additions & 33 deletions
Original file line numberDiff line numberDiff line change
@@ -3,10 +3,15 @@
33
* timer.c
44
* Microsoft Windows Win32 Timer Implementation
55
*
6+
* Limitations of this implementation:
7+
*
8+
* - Does not support interval timer (value->it_interval)
9+
* - Only supports ITIMER_REAL
10+
*
611
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
712
*
813
* IDENTIFICATION
9-
* $PostgreSQL: pgsql/src/backend/port/win32/timer.c,v 1.5 2004/12/31 22:00:37 pgsql Exp $
14+
* $PostgreSQL: pgsql/src/backend/port/win32/timer.c,v 1.6 2005/10/25 15:15:16 tgl Exp $
1015
*
1116
*-------------------------------------------------------------------------
1217
*/
@@ -16,56 +21,98 @@
1621
#include "libpq/pqsignal.h"
1722

1823

19-
static HANDLE timerHandle = INVALID_HANDLE_VALUE;
24+
/* Communication area for inter-thread communication */
25+
typedef struct timerCA {
26+
struct itimerval value;
27+
HANDLE event;
28+
CRITICAL_SECTION crit_sec;
29+
} timerCA;
30+
31+
static timerCA timerCommArea;
32+
static HANDLE timerThreadHandle = INVALID_HANDLE_VALUE;
2033

21-
static VOID CALLBACK
22-
timer_completion(LPVOID arg, DWORD timeLow, DWORD timeHigh)
34+
35+
/* Timer management thread */
36+
static DWORD WINAPI
37+
pg_timer_thread(LPVOID param)
2338
{
24-
pg_queue_signal(SIGALRM);
25-
}
39+
DWORD waittime;
40+
41+
Assert(param == NULL);
2642

43+
waittime = INFINITE;
44+
45+
for (;;)
46+
{
47+
int r;
48+
49+
r = WaitForSingleObjectEx(timerCommArea.event, waittime, FALSE);
50+
if (r == WAIT_OBJECT_0)
51+
{
52+
/* Event signalled from main thread, change the timer */
53+
EnterCriticalSection(&timerCommArea.crit_sec);
54+
if (timerCommArea.value.it_value.tv_sec == 0 &&
55+
timerCommArea.value.it_value.tv_usec == 0)
56+
waittime = INFINITE; /* Cancel the interrupt */
57+
else
58+
waittime = timerCommArea.value.it_value.tv_usec / 10 + timerCommArea.value.it_value.tv_sec * 1000;
59+
ResetEvent(timerCommArea.event);
60+
LeaveCriticalSection(&timerCommArea.crit_sec);
61+
}
62+
else if (r == WAIT_TIMEOUT)
63+
{
64+
/* Timeout expired, signal SIGALRM and turn it off */
65+
pg_queue_signal(SIGALRM);
66+
waittime = INFINITE;
67+
}
68+
else
69+
{
70+
/* Should never happen */
71+
Assert(false);
72+
}
73+
}
74+
75+
return 0;
76+
}
2777

2878
/*
29-
* Limitations of this implementation:
30-
*
31-
* - Does not support setting ovalue
32-
* - Does not support interval timer (value->it_interval)
33-
* - Only supports ITIMER_REAL
79+
* Win32 setitimer emulation by creating a persistent thread
80+
* to handle the timer setting and notification upon timeout.
3481
*/
3582
int
3683
setitimer(int which, const struct itimerval * value, struct itimerval * ovalue)
3784
{
38-
LARGE_INTEGER dueTime;
39-
40-
Assert(ovalue == NULL);
4185
Assert(value != NULL);
4286
Assert(value->it_interval.tv_sec == 0 && value->it_interval.tv_usec == 0);
4387
Assert(which == ITIMER_REAL);
4488

45-
if (timerHandle == INVALID_HANDLE_VALUE)
89+
if (timerThreadHandle == INVALID_HANDLE_VALUE)
4690
{
47-
/* First call in this backend, create new timer object */
48-
timerHandle = CreateWaitableTimer(NULL, TRUE, NULL);
49-
if (timerHandle == NULL)
91+
/* First call in this backend, create event and the timer thread */
92+
timerCommArea.event = CreateEvent(NULL, TRUE, FALSE, NULL);
93+
if (timerCommArea.event == NULL)
5094
ereport(FATAL,
51-
(errmsg_internal("failed to create waitable timer: %i", (int) GetLastError())));
52-
}
95+
(errmsg_internal("failed to create timer event: %d",
96+
(int) GetLastError())));
5397

54-
if (value->it_value.tv_sec == 0 &&
55-
value->it_value.tv_usec == 0)
56-
{
57-
/* Turn timer off */
58-
CancelWaitableTimer(timerHandle);
59-
return 0;
60-
}
98+
MemSet(&timerCommArea.value, 0, sizeof(struct itimerval));
99+
100+
InitializeCriticalSection(&timerCommArea.crit_sec);
61101

62-
/* Negative time to SetWaitableTimer means relative time */
63-
dueTime.QuadPart = -(value->it_value.tv_usec * 10 + value->it_value.tv_sec * 10000000L);
102+
timerThreadHandle = CreateThread(NULL, 0, pg_timer_thread, NULL, 0, NULL);
103+
if (timerThreadHandle == INVALID_HANDLE_VALUE)
104+
ereport(FATAL,
105+
(errmsg_internal("failed to create timer thread: %d",
106+
(int) GetLastError())));
107+
}
64108

65-
/* Turn timer on, or change timer */
66-
if (!SetWaitableTimer(timerHandle, &dueTime, 0, timer_completion, NULL, FALSE))
67-
ereport(FATAL,
68-
(errmsg_internal("failed to set waitable timer: %i", (int) GetLastError())));
109+
/* Request the timer thread to change settings */
110+
EnterCriticalSection(&timerCommArea.crit_sec);
111+
if (ovalue)
112+
*ovalue = timerCommArea.value;
113+
timerCommArea.value = *value;
114+
LeaveCriticalSection(&timerCommArea.crit_sec);
115+
SetEvent(timerCommArea.event);
69116

70117
return 0;
71118
}

‎src/include/miscadmin.h

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -13,7 +13,7 @@
1313
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
1414
* Portions Copyright (c) 1994, Regents of the University of California
1515
*
16-
* $PostgreSQL: pgsql/src/include/miscadmin.h,v 1.182 2005/10/22 17:09:48 tgl Exp $
16+
* $PostgreSQL: pgsql/src/include/miscadmin.h,v 1.183 2005/10/25 15:15:16 tgl Exp $
1717
*
1818
* NOTES
1919
* some of the information in this file should be moved to other files.
@@ -88,7 +88,8 @@ do { \
8888

8989
#define CHECK_FOR_INTERRUPTS() \
9090
do { \
91-
pgwin32_check_queued_signals(); \
91+
if (UNBLOCKED_SIGNAL_QUEUE()) \
92+
pgwin32_dispatch_queued_signals(); \
9293
if (InterruptPending) \
9394
ProcessInterrupts(); \
9495
} while(0)

‎src/include/port/win32.h

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
/* $PostgreSQL: pgsql/src/include/port/win32.h,v 1.48 2005/10/21 21:43:46 tgl Exp $ */
1+
/* $PostgreSQL: pgsql/src/include/port/win32.h,v 1.49 2005/10/25 15:15:16 tgl Exp $ */
22

33
/* undefine and redefine after #include */
44
#undef mkdir
@@ -224,7 +224,6 @@ extern HANDLE pgwin32_initial_signal_pipe;
224224

225225
void pgwin32_signal_initialize(void);
226226
HANDLE pgwin32_create_signal_listener(pid_t pid);
227-
void pgwin32_check_queued_signals(void);
228227
void pgwin32_dispatch_queued_signals(void);
229228
void pg_queue_signal(int signum);
230229

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