| /* |
| * |
| * Copyright 2015, Google Inc. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: |
| * |
| * * Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * * Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following disclaimer |
| * in the documentation and/or other materials provided with the |
| * distribution. |
| * * Neither the name of Google Inc. nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| * |
| */ |
| |
| 'use strict'; |
| |
| var _ = require('lodash'); |
| |
| /** |
| * This class represents a queue of callbacks that must happen sequentially, each |
| * with a specific delay after the previous event. |
| */ |
| function AsyncDelayQueue() { |
| this.queue = []; |
| |
| this.callback_pending = false; |
| } |
| |
| /** |
| * Run the next callback after its corresponding delay, if there are any |
| * remaining. |
| */ |
| AsyncDelayQueue.prototype.runNext = function() { |
| var next = this.queue.shift(); |
| var continueCallback = _.bind(this.runNext, this); |
| if (next) { |
| this.callback_pending = true; |
| setTimeout(function() { |
| next.callback(continueCallback); |
| }, next.delay); |
| } else { |
| this.callback_pending = false; |
| } |
| }; |
| |
| /** |
| * Add a callback to be called with a specific delay after now or after the |
| * current last item in the queue or current pending callback, whichever is |
| * latest. |
| * @param {function(function())} callback The callback |
| * @param {Number} The delay to apply, in milliseconds |
| */ |
| AsyncDelayQueue.prototype.add = function(callback, delay) { |
| this.queue.push({callback: callback, delay: delay}); |
| if (!this.callback_pending) { |
| this.runNext(); |
| } |
| }; |
| |
| module.exports = AsyncDelayQueue; |