Prototype extension API support (#5884)

* Prototype extension API support

Adds a new experimental API to the C# extension that allows other extensions to communicate with the C# language server. This API is not yet finalized and may change in the future. Relates to dotnet/roslyn#68696.

* Define an export for getting the path of the LSP server being run.

* Move the experimental APIs into an explicitly labeled `experimental` block.

* Prettier

* Adjust settings.json for standard repo settings.

* Implement extension path scanning instead of exposing the location of the LSP

* Remove unused function

* Revert the rest of the serverPath changes

* PR Feedback

* Prettier

Author: 333fred

.vscode/settings.json

@@ -11,10 +11,14 @@
         "out/": true,
         "vsix/": true
     },
+    "[typescript]": {
+        "editor.defaultFormatter": "esbenp.prettier-vscode"
+    },
     "csharp.suppressDotnetRestoreNotification": true,
     "typescript.tsdk": "./node_modules/typescript/lib",
     "mocha.enabled": true,
     "omnisharp.autoStart": false,
     "editor.formatOnSave": false,
-    "eslint.lintTask.enable": true
-}
+    "eslint.lintTask.enable": true,
+    "dotnet.defaultSolution": "disable"
+}

src/csharpExtensionExports.ts

@@ -3,10 +3,12 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
+import * as vscode from 'vscode';
 import { Advisor } from './features/diagnosticsProvider';
 import { EventStream } from './eventStream';
 import TestManager from './features/dotnetTest';
 import { GlobalBrokeredServiceContainer } from '@microsoft/servicehub-framework';
+import { RequestType } from 'vscode-languageclient/node';
 
 export interface OmnisharpExtensionExports {
     initializationFinished: () => Promise<void>;
@@ -21,4 +23,13 @@ export interface CSharpExtensionExports {
     logDirectory: string;
     profferBrokeredServices: (container: GlobalBrokeredServiceContainer) => void;
     determineBrowserType: () => Promise<string | undefined>;
+    experimental: CSharpExtensionExperimentalExports;
+}
+
+export interface CSharpExtensionExperimentalExports {
+    sendServerRequest: <Params, Response, Error>(
+        type: RequestType<Params, Response, Error>,
+        params: Params,
+        token: vscode.CancellationToken
+    ) => Promise<Response>;
 }

src/lsptoolshost/roslynLanguageServer.ts

@@ -119,7 +119,8 @@ export class RoslynLanguageServer {
         private hostExecutableResolver: IHostExecutableResolver,
         private optionProvider: OptionProvider,
         private context: vscode.ExtensionContext,
-        private telemetryReporter: TelemetryReporter
+        private telemetryReporter: TelemetryReporter,
+        private additionalExtensionPaths: string[]
     ) {}
 
     /**
@@ -412,6 +413,10 @@ export class RoslynLanguageServer {
             args.push('--logLevel', logLevel);
         }
 
+        for (const extensionPath of this.additionalExtensionPaths) {
+            args.push('--extension', `"${extensionPath}"`);
+        }
+
         // Get the brokered service pipe name from C# Dev Kit (if installed).
         // We explicitly call this in the LSP server start action instead of awaiting it
         // in our activation because C# Dev Kit depends on C# activation completing.
@@ -621,14 +626,22 @@ export async function activateRoslynLanguageServer(
     outputChannel: vscode.OutputChannel,
     dotnetTestChannel: vscode.OutputChannel,
     reporter: TelemetryReporter
-) {
+): Promise<RoslynLanguageServer> {
     // Create a channel for outputting general logs from the language server.
     _channel = outputChannel;
     // Create a separate channel for outputting trace logs - these are incredibly verbose and make other logs very difficult to see.
     _traceChannel = vscode.window.createOutputChannel('C# LSP Trace Logs');
 
     const hostExecutableResolver = new DotnetRuntimeExtensionResolver(platformInfo, getServerPath);
-    _languageServer = new RoslynLanguageServer(platformInfo, hostExecutableResolver, optionProvider, context, reporter);
+    const additionalExtensionPaths = scanExtensionPlugins();
+    _languageServer = new RoslynLanguageServer(
+        platformInfo,
+        hostExecutableResolver,
+        optionProvider,
+        context,
+        reporter,
+        additionalExtensionPaths
+    );
 
     // Register any commands that need to be handled by the extension.
     registerCommands(context, _languageServer, optionProvider, hostExecutableResolver);
@@ -672,6 +685,29 @@ export async function activateRoslynLanguageServer(
 
     // Start the language server.
     _languageServer.start();
+
+    return _languageServer;
+
+    function scanExtensionPlugins(): string[] {
+        return vscode.extensions.all.flatMap((extension) => {
+            let loadPaths = extension.packageJSON.contributes?.['csharpExtensionLoadPaths'];
+            if (loadPaths === undefined || loadPaths === null) {
+                _traceChannel.appendLine(`Extension ${extension.id} does not contribute csharpExtensionLoadPaths`);
+                return [];
+            }
+
+            if (!Array.isArray(loadPaths) || loadPaths.some((loadPath) => typeof loadPath !== 'string')) {
+                _channel.appendLine(
+                    `Extension ${extension.id} has invalid csharpExtensionLoadPaths. Expected string array, found ${loadPaths}`
+                );
+                return [];
+            }
+
+            loadPaths = loadPaths.map((loadPath) => path.join(extension.extensionPath, loadPath));
+            _traceChannel.appendLine(`Extension ${extension.id} contributes csharpExtensionLoadPaths: ${loadPaths}`);
+            return loadPaths;
+        });
+    }
 }
 
 function getServerPath(options: Options, platformInfo: PlatformInformation) {

src/lsptoolshost/roslynLanguageServerExportChannel.ts

@@ -0,0 +1,33 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+import * as vscode from 'vscode';
+import { RequestType } from 'vscode-languageclient/node';
+import { RoslynLanguageServer } from './roslynLanguageServer';
+
+export class RoslynLanguageServerExport {
+    private _server: RoslynLanguageServer | undefined;
+
+    constructor(private serverPromise: Promise<RoslynLanguageServer>) {}
+
+    private async ensureServer(): Promise<RoslynLanguageServer> {
+        if (this._server === undefined) {
+            this._server = await this.serverPromise;
+        }
+
+        return this._server;
+    }
+
+    public async sendRequest<Params, Response, Error>(
+        type: RequestType<Params, Response, Error>,
+        params: Params,
+        token: vscode.CancellationToken
+    ): Promise<Response> {
+        const server = await this.ensureServer();
+        // We need to recreate the type parameter to ensure that the prototypes line up. The `RequestType` we receive could have been
+        // from a different version.
+        const newType = new RequestType<Params, Response, Error>(type.method);
+        return await server.sendRequest(newType, params, token);
+    }
+}

src/main.ts

@@ -42,7 +42,11 @@ import { installRuntimeDependencies } from './installRuntimeDependencies';
 import { isValidDownload } from './packageManager/isValidDownload';
 import { BackgroundWorkStatusBarObserver } from './observers/backgroundWorkStatusBarObserver';
 import { getDotnetPackApi } from './dotnetPack';
-import { SolutionSnapshotProvider, activateRoslynLanguageServer } from './lsptoolshost/roslynLanguageServer';
+import {
+    RoslynLanguageServer,
+    SolutionSnapshotProvider,
+    activateRoslynLanguageServer,
+} from './lsptoolshost/roslynLanguageServer';
 import { Options } from './shared/options';
 import { MigrateOptions } from './shared/migrateOptions';
 import { getBrokeredServiceContainer } from './lsptoolshost/services/brokeredServicesHosting';
@@ -53,6 +57,7 @@ import { CSharpExtensionExports, OmnisharpExtensionExports } from './csharpExten
 import { csharpDevkitExtensionId, getCSharpDevKit } from './utils/getCSharpDevKit';
 import { BlazorDebugConfigurationProvider } from './razor/src/blazorDebug/blazorDebugConfigurationProvider';
 import { RazorOmnisharpDownloader } from './razor/razorOmnisharpDownloader';
+import { RoslynLanguageServerExport } from './lsptoolshost/roslynLanguageServerExportChannel';
 
 export async function activate(
     context: vscode.ExtensionContext
@@ -117,7 +122,7 @@ export async function activate(
 
     let omnisharpLangServicePromise: Promise<OmniSharp.ActivationResult> | undefined = undefined;
     let omnisharpRazorPromise: Promise<void> | undefined = undefined;
-    let roslynLanguageServerPromise: Promise<void> | undefined = undefined;
+    let roslynLanguageServerPromise: Promise<RoslynLanguageServer> | undefined = undefined;
 
     if (!useOmnisharpServer) {
         // Activate Razor. Needs to be activated before Roslyn so commands are registered in the correct order.
@@ -306,6 +311,7 @@ export async function activate(
     if (!useOmnisharpServer) {
         tryGetCSharpDevKitExtensionExports(csharpLogObserver);
 
+        const languageServerExport = new RoslynLanguageServerExport(roslynLanguageServerPromise!);
         return {
             initializationFinished: async () => {
                 await coreClrDebugPromise;
@@ -314,6 +320,9 @@ export async function activate(
             profferBrokeredServices: (container) => profferBrokeredServices(context, container),
             logDirectory: context.logUri.fsPath,
             determineBrowserType: BlazorDebugConfigurationProvider.determineBrowserType,
+            experimental: {
+                sendServerRequest: async (t, p, ct) => await languageServerExport.sendRequest(t, p, ct),
+            },
         };
     } else {
         return {