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/*
*
* 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;
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