68 lines
1.2 KiB
JavaScript
68 lines
1.2 KiB
JavaScript
'use strict';
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function Queue(options) {
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if (!(this instanceof Queue)) {
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return new Queue(options);
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}
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options = options || {};
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this.concurrency = options.concurrency || Infinity;
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this.pending = 0;
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this.jobs = [];
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this.cbs = [];
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this._done = done.bind(this);
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}
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var arrayAddMethods = [
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'push',
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'unshift',
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'splice'
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];
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arrayAddMethods.forEach(function(method) {
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Queue.prototype[method] = function() {
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var methodResult = Array.prototype[method].apply(this.jobs, arguments);
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this._run();
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return methodResult;
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};
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});
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Object.defineProperty(Queue.prototype, 'length', {
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get: function() {
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return this.pending + this.jobs.length;
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}
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});
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Queue.prototype._run = function() {
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if (this.pending === this.concurrency) {
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return;
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}
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if (this.jobs.length) {
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var job = this.jobs.shift();
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this.pending++;
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job(this._done);
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this._run();
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}
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if (this.pending === 0) {
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while (this.cbs.length !== 0) {
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var cb = this.cbs.pop();
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process.nextTick(cb);
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}
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}
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};
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Queue.prototype.onDone = function(cb) {
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if (typeof cb === 'function') {
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this.cbs.push(cb);
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this._run();
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}
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};
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function done() {
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this.pending--;
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this._run();
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}
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module.exports = Queue;
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