[dds/dap] Don't call setLibraryDebuggable unnecessarily

Fixes https://github.com/Dart-Code/Dart-Code/issues/4464.

TEST=DAP tests included, VM changes are only a comment
Change-Id: I5ee44fda5b954d371bd00345815c24515eb14f61
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/291282
Reviewed-by: Ben Konyi <bkonyi@google.com>
Commit-Queue: Ben Konyi <bkonyi@google.com>

pkg/dds/lib/src/dap/adapters/dart.dart

@@ -317,7 +317,8 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
 
   /// Manages VM Isolates and their events, including fanning out any requests
   /// to set breakpoints etc. from the client to all Isolates.
-  late IsolateManager _isolateManager;
+  @visibleForTesting
+  late IsolateManager isolateManager;
 
   /// A helper that handlers converting to/from DAP and VM Service types.
   late ProtocolConverter _converter;
@@ -459,11 +460,11 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
   Future<void> preventBreakingAndResume() async {
     // Remove anything that may cause us to pause again.
     await Future.wait([
-      _isolateManager.clearAllBreakpoints(),
-      _isolateManager.setExceptionPauseMode('None'),
+      isolateManager.clearAllBreakpoints(),
+      isolateManager.setExceptionPauseMode('None'),
     ]);
     // Once those have completed, it's safe to resume anything paused.
-    await _isolateManager.resumeAll();
+    await isolateManager.resumeAll();
   }
 
   DartDebugAdapter(
@@ -480,7 +481,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
     dartSdkRoot = path.dirname(path.dirname(vmPath));
     orgDartlangSdkMappings[dartSdkRoot] = Uri.parse('org-dartlang-sdk:///sdk');
 
-    _isolateManager = IsolateManager(this);
+    isolateManager = IsolateManager(this);
     _converter = ProtocolConverter(this);
   }
 
@@ -542,7 +543,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
 
     // When attaching to a process, suppress auto-resuming isolates until the
     // first time the user resumes anything.
-    _isolateManager.autoResumeStartingIsolates = false;
+    isolateManager.autoResumeStartingIsolates = false;
 
     // Common setup.
     await _prepareForLaunchOrAttach(null);
@@ -745,7 +746,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
           ? vm.EventKind.kIsolateRunnable
           : vm.EventKind.kIsolateStart;
       final thread =
-          await _isolateManager.registerIsolate(isolate, pauseEventKind);
+          await isolateManager.registerIsolate(isolate, pauseEventKind);
 
       // If the Isolate already has a Pause event we can give it to the
       // IsolateManager to handle (if it's PausePostStart it will re-configure
@@ -753,16 +754,16 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
       // runnable - otherwise we'll handle this when it becomes runnable in an
       // event later).
       if (isolate.pauseEvent?.kind?.startsWith('Pause') ?? false) {
-        await _isolateManager.handleEvent(
+        await isolateManager.handleEvent(
           isolate.pauseEvent!,
         );
       } else if (isolate.runnable == true) {
         // If requested, automatically resume. Otherwise send a Stopped event to
         // inform the client UI the thread is paused.
-        if (_isolateManager.autoResumeStartingIsolates) {
-          await _isolateManager.resumeIsolate(isolate);
+        if (isolateManager.autoResumeStartingIsolates) {
+          await isolateManager.resumeIsolate(isolate);
         } else {
-          _isolateManager.sendStoppedOnEntryEvent(thread.threadId);
+          isolateManager.sendStoppedOnEntryEvent(thread.threadId);
         }
       }
     }));
@@ -776,7 +777,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
     ContinueArguments args,
     void Function(ContinueResponseBody) sendResponse,
   ) async {
-    await _isolateManager.resumeThread(args.threadId);
+    await isolateManager.resumeThread(args.threadId);
     sendResponse(ContinueResponseBody(allThreadsContinued: false));
   }
 
@@ -839,7 +840,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
       // through the run daemon) as it needs to perform additional work to
       // rebuild widgets afterwards.
       case 'hotReload':
-        await _isolateManager.reloadSources();
+        await isolateManager.reloadSources();
         sendResponse(_noResult);
         break;
 
@@ -919,7 +920,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
     ThreadInfo? thread;
     int? frameIndex;
     if (frameId != null) {
-      final data = _isolateManager.getStoredData(frameId);
+      final data = isolateManager.getStoredData(frameId);
       if (data != null) {
         thread = data.thread;
         frameIndex = (data.data as vm.Frame).index;
@@ -1182,9 +1183,9 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
   /// by the `updateDebugOptions` custom request.
   Future<bool> libraryIsDebuggable(ThreadInfo thread, Uri uri) async {
     if (isSdkLibrary(uri)) {
-      return _isolateManager.debugSdkLibraries;
+      return isolateManager.debugSdkLibraries;
     } else if (await isExternalPackageLibrary(thread, uri)) {
-      return _isolateManager.debugExternalPackageLibraries;
+      return isolateManager.debugExternalPackageLibraries;
     } else {
       return true;
     }
@@ -1198,7 +1199,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
     NextArguments args,
     void Function() sendResponse,
   ) async {
-    await _isolateManager.resumeThread(args.threadId, vm.StepOption.kOver);
+    await isolateManager.resumeThread(args.threadId, vm.StepOption.kOver);
     sendResponse();
   }
 
@@ -1227,7 +1228,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
     ScopesArguments args,
     void Function(ScopesResponseBody) sendResponse,
   ) async {
-    final storedData = _isolateManager.getStoredData(args.frameId);
+    final storedData = isolateManager.getStoredData(args.frameId);
     final thread = storedData?.thread;
     final data = storedData?.data;
     final frameData = data is vm.Frame ? data : null;
@@ -1237,7 +1238,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
       scopes.add(Scope(
         name: 'Locals',
         presentationHint: 'locals',
-        variablesReference: _isolateManager.storeData(
+        variablesReference: isolateManager.storeData(
           thread,
           FrameScopeData(frameData, FrameScopeDataKind.locals),
         ),
@@ -1247,7 +1248,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
       scopes.add(Scope(
         name: 'Globals',
         presentationHint: 'globals',
-        variablesReference: _isolateManager.storeData(
+        variablesReference: isolateManager.storeData(
           thread,
           FrameScopeData(frameData, FrameScopeDataKind.globals),
         ),
@@ -1325,7 +1326,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
   /// the file URI in [args.source.path].
   ///
   /// The VM requires breakpoints to be set per-isolate so these will be passed
-  /// to [_isolateManager] that will fan them out to each isolate.
+  /// to [isolateManager] that will fan them out to each isolate.
   ///
   /// When new isolates are registered, it is [isolateManager]'s responsibility
   /// to ensure all breakpoints are given to them (and like at startup, this
@@ -1343,7 +1344,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
     final uri = path != null ? Uri.file(normalizePath(path)).toString() : name!;
 
     final clientBreakpoints = breakpoints.map(ClientBreakpoint.new).toList();
-    await _isolateManager.setBreakpoints(uri, clientBreakpoints);
+    await isolateManager.setBreakpoints(uri, clientBreakpoints);
 
     sendResponse(SetBreakpointsResponseBody(
       // Send breakpoints back as unverified and with our generated IDs so we
@@ -1361,7 +1362,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
   /// the app is running).
   ///
   /// The VM requires exception modes to be set per-isolate so these will be
-  /// passed to [_isolateManager] that will fan them out to each isolate.
+  /// passed to [isolateManager] that will fan them out to each isolate.
   ///
   /// When new isolates are registered, it is [isolateManager]'s responsibility
   /// to ensure the pause mode is given to them (and like at startup, this
@@ -1378,7 +1379,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
             ? 'Unhandled'
             : 'None';
 
-    await _isolateManager.setExceptionPauseMode(mode);
+    await isolateManager.setExceptionPauseMode(mode);
 
     sendResponse(SetExceptionBreakpointsResponseBody());
   }
@@ -1477,7 +1478,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
     SourceArguments args,
     void Function(SourceResponseBody) sendResponse,
   ) async {
-    final storedData = _isolateManager.getStoredData(
+    final storedData = isolateManager.getStoredData(
       args.source?.sourceReference ?? args.sourceReference,
     );
     if (storedData == null) {
@@ -1528,7 +1529,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
     const stackFrameBatchSize = 20;
 
     final threadId = args.threadId;
-    final thread = _isolateManager.getThread(threadId);
+    final thread = isolateManager.getThread(threadId);
     final topFrame = thread?.pauseEvent?.topFrame;
     final startFrame = args.startFrame ?? 0;
     final numFrames = args.levels ?? 0;
@@ -1625,7 +1626,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
     StepInArguments args,
     void Function() sendResponse,
   ) async {
-    await _isolateManager.resumeThread(args.threadId, vm.StepOption.kInto);
+    await isolateManager.resumeThread(args.threadId, vm.StepOption.kInto);
     sendResponse();
   }
 
@@ -1636,7 +1637,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
     StepOutArguments args,
     void Function() sendResponse,
   ) async {
-    await _isolateManager.resumeThread(args.threadId, vm.StepOption.kOut);
+    await isolateManager.resumeThread(args.threadId, vm.StepOption.kOut);
     sendResponse();
   }
 
@@ -1687,7 +1688,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
     void Function(ThreadsResponseBody) sendResponse,
   ) async {
     final threads = [
-      for (final thread in _isolateManager.threads)
+      for (final thread in isolateManager.threads)
         Thread(
           id: thread.threadId,
           name: thread.isolate.name ?? '<unnamed isolate>',
@@ -1716,7 +1717,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
   ) async {
     final childStart = args.start;
     final childCount = args.count;
-    final storedData = _isolateManager.getStoredData(args.variablesReference);
+    final storedData = isolateManager.getStoredData(args.variablesReference);
     if (storedData == null) {
       throw StateError('variablesReference is no longer valid');
     }
@@ -1819,7 +1820,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
         ]);
       }
     } else if (data is vm.ObjRef) {
-      final object = await _isolateManager.getObject(
+      final object = await isolateManager.getObject(
         storedData.thread.isolate,
         data,
         offset: childStart,
@@ -1957,7 +1958,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
     // isolate printed an error to stderr, we just have to use the first one and
     // hope the packages are available. If one is not available (which should
     // never be the case), we will just skip resolution.
-    final thread = _isolateManager.threads.firstOrNull;
+    final thread = isolateManager.threads.firstOrNull;
 
     // Send a batch request. This will cache the results so we can easily use
     // them in the loop below by calling the method again.
@@ -2028,7 +2029,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
     String expression,
     ThreadInfo thread,
   ) async {
-    final exception = _isolateManager.getStoredData(exceptionReference)?.data
+    final exception = isolateManager.getStoredData(exceptionReference)?.data
         as vm.InstanceRef?;
 
     if (exception == null) {
@@ -2060,7 +2061,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
     // it's doing is own initialization that this may interfere with.
     await debuggerInitialized;
 
-    await _isolateManager.handleEvent(event);
+    await isolateManager.handleEvent(event);
 
     final eventKind = event.kind;
     final isolate = event.isolate;
@@ -2071,7 +2072,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
         eventKind == vm.EventKind.kPauseExit &&
         isolate != null) {
       await _waitForPendingOutputEvents();
-      await _isolateManager.resumeIsolate(isolate);
+      await isolateManager.resumeIsolate(isolate);
     }
   }
 
@@ -2093,7 +2094,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
     await debuggerInitialized;
 
     // Allow IsolateManager to handle any state-related events.
-    await _isolateManager.handleEvent(event);
+    await isolateManager.handleEvent(event);
 
     switch (event.kind) {
       // Pass any Service Extension events on to the client so they can enable
@@ -2143,7 +2144,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
   @mustCallSuper
   Future<void> handleLoggingEvent(vm.Event event) async {
     final record = event.logRecord;
-    final thread = _isolateManager.threadForIsolate(event.isolate);
+    final thread = isolateManager.threadForIsolate(event.isolate);
     if (record == null || thread == null) {
       return;
     }
@@ -2196,7 +2197,7 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
     Map<String, Object?> data,
     String field,
   ) async {
-    final thread = _isolateManager.threadForIsolate(isolate);
+    final thread = isolateManager.threadForIsolate(isolate);
     if (thread == null) {
       return;
     }
@@ -2283,9 +2284,9 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
     // Notify IsolateManager if we'll be debugging so it knows whether to set
     // up breakpoints etc. when isolates are registered.
     final debug = !(noDebug ?? false);
-    _isolateManager.debug = debug;
-    _isolateManager.debugSdkLibraries = args.debugSdkLibraries ?? true;
-    _isolateManager.debugExternalPackageLibraries =
+    isolateManager.debug = debug;
+    isolateManager.debugSdkLibraries = args.debugSdkLibraries ?? true;
+    isolateManager.debugExternalPackageLibraries =
         args.debugExternalPackageLibraries ?? true;
   }
 
@@ -2328,13 +2329,13 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
   /// in the map will not be updated by this method.
   Future<void> _updateDebugOptions(Map<String, Object?> args) async {
     if (args.containsKey('debugSdkLibraries')) {
-      _isolateManager.debugSdkLibraries = args['debugSdkLibraries'] as bool;
+      isolateManager.debugSdkLibraries = args['debugSdkLibraries'] as bool;
     }
     if (args.containsKey('debugExternalPackageLibraries')) {
-      _isolateManager.debugExternalPackageLibraries =
+      isolateManager.debugExternalPackageLibraries =
           args['debugExternalPackageLibraries'] as bool;
     }
-    await _isolateManager.applyDebugOptions();
+    await isolateManager.applyDebugOptions();
   }
 
   /// A wrapper around the same name function from package:vm_service that

pkg/dds/lib/src/dap/isolate_manager.dart

@@ -777,12 +777,18 @@ class IsolateManager {
 
     await Future.wait(libraries.map((library) async {
       final libraryUri = library.uri;
-      final isDebuggable = libraryUri != null
+      final isDebuggableNew = libraryUri != null
           ? await _adapter.libraryIsDebuggable(thread, Uri.parse(libraryUri))
           : false;
+      final isDebuggableCurrent =
+          thread.getIsLibraryCurrentlyDebuggable(library);
+      thread.setIsLibraryCurrentlyDebuggable(library, isDebuggableNew);
+      if (isDebuggableNew == isDebuggableCurrent) {
+        return;
+      }
       try {
         await service.setLibraryDebuggable(
-            isolateId, library.id!, isDebuggable);
+            isolateId, library.id!, isDebuggableNew);
       } on vm.RPCError catch (e) {
         // DWDS does not currently support `setLibraryDebuggable` so instead of
         // failing (because this code runs in a VM event handler where there's
@@ -999,6 +1005,46 @@ class ThreadInfo {
     return Future.wait(futures);
   }
 
+  /// Returns whether [library] is currently debuggable according to the VM
+  /// (or there is a request in-flight to set it).
+  bool getIsLibraryCurrentlyDebuggable(vm.LibraryRef library) {
+    return _libraryIsDebuggableById[library.id!] ??
+        _getIsLibraryDebuggableByDefault(library);
+  }
+
+  /// Records whether [library] is currently debuggable for this isolate.
+  ///
+  /// This should be called whenever a `setLibraryDebuggable` request is made
+  /// to the VM.
+  void setIsLibraryCurrentlyDebuggable(
+    vm.LibraryRef library,
+    bool isDebuggable,
+  ) {
+    if (isDebuggable == _getIsLibraryDebuggableByDefault(library)) {
+      _libraryIsDebuggableById.remove(library.id!);
+    } else {
+      _libraryIsDebuggableById[library.id!] = isDebuggable;
+    }
+  }
+
+  /// Returns whether [library] is debuggable by default.
+  ///
+  /// This value is _assumed_ to avoid having to fetch each library for each
+  /// isolate.
+  bool _getIsLibraryDebuggableByDefault(vm.LibraryRef library) {
+    final isSdkLibrary = library.uri?.startsWith('dart:') ?? false;
+    return !isSdkLibrary;
+  }
+
+  /// Tracks whether libraries are currently marked as debuggable in the VM.
+  ///
+  /// If a library ID is not in the map, it is set to the default (which is
+  /// debuggable for non-SDK sources, and not-debuggable for SDK sources).
+  ///
+  /// This can be used to avoid calling setLibraryDebuggable where the value
+  /// would not be changed.
+  final _libraryIsDebuggableById = <String, bool>{};
+
   /// Resolves a source URI to a file path for the lib folder of its package.
   ///
   /// package:foo/a/b/c/d.dart -> /code/packages/foo/lib

pkg/dds/test/dap/isolate_manager_test.dart

@@ -0,0 +1,103 @@
+// Copyright (c) 2023, 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.
+
+import 'package:test/test.dart';
+import 'package:vm_service/vm_service.dart';
+
+import 'mocks.dart';
+
+main() {
+  group('IsolateManager', () {
+    final adapter = MockDartCliDebugAdapter();
+    final isolateManager = adapter.isolateManager;
+
+    setUp(() async {
+      isolateManager.debug = true;
+      isolateManager.debugSdkLibraries = false;
+      isolateManager.debugExternalPackageLibraries = true;
+      await isolateManager.registerIsolate(
+        adapter.mockService.isolate,
+        EventKind.kIsolateStart,
+      );
+    });
+
+    test('sends only changes to SDK libraries debuggable flag', () async {
+      // Default is false, so should not send anything.
+      isolateManager.debugSdkLibraries = false;
+      await isolateManager.applyDebugOptions();
+      expect(
+        adapter.mockService.requests,
+        isNot(
+          contains(startsWith('setLibraryDebuggable(isolate1, libSdk,')),
+        ),
+      );
+
+      // Changing to non-default should send a request.
+      isolateManager.debugSdkLibraries = true;
+      await isolateManager.applyDebugOptions();
+      expect(
+        adapter.mockService.requests,
+        contains('setLibraryDebuggable(isolate1, libSdk, true)'),
+      );
+
+      // Setting back to default should now send.
+      isolateManager.debugSdkLibraries = false;
+      await isolateManager.applyDebugOptions();
+      expect(
+        adapter.mockService.requests,
+        contains('setLibraryDebuggable(isolate1, libSdk, false)'),
+      );
+    });
+
+    test('sends only changes to external package libraries debuggable flag',
+        () async {
+      // Default is true, so should not send anything.
+      isolateManager.debugExternalPackageLibraries = true;
+      await isolateManager.applyDebugOptions();
+      expect(
+        adapter.mockService.requests,
+        isNot(
+          contains(
+              startsWith('setLibraryDebuggable(isolate1, libPkgExternal,')),
+        ),
+      );
+
+      // Changing to non-default should send a request.
+      isolateManager.debugExternalPackageLibraries = false;
+      await isolateManager.applyDebugOptions();
+      expect(
+        adapter.mockService.requests,
+        contains('setLibraryDebuggable(isolate1, libPkgExternal, false)'),
+      );
+
+      // Setting back to default should now send.
+      isolateManager.debugExternalPackageLibraries = true;
+      await isolateManager.applyDebugOptions();
+      expect(
+        adapter.mockService.requests,
+        contains('setLibraryDebuggable(isolate1, libPkgExternal, true)'),
+      );
+    });
+
+    /// Local packages are always debuggable, in the VM and because we have no
+    /// settings. No changes should ever cause requests for them.
+    test('never sends values for local package libraries debuggable flag',
+        () async {
+      isolateManager.debugSdkLibraries = true;
+      isolateManager.debugExternalPackageLibraries = true;
+      await isolateManager.applyDebugOptions();
+
+      isolateManager.debugSdkLibraries = false;
+      isolateManager.debugExternalPackageLibraries = false;
+      await isolateManager.applyDebugOptions();
+
+      expect(
+        adapter.mockService.requests,
+        isNot(
+          contains(startsWith('setLibraryDebuggable(isolate1, libPkgLocal,')),
+        ),
+      );
+    });
+  });
+}

pkg/dds/test/dap/mocks.dart

@@ -7,6 +7,8 @@ import 'dart:async';
 import 'package:dds/dap.dart';
 import 'package:dds/src/dap/adapters/dart_cli_adapter.dart';
 import 'package:dds/src/dap/adapters/dart_test_adapter.dart';
+import 'package:dds/src/dap/isolate_manager.dart';
+import 'package:vm_service/vm_service.dart';
 
 /// A [DartCliDebugAdapter] that captures information about the process that
 /// will be launched.
@@ -14,6 +16,8 @@ class MockDartCliDebugAdapter extends DartCliDebugAdapter {
   final StreamSink<List<int>> stdin;
   final Stream<List<int>> stdout;
 
+  final mockService = MockVmService();
+
   late bool launchedInTerminal;
   late String executable;
   late List<String> processArgs;
@@ -32,7 +36,14 @@ class MockDartCliDebugAdapter extends DartCliDebugAdapter {
 
   MockDartCliDebugAdapter.withStreams(
       this.stdin, this.stdout, ByteStreamServerChannel channel)
-      : super(channel);
+      : super(channel) {
+    vmService = mockService;
+  }
+
+  @override
+  Future<bool> isExternalPackageLibrary(ThreadInfo thread, Uri uri) async {
+    return uri.isScheme('package') && uri.path.startsWith('external');
+  }
 
   @override
   Future<void> launchAsProcess(
@@ -116,3 +127,53 @@ class MockRequest extends Request {
           'seq': _requestId++,
         });
 }
+
+class MockVmService implements VmServiceInterface {
+  @override
+  dynamic noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
+
+  final isolate = IsolateRef(id: 'isolate1');
+  final sdkLibrary = LibraryRef(id: 'libSdk', uri: 'dart:core');
+  final externalPackageLibrary =
+      LibraryRef(id: 'libPkgExternal', uri: 'package:external/foo.dart');
+  final localPackageLibrary =
+      LibraryRef(id: 'libPkgLocal', uri: 'package:local/foo.dart');
+
+  /// A human-readable string for each request made, useful for verifying in
+  /// tests.
+  final List<String> requests = [];
+
+  @override
+  Future<Success> setLibraryDebuggable(
+    String isolateId,
+    String libraryId,
+    bool isDebuggable,
+  ) async {
+    requests.add('setLibraryDebuggable($isolateId, $libraryId, $isDebuggable)');
+    return Success();
+  }
+
+  @override
+  Future<Isolate> getIsolate(String isolateId) async {
+    return Isolate(
+      id: isolate.id,
+      libraries: [sdkLibrary, externalPackageLibrary, localPackageLibrary],
+    );
+  }
+
+  @override
+  Future<UriList> lookupResolvedPackageUris(
+    String isolateId,
+    List<String> uris, {
+    bool? local,
+  }) async {
+    return UriList(uris: uris.map((e) => null).toList());
+  }
+
+  @override
+  Future<VM> getVM() async {
+    return VM(
+      isolates: [isolate],
+    );
+  }
+}

runtime/vm/object.cc

@@ -13996,6 +13996,10 @@ LibraryPtr Library::NewLibraryHelper(const String& url, bool import_core_lib) {
   result.set_flags(0);
   result.set_is_in_fullsnapshot(false);
   result.set_is_nnbd(false);
+  // This logic is also in the DAP debug adapter in DDS to avoid needing
+  // to call setLibraryDebuggable for every library for every isolate.
+  // If these defaults change, the same should be done there in
+  // dap/IsolateManager._getIsLibraryDebuggableByDefault.
   if (dart_scheme) {
     // Only debug dart: libraries if we have been requested to show invisible
     // frames.