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streaming.ts
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streaming.ts
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/**
* Copyright 2020 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* This file describes the gRPC-streaming. */
import {Duplex, DuplexOptions, Readable, Stream, Writable} from 'stream';
import {
APICallback,
CancellableStream,
GRPCCallResult,
SimpleCallbackFunction,
} from '../apitypes';
import {RetryRequestOptions} from '../gax';
// eslint-disable-next-line @typescript-eslint/no-var-requires
const duplexify: DuplexifyConstructor = require('duplexify');
// eslint-disable-next-line @typescript-eslint/no-var-requires
const retryRequest = require('retry-request');
// Directly copy over Duplexify interfaces
export interface DuplexifyOptions extends DuplexOptions {
autoDestroy?: boolean;
end?: boolean;
}
export interface Duplexify extends Duplex {
readonly destroyed: boolean;
setWritable(writable: Writable | false | null): void;
setReadable(readable: Readable | false | null): void;
}
export interface DuplexifyConstructor {
obj(
writable?: Writable | false | null,
readable?: Readable | false | null,
options?: DuplexifyOptions
): Duplexify;
new (
writable?: Writable | false | null,
readable?: Readable | false | null,
options?: DuplexifyOptions
): Duplexify;
(
writable?: Writable | false | null,
readable?: Readable | false | null,
options?: DuplexifyOptions
): Duplexify;
}
/**
* The type of gRPC streaming.
* @enum {number}
*/
export enum StreamType {
/** Client sends a single request, server streams responses. */
SERVER_STREAMING = 1,
/** Client streams requests, server returns a single response. */
CLIENT_STREAMING = 2,
/** Both client and server stream objects. */
BIDI_STREAMING = 3,
}
export class StreamProxy extends duplexify implements GRPCCallResult {
type: StreamType;
private _callback: APICallback;
private _isCancelCalled: boolean;
stream?: CancellableStream;
/**
* StreamProxy is a proxy to gRPC-streaming method.
*
* @private
* @constructor
* @param {StreamType} type - the type of gRPC stream.
* @param {ApiCallback} callback - the callback for further API call.
*/
constructor(type: StreamType, callback: APICallback) {
super(undefined, undefined, {
objectMode: true,
readable: type !== StreamType.CLIENT_STREAMING,
writable: type !== StreamType.SERVER_STREAMING,
} as DuplexOptions);
this.type = type;
this._callback = callback;
this._isCancelCalled = false;
}
cancel() {
if (this.stream) {
this.stream.cancel();
} else {
this._isCancelCalled = true;
}
}
/**
* Forward events from an API request stream to the user's stream.
* @param {Stream} stream - The API request stream.
*/
forwardEvents(stream: Stream) {
const eventsToForward = ['metadata', 'response', 'status'];
eventsToForward.forEach(event => {
stream.on(event, this.emit.bind(this, event));
});
// We also want to supply the status data as 'response' event to support
// the behavior of google-cloud-node expects.
// see:
// https://github.com/GoogleCloudPlatform/google-cloud-node/pull/1775#issuecomment-259141029
// https://github.com/GoogleCloudPlatform/google-cloud-node/blob/116436fa789d8b0f7fc5100b19b424e3ec63e6bf/packages/common/src/grpc-service.js#L355
stream.on('metadata', metadata => {
// Create a response object with succeeds.
// TODO: unify this logic with the decoration of gRPC response when it's
// added. see: https://github.com/googleapis/gax-nodejs/issues/65
stream.emit('response', {
code: 200,
details: '',
message: 'OK',
metadata,
});
});
}
/**
* Specifies the target stream.
* @param {ApiCall} apiCall - the API function to be called.
* @param {Object} argument - the argument to be passed to the apiCall.
*/
setStream(
apiCall: SimpleCallbackFunction,
argument: {},
retryRequestOptions: RetryRequestOptions = {}
) {
if (this.type === StreamType.SERVER_STREAMING) {
const retryStream = retryRequest(null, {
objectMode: true,
request: () => {
if (this._isCancelCalled) {
if (this.stream) {
this.stream.cancel();
}
return;
}
const stream = apiCall(argument, this._callback) as CancellableStream;
this.stream = stream;
this.forwardEvents(stream);
return stream;
},
retries: retryRequestOptions!.retries,
currentRetryAttempt: retryRequestOptions!.currentRetryAttempt,
noResponseRetries: retryRequestOptions!.noResponseRetries,
shouldRetryFn: retryRequestOptions!.shouldRetryFn,
});
this.setReadable(retryStream);
return;
}
const stream = apiCall(argument, this._callback) as CancellableStream;
this.stream = stream;
this.forwardEvents(stream);
if (this.type === StreamType.CLIENT_STREAMING) {
this.setWritable(stream);
}
if (this.type === StreamType.BIDI_STREAMING) {
this.setReadable(stream);
this.setWritable(stream);
}
if (this._isCancelCalled && this.stream) {
this.stream.cancel();
}
}
}