aaac7fed
 liuqimichale
add
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'use strict';
var RingBuffer = require('./ring_buffer');
var Pledge = function() {
this._complete = false;
this._callbacks = new RingBuffer(Pledge.QUEUE_SIZE);
};
Pledge.QUEUE_SIZE = 4;
Pledge.all = function(list) {
var pledge = new Pledge(),
pending = list.length,
n = pending;
if (pending === 0) pledge.done();
while (n--) list[n].then(function() {
pending -= 1;
if (pending === 0) pledge.done();
});
return pledge;
};
Pledge.prototype.then = function(callback) {
if (this._complete) callback();
else this._callbacks.push(callback);
};
Pledge.prototype.done = function() {
this._complete = true;
var callbacks = this._callbacks, callback;
while (callback = callbacks.shift()) callback();
};
module.exports = Pledge;
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