[ package:vm_service ] Don't try to send service extension response after service connection disposal

Also prepares for 14.3.1 release.

Fixes https://github.com/flutter/flutter/issues/157296

Change-Id: I623102a54ad7ca4481dd5957a7da65dbc5a2e9b3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/391500
Commit-Queue: Ben Konyi <bkonyi@google.com>
Auto-Submit: Ben Konyi <bkonyi@google.com>
Reviewed-by: Derek Xu <derekx@google.com>

pkg/vm_service/CHANGELOG.md

@@ -1,3 +1,9 @@
+## 14.3.1
+- Fix crash that could occur when trying to send a service extension response
+  after the service connection had already been disposed of ([flutter/flutter #157296]).
+
+[flutter/flutter #157296]: https://github.com/flutter/flutter/issues/157296
+
 ## 14.3.0
 - Update to version `4.16` of the spec.
 - Add `reloadFailureReason` property to `Event`.

pkg/vm_service/lib/src/vm_service.dart

@@ -2023,6 +2023,10 @@ class VmService {
   Future _processRequest(Map<String, dynamic> json) async {
     final result = await _routeRequest(
         json['method'], json['params'] ?? <String, dynamic>{});
+    if (_disposed) {
+      // The service has disappeared. Don't try to send the response.
+      return;
+    }
     result['id'] = json['id'];
     result['jsonrpc'] = '2.0';
     String message = jsonEncode(result);

pkg/vm_service/pubspec.yaml

@@ -1,5 +1,5 @@
 name: vm_service
-version: 14.3.0
+version: 14.3.1
 description: >-
   A library to communicate with a service implementing the Dart VM
   service protocol.

pkg/vm_service/test/regress_157296_test.dart

@@ -0,0 +1,78 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Regression test for https://github.com/flutter/flutter/issues/157296
+
+import 'dart:async';
+
+import 'package:vm_service/vm_service.dart';
+import 'package:vm_service/vm_service_io.dart';
+
+import 'common/service_test_common.dart';
+import 'common/test_helper.dart';
+
+Future<void> testMain() async {}
+
+final tests = <IsolateTest>[
+  hasStoppedAtExit,
+  (VmService service, IsolateRef isolateRef) async {
+    final continueExtensionExecutionCompleter = Completer<void>();
+    final extensionInvokedCompleter = Completer<void>();
+
+    // Setup the service extension.
+    const String serviceName = 'testService';
+    service.registerServiceCallback(
+      serviceName,
+      (Map<String, dynamic> params) async {
+        extensionInvokedCompleter.complete();
+        // Wait for the connection to go down before trying to send the
+        // response.
+        await continueExtensionExecutionCompleter.future;
+        return <String, dynamic>{};
+      },
+    );
+    await service.registerService(serviceName, '');
+
+    // Create a secondary service client to invoke the extension.
+    final client = await vmServiceConnectUri(service.wsUri!);
+    final serviceExtensionCompleter = Completer<String>();
+    client.onServiceEvent.listen((e) {
+      if (e.kind == EventKind.kServiceRegistered) {
+        print('Service extension registered: ${e.method}');
+        serviceExtensionCompleter.complete(e.method!);
+      }
+    });
+    await client.streamListen(EventStreams.kService);
+
+    // Invoke the extension and wait for the extension to begin executing.
+    final extensionName = await serviceExtensionCompleter.future;
+    unawaited(
+      client
+          .callServiceExtension(extensionName)
+          .catchError((_) => Response(), test: (o) => o is RPCError),
+    );
+    await extensionInvokedCompleter.future;
+
+    // Dispose the connection for the VmService instance with the service
+    // extension registered to simulate the VM service connection disappearing
+    // in the middle of handling a service extension request.
+    await service.dispose();
+
+    // Resume the service extension handler. This will cause a
+    // `Bad state: StreamSink is closed` error if there's a regression.
+    continueExtensionExecutionCompleter.complete();
+
+    // Wait a bit to make sure the exception is thrown before the test
+    // completes.
+    await Future.delayed(const Duration(milliseconds: 200));
+  },
+];
+
+void main([args = const <String>[]]) => runIsolateTests(
+      args,
+      tests,
+      'regress_157296_test.dart',
+      testeeConcurrent: testMain,
+      pauseOnExit: true,
+    );

pkg/vm_service/tool/dart/generate_dart_client.dart

@@ -215,6 +215,10 @@ export 'snapshot_graph.dart' show HeapSnapshotClass,
 
   Future _processRequest(Map<String, dynamic> json) async {
     final result = await _routeRequest(json['method'], json['params'] ?? <String, dynamic>{});
+    if (_disposed) {
+      // The service has disappeared. Don't try to send the response.
+      return;
+    }
     result['id'] = json['id'];
     result['jsonrpc'] = '2.0';
     String message = jsonEncode(result);