90 lines
2.8 KiB
TypeScript
90 lines
2.8 KiB
TypeScript
/**
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* Copyright 2018 Google Inc. All rights reserved.
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* Modifications copyright (c) Microsoft Corporation.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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import { ConnectionTransport } from '../ConnectionTransport';
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import * as WebSocket from 'ws';
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export class WebSocketTransport implements ConnectionTransport {
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_ws: WebSocket;
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_dispatchQueue: DispatchQueue;
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onclose?: () => void;
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onmessage?: (message: string) => void;
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static create(url: string): Promise<WebSocketTransport> {
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return new Promise((resolve, reject) => {
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const ws = new WebSocket(url, [], { perMessageDeflate: false });
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ws.addEventListener('open', () => resolve(new WebSocketTransport(ws)));
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ws.addEventListener('error', reject);
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});
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}
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constructor(ws: WebSocket) {
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this._ws = ws;
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this._dispatchQueue = new DispatchQueue(this);
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this._ws.addEventListener('message', event => {
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this._dispatchQueue.enqueue(event.data);
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});
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this._ws.addEventListener('close', event => {
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if (this.onclose)
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this.onclose.call(null);
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});
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// Silently ignore all errors - we don't know what to do with them.
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this._ws.addEventListener('error', () => {});
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}
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send(message: string) {
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this._ws.send(message);
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}
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close() {
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this._ws.close();
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}
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}
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// We want to dispatch all "message" events in separate tasks
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// to make sure all message-related promises are resolved first
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// before dispatching next message.
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//
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// We cannot just use setTimeout() in Node.js here like we would
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// do in Browser - see https://github.com/nodejs/node/issues/23773
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// Thus implement a dispatch queue that enforces new tasks manually.
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class DispatchQueue {
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_transport: ConnectionTransport;
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_timeoutId: NodeJS.Timer = null;
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_queue: string[] = [];
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constructor(transport : ConnectionTransport) {
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this._transport = transport;
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this._dispatch = this._dispatch.bind(this);
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}
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enqueue(message: string) {
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this._queue.push(message);
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if (!this._timeoutId)
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this._timeoutId = setTimeout(this._dispatch, 0);
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}
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_dispatch() {
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const message = this._queue.shift();
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if (this._queue.length)
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this._timeoutId = setTimeout(this._dispatch, 0);
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else
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this._timeoutId = null;
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if (this._transport.onmessage)
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this._transport.onmessage.call(null, message);
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}
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}
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