Introduce timeout for keeping connection contexts alive

Fixes #12823

- refactor front end to allow for multiple reconnections
- remove IWebsockt abstractions
- separate front end connections from service channel management
- introduce mechanism to reconnect front end to existing connection
  context based on timeouts

Contributed on behalf of STMicroelectronics

Signed-off-by: Thomas Mäder <t.s.maeder@gmail.com>

dev-packages/application-package/src/application-props.ts

@@ -86,7 +86,8 @@ export namespace FrontendApplicationConfig {
         defaultIconTheme: 'theia-file-icons',
         electron: ElectronFrontendApplicationConfig.DEFAULT,
         defaultLocale: '',
-        validatePreferencesSchema: true
+        validatePreferencesSchema: true,
+        reloadOnReconnect: false
     };
     export interface Partial extends ApplicationConfig {
 
@@ -132,6 +133,12 @@ export namespace FrontendApplicationConfig {
          * Defaults to `true`.
          */
         readonly validatePreferencesSchema?: boolean;
+
+        /**
+         * When 'true', the window will reload in case the front end reconnects to a back-end,
+         * but the back end does not have a connection context for this front end anymore.
+         */
+        readonly reloadOnReconnect?: boolean;
     }
 }
 
@@ -142,6 +149,7 @@ export type BackendApplicationConfig = RequiredRecursive<BackendApplicationConfi
 export namespace BackendApplicationConfig {
     export const DEFAULT: BackendApplicationConfig = {
         singleInstance: false,
+        frontendConnectionTimeout: 1000
     };
     export interface Partial extends ApplicationConfig {
 
@@ -151,6 +159,11 @@ export namespace BackendApplicationConfig {
          * Defaults to `false`.
          */
         readonly singleInstance?: boolean;
+
+        /**
+         * The time in ms the connection context will be preserved for reconnection after a front end disconnects.
+         */
+        readonly frontendConnectionTimeout?: number;
     }
 }
 

examples/api-samples/src/electron-browser/updater/sample-updater-frontend-module.ts

@@ -15,7 +15,7 @@
 // *****************************************************************************
 
 import { ContainerModule } from '@theia/core/shared/inversify';
-import { ElectronIpcConnectionProvider } from '@theia/core/lib/electron-browser/messaging/electron-ipc-connection-provider';
+import { ElectronIpcConnectionProvider } from '@theia/core/lib/electron-browser/messaging/electron-ipc-connection-source';
 import { CommandContribution, MenuContribution } from '@theia/core/lib/common';
 import { SampleUpdater, SampleUpdaterPath, SampleUpdaterClient } from '../../common/updater/sample-updater';
 import { SampleUpdaterFrontendContribution, ElectronMenuUpdater, SampleUpdaterClientImpl } from './sample-updater-frontend-contribution';

examples/api-samples/src/electron-main/update/sample-updater-main-module.ts

@@ -17,15 +17,15 @@
 import { ContainerModule } from '@theia/core/shared/inversify';
 import { RpcConnectionHandler } from '@theia/core/lib/common/messaging/proxy-factory';
 import { ElectronMainApplicationContribution } from '@theia/core/lib/electron-main/electron-main-application';
-import { ElectronConnectionHandler } from '@theia/core/lib/electron-common/messaging/electron-connection-handler';
 import { SampleUpdaterPath, SampleUpdater, SampleUpdaterClient } from '../../common/updater/sample-updater';
 import { SampleUpdaterImpl } from './sample-updater-impl';
+import { ConnectionHandler } from '@theia/core';
 
 export default new ContainerModule(bind => {
     bind(SampleUpdaterImpl).toSelf().inSingletonScope();
     bind(SampleUpdater).toService(SampleUpdaterImpl);
     bind(ElectronMainApplicationContribution).toService(SampleUpdater);
-    bind(ElectronConnectionHandler).toDynamicValue(context =>
+    bind(ConnectionHandler).toDynamicValue(context =>
         new RpcConnectionHandler<SampleUpdaterClient>(SampleUpdaterPath, client => {
             const server = context.container.get<SampleUpdater>(SampleUpdater);
             server.setClient(client);

examples/browser/package.json

@@ -9,8 +9,15 @@
         "applicationName": "Theia Browser Example",
         "preferences": {
           "files.enableTrash": false
-        }
+        },
+        "reloadOnReconnect": true
       }
+    },
+    "backend": {
+      "config": {
+        "frontendConnectionTimeout": 3000
+      }
+
     }
   },
   "dependencies": {

examples/electron/package.json

@@ -9,7 +9,13 @@
     "target": "electron",
     "frontend": {
       "config": {
-        "applicationName": "Theia Electron Example"
+        "applicationName": "Theia Electron Example",
+        "reloadOnReconnect": true
+      }
+    },
+    "backend": {
+      "config": {
+        "frontendConnectionTimeout": -1
       }
     }
   },

packages/core/src/browser/connection-status-service.spec.ts

@@ -33,8 +33,8 @@ import { MockConnectionStatusService } from './test/mock-connection-status-servi
 import * as sinon from 'sinon';
 
 import { Container } from 'inversify';
-import { WebSocketConnectionProvider } from './messaging/ws-connection-provider';
 import { ILogger, Emitter, Loggable } from '../common';
+import { WebsocketConnectionSource } from './messaging/ws-connection-source';
 
 disableJSDOM();
 
@@ -101,7 +101,7 @@ describe('frontend-connection-status', function (): void {
     let timer: sinon.SinonFakeTimers;
     let pingSpy: sinon.SinonSpy;
     beforeEach(() => {
-        const mockWebSocketConnectionProvider = sinon.createStubInstance(WebSocketConnectionProvider);
+        const mockWebSocketConnectionSource = sinon.createStubInstance(WebsocketConnectionSource);
         const mockPingService: PingService = <PingService>{
             ping(): Promise<void> {
                 return Promise.resolve(undefined);
@@ -118,11 +118,11 @@ describe('frontend-connection-status', function (): void {
         testContainer.bind(PingService).toConstantValue(mockPingService);
         testContainer.bind(ILogger).toConstantValue(mockILogger);
         testContainer.bind(ConnectionStatusOptions).toConstantValue({ offlineTimeout: OFFLINE_TIMEOUT });
-        testContainer.bind(WebSocketConnectionProvider).toConstantValue(mockWebSocketConnectionProvider);
+        testContainer.bind(WebsocketConnectionSource).toConstantValue(mockWebSocketConnectionSource);
 
-        sinon.stub(mockWebSocketConnectionProvider, 'onSocketDidOpen').value(mockSocketOpenedEmitter.event);
-        sinon.stub(mockWebSocketConnectionProvider, 'onSocketDidClose').value(mockSocketClosedEmitter.event);
-        sinon.stub(mockWebSocketConnectionProvider, 'onIncomingMessageActivity').value(mockIncomingMessageActivityEmitter.event);
+        sinon.stub(mockWebSocketConnectionSource, 'onSocketDidOpen').value(mockSocketOpenedEmitter.event);
+        sinon.stub(mockWebSocketConnectionSource, 'onSocketDidClose').value(mockSocketClosedEmitter.event);
+        sinon.stub(mockWebSocketConnectionSource, 'onIncomingMessageActivity').value(mockIncomingMessageActivityEmitter.event);
 
         timer = sinon.useFakeTimers();
 

packages/core/src/browser/connection-status-service.ts

@@ -19,8 +19,8 @@ import { ILogger } from '../common/logger';
 import { Event, Emitter } from '../common/event';
 import { DefaultFrontendApplicationContribution } from './frontend-application-contribution';
 import { StatusBar, StatusBarAlignment } from './status-bar/status-bar';
-import { WebSocketConnectionProvider } from './messaging/ws-connection-provider';
 import { Disposable, DisposableCollection, nls } from '../common';
+import { WebsocketConnectionSource } from './messaging/ws-connection-source';
 
 /**
  * Service for listening on backend connection changes.
@@ -119,7 +119,7 @@ export class FrontendConnectionStatusService extends AbstractConnectionStatusSer
 
     private scheduledPing: number | undefined;
 
-    @inject(WebSocketConnectionProvider) protected readonly wsConnectionProvider: WebSocketConnectionProvider;
+    @inject(WebsocketConnectionSource) protected readonly wsConnectionProvider: WebsocketConnectionSource;
     @inject(PingService) protected readonly pingService: PingService;
 
     @postConstruct()

packages/core/src/browser/messaging/connection-source.ts

@@ -0,0 +1,26 @@
+// *****************************************************************************
+// Copyright (C) 2023 STMicroelectronics and others.
+//
+// This program and the accompanying materials are made available under the
+// terms of the Eclipse Public License v. 2.0 which is available at
+// http://www.eclipse.org/legal/epl-2.0.
+//
+// This Source Code may also be made available under the following Secondary
+// Licenses when the conditions for such availability set forth in the Eclipse
+// Public License v. 2.0 are satisfied: GNU General Public License, version 2
+// with the GNU Classpath Exception which is available at
+// https://www.gnu.org/software/classpath/license.html.
+//
+// SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0
+// *****************************************************************************
+
+import { Channel, Event } from "../../common";
+
+export const ConnectionSource = Symbol('ConnectionSource');
+
+/**
+ * A ConnectionSource creates a Channel. The channel is valid until it sends a close event.
+ */
+export interface ConnectionSource {
+    onConnectionDidOpen: Event<Channel>;
+}

packages/core/src/browser/messaging/frontend-id-provider.ts

@@ -0,0 +1,38 @@
+// *****************************************************************************
+// Copyright (C) 2023 STMicroelectronics and others.
+//
+// This program and the accompanying materials are made available under the
+// terms of the Eclipse Public License v. 2.0 which is available at
+// http://www.eclipse.org/legal/epl-2.0.
+//
+// This Source Code may also be made available under the following Secondary
+// Licenses when the conditions for such availability set forth in the Eclipse
+// Public License v. 2.0 are satisfied: GNU General Public License, version 2
+// with the GNU Classpath Exception which is available at
+// https://www.gnu.org/software/classpath/license.html.
+//
+// SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0
+// *****************************************************************************
+
+import { injectable } from "inversify";
+import { generateUuid } from "../../common/uuid";
+
+export const FrontendIdProvider = Symbol('FrontendIdProvider');
+
+/**
+ * A FronendIdProvider computes an id for an instance of the front end that may be reconnected to a back end 
+ * connection context.
+ */
+export interface FrontendIdProvider {
+    getId(): string;
+}
+
+@injectable()
+export class BrowserFrontendIdProvider implements FrontendIdProvider {
+    protected readonly id = generateUuid(); // generate a new id each time we load the application
+
+    getId(): string {
+        return this.id;
+    }
+
+}

packages/core/src/browser/messaging/messaging-frontend-module.ts

@@ -15,9 +15,29 @@
 // *****************************************************************************
 
 import { ContainerModule } from 'inversify';
-import { LocalWebSocketConnectionProvider, WebSocketConnectionProvider } from './ws-connection-provider';
+import { BrowserFrontendIdProvider, FrontendIdProvider } from './frontend-id-provider';
+import { WebsocketConnectionSource } from './ws-connection-source';
+import { LocalConnectionProvider, RemoteConnectionProvider, ServiceConnectionProvider } from './service-connection-provider';
+import { ConnectionSource } from './connection-source';
+import { ConnectionCloseService, connectionCloseServicePath } from '../../common/messaging/connection-management';
+import { WebSocketConnectionProvider } from './ws-connection-provider';
+
+const backendServiceProvider = Symbol('backendServiceProvider');
 
 export const messagingFrontendModule = new ContainerModule(bind => {
+    bind(ConnectionCloseService).toDynamicValue(ctx => {
+        return WebSocketConnectionProvider.createProxy(ctx.container, connectionCloseServicePath);
+    }).inSingletonScope();
+    bind(BrowserFrontendIdProvider).toSelf().inSingletonScope();
+    bind(FrontendIdProvider).toService(BrowserFrontendIdProvider);
+    bind(WebsocketConnectionSource).toSelf().inSingletonScope();
+    bind(backendServiceProvider).toDynamicValue(ctx => {
+        bind(ServiceConnectionProvider).toSelf().inSingletonScope();
+        const container = ctx.container.createChild();
+        container.bind(ConnectionSource).toService(WebsocketConnectionSource);
+        return container.get(ServiceConnectionProvider);
+    }).inSingletonScope();
+    bind(LocalConnectionProvider).toService(backendServiceProvider);
+    bind(RemoteConnectionProvider).toService(backendServiceProvider);
     bind(WebSocketConnectionProvider).toSelf().inSingletonScope();
-    bind(LocalWebSocketConnectionProvider).toService(WebSocketConnectionProvider);
 });

packages/core/src/browser/messaging/service-connection-provider.ts

@@ -0,0 +1,127 @@
+// *****************************************************************************
+// Copyright (C) 2020 Ericsson and others.
+//
+// This program and the accompanying materials are made available under the
+// terms of the Eclipse Public License v. 2.0 which is available at
+// http://www.eclipse.org/legal/epl-2.0.
+//
+// This Source Code may also be made available under the following Secondary
+// Licenses when the conditions for such availability set forth in the Eclipse
+// Public License v. 2.0 are satisfied: GNU General Public License, version 2
+// with the GNU Classpath Exception which is available at
+// https://www.gnu.org/software/classpath/license.html.
+//
+// SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0
+// *****************************************************************************
+
+import { inject, injectable, interfaces, postConstruct } from 'inversify';
+import { Channel, RpcProxy, RpcProxyFactory } from '../../common';
+import { ChannelMultiplexer } from '../../common/message-rpc/channel';
+import { Deferred } from '../../common/promise-util';
+import { ConnectionSource } from './connection-source';
+
+
+export const LocalConnectionProvider = Symbol('LocalConnectionProvider');
+export const RemoteConnectionProvider = Symbol('RemoteConnectionProvider');
+
+export namespace ServiceConnectionProvider {
+    export type ConnectionHandler = (path: String, channel: Channel) => void;
+}
+
+/**
+ * This class manages the channels for remote services in the back end
+ */
+@injectable()
+export class ServiceConnectionProvider {
+
+    static createProxy<T extends object>(container: interfaces.Container, path: string, arg?: object): RpcProxy<T> {
+        return container.get<ServiceConnectionProvider>(RemoteConnectionProvider).createProxy(path, arg);
+    }
+
+    static createLocalProxy<T extends object>(container: interfaces.Container, path: string, arg?: object): RpcProxy<T> {
+        return container.get<ServiceConnectionProvider>(LocalConnectionProvider).createProxy(path, arg);
+    }
+
+    static createHandler(container: interfaces.Container, path: string, arg?: object): void {
+        const remote = container.get<ServiceConnectionProvider>(RemoteConnectionProvider);
+        const local = container.get<ServiceConnectionProvider>(LocalConnectionProvider);
+        remote.createProxy(path, arg);
+        if (remote !== local) {
+            local.createProxy(path, arg);
+        }
+    }
+
+    protected readonly channelHandlers = new Map<string, ServiceConnectionProvider.ConnectionHandler>();
+
+    /**
+     * Create a proxy object to remote interface of T type
+     * over a web socket connection for the given path and proxy factory.
+     */
+    createProxy<T extends object>(path: string, factory: RpcProxyFactory<T>): RpcProxy<T>;
+    /**
+     * Create a proxy object to remote interface of T type
+     * over a web socket connection for the given path.
+     *
+     * An optional target can be provided to handle
+     * notifications and requests from a remote side.
+     */
+    createProxy<T extends object>(path: string, target?: object): RpcProxy<T>;
+    createProxy<T extends object>(path: string, arg?: object): RpcProxy<T> {
+        const factory = arg instanceof RpcProxyFactory ? arg : new RpcProxyFactory<T>(arg);
+        this.listen(path, (_, c) => factory.listen(c), true);
+        return factory.createProxy();
+    }
+
+    protected channelMultiplexer: ChannelMultiplexer;
+
+    private channelReadyDeferred = new Deferred<void>();
+    protected get channelReady(): Promise<void> {
+        return this.channelReadyDeferred.promise;
+    }
+
+    @postConstruct()
+    init(): void {
+        this.connectionSource.onConnectionDidOpen(channel => this.handleChannelCreated(channel));
+    }
+
+    @inject(ConnectionSource)
+    protected connectionSource: ConnectionSource;
+
+    /**
+     * This method must be invoked by subclasses when they have created the main channel.
+     * @param mainChannel
+     */
+    protected handleChannelCreated(channel: Channel): void {
+        channel.onClose(() => {
+            this.handleChannelClosed(channel);
+        });
+
+        this.channelMultiplexer = new ChannelMultiplexer(channel);
+        this.channelReadyDeferred.resolve();
+        for (const entry of this.channelHandlers.entries()) {
+            this.openChannel(entry[0], entry[1]);
+        }
+    }
+
+    handleChannelClosed(channel: Channel): void {
+        this.channelReadyDeferred = new Deferred();
+    }
+
+    /**
+     * Install a connection handler for the given path.
+     */
+    listen(path: string, handler: ServiceConnectionProvider.ConnectionHandler, reconnect: boolean): void {
+        this.openChannel(path, handler).then(() => {
+            if (reconnect) {
+                this.channelHandlers.set(path, handler);
+            }
+        });
+
+    }
+
+    private async openChannel(path: string, handler: ServiceConnectionProvider.ConnectionHandler): Promise<void> {
+        await this.channelReady;
+        const newChannel = await this.channelMultiplexer.open(path);
+        handler(path, newChannel);
+    }
+}