gx

chenyc

2025-06-12 7b72ac13a83764a662159d4a49b7fffb90476ecb

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'use strict';
 
/*!
 * Module dependencies.
 */
 
const EventEmitter = require('events').EventEmitter;
 
/*!
 * ignore
 */
 
class ChangeStream extends EventEmitter {
  constructor(changeStreamThunk, pipeline, options) {
    super();
 
    this.driverChangeStream = null;
    this.closed = false;
    this.pipeline = pipeline;
    this.options = options;
 
    // This wrapper is necessary because of buffering.
    changeStreamThunk((err, driverChangeStream) => {
      if (err != null) {
        this.emit('error', err);
        return;
      }
 
      this.driverChangeStream = driverChangeStream;
      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;