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124 lines
3.1 KiB
C
124 lines
3.1 KiB
C
/*-------------------------------------------------------------------------
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*
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* timer.c
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* Microsoft Windows Win32 Timer Implementation
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*
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* Limitations of this implementation:
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*
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* - Does not support interval timer (value->it_interval)
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* - Only supports ITIMER_REAL
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*
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* Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* src/backend/port/win32/timer.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "libpq/pqsignal.h"
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/* Communication area for inter-thread communication */
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typedef struct timerCA
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{
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struct itimerval value;
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HANDLE event;
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CRITICAL_SECTION crit_sec;
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} timerCA;
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static timerCA timerCommArea;
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static HANDLE timerThreadHandle = INVALID_HANDLE_VALUE;
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/* Timer management thread */
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static DWORD WINAPI
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pg_timer_thread(LPVOID param)
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{
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DWORD waittime;
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Assert(param == NULL);
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waittime = INFINITE;
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for (;;)
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{
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int r;
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r = WaitForSingleObjectEx(timerCommArea.event, waittime, FALSE);
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if (r == WAIT_OBJECT_0)
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{
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/* Event signalled from main thread, change the timer */
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EnterCriticalSection(&timerCommArea.crit_sec);
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if (timerCommArea.value.it_value.tv_sec == 0 &&
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timerCommArea.value.it_value.tv_usec == 0)
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waittime = INFINITE; /* Cancel the interrupt */
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else
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{
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/* WaitForSingleObjectEx() uses milliseconds, round up */
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waittime = (timerCommArea.value.it_value.tv_usec + 999) / 1000 +
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timerCommArea.value.it_value.tv_sec * 1000;
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}
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ResetEvent(timerCommArea.event);
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LeaveCriticalSection(&timerCommArea.crit_sec);
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}
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else if (r == WAIT_TIMEOUT)
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{
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/* Timeout expired, signal SIGALRM and turn it off */
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pg_queue_signal(SIGALRM);
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waittime = INFINITE;
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}
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else
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{
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/* Should never happen */
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Assert(false);
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}
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}
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return 0;
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}
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/*
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* Win32 setitimer emulation by creating a persistent thread
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* to handle the timer setting and notification upon timeout.
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*/
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int
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setitimer(int which, const struct itimerval * value, struct itimerval * ovalue)
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{
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Assert(value != NULL);
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Assert(value->it_interval.tv_sec == 0 && value->it_interval.tv_usec == 0);
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Assert(which == ITIMER_REAL);
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if (timerThreadHandle == INVALID_HANDLE_VALUE)
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{
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/* First call in this backend, create event and the timer thread */
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timerCommArea.event = CreateEvent(NULL, TRUE, FALSE, NULL);
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if (timerCommArea.event == NULL)
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ereport(FATAL,
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(errmsg_internal("could not create timer event: %d",
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(int) GetLastError())));
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MemSet(&timerCommArea.value, 0, sizeof(struct itimerval));
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InitializeCriticalSection(&timerCommArea.crit_sec);
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timerThreadHandle = CreateThread(NULL, 0, pg_timer_thread, NULL, 0, NULL);
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if (timerThreadHandle == INVALID_HANDLE_VALUE)
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ereport(FATAL,
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(errmsg_internal("could not create timer thread: %d",
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(int) GetLastError())));
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}
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/* Request the timer thread to change settings */
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EnterCriticalSection(&timerCommArea.crit_sec);
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if (ovalue)
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*ovalue = timerCommArea.value;
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timerCommArea.value = *value;
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LeaveCriticalSection(&timerCommArea.crit_sec);
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SetEvent(timerCommArea.event);
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return 0;
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}
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