ChangeStream.js
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'use strict';
/*!
* Module dependencies.
*/
const EventEmitter = require('events').EventEmitter;
/*!
* ignore
*/
class ChangeStream extends EventEmitter {
constructor(model, pipeline, options) {
super();
this.driverChangeStream = null;
this.closed = false;
// This wrapper is necessary because of buffering.
if (model.collection.buffer) {
model.collection.addQueue(() => {
if (this.closed) {
return;
}
this.driverChangeStream = model.collection.watch(pipeline, options);
this._bindEvents();
this.emit('ready');
});
} else {
this.driverChangeStream = model.collection.watch(pipeline, options);
this._bindEvents();
this.emit('ready');
}
}
_bindEvents() {
this.driverChangeStream.on('close', () => {
this.closed = true;
});
['close', 'change', 'end', 'error'].forEach(ev => {
this.driverChangeStream.on(ev, data => this.emit(ev, data));
});
}
_queue(cb) {
this.once('ready', () => cb());
}
close() {
this.closed = true;
if (this.driverChangeStream) {
this.driverChangeStream.close();
}
}
}
/*!
* ignore
*/
module.exports = ChangeStream;