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166 lines
3.9 KiB
JavaScript

'use strict';
/*!
* Module dependencies.
*/
const EventEmitter = require('events').EventEmitter;
/*!
* ignore
*/
const driverChangeStreamEvents = ['close', 'change', 'end', 'error', 'resumeTokenChanged'];
/*!
* ignore
*/
class ChangeStream extends EventEmitter {
constructor(changeStreamThunk, pipeline, options) {
super();
this.driverChangeStream = null;
this.closed = false;
this.bindedEvents = false;
this.pipeline = pipeline;
this.options = options;
if (options && options.hydrate && !options.model) {
throw new Error(
'Cannot create change stream with `hydrate: true` ' +
'unless calling `Model.watch()`'
);
}
// This wrapper is necessary because of buffering.
changeStreamThunk((err, driverChangeStream) => {
if (err != null) {
this.emit('error', err);
return;
}
this.driverChangeStream = driverChangeStream;
this.emit('ready');
});
}
_bindEvents() {
if (this.bindedEvents) {
return;
}
this.bindedEvents = true;
if (this.driverChangeStream == null) {
this.once('ready', () => {
this.driverChangeStream.on('close', () => {
this.closed = true;
});
driverChangeStreamEvents.forEach(ev => {
this.driverChangeStream.on(ev, data => {
// Sometimes Node driver still polls after close, so
// avoid any uncaught exceptions due to closed change streams
// See tests for gh-7022
if (ev === 'error' && this.closed) {
return;
}
if (data != null && data.fullDocument != null && this.options && this.options.hydrate) {
data.fullDocument = this.options.model.hydrate(data.fullDocument);
}
this.emit(ev, data);
});
});
});
return;
}
this.driverChangeStream.on('close', () => {
this.closed = true;
});
driverChangeStreamEvents.forEach(ev => {
this.driverChangeStream.on(ev, data => {
// Sometimes Node driver still polls after close, so
// avoid any uncaught exceptions due to closed change streams
// See tests for gh-7022
if (ev === 'error' && this.closed) {
return;
}
if (data != null && data.fullDocument != null && this.options && this.options.hydrate) {
data.fullDocument = this.options.model.hydrate(data.fullDocument);
}
this.emit(ev, data);
});
});
}
hasNext(cb) {
return this.driverChangeStream.hasNext(cb);
}
next(cb) {
if (this.options && this.options.hydrate) {
if (cb != null) {
const originalCb = cb;
cb = (err, data) => {
if (err != null) {
return originalCb(err);
}
if (data.fullDocument != null) {
data.fullDocument = this.options.model.hydrate(data.fullDocument);
}
return originalCb(null, data);
};
}
let maybePromise = this.driverChangeStream.next(cb);
if (maybePromise && typeof maybePromise.then === 'function') {
maybePromise = maybePromise.then(data => {
if (data.fullDocument != null) {
data.fullDocument = this.options.model.hydrate(data.fullDocument);
}
return data;
});
}
return maybePromise;
}
return this.driverChangeStream.next(cb);
}
addListener(event, handler) {
this._bindEvents();
return super.addListener(event, handler);
}
on(event, handler) {
this._bindEvents();
return super.on(event, handler);
}
once(event, handler) {
this._bindEvents();
return super.once(event, handler);
}
_queue(cb) {
this.once('ready', () => cb());
}
close() {
this.closed = true;
if (this.driverChangeStream) {
this.driverChangeStream.close();
}
}
}
/*!
* ignore
*/
module.exports = ChangeStream;