/*-------------------------------------------------------------------------
 *
 * shmem.c
 *	  Microsoft Windows Win32 Timer Implementation
 *
 * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include "libpq/pqsignal.h"


static HANDLE timerHandle = INVALID_HANDLE_VALUE;

static VOID CALLBACK timer_completion(LPVOID arg, DWORD timeLow, DWORD timeHigh) {
	pg_queue_signal(SIGALRM);
}


/*
 * Limitations of this implementation:
 * 
 * - Does not support setting ovalue
 * - Does not support interval timer (value->it_interval)
 * - Only supports ITIMER_REAL
 */
int setitimer(int which, const struct itimerval *value, struct itimerval *ovalue) {
	LARGE_INTEGER dueTime;

	Assert(which == ITIMER_REAL);

	if (timerHandle == INVALID_HANDLE_VALUE) {
		/* First call in this backend, create new timer object */
		timerHandle = CreateWaitableTimer(NULL, TRUE, NULL);
		if (timerHandle == NULL)
			ereport(FATAL,
					(errmsg_internal("failed to create waitable timer: %i",GetLastError())));
	}
	
	if (value == NULL) {
		errno = EFAULT;
		return -1;
	}
	if (value->it_value.tv_sec == 0 &&
		value->it_value.tv_usec == 0) {
		/* Turn timer off */
		CancelWaitableTimer(timerHandle);
		return 0;
	}

	/* Negative time to SetWaitableTimer means relative time */
	dueTime.QuadPart = -(value->it_value.tv_usec*10 + value->it_value.tv_sec*10000000L);
	
	/* 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",GetLastError())));

	return 0;
}