source: gs3-extensions/web-audio/trunk/js-mad/sink.js-master/src/core/do-interval.js@ 28388

void function (Sink) {

/**
 * Creates a timer with consistent (ie. not clamped) intervals even in background tabs.
 * Uses inline workers to achieve this. If not available, will revert to regular timers.
 *
 * @static Sink
 * @name doInterval
 *
 * @arg {Function} callback The callback to trigger on timer hit.
 * @arg {Number} timeout The interval between timer hits.
 *
 * @return {Function} A function to cancel the timer.
*/

Sink.doInterval = function (callback, timeout) {
    var timer, kill;

    function create (noWorker) {
        if (Sink.inlineWorker.working && !noWorker) {
            timer = Sink.inlineWorker('setInterval(function (){ postMessage("tic"); }, ' + timeout + ');');
            timer.onmessage = function (){
                callback();
            };
            kill = function () {
                timer.terminate();
            };
        } else {
            timer = setInterval(callback, timeout);
            kill = function (){
                clearInterval(timer);
            };
        }
    }

    if (Sink.inlineWorker.ready) {
        create();
    } else {
        Sink.inlineWorker.on('ready', function () {
            create();
        });
    }

    return function () {
        if (!kill) {
            if (!Sink.inlineWorker.ready) {
                Sink.inlineWorker.on('ready', function () {
                    if (kill) kill();
                });
            }
        } else {
            kill();
        }
    };
};

}(this.Sink);