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/*
*
* 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;
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