| /* |
| * |
| * Copyright 2015 gRPC authors. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| */ |
| |
| '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; |