Haketilo

"use strict";

(() => {

    function make_lock() {

	return {free: true, queue: []};

    function _lock(lock, cb) {

	if (lock.free) {

	    lock.free = false;

	    setTimeout(cb);

	} else {

	    lock.queue.push(cb);

	}

    function lock(lock) {

	return new Promise((resolve, reject) => _lock(lock, resolve));

    }

    function unlock(lock) {

	if (lock.free)

	    throw new Exception("Attempting to release a free lock");

	if (lock.queue.length === 0) {

	    lock.free = true;

	} else {

	    let cb = lock.queue[0];

	    lock.queue.splice(0, 1);

	    setTimeout(cb);

	}

    }

    window.make_lock = make_lock;

    window.lock = lock;

    window.unlock = unlock;

})();