Robin Davies
312 lines
9.5 KiB
TypeScript
312 lines
9.5 KiB
TypeScript
// Copyright (c) 2022 Robin Davies
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy of
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// this software and associated documentation files (the "Software"), to deal in
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// the Software without restriction, including without limitation the rights to
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// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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// the Software, and to permit persons to whom the Software is furnished to do so,
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// subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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import { PiPedalStateError } from './PiPedalError';
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import Utility from './Utility';
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export type MessageHandler = (header: PiPedalMessageHeader, body: any | null) => void;
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export type ErrorHandler = (message: string, exception?: Error) => void;
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export type ReconnectHandler = () => void;
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export type ReconnectingHandler = (retry: number, maxRetries: number) => void;
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const MAX_RETRIES = 6;
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const MAX_RETRY_TIME = 90*1000;
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export type PiPedalMessageHeader = {
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replyTo?: number;
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reply?: number;
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message: string;
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}
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type ReplyHandler = (header: PiPedalMessageHeader, body: any | null) => void;
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class PiPedalSocket {
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onMessageReceived: MessageHandler;
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onError: ErrorHandler;
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onReconnecting: ReconnectingHandler;
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onReconnect: ReconnectHandler;
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socket?: WebSocket;
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nextResponseCode: number = 0;
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url: string;
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retrying: boolean = false;
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retryCount: number = 0;
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retryDelay: number = 0;
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totalRetryDelay: number = 0;
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constructor(
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url: string,
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onMessageReceived: MessageHandler,
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onError: ErrorHandler,
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onReconnecting: ReconnectingHandler,
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onReconnect: ReconnectHandler) {
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this.url = url;
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this.onMessageReceived = onMessageReceived;
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this.onError = onError;
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this.onReconnecting = onReconnecting;
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this.onReconnect = onReconnect;
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}
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handleOpen(event: Event): any {
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}
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sendInternal_(json: string) {
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if (!this.retrying) {
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this.socket?.send(json);
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}
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}
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send(message: string, jsonObject?: any) {
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let msg: any;
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if (jsonObject === undefined) {
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msg = [{ message: message }];
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} else {
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msg = [{ message: message }, jsonObject];
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}
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let json = JSON.stringify(msg);
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this.sendInternal_(json);
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}
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reply(replyTo: number, message: string, jsonObject?: any) {
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if (replyTo !== -1) {
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let msg: any;
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if (jsonObject === undefined) {
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msg = [{ reply: replyTo, message: message }];
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} else {
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msg = [{ reply: replyTo, message: message }, jsonObject];
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}
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let json = JSON.stringify(msg);
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this.sendInternal_(json);
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}
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}
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_nextResponseCode(): number {
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return ++this.nextResponseCode;
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}
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_replyMap: Map<number, ReplyHandler> = new Map<number, ReplyHandler>();
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_discardReplyReservations()
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{
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// it's ok. All pending reservations disappear into the GC.
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this._replyMap = new Map<number, ReplyHandler>();
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}
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_addReservation(replyCode: number, handler: ReplyHandler): void {
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this._replyMap.set(replyCode, handler);
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}
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request<Type = any>(message_: string, requestArgs?: any): Promise<Type> {
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let responseCode = this._nextResponseCode();
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return new Promise<Type>((resolve, reject) => {
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try {
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this._addReservation(responseCode, (header: PiPedalMessageHeader, jsonObject?: any) => {
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if (header.message === "error") {
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reject(jsonObject + "");
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} else {
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resolve(jsonObject as Type);
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}
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});
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let msg: any;
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if (requestArgs !== undefined) {
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msg = [{ message: message_, replyTo: responseCode }, requestArgs];
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} else {
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msg = [{ message: message_, replyTo: responseCode }];
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}
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let jsonMessage = JSON.stringify(msg);
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this.sendInternal_(jsonMessage);
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} catch (err) {
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reject(err);
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}
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});
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}
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handleMessage(event: MessageEvent<string>): any {
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try {
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let message: any = JSON.parse(event.data);
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if (!Array.isArray(message)) {
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throw new PiPedalStateError("Invalid message received from server.");
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}
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let header = message[0] as PiPedalMessageHeader;
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let body = undefined;
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if (message.length === 2) {
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body = message[1];
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}
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if (header.reply !== undefined) {
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let handler = this._replyMap.get(header.reply);
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if (handler) {
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handler(header, body);
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}
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return;
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} else {
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if (header.message === "error") {
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throw new PiPedalStateError("Server error: " + body);
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}
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this.onMessageReceived(header, body);
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}
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} catch (error) {
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if (this.onError) {
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this.onError("Invalid server response. " + error, error as Error);
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} else {
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throw new PiPedalStateError("Invalid server response.");
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}
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}
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}
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handleError(_event: Event): any {
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if (this.onError) {
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this.onError("Server connection lost.");
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} else {
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throw new PiPedalStateError("Server connection lost.");
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}
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}
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canReconnect: boolean = false;
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handleClose(_event: any): any {
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if (this.retrying) {
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// treat this as a fatal error.
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if (this.onError) {
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this.onError("Server connection lost.");
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} else {
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throw new PiPedalStateError("Server connection closed.");
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}
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return;
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}
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if (this.canReconnect)
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{
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this._reconnect();
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}
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}
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_reconnect() {
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this._discardReplyReservations();
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this.retrying = true;
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this.retryCount = 0;
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this.socket = undefined;
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this.retryDelay = 10000;
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this.totalRetryDelay = 0;
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this.reconnect();
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}
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isBackground: boolean = false;
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enterBackgroundState()
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{
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this.isBackground = true;
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this.socket?.close();
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}
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exitBackgroundState()
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{
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this.isBackground = false;
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this._reconnect();
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}
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reconnect() {
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if (this.socket)
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{
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this.close();
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}
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this.onReconnecting(this.retryCount,MAX_RETRIES);
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++this.retryCount;
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this.connectInternal_()
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.then((socket) => {
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this.socket = socket;
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this.retrying = false;
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this.onReconnect();
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})
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.catch(error => {
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if (this.totalRetryDelay === MAX_RETRY_TIME)
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{
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this.onError("Server connection lost.");
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return;
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} else {
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this.totalRetryDelay += this.retryDelay;
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Utility.delay(this.retryDelay).then(() => this.reconnect());
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this.retryDelay *= 2;
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if (this.retryDelay > 3000) this.retryDelay = 3000;
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}
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});
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}
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close(): void {
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try {
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if (this.socket)
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{
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this.socket.onclose = null;
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this.socket.onerror = null;
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this.socket.onmessage = null;
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this.socket.onopen = null;
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this.socket?.close();
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}
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} catch (ignored)
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{
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}
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this.socket = undefined;
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}
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connectInternal_(): Promise<WebSocket> {
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return new Promise<WebSocket>((resolve, reject) => {
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let ws = new WebSocket(this.url);
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let self = this;
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ws.onmessage = this.handleMessage.bind(this);
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ws.onclose = (event: Event) => {
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ws.onclose = null;
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ws.onerror = null;
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reject("Can't connect to server.");
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};
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ws.onerror = (event: Event) => {
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ws.onclose = null;
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ws.onerror = null;
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reject("Can't connect to server.");
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};
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ws.onopen = (event: Event) => {
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ws.onerror = self.handleError.bind(self);
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ws.onclose = self.handleClose.bind(self);
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ws.onopen = null;
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resolve(ws);
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};
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});
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}
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connect(): Promise<void> {
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return new Promise<void>((resolve, reject) => {
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this.connectInternal_()
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.then((socket) => {
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this.socket = socket;
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resolve();
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})
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.catch((reason) => {
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reject(reason);
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});
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});
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}
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}
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export default PiPedalSocket;
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