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Aravind142857
397
node_modules/mongodb/lib/change_stream.js
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397
node_modules/mongodb/lib/change_stream.js
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"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.ChangeStream = void 0;
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const collection_1 = require("./collection");
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const constants_1 = require("./constants");
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const change_stream_cursor_1 = require("./cursor/change_stream_cursor");
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const db_1 = require("./db");
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const error_1 = require("./error");
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const mongo_client_1 = require("./mongo_client");
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const mongo_types_1 = require("./mongo_types");
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const utils_1 = require("./utils");
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/** @internal */
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const kCursorStream = Symbol('cursorStream');
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/** @internal */
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const kClosed = Symbol('closed');
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/** @internal */
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const kMode = Symbol('mode');
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const CHANGE_STREAM_OPTIONS = [
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'resumeAfter',
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'startAfter',
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'startAtOperationTime',
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'fullDocument',
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'fullDocumentBeforeChange',
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'showExpandedEvents'
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];
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const CHANGE_DOMAIN_TYPES = {
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COLLECTION: Symbol('Collection'),
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DATABASE: Symbol('Database'),
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CLUSTER: Symbol('Cluster')
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};
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const CHANGE_STREAM_EVENTS = [constants_1.RESUME_TOKEN_CHANGED, constants_1.END, constants_1.CLOSE];
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const NO_RESUME_TOKEN_ERROR = 'A change stream document has been received that lacks a resume token (_id).';
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const CHANGESTREAM_CLOSED_ERROR = 'ChangeStream is closed';
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/**
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* Creates a new Change Stream instance. Normally created using {@link Collection#watch|Collection.watch()}.
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* @public
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*/
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class ChangeStream extends mongo_types_1.TypedEventEmitter {
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/**
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* @internal
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*
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* @param parent - The parent object that created this change stream
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* @param pipeline - An array of {@link https://www.mongodb.com/docs/manual/reference/operator/aggregation-pipeline/|aggregation pipeline stages} through which to pass change stream documents
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*/
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constructor(parent, pipeline = [], options = {}) {
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super();
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this.pipeline = pipeline;
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this.options = { ...options };
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delete this.options.writeConcern;
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if (parent instanceof collection_1.Collection) {
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this.type = CHANGE_DOMAIN_TYPES.COLLECTION;
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}
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else if (parent instanceof db_1.Db) {
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this.type = CHANGE_DOMAIN_TYPES.DATABASE;
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}
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else if (parent instanceof mongo_client_1.MongoClient) {
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this.type = CHANGE_DOMAIN_TYPES.CLUSTER;
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}
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else {
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throw new error_1.MongoChangeStreamError('Parent provided to ChangeStream constructor must be an instance of Collection, Db, or MongoClient');
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}
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this.parent = parent;
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this.namespace = parent.s.namespace;
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if (!this.options.readPreference && parent.readPreference) {
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this.options.readPreference = parent.readPreference;
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}
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// Create contained Change Stream cursor
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this.cursor = this._createChangeStreamCursor(options);
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this[kClosed] = false;
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this[kMode] = false;
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// Listen for any `change` listeners being added to ChangeStream
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this.on('newListener', eventName => {
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if (eventName === 'change' && this.cursor && this.listenerCount('change') === 0) {
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this._streamEvents(this.cursor);
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}
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});
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this.on('removeListener', eventName => {
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if (eventName === 'change' && this.listenerCount('change') === 0 && this.cursor) {
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this[kCursorStream]?.removeAllListeners('data');
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}
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});
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}
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/** @internal */
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get cursorStream() {
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return this[kCursorStream];
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}
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/** The cached resume token that is used to resume after the most recently returned change. */
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get resumeToken() {
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return this.cursor?.resumeToken;
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}
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/** Check if there is any document still available in the Change Stream */
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async hasNext() {
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this._setIsIterator();
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// Change streams must resume indefinitely while each resume event succeeds.
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// This loop continues until either a change event is received or until a resume attempt
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// fails.
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// eslint-disable-next-line no-constant-condition
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while (true) {
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try {
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const hasNext = await this.cursor.hasNext();
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return hasNext;
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}
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catch (error) {
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try {
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await this._processErrorIteratorMode(error);
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}
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catch (error) {
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try {
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await this.close();
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}
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catch {
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// We are not concerned with errors from close()
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}
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throw error;
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}
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}
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}
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}
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/** Get the next available document from the Change Stream. */
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async next() {
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this._setIsIterator();
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// Change streams must resume indefinitely while each resume event succeeds.
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// This loop continues until either a change event is received or until a resume attempt
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// fails.
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// eslint-disable-next-line no-constant-condition
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while (true) {
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try {
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const change = await this.cursor.next();
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const processedChange = this._processChange(change ?? null);
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return processedChange;
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}
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catch (error) {
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try {
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await this._processErrorIteratorMode(error);
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}
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catch (error) {
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try {
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await this.close();
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}
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catch {
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// We are not concerned with errors from close()
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}
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throw error;
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}
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}
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}
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}
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/**
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* Try to get the next available document from the Change Stream's cursor or `null` if an empty batch is returned
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*/
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async tryNext() {
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this._setIsIterator();
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// Change streams must resume indefinitely while each resume event succeeds.
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// This loop continues until either a change event is received or until a resume attempt
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// fails.
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// eslint-disable-next-line no-constant-condition
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while (true) {
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try {
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const change = await this.cursor.tryNext();
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return change ?? null;
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}
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catch (error) {
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try {
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await this._processErrorIteratorMode(error);
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}
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catch (error) {
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try {
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await this.close();
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}
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catch {
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// We are not concerned with errors from close()
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}
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throw error;
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}
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}
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}
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}
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async *[Symbol.asyncIterator]() {
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if (this.closed) {
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return;
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}
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try {
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// Change streams run indefinitely as long as errors are resumable
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// So the only loop breaking condition is if `next()` throws
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while (true) {
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yield await this.next();
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}
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}
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finally {
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try {
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await this.close();
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}
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catch {
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// we're not concerned with errors from close()
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}
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}
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}
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/** Is the cursor closed */
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get closed() {
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return this[kClosed] || this.cursor.closed;
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}
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/** Close the Change Stream */
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async close() {
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this[kClosed] = true;
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const cursor = this.cursor;
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try {
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await cursor.close();
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}
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finally {
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this._endStream();
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}
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}
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/**
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* Return a modified Readable stream including a possible transform method.
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*
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* NOTE: When using a Stream to process change stream events, the stream will
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* NOT automatically resume in the case a resumable error is encountered.
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*
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* @throws MongoChangeStreamError if the underlying cursor or the change stream is closed
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*/
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stream(options) {
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if (this.closed) {
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throw new error_1.MongoChangeStreamError(CHANGESTREAM_CLOSED_ERROR);
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}
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this.streamOptions = options;
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return this.cursor.stream(options);
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}
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/** @internal */
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_setIsEmitter() {
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if (this[kMode] === 'iterator') {
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// TODO(NODE-3485): Replace with MongoChangeStreamModeError
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throw new error_1.MongoAPIError('ChangeStream cannot be used as an EventEmitter after being used as an iterator');
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}
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this[kMode] = 'emitter';
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}
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/** @internal */
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_setIsIterator() {
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if (this[kMode] === 'emitter') {
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// TODO(NODE-3485): Replace with MongoChangeStreamModeError
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throw new error_1.MongoAPIError('ChangeStream cannot be used as an iterator after being used as an EventEmitter');
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}
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this[kMode] = 'iterator';
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}
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/**
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* Create a new change stream cursor based on self's configuration
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* @internal
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*/
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_createChangeStreamCursor(options) {
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const changeStreamStageOptions = (0, utils_1.filterOptions)(options, CHANGE_STREAM_OPTIONS);
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if (this.type === CHANGE_DOMAIN_TYPES.CLUSTER) {
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changeStreamStageOptions.allChangesForCluster = true;
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}
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const pipeline = [{ $changeStream: changeStreamStageOptions }, ...this.pipeline];
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const client = this.type === CHANGE_DOMAIN_TYPES.CLUSTER
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? this.parent
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: this.type === CHANGE_DOMAIN_TYPES.DATABASE
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? this.parent.client
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: this.type === CHANGE_DOMAIN_TYPES.COLLECTION
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? this.parent.client
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: null;
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if (client == null) {
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// This should never happen because of the assertion in the constructor
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throw new error_1.MongoRuntimeError(`Changestream type should only be one of cluster, database, collection. Found ${this.type.toString()}`);
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}
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const changeStreamCursor = new change_stream_cursor_1.ChangeStreamCursor(client, this.namespace, pipeline, options);
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for (const event of CHANGE_STREAM_EVENTS) {
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changeStreamCursor.on(event, e => this.emit(event, e));
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}
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if (this.listenerCount(ChangeStream.CHANGE) > 0) {
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this._streamEvents(changeStreamCursor);
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}
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return changeStreamCursor;
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}
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/** @internal */
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_closeEmitterModeWithError(error) {
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this.emit(ChangeStream.ERROR, error);
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this.close().catch(() => null);
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}
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/** @internal */
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_streamEvents(cursor) {
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this._setIsEmitter();
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const stream = this[kCursorStream] ?? cursor.stream();
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this[kCursorStream] = stream;
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stream.on('data', change => {
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try {
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const processedChange = this._processChange(change);
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this.emit(ChangeStream.CHANGE, processedChange);
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}
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catch (error) {
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this.emit(ChangeStream.ERROR, error);
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}
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});
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stream.on('error', error => this._processErrorStreamMode(error));
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}
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/** @internal */
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_endStream() {
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const cursorStream = this[kCursorStream];
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if (cursorStream) {
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['data', 'close', 'end', 'error'].forEach(event => cursorStream.removeAllListeners(event));
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cursorStream.destroy();
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}
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this[kCursorStream] = undefined;
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}
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/** @internal */
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_processChange(change) {
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if (this[kClosed]) {
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// TODO(NODE-3485): Replace with MongoChangeStreamClosedError
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throw new error_1.MongoAPIError(CHANGESTREAM_CLOSED_ERROR);
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}
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// a null change means the cursor has been notified, implicitly closing the change stream
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if (change == null) {
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// TODO(NODE-3485): Replace with MongoChangeStreamClosedError
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throw new error_1.MongoRuntimeError(CHANGESTREAM_CLOSED_ERROR);
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}
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if (change && !change._id) {
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throw new error_1.MongoChangeStreamError(NO_RESUME_TOKEN_ERROR);
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}
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// cache the resume token
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this.cursor.cacheResumeToken(change._id);
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// wipe the startAtOperationTime if there was one so that there won't be a conflict
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// between resumeToken and startAtOperationTime if we need to reconnect the cursor
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this.options.startAtOperationTime = undefined;
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return change;
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}
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/** @internal */
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_processErrorStreamMode(changeStreamError) {
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// If the change stream has been closed explicitly, do not process error.
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if (this[kClosed])
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return;
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if ((0, error_1.isResumableError)(changeStreamError, this.cursor.maxWireVersion)) {
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this._endStream();
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this.cursor.close().catch(() => null);
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const topology = (0, utils_1.getTopology)(this.parent);
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topology.selectServer(this.cursor.readPreference, {}, serverSelectionError => {
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if (serverSelectionError)
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return this._closeEmitterModeWithError(changeStreamError);
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this.cursor = this._createChangeStreamCursor(this.cursor.resumeOptions);
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});
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}
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else {
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this._closeEmitterModeWithError(changeStreamError);
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}
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}
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/** @internal */
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async _processErrorIteratorMode(changeStreamError) {
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if (this[kClosed]) {
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// TODO(NODE-3485): Replace with MongoChangeStreamClosedError
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throw new error_1.MongoAPIError(CHANGESTREAM_CLOSED_ERROR);
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}
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if (!(0, error_1.isResumableError)(changeStreamError, this.cursor.maxWireVersion)) {
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try {
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await this.close();
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}
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catch {
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// ignore errors from close
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}
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throw changeStreamError;
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}
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await this.cursor.close().catch(() => null);
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const topology = (0, utils_1.getTopology)(this.parent);
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try {
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await topology.selectServerAsync(this.cursor.readPreference, {});
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this.cursor = this._createChangeStreamCursor(this.cursor.resumeOptions);
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}
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catch {
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// if the topology can't reconnect, close the stream
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await this.close();
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throw changeStreamError;
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}
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}
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}
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exports.ChangeStream = ChangeStream;
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/** @event */
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ChangeStream.RESPONSE = constants_1.RESPONSE;
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/** @event */
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ChangeStream.MORE = constants_1.MORE;
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/** @event */
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ChangeStream.INIT = constants_1.INIT;
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/** @event */
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ChangeStream.CLOSE = constants_1.CLOSE;
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/**
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* Fired for each new matching change in the specified namespace. Attaching a `change`
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* event listener to a Change Stream will switch the stream into flowing mode. Data will
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* then be passed as soon as it is available.
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* @event
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*/
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ChangeStream.CHANGE = constants_1.CHANGE;
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/** @event */
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ChangeStream.END = constants_1.END;
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/** @event */
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ChangeStream.ERROR = constants_1.ERROR;
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/**
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* Emitted each time the change stream stores a new resume token.
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* @event
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*/
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ChangeStream.RESUME_TOKEN_CHANGED = constants_1.RESUME_TOKEN_CHANGED;
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//# sourceMappingURL=change_stream.js.map
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