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change_stream.ts
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import type { Readable } from 'stream';
import type { Binary, Document, Timestamp } from './bson';
import { Collection } from './collection';
import { CHANGE, CLOSE, END, ERROR, INIT, MORE, RESPONSE, RESUME_TOKEN_CHANGED } from './constants';
import type { AbstractCursorEvents, CursorStreamOptions } from './cursor/abstract_cursor';
import { ChangeStreamCursor, ChangeStreamCursorOptions } from './cursor/change_stream_cursor';
import { Db } from './db';
import {
AnyError,
isResumableError,
MongoAPIError,
MongoChangeStreamError,
MongoRuntimeError
} from './error';
import { MongoClient } from './mongo_client';
import { InferIdType, TypedEventEmitter } from './mongo_types';
import type { AggregateOptions } from './operations/aggregate';
import type { CollationOptions, OperationParent } from './operations/command';
import type { ReadPreference } from './read_preference';
import type { ServerSessionId } from './sessions';
import { filterOptions, getTopology, MongoDBNamespace } from './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'
] as const;
const CHANGE_DOMAIN_TYPES = {
COLLECTION: Symbol('Collection'),
DATABASE: Symbol('Database'),
CLUSTER: Symbol('Cluster')
};
const CHANGE_STREAM_EVENTS = [RESUME_TOKEN_CHANGED, END, 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';
/**
* @public
* @deprecated Please use the ChangeStreamCursorOptions type instead.
*/
export interface ResumeOptions {
startAtOperationTime?: Timestamp;
batchSize?: number;
maxAwaitTimeMS?: number;
collation?: CollationOptions;
readPreference?: ReadPreference;
resumeAfter?: ResumeToken;
startAfter?: ResumeToken;
fullDocument?: string;
}
/**
* Represents the logical starting point for a new ChangeStream or resuming a ChangeStream on the server.
* @see https://www.mongodb.com/docs/manual/changeStreams/#std-label-change-stream-resume
* @public
*/
export type ResumeToken = unknown;
/**
* Represents a specific point in time on a server. Can be retrieved by using `db.command()`
* @public
* @see https://www.mongodb.com/docs/manual/reference/method/db.runCommand/#response
*/
export type OperationTime = Timestamp;
/**
* Options that can be passed to a ChangeStream. Note that startAfter, resumeAfter, and startAtOperationTime are all mutually exclusive, and the server will error if more than one is specified.
* @public
*/
export interface ChangeStreamOptions extends Omit<AggregateOptions, 'writeConcern'> {
/**
* Allowed values: 'updateLookup', 'whenAvailable', 'required'.
*
* When set to 'updateLookup', the change notification for partial updates
* will include both a delta describing the changes to the document as well
* as a copy of the entire document that was changed from some time after
* the change occurred.
*
* When set to 'whenAvailable', configures the change stream to return the
* post-image of the modified document for replace and update change events
* if the post-image for this event is available.
*
* When set to 'required', the same behavior as 'whenAvailable' except that
* an error is raised if the post-image is not available.
*/
fullDocument?: string;
/**
* Allowed values: 'whenAvailable', 'required', 'off'.
*
* The default is to not send a value, which is equivalent to 'off'.
*
* When set to 'whenAvailable', configures the change stream to return the
* pre-image of the modified document for replace, update, and delete change
* events if it is available.
*
* When set to 'required', the same behavior as 'whenAvailable' except that
* an error is raised if the pre-image is not available.
*/
fullDocumentBeforeChange?: string;
/** The maximum amount of time for the server to wait on new documents to satisfy a change stream query. */
maxAwaitTimeMS?: number;
/**
* Allows you to start a changeStream after a specified event.
* @see https://www.mongodb.com/docs/manual/changeStreams/#resumeafter-for-change-streams
*/
resumeAfter?: ResumeToken;
/**
* Similar to resumeAfter, but will allow you to start after an invalidated event.
* @see https://www.mongodb.com/docs/manual/changeStreams/#startafter-for-change-streams
*/
startAfter?: ResumeToken;
/** Will start the changeStream after the specified operationTime. */
startAtOperationTime?: OperationTime;
/**
* The number of documents to return per batch.
* @see https://www.mongodb.com/docs/manual/reference/command/aggregate
*/
batchSize?: number;
/**
* When enabled, configures the change stream to include extra change events.
*
* - createIndexes
* - dropIndexes
* - modify
* - create
* - shardCollection
* - reshardCollection
* - refineCollectionShardKey
*/
showExpandedEvents?: boolean;
}
/** @public */
export interface ChangeStreamNameSpace {
db: string;
coll: string;
}
/** @public */
export interface ChangeStreamDocumentKey<TSchema extends Document = Document> {
/**
* For unsharded collections this contains a single field `_id`.
* For sharded collections, this will contain all the components of the shard key
*/
documentKey: { _id: InferIdType<TSchema>; [shardKey: string]: any };
}
/** @public */
export interface ChangeStreamDocumentCommon {
/**
* The id functions as an opaque token for use when resuming an interrupted
* change stream.
*/
_id: ResumeToken;
/**
* The timestamp from the oplog entry associated with the event.
* For events that happened as part of a multi-document transaction, the associated change stream
* notifications will have the same clusterTime value, namely the time when the transaction was committed.
* On a sharded cluster, events that occur on different shards can have the same clusterTime but be
* associated with different transactions or even not be associated with any transaction.
* To identify events for a single transaction, you can use the combination of lsid and txnNumber in the change stream event document.
*/
clusterTime?: Timestamp;
/**
* The transaction number.
* Only present if the operation is part of a multi-document transaction.
*
* **NOTE:** txnNumber can be a Long if promoteLongs is set to false
*/
txnNumber?: number;
/**
* The identifier for the session associated with the transaction.
* Only present if the operation is part of a multi-document transaction.
*/
lsid?: ServerSessionId;
}
/** @public */
export interface ChangeStreamDocumentCollectionUUID {
/**
* The UUID (Binary subtype 4) of the collection that the operation was performed on.
*
* Only present when the `showExpandedEvents` flag is enabled.
*
* **NOTE:** collectionUUID will be converted to a NodeJS Buffer if the promoteBuffers
* flag is enabled.
*
* @sinceServerVersion 6.1.0
*/
collectionUUID: Binary;
}
/** @public */
export interface ChangeStreamDocumentOperationDescription {
/**
* An description of the operation.
*
* Only present when the `showExpandedEvents` flag is enabled.
*
* @sinceServerVersion 6.1.0
*/
operationDescription?: Document;
}
/**
* @public
* @see https://www.mongodb.com/docs/manual/reference/change-events/#insert-event
*/
export interface ChangeStreamInsertDocument<TSchema extends Document = Document>
extends ChangeStreamDocumentCommon,
ChangeStreamDocumentKey<TSchema>,
ChangeStreamDocumentCollectionUUID {
/** Describes the type of operation represented in this change notification */
operationType: 'insert';
/** This key will contain the document being inserted */
fullDocument: TSchema;
/** Namespace the insert event occurred on */
ns: ChangeStreamNameSpace;
}
/**
* @public
* @see https://www.mongodb.com/docs/manual/reference/change-events/#update-event
*/
export interface ChangeStreamUpdateDocument<TSchema extends Document = Document>
extends ChangeStreamDocumentCommon,
ChangeStreamDocumentKey<TSchema>,
ChangeStreamDocumentCollectionUUID {
/** Describes the type of operation represented in this change notification */
operationType: 'update';
/**
* This is only set if `fullDocument` is set to `'updateLookup'`
* Contains the point-in-time post-image of the modified document if the
* post-image is available and either 'required' or 'whenAvailable' was
* specified for the 'fullDocument' option when creating the change stream.
*/
fullDocument?: TSchema;
/** Contains a description of updated and removed fields in this operation */
updateDescription: UpdateDescription<TSchema>;
/** Namespace the update event occurred on */
ns: ChangeStreamNameSpace;
/**
* Contains the pre-image of the modified or deleted document if the
* pre-image is available for the change event and either 'required' or
* 'whenAvailable' was specified for the 'fullDocumentBeforeChange' option
* when creating the change stream. If 'whenAvailable' was specified but the
* pre-image is unavailable, this will be explicitly set to null.
*/
fullDocumentBeforeChange?: TSchema;
}
/**
* @public
* @see https://www.mongodb.com/docs/manual/reference/change-events/#replace-event
*/
export interface ChangeStreamReplaceDocument<TSchema extends Document = Document>
extends ChangeStreamDocumentCommon,
ChangeStreamDocumentKey<TSchema> {
/** Describes the type of operation represented in this change notification */
operationType: 'replace';
/** The fullDocument of a replace event represents the document after the insert of the replacement document */
fullDocument: TSchema;
/** Namespace the replace event occurred on */
ns: ChangeStreamNameSpace;
/**
* Contains the pre-image of the modified or deleted document if the
* pre-image is available for the change event and either 'required' or
* 'whenAvailable' was specified for the 'fullDocumentBeforeChange' option
* when creating the change stream. If 'whenAvailable' was specified but the
* pre-image is unavailable, this will be explicitly set to null.
*/
fullDocumentBeforeChange?: TSchema;
}
/**
* @public
* @see https://www.mongodb.com/docs/manual/reference/change-events/#delete-event
*/
export interface ChangeStreamDeleteDocument<TSchema extends Document = Document>
extends ChangeStreamDocumentCommon,
ChangeStreamDocumentKey<TSchema>,
ChangeStreamDocumentCollectionUUID {
/** Describes the type of operation represented in this change notification */
operationType: 'delete';
/** Namespace the delete event occurred on */
ns: ChangeStreamNameSpace;
/**
* Contains the pre-image of the modified or deleted document if the
* pre-image is available for the change event and either 'required' or
* 'whenAvailable' was specified for the 'fullDocumentBeforeChange' option
* when creating the change stream. If 'whenAvailable' was specified but the
* pre-image is unavailable, this will be explicitly set to null.
*/
fullDocumentBeforeChange?: TSchema;
}
/**
* @public
* @see https://www.mongodb.com/docs/manual/reference/change-events/#drop-event
*/
export interface ChangeStreamDropDocument
extends ChangeStreamDocumentCommon,
ChangeStreamDocumentCollectionUUID {
/** Describes the type of operation represented in this change notification */
operationType: 'drop';
/** Namespace the drop event occurred on */
ns: ChangeStreamNameSpace;
}
/**
* @public
* @see https://www.mongodb.com/docs/manual/reference/change-events/#rename-event
*/
export interface ChangeStreamRenameDocument
extends ChangeStreamDocumentCommon,
ChangeStreamDocumentCollectionUUID {
/** Describes the type of operation represented in this change notification */
operationType: 'rename';
/** The new name for the `ns.coll` collection */
to: { db: string; coll: string };
/** The "from" namespace that the rename occurred on */
ns: ChangeStreamNameSpace;
}
/**
* @public
* @see https://www.mongodb.com/docs/manual/reference/change-events/#dropdatabase-event
*/
export interface ChangeStreamDropDatabaseDocument extends ChangeStreamDocumentCommon {
/** Describes the type of operation represented in this change notification */
operationType: 'dropDatabase';
/** The database dropped */
ns: { db: string };
}
/**
* @public
* @see https://www.mongodb.com/docs/manual/reference/change-events/#invalidate-event
*/
export interface ChangeStreamInvalidateDocument extends ChangeStreamDocumentCommon {
/** Describes the type of operation represented in this change notification */
operationType: 'invalidate';
}
/**
* Only present when the `showExpandedEvents` flag is enabled.
* @public
* @see https://www.mongodb.com/docs/manual/reference/change-events/
*/
export interface ChangeStreamCreateIndexDocument
extends ChangeStreamDocumentCommon,
ChangeStreamDocumentCollectionUUID,
ChangeStreamDocumentOperationDescription {
/** Describes the type of operation represented in this change notification */
operationType: 'createIndexes';
}
/**
* Only present when the `showExpandedEvents` flag is enabled.
* @public
* @see https://www.mongodb.com/docs/manual/reference/change-events/
*/
export interface ChangeStreamDropIndexDocument
extends ChangeStreamDocumentCommon,
ChangeStreamDocumentCollectionUUID,
ChangeStreamDocumentOperationDescription {
/** Describes the type of operation represented in this change notification */
operationType: 'dropIndexes';
}
/**
* Only present when the `showExpandedEvents` flag is enabled.
* @public
* @see https://www.mongodb.com/docs/manual/reference/change-events/
*/
export interface ChangeStreamCollModDocument
extends ChangeStreamDocumentCommon,
ChangeStreamDocumentCollectionUUID {
/** Describes the type of operation represented in this change notification */
operationType: 'modify';
}
/**
* @public
* @see https://www.mongodb.com/docs/manual/reference/change-events/
*/
export interface ChangeStreamCreateDocument
extends ChangeStreamDocumentCommon,
ChangeStreamDocumentCollectionUUID {
/** Describes the type of operation represented in this change notification */
operationType: 'create';
}
/**
* @public
* @see https://www.mongodb.com/docs/manual/reference/change-events/
*/
export interface ChangeStreamShardCollectionDocument
extends ChangeStreamDocumentCommon,
ChangeStreamDocumentCollectionUUID,
ChangeStreamDocumentOperationDescription {
/** Describes the type of operation represented in this change notification */
operationType: 'shardCollection';
}
/**
* @public
* @see https://www.mongodb.com/docs/manual/reference/change-events/
*/
export interface ChangeStreamReshardCollectionDocument
extends ChangeStreamDocumentCommon,
ChangeStreamDocumentCollectionUUID,
ChangeStreamDocumentOperationDescription {
/** Describes the type of operation represented in this change notification */
operationType: 'reshardCollection';
}
/**
* @public
* @see https://www.mongodb.com/docs/manual/reference/change-events/
*/
export interface ChangeStreamRefineCollectionShardKeyDocument
extends ChangeStreamDocumentCommon,
ChangeStreamDocumentCollectionUUID,
ChangeStreamDocumentOperationDescription {
/** Describes the type of operation represented in this change notification */
operationType: 'refineCollectionShardKey';
}
/** @public */
export type ChangeStreamDocument<TSchema extends Document = Document> =
| ChangeStreamInsertDocument<TSchema>
| ChangeStreamUpdateDocument<TSchema>
| ChangeStreamReplaceDocument<TSchema>
| ChangeStreamDeleteDocument<TSchema>
| ChangeStreamDropDocument
| ChangeStreamRenameDocument
| ChangeStreamDropDatabaseDocument
| ChangeStreamInvalidateDocument
| ChangeStreamCreateIndexDocument
| ChangeStreamCreateDocument
| ChangeStreamCollModDocument
| ChangeStreamDropIndexDocument
| ChangeStreamShardCollectionDocument
| ChangeStreamReshardCollectionDocument
| ChangeStreamRefineCollectionShardKeyDocument;
/** @public */
export interface UpdateDescription<TSchema extends Document = Document> {
/**
* A document containing key:value pairs of names of the fields that were
* changed, and the new value for those fields.
*/
updatedFields?: Partial<TSchema>;
/**
* An array of field names that were removed from the document.
*/
removedFields?: string[];
/**
* An array of documents which record array truncations performed with pipeline-based updates using one or more of the following stages:
* - $addFields
* - $set
* - $replaceRoot
* - $replaceWith
*/
truncatedArrays?: Array<{
/** The name of the truncated field. */
field: string;
/** The number of elements in the truncated array. */
newSize: number;
}>;
/**
* A document containing additional information about any ambiguous update paths from the update event. The document
* maps the full ambiguous update path to an array containing the actual resolved components of the path. For example,
* given a document shaped like `{ a: { '0': 0 } }`, and an update of `{ $inc: 'a.0' }`, disambiguated paths would look like
* the following:
*
* ```
* {
* 'a.0': ['a', '0']
* }
* ```
*
* This field is only present when there are ambiguous paths that are updated as a part of the update event and `showExpandedEvents`
* is enabled for the change stream.
* @sinceServerVersion 6.1.0
*/
disambiguatedPaths?: Document;
}
/** @public */
export type ChangeStreamEvents<
TSchema extends Document = Document,
TChange extends Document = ChangeStreamDocument<TSchema>
> = {
resumeTokenChanged(token: ResumeToken): void;
init(response: any): void;
more(response?: any): void;
response(): void;
end(): void;
error(error: Error): void;
change(change: TChange): void;
} & AbstractCursorEvents;
/**
* Creates a new Change Stream instance. Normally created using {@link Collection#watch|Collection.watch()}.
* @public
*/
export class ChangeStream<
TSchema extends Document = Document,
TChange extends Document = ChangeStreamDocument<TSchema>
> extends TypedEventEmitter<ChangeStreamEvents<TSchema, TChange>> {
pipeline: Document[];
/**
* @remarks WriteConcern can still be present on the options because
* we inherit options from the client/db/collection. The
* key must be present on the options in order to delete it.
* This allows typescript to delete the key but will
* not allow a writeConcern to be assigned as a property on options.
*/
options: ChangeStreamOptions & { writeConcern?: never };
parent: MongoClient | Db | Collection;
namespace: MongoDBNamespace;
type: symbol;
/** @internal */
cursor: ChangeStreamCursor<TSchema, TChange>;
streamOptions?: CursorStreamOptions;
/** @internal */
[kCursorStream]?: Readable & AsyncIterable<TChange>;
/** @internal */
[kClosed]: boolean;
/** @internal */
[kMode]: false | 'iterator' | 'emitter';
/** @event */
static readonly RESPONSE = RESPONSE;
/** @event */
static readonly MORE = MORE;
/** @event */
static readonly INIT = INIT;
/** @event */
static readonly CLOSE = 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
*/
static readonly CHANGE = CHANGE;
/** @event */
static readonly END = END;
/** @event */
static readonly ERROR = ERROR;
/**
* Emitted each time the change stream stores a new resume token.
* @event
*/
static readonly RESUME_TOKEN_CHANGED = RESUME_TOKEN_CHANGED;
/**
* @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: OperationParent,
pipeline: Document[] = [],
options: ChangeStreamOptions = {}
) {
super();
this.pipeline = pipeline;
this.options = { ...options };
delete this.options.writeConcern;
if (parent instanceof Collection) {
this.type = CHANGE_DOMAIN_TYPES.COLLECTION;
} else if (parent instanceof Db) {
this.type = CHANGE_DOMAIN_TYPES.DATABASE;
} else if (parent instanceof MongoClient) {
this.type = CHANGE_DOMAIN_TYPES.CLUSTER;
} else {
throw new 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(): (Readable & AsyncIterable<TChange>) | undefined {
return this[kCursorStream];
}
/** The cached resume token that is used to resume after the most recently returned change. */
get resumeToken(): ResumeToken {
return this.cursor?.resumeToken;
}
/** Check if there is any document still available in the Change Stream */
async hasNext(): Promise<boolean> {
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 {
// We are not concerned with errors from close()
}
throw error;
}
}
}
}
/** Get the next available document from the Change Stream. */
async next(): Promise<TChange> {
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 {
// We are not concerned with errors from close()
}
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(): Promise<TChange | null> {
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 {
// We are not concerned with errors from close()
}
throw error;
}
}
}
}
async *[Symbol.asyncIterator](): AsyncGenerator<TChange, void, void> {
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 {
// we're not concerned with errors from close()
}
}
}
/** Is the cursor closed */
get closed(): boolean {
return this[kClosed] || this.cursor.closed;
}
/** Close the Change Stream */
async close(): Promise<void> {
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?: CursorStreamOptions): Readable & AsyncIterable<TChange> {
if (this.closed) {
throw new MongoChangeStreamError(CHANGESTREAM_CLOSED_ERROR);
}
this.streamOptions = options;
return this.cursor.stream(options);
}
/** @internal */
private _setIsEmitter(): void {
if (this[kMode] === 'iterator') {
// TODO(NODE-3485): Replace with MongoChangeStreamModeError
throw new MongoAPIError(
'ChangeStream cannot be used as an EventEmitter after being used as an iterator'
);
}
this[kMode] = 'emitter';
}
/** @internal */
private _setIsIterator(): void {
if (this[kMode] === 'emitter') {
// TODO(NODE-3485): Replace with MongoChangeStreamModeError
throw new 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
*/
private _createChangeStreamCursor(
options: ChangeStreamOptions | ChangeStreamCursorOptions
): ChangeStreamCursor<TSchema, TChange> {
const changeStreamStageOptions = filterOptions(options, CHANGE_STREAM_OPTIONS);
if (this.type === CHANGE_DOMAIN_TYPES.CLUSTER) {
changeStreamStageOptions.allChangesForCluster = true;
}
const pipeline = [{ $changeStream: changeStreamStageOptions }, ...this.pipeline];
const client: MongoClient | null =
this.type === CHANGE_DOMAIN_TYPES.CLUSTER
? (this.parent as MongoClient)
: this.type === CHANGE_DOMAIN_TYPES.DATABASE
? (this.parent as Db).s.client
: this.type === CHANGE_DOMAIN_TYPES.COLLECTION
? (this.parent as Collection).s.db.s.client
: null;
if (client == null) {
// This should never happen because of the assertion in the constructor
throw new MongoRuntimeError(
`Changestream type should only be one of cluster, database, collection. Found ${this.type.toString()}`
);
}
const changeStreamCursor = new ChangeStreamCursor<TSchema, TChange>(
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 */
private _closeEmitterModeWithError(error: AnyError): void {
this.emit(ChangeStream.ERROR, error);
this.close().catch(() => null);
}
/** @internal */
private _streamEvents(cursor: ChangeStreamCursor<TSchema, TChange>): void {
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 */
private _endStream(): void {
const cursorStream = this[kCursorStream];
if (cursorStream) {
['data', 'close', 'end', 'error'].forEach(event => cursorStream.removeAllListeners(event));
cursorStream.destroy();
}
this[kCursorStream] = undefined;
}
/** @internal */
private _processChange(change: TChange | null): TChange {
if (this[kClosed]) {
// TODO(NODE-3485): Replace with MongoChangeStreamClosedError
throw new 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 MongoRuntimeError(CHANGESTREAM_CLOSED_ERROR);
}
if (change && !change._id) {
throw new 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 */
private _processErrorStreamMode(changeStreamError: AnyError) {
// If the change stream has been closed explicitly, do not process error.
if (this[kClosed]) return;
if (isResumableError(changeStreamError, this.cursor.maxWireVersion)) {
this._endStream();
this.cursor.close().catch(() => null);
const topology = getTopology(this.parent);
topology.selectServer(this.cursor.readPreference, {}, serverSelectionError => {
if (serverSelectionError) return this._closeEmitterModeWithError(changeStreamError);
this.cursor = this._createChangeStreamCursor(this.cursor.resumeOptions);
});
} else {
this._closeEmitterModeWithError(changeStreamError);
}
}
/** @internal */
private async _processErrorIteratorMode(changeStreamError: AnyError) {
if (this[kClosed]) {
// TODO(NODE-3485): Replace with MongoChangeStreamClosedError
throw new MongoAPIError(CHANGESTREAM_CLOSED_ERROR);
}
if (!isResumableError(changeStreamError, this.cursor.maxWireVersion)) {
try {
await this.close();
} catch {
// ignore errors from close
}
throw changeStreamError;
}
await this.cursor.close().catch(() => null);
const topology = getTopology(this.parent);
try {
await topology.selectServerAsync(this.cursor.readPreference, {});
this.cursor = this._createChangeStreamCursor(this.cursor.resumeOptions);
} catch {
// if the topology can't reconnect, close the stream
await this.close();
throw changeStreamError;
}
}
}