tcltimer.c

linux系统下的音频通信

 *	idle and after timer lists.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	May queue an event and update the maximum notifier block time.
 *
 *----------------------------------------------------------------------
 */

static void
TimerCheckProc(data, flags)
    ClientData data;		/* Not used. */
    int flags;			/* Event flags as passed to Tcl_DoOneEvent. */
{
    Tcl_Event *timerEvPtr;
    Tcl_Time blockTime;

    if ((flags & TCL_TIMER_EVENTS) && firstTimerHandlerPtr) {
	/*
	 * Compute the timeout for the next timer on the list.
	 */

	TclpGetTime(&blockTime);
	blockTime.sec = firstTimerHandlerPtr->time.sec - blockTime.sec;
	blockTime.usec = firstTimerHandlerPtr->time.usec - blockTime.usec;
	if (blockTime.usec < 0) {
	    blockTime.sec -= 1;
	    blockTime.usec += 1000000;
	}
	if (blockTime.sec < 0) {
	    blockTime.sec = 0;
	    blockTime.usec = 0;
	}

	/*
	 * If the first timer has expired, stick an event on the queue.
	 */

	if (blockTime.sec == 0 && blockTime.usec == 0 && !timerPending) {
	    timerPending = 1;
	    timerEvPtr = (Tcl_Event *) ckalloc(sizeof(Tcl_Event));
	    timerEvPtr->proc = TimerHandlerEventProc;
	    Tcl_QueueEvent(timerEvPtr, TCL_QUEUE_TAIL);
	}
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TimerHandlerEventProc --
 *
 *	This procedure is called by Tcl_ServiceEvent when a timer event
 *	reaches the front of the event queue.  This procedure handles
 *	the event by invoking the callbacks for all timers that are
 *	ready.
 *
 * Results:
 *	Returns 1 if the event was handled, meaning it should be removed
 *	from the queue.  Returns 0 if the event was not handled, meaning
 *	it should stay on the queue.  The only time the event isn't
 *	handled is if the TCL_TIMER_EVENTS flag bit isn't set.
 *
 * Side effects:
 *	Whatever the timer handler callback procedures do.
 *
 *----------------------------------------------------------------------
 */

static int
TimerHandlerEventProc(evPtr, flags)
    Tcl_Event *evPtr;		/* Event to service. */
    int flags;			/* Flags that indicate what events to
				 * handle, such as TCL_FILE_EVENTS. */
{
    TimerHandler *timerHandlerPtr, **nextPtrPtr;
    Tcl_Time time;
    int currentTimerId;

    /*
     * Do nothing if timers aren't enabled.  This leaves the event on the
     * queue, so we will get to it as soon as ServiceEvents() is called
     * with timers enabled.
     */

    if (!(flags & TCL_TIMER_EVENTS)) {
	return 0;
    }

    /*
     * The code below is trickier than it may look, for the following
     * reasons:
     *
     * 1. New handlers can get added to the list while the current
     *    one is being processed.  If new ones get added, we don't
     *    want to process them during this pass through the list to avoid
     *	  starving other event sources.  This is implemented using the
     *	  token number in the handler:  new handlers will have a
     *    newer token than any of the ones currently on the list.
     * 2. The handler can call Tcl_DoOneEvent, so we have to remove
     *    the handler from the list before calling it. Otherwise an
     *    infinite loop could result.
     * 3. Tcl_DeleteTimerHandler can be called to remove an element from
     *    the list while a handler is executing, so the list could
     *    change structure during the call.
     * 4. Because we only fetch the current time before entering the loop,
     *    the only way a new timer will even be considered runnable is if
     *	  its expiration time is within the same millisecond as the
     *	  current time.  This is fairly likely on Windows, since it has
     *	  a course granularity clock.  Since timers are placed
     *	  on the queue in time order with the most recently created
     *    handler appearing after earlier ones with the same expiration
     *	  time, we don't have to worry about newer generation timers
     *	  appearing before later ones.
     */

    timerPending = 0;
    currentTimerId = lastTimerId;
    TclpGetTime(&time);
    while (1) {
	nextPtrPtr = &firstTimerHandlerPtr;
	timerHandlerPtr = firstTimerHandlerPtr;
	if (timerHandlerPtr == NULL) {
	    break;
	}
	    
	if ((timerHandlerPtr->time.sec > time.sec)
		|| ((timerHandlerPtr->time.sec == time.sec)
			&& (timerHandlerPtr->time.usec > time.usec))) {
	    break;
	}

	/*
	 * Bail out if the next timer is of a newer generation.
	 */

	if ((currentTimerId - (int)timerHandlerPtr->token) < 0) {
	    break;
	}

	/*
	 * Remove the handler from the queue before invoking it,
	 * to avoid potential reentrancy problems.
	 */

	(*nextPtrPtr) = timerHandlerPtr->nextPtr;
	(*timerHandlerPtr->proc)(timerHandlerPtr->clientData);
	ckfree((char *) timerHandlerPtr);
    }
    TimerSetupProc(NULL, TCL_TIMER_EVENTS);
    return 1;
}

/*
 *--------------------------------------------------------------
 *
 * Tcl_DoWhenIdle --
 *
 *	Arrange for proc to be invoked the next time the system is
 *	idle (i.e., just before the next time that Tcl_DoOneEvent
 *	would have to wait for something to happen).
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Proc will eventually be called, with clientData as argument.
 *	See the manual entry for details.
 *
 *--------------------------------------------------------------
 */

void
Tcl_DoWhenIdle(proc, clientData)
    Tcl_IdleProc *proc;		/* Procedure to invoke. */
    ClientData clientData;	/* Arbitrary value to pass to proc. */
{
    register IdleHandler *idlePtr;
    Tcl_Time blockTime;

    if (!initialized) {
	InitTimer();
    }

    idlePtr = (IdleHandler *) ckalloc(sizeof(IdleHandler));
    idlePtr->proc = proc;
    idlePtr->clientData = clientData;
    idlePtr->generation = idleGeneration;
    idlePtr->nextPtr = NULL;
    if (lastIdlePtr == NULL) {
	idleList = idlePtr;
    } else {
	lastIdlePtr->nextPtr = idlePtr;
    }
    lastIdlePtr = idlePtr;

    blockTime.sec = 0;
    blockTime.usec = 0;
    Tcl_SetMaxBlockTime(&blockTime);
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_CancelIdleCall --
 *
 *	If there are any when-idle calls requested to a given procedure
 *	with given clientData, cancel all of them.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	If the proc/clientData combination were on the when-idle list,
 *	they are removed so that they will never be called.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_CancelIdleCall(proc, clientData)
    Tcl_IdleProc *proc;		/* Procedure that was previously registered. */
    ClientData clientData;	/* Arbitrary value to pass to proc. */
{
    register IdleHandler *idlePtr, *prevPtr;
    IdleHandler *nextPtr;

    for (prevPtr = NULL, idlePtr = idleList; idlePtr != NULL;
	    prevPtr = idlePtr, idlePtr = idlePtr->nextPtr) {
	while ((idlePtr->proc == proc)
		&& (idlePtr->clientData == clientData)) {
	    nextPtr = idlePtr->nextPtr;
	    ckfree((char *) idlePtr);
	    idlePtr = nextPtr;
	    if (prevPtr == NULL) {
		idleList = idlePtr;
	    } else {
		prevPtr->nextPtr = idlePtr;
	    }
	    if (idlePtr == NULL) {
		lastIdlePtr = prevPtr;
		return;
	    }
	}
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TclServiceIdle --
 *
 *	This procedure is invoked by the notifier when it becomes
 *	idle.  It will invoke all idle handlers that are present at
 *	the time the call is invoked, but not those added during idle
 *	processing.
 *
 * Results:
 *	The return value is 1 if TclServiceIdle found something to
 *	do, otherwise return value is 0.
 *
 * Side effects:
 *	Invokes all pending idle handlers.
 *
 *----------------------------------------------------------------------
 */

int
TclServiceIdle()
{
    IdleHandler *idlePtr;
    int oldGeneration;
    Tcl_Time blockTime;

    if (idleList == NULL) {
	return 0;
    }

    oldGeneration = idleGeneration;
    idleGeneration++;

    /*
     * The code below is trickier than it may look, for the following
     * reasons:
     *
     * 1. New handlers can get added to the list while the current
     *    one is being processed.  If new ones get added, we don't
     *    want to process them during this pass through the list (want
     *    to check for other work to do first).  This is implemented
     *    using the generation number in the handler:  new handlers
     *    will have a different generation than any of the ones currently
     *    on the list.
     * 2. The handler can call Tcl_DoOneEvent, so we have to remove
     *    the handler from the list before calling it. Otherwise an
     *    infinite loop could result.
     * 3. Tcl_CancelIdleCall can be called to remove an element from
     *    the list while a handler is executing, so the list could
     *    change structure during the call.
     */

    for (idlePtr = idleList;
	    ((idlePtr != NULL)
		    && ((oldGeneration - idlePtr->generation) >= 0));
	    idlePtr = idleList) {
	idleList = idlePtr->nextPtr;
	if (idleList == NULL) {
	    lastIdlePtr = NULL;
	}
	(*idlePtr->proc)(idlePtr->clientData);
	ckfree((char *) idlePtr);
    }
    if (idleList) {
	blockTime.sec = 0;
	blockTime.usec = 0;
	Tcl_SetMaxBlockTime(&blockTime);
    }
    return 1;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_AfterObjCmd --
 *
 *	This procedure is invoked to process the "after" Tcl command.
 *	See the user documentation for details on what it does.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
int
Tcl_AfterObjCmd(clientData, interp, objc, objv)
    ClientData clientData;	/* Points to the "tclAfter" assocData for
				 * this interpreter, or NULL if the assocData
				 * hasn't been created yet.*/
    Tcl_Interp *interp;		/* Current interpreter. */
    int objc;			/* Number of arguments. */
    Tcl_Obj *CONST objv[];	/* Argument objects. */
{
    /*
     * The variable below is used to generate unique identifiers for
     * after commands.  This id can wrap around, which can potentially
     * cause problems.  However, there are not likely to be problems
     * in practice, because after commands can only be requested to
     * about a month in the future, and wrap-around is unlikely to
     * occur in less than about 1-10 years.  Thus it's unlikely that
     * any old ids will still be around when wrap-around occurs.
     */

    static int nextId = 1;
    int ms;
    AfterInfo *afterPtr;
    AfterAssocData *assocPtr = (AfterAssocData *) clientData;
    Tcl_CmdInfo cmdInfo;
    int length;
    char *arg;
    int index, result;
    static char *subCmds[] = {
        "cancel", "idle", "info",
        (char *) NULL};