29 lines
681 B
JavaScript
29 lines
681 B
JavaScript
var Class = require('./Class');
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var Queue = require('./Queue');
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exports = Class({
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initialize: function Semaphore() {
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var counter =
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arguments.length > 0 && arguments[0] !== undefined
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? arguments[0]
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: 1;
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this._counter = counter;
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this._tasks = new Queue();
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},
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wait: function(fn) {
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if (this._counter > 0) {
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this._counter--;
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return fn();
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}
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this._tasks.enqueue(fn);
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},
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signal: function() {
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var task = this._tasks.dequeue();
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if (task) {
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return task();
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}
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this._counter++;
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}
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});
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module.exports = exports;
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