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