[ VM / Service ] Stream light-weight version of CpuSamples for CPU

profiler events.

`Event.cpuSamples` is now a `CpuSamplesEvent` rather than a `CpuSamples`
object, where `CpuSamplesEvent` returns `(@Object|NativeFunction)[]` rather
than `(@Func|NativeFunction)[]`, resulting in a smaller JSON payload.

TEST=get_object_rpc_test.dart,get_cached_cpu_samples_test.dart

Change-Id: I1ad5e3df8840b8c41735d10c6c8669f6503e54a8
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/219284
Commit-Queue: Ben Konyi <bkonyi@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>

pkg/dds/CHANGELOG.md

@@ -1,3 +1,7 @@
+# 2.1.5
+- Update to new CpuSamplesEvent format for CPU sample caching for improved
+  performance.
+
 # 2.1.4
 - A new library `package:dds/dap.dart` exposes classes required to build a custom DAP
   debug-adapter on top of the base Dart DAP functionality in DDS.

pkg/dds/lib/src/cpu_samples_manager.dart

@@ -52,21 +52,31 @@ class CpuSamplesRepository extends RingBuffer<CpuSample> {
     int bufferSize = 1000000,
   ]) : super(bufferSize);
 
-  void cacheSamples(CpuSamples samples) {
-    String getFunctionId(ProfileFunction function) {
-      final functionObject = function.function;
-      if (functionObject is NativeFunction) {
-        return 'native/${functionObject.name}';
-      }
-      return functionObject.id!;
-    }
+  ProfileFunction _buildProfileFunction(dynamic function) {
+    // `kind` and `resolvedUrl` are populated in `populateFunctionDetails()`.
+    return ProfileFunction(
+      kind: '',
+      inclusiveTicks: -1,
+      exclusiveTicks: -1,
+      resolvedUrl: '',
+      function: function,
+    );
+  }
 
+  String _getFunctionId(dynamic function) {
+    if (function is NativeFunction) {
+      return 'native/${function.name}';
+    }
+    return function.id!;
+  }
+
+  void cacheSamples(CpuSamplesEvent samples) {
     // Initialize upon seeing our first samples.
     if (functions.isEmpty) {
       samplePeriod = samples.samplePeriod!;
       maxStackDepth = samples.maxStackDepth!;
       pid = samples.pid!;
-      functions.addAll(samples.functions!);
+      functions.addAll(samples.functions!.map(_buildProfileFunction));
 
       // Build the initial id to function index mapping. This allows for us to
       // lookup a ProfileFunction in the global function list stored in this
@@ -77,7 +87,7 @@ class CpuSamplesRepository extends RingBuffer<CpuSample> {
       // TODO(bkonyi): investigate creating some form of stable ID for
       // Functions tied to closures.
       for (int i = 0; i < functions.length; ++i) {
-        idToFunctionIndex[getFunctionId(functions[i])] = i;
+        idToFunctionIndex[_getFunctionId(functions[i].function)] = i;
       }
 
       // Clear tick information as we'll need to recalculate these values later
@@ -94,14 +104,14 @@ class CpuSamplesRepository extends RingBuffer<CpuSample> {
 
       // Check to see if we've got a function object we've never seen before.
       for (int i = 0; i < newFunctions.length; ++i) {
-        final key = getFunctionId(newFunctions[i]);
+        final key = _getFunctionId(newFunctions[i]);
         if (!idToFunctionIndex.containsKey(key)) {
           idToFunctionIndex[key] = functions.length;
           // Keep track of the original index and the location of the function
           // in the master function list so we can update the function indicies
           // for each sample in this batch.
           indexMapping[i] = functions.length;
-          functions.add(newFunctions[i]);
+          functions.add(_buildProfileFunction(newFunctions[i]));
 
           // Reset tick state as we'll recalculate later.
           functions.last.inclusiveTicks = 0;
@@ -159,6 +169,28 @@ class CpuSamplesRepository extends RingBuffer<CpuSample> {
     return evicted;
   }
 
+  Future<void> populateFunctionDetails(
+      DartDevelopmentServiceImpl dds, String isolateId) async {
+    final cpuSamples = await dds.vmServiceClient.sendRequest('getCpuSamples', {
+      'isolateId': isolateId,
+      'timeOriginMicros': 0,
+      'timeExtentMicros': 0,
+    });
+    final fullFunctions = cpuSamples['functions'];
+    for (final func in fullFunctions) {
+      final profileFunc = ProfileFunction.parse(func)!;
+      final id = _getFunctionId(profileFunc.function!);
+      final index = idToFunctionIndex[id];
+      if (index == null) {
+        continue;
+      }
+      final result = functions[index];
+      result.kind = profileFunc.kind;
+      result.resolvedUrl = profileFunc.resolvedUrl;
+      result.function = profileFunc.function;
+    }
+  }
+
   Map<String, dynamic> toJson() {
     return {
       'type': 'CachedCpuSamples',

pkg/dds/lib/src/isolate_manager.dart

@@ -110,13 +110,14 @@ class _RunningIsolate {
   /// Should always be called after an isolate is resumed.
   void clearResumeApprovals() => _resumeApprovalsByName.clear();
 
-  Map<String, dynamic> getCachedCpuSamples(String userTag) {
+  Future<Map<String, dynamic>> getCachedCpuSamples(String userTag) async {
     final repo = cpuSamplesManager.cpuSamplesCaches[userTag];
     if (repo == null) {
       throw json_rpc.RpcException.invalidParams(
         'CPU sample caching is not enabled for tag: "$userTag"',
       );
     }
+    await repo.populateFunctionDetails(isolateManager.dds, id);
     return repo.toJson();
   }
 
@@ -283,14 +284,15 @@ class IsolateManager {
     );
   }
 
-  Map<String, dynamic> getCachedCpuSamples(json_rpc.Parameters parameters) {
+  Future<Map<String, dynamic>> getCachedCpuSamples(
+      json_rpc.Parameters parameters) async {
     final isolateId = parameters['isolateId'].asString;
     if (!isolates.containsKey(isolateId)) {
       return RPCResponses.collectedSentinel;
     }
     final isolate = isolates[isolateId]!;
     final userTag = parameters['userTag'].asString;
-    return isolate.getCachedCpuSamples(userTag);
+    return await isolate.getCachedCpuSamples(userTag);
   }
 
   /// Forwards a `resume` request to the VM service.

pkg/dds/pubspec.yaml

@@ -3,7 +3,7 @@ description: >-
   A library used to spawn the Dart Developer Service, used to communicate with
   a Dart VM Service instance.
 
-version: 2.1.4
+version: 2.1.5
 
 homepage: https://github.com/dart-lang/sdk/tree/master/pkg/dds
 

pkg/dds/test/get_cached_cpu_samples_test.dart

@@ -42,8 +42,15 @@ void main() {
       final availableCaches = await service.getAvailableCachedCpuSamples();
       expect(availableCaches.cacheNames.length, 0);
 
-      final isolate = (await service.getVM()).isolates!.first;
-
+      IsolateRef isolate;
+      while (true) {
+        final vm = await service.getVM();
+        if (vm.isolates!.isNotEmpty) {
+          isolate = vm.isolates!.first;
+          break;
+        }
+        await Future.delayed(const Duration(seconds: 1));
+      }
       try {
         await service.getCachedCpuSamples(isolate.id!, 'Fake');
         fail('Invalid userTag did not cause an exception');
@@ -73,7 +80,18 @@ void main() {
       expect(availableCaches.cacheNames.length, 1);
       expect(availableCaches.cacheNames.first, kUserTag);
 
-      final isolate = (await service.getVM()).isolates!.first;
+      IsolateRef isolate;
+      while (true) {
+        final vm = await service.getVM();
+        if (vm.isolates!.isNotEmpty) {
+          isolate = vm.isolates!.first;
+          isolate = await service.getIsolate(isolate.id!);
+          if ((isolate as Isolate).runnable!) {
+            break;
+          }
+        }
+        await Future.delayed(const Duration(seconds: 1));
+      }
 
       final completer = Completer<void>();
       int i = 0;

pkg/vm_service/CHANGELOG.md

@@ -1,5 +1,10 @@
 # Changelog
 
+## 8.0.0
+- *breaking* Updated type of `Event.cpuSamples` from `CpuSamples` to
+  `CpuSamplesEvent`, which is less expensive to generate and serialize.
+- Added `CpuSamplesEvent` object.
+
 ## 7.5.0
 - Update to version `3.53` of the spec.
 - Added `setIsolatePauseMode` RPC.

pkg/vm_service/example/vm_service_assert.dart

@@ -453,6 +453,20 @@ vms.CpuSamples assertCpuSamples(vms.CpuSamples obj) {
   return obj;
 }
 
+vms.CpuSamplesEvent assertCpuSamplesEvent(vms.CpuSamplesEvent obj) {
+  assertNotNull(obj);
+  assertInt(obj.samplePeriod!);
+  assertInt(obj.maxStackDepth!);
+  assertInt(obj.sampleCount!);
+  assertInt(obj.timeSpan!);
+  assertInt(obj.timeOriginMicros!);
+  assertInt(obj.timeExtentMicros!);
+  assertInt(obj.pid!);
+  assertListOfDynamic(obj.functions!);
+  assertListOfCpuSample(obj.samples!);
+  return obj;
+}
+
 vms.CpuSample assertCpuSample(vms.CpuSample obj) {
   assertNotNull(obj);
   assertInt(obj.tid!);

pkg/vm_service/java/.gitignore

@@ -63,6 +63,7 @@ src/org/dartlang/vm/service/element/ContextElement.java
 src/org/dartlang/vm/service/element/ContextRef.java
 src/org/dartlang/vm/service/element/CpuSample.java
 src/org/dartlang/vm/service/element/CpuSamples.java
+src/org/dartlang/vm/service/element/CpuSamplesEvent.java
 src/org/dartlang/vm/service/element/ErrorKind.java
 src/org/dartlang/vm/service/element/ErrorObj.java
 src/org/dartlang/vm/service/element/ErrorRef.java

pkg/vm_service/java/version.properties

@@ -1 +1 @@
-version=3.53
+version=3.54

pkg/vm_service/lib/src/vm_service.dart

@@ -26,7 +26,7 @@ export 'snapshot_graph.dart'
         HeapSnapshotObjectNoData,
         HeapSnapshotObjectNullData;
 
-const String vmServiceVersion = '3.53.0';
+const String vmServiceVersion = '3.54.0';
 
 /// @optional
 const String optional = 'optional';
@@ -123,6 +123,7 @@ Map<String, Function> _typeFactories = {
   'Context': Context.parse,
   'ContextElement': ContextElement.parse,
   'CpuSamples': CpuSamples.parse,
+  'CpuSamplesEvent': CpuSamplesEvent.parse,
   'CpuSample': CpuSample.parse,
   '@Error': ErrorRef.parse,
   'Error': Error.parse,
@@ -3658,6 +3659,92 @@ class CpuSamples extends Response {
   String toString() => '[CpuSamples]';
 }
 
+class CpuSamplesEvent {
+  static CpuSamplesEvent? parse(Map<String, dynamic>? json) =>
+      json == null ? null : CpuSamplesEvent._fromJson(json);
+
+  /// The sampling rate for the profiler in microseconds.
+  int? samplePeriod;
+
+  /// The maximum possible stack depth for samples.
+  int? maxStackDepth;
+
+  /// The number of samples returned.
+  int? sampleCount;
+
+  /// The timespan the set of returned samples covers, in microseconds
+  /// (deprecated).
+  ///
+  /// Note: this property is deprecated and will always return -1. Use
+  /// `timeExtentMicros` instead.
+  int? timeSpan;
+
+  /// The start of the period of time in which the returned samples were
+  /// collected.
+  int? timeOriginMicros;
+
+  /// The duration of time covered by the returned samples.
+  int? timeExtentMicros;
+
+  /// The process ID for the VM.
+  int? pid;
+
+  /// A list of references to functions seen in the relevant samples. These
+  /// references can be looked up using the indicies provided in a `CpuSample`
+  /// `stack` to determine which function was on the stack.
+  List<dynamic>? functions;
+
+  /// A list of samples collected in the range `[timeOriginMicros,
+  /// timeOriginMicros + timeExtentMicros]`
+  List<CpuSample>? samples;
+
+  CpuSamplesEvent({
+    required this.samplePeriod,
+    required this.maxStackDepth,
+    required this.sampleCount,
+    required this.timeSpan,
+    required this.timeOriginMicros,
+    required this.timeExtentMicros,
+    required this.pid,
+    required this.functions,
+    required this.samples,
+  });
+
+  CpuSamplesEvent._fromJson(Map<String, dynamic> json) {
+    samplePeriod = json['samplePeriod'] ?? -1;
+    maxStackDepth = json['maxStackDepth'] ?? -1;
+    sampleCount = json['sampleCount'] ?? -1;
+    timeSpan = json['timeSpan'] ?? -1;
+    timeOriginMicros = json['timeOriginMicros'] ?? -1;
+    timeExtentMicros = json['timeExtentMicros'] ?? -1;
+    pid = json['pid'] ?? -1;
+    functions = List<dynamic>.from(
+        createServiceObject(json['functions'], const ['dynamic']) as List? ??
+            []);
+    samples = List<CpuSample>.from(
+        createServiceObject(json['samples'], const ['CpuSample']) as List? ??
+            []);
+  }
+
+  Map<String, dynamic> toJson() {
+    final json = <String, dynamic>{};
+    json.addAll({
+      'samplePeriod': samplePeriod,
+      'maxStackDepth': maxStackDepth,
+      'sampleCount': sampleCount,
+      'timeSpan': timeSpan,
+      'timeOriginMicros': timeOriginMicros,
+      'timeExtentMicros': timeExtentMicros,
+      'pid': pid,
+      'functions': functions?.map((f) => f.toJson()).toList(),
+      'samples': samples?.map((f) => f.toJson()).toList(),
+    });
+    return json;
+  }
+
+  String toString() => '[CpuSamplesEvent]';
+}
+
 /// See [getCpuSamples] and [CpuSamples].
 class CpuSample {
   static CpuSample? parse(Map<String, dynamic>? json) =>
@@ -4051,7 +4138,7 @@ class Event extends Response {
 
   /// A CPU profile containing recent samples.
   @optional
-  CpuSamples? cpuSamples;
+  CpuSamplesEvent? cpuSamples;
 
   /// Binary data associated with the event.
   ///
@@ -4132,8 +4219,9 @@ class Event extends Response {
     last = json['last'];
     updatedTag = json['updatedTag'];
     previousTag = json['previousTag'];
-    cpuSamples = createServiceObject(json['cpuSamples'], const ['CpuSamples'])
-        as CpuSamples?;
+    cpuSamples =
+        createServiceObject(json['cpuSamples'], const ['CpuSamplesEvent'])
+            as CpuSamplesEvent?;
     data = json['data'];
   }
 

pkg/vm_service/pubspec.yaml

@@ -3,7 +3,7 @@ description: >-
   A library to communicate with a service implementing the Dart VM
   service protocol.
 
-version: 7.5.0
+version: 8.0.0
 
 homepage: https://github.com/dart-lang/sdk/tree/master/pkg/vm_service
 

pkg/vm_service/test/common/test_helper.dart

@@ -277,6 +277,7 @@ class _ServiceTesterRunner {
         vm = await vmServiceConnectUri(serviceWebsocketAddress);
         print('Done loading VM');
         isolate = await getFirstIsolate(vm);
+        print('Got first isolate');
       });
     });
 
@@ -342,6 +343,8 @@ class _ServiceTesterRunner {
     });
     await service.streamListen(EventStreams.kIsolate);
 
+    await service.streamListen(EventStreams.kIsolate);
+
     // The isolate may have started before we subscribed.
     vm = await service.getVM();
     if (vmIsolates.isNotEmpty) {

pkg/vm_service/tool/dart/generate_dart.dart

@@ -935,6 +935,10 @@ dynamic assertDynamic(dynamic obj) {
   return obj;
 }
 
+List<dynamic> assertListOfDynamic(List<dynamic> list) {
+  return list;
+}
+
 List<int> assertListOfInt(List<int> list) {
   for (int elem in list) {
     assertInt(elem);

runtime/observatory/tests/service/get_object_rpc_test.dart

@@ -14,8 +14,12 @@ import 'test_helper.dart';
 class _DummyClass {
   static var dummyVar = 11;
   final List<String> dummyList = new List<String>.filled(20, '');
+  static var dummyVarWithInit = foo();
+  late String dummyLateVarWithInit = 'bar';
+  late String dummyLateVar;
   void dummyFunction(int a, [bool b = false]) {}
   void dummyGenericFunction<K, V>(K a, {required V param}) {}
+  static List foo() => List<String>.filled(20, '');
 }
 
 class _DummySubClass extends _DummyClass {}
@@ -982,6 +986,83 @@ var tests = <IsolateTest>[
     expect(result['_guardLength'], isNotNull);
   },
 
+  // static field initializer
+  (Isolate isolate) async {
+    // Call eval to get a class id.
+    var evalResult = await invoke(isolate, 'getDummyClass');
+    var id = "${evalResult['class']['id']}/field_inits/dummyVarWithInit";
+    var params = {
+      'objectId': id,
+    };
+    var result = await isolate.invokeRpcNoUpgrade('getObject', params);
+    expect(result['type'], equals('Function'));
+    expect(result['id'], equals(id));
+    expect(result['name'], equals('dummyVarWithInit'));
+    expect(result['_kind'], equals('FieldInitializer'));
+    expect(result['static'], equals(true));
+    expect(result['const'], equals(false));
+    expect(result['implicit'], equals(false));
+    expect(result['signature']['typeParameters'], isNull);
+    expect(result['signature']['returnType'], isNotNull);
+    expect(result['signature']['parameters'].length, 0);
+    expect(result['location']['type'], equals('SourceLocation'));
+    expect(result['code']['type'], equals('@Code'));
+    expect(result['_optimizable'], equals(true));
+    expect(result['_inlinable'], equals(false));
+    expect(result['_usageCounter'], isZero);
+    expect(result['_optimizedCallSiteCount'], isZero);
+    expect(result['_deoptimizations'], isZero);
+  },
+
+  // late field initializer
+  (Isolate isolate) async {
+    // Call eval to get a class id.
+    var evalResult = await invoke(isolate, 'getDummyClass');
+    var id = "${evalResult['class']['id']}/field_inits/dummyLateVarWithInit";
+    var params = {
+      'objectId': id,
+    };
+    var result = await isolate.invokeRpcNoUpgrade('getObject', params);
+    expect(result['type'], equals('Function'));
+    expect(result['id'], equals(id));
+    expect(result['name'], equals('dummyLateVarWithInit'));
+    expect(result['_kind'], equals('FieldInitializer'));
+    expect(result['static'], equals(false));
+    expect(result['const'], equals(false));
+    expect(result['implicit'], equals(false));
+    expect(result['signature']['typeParameters'], isNull);
+    expect(result['signature']['returnType'], isNotNull);
+    expect(result['signature']['parameters'].length, 1);
+    expect(result['location']['type'], equals('SourceLocation'));
+    expect(result['code']['type'], equals('@Code'));
+    expect(result['_optimizable'], equals(true));
+    expect(result['_inlinable'], equals(false));
+    expect(result['_usageCounter'], isZero);
+    expect(result['_optimizedCallSiteCount'], isZero);
+    expect(result['_deoptimizations'], isZero);
+  },
+
+  // invalid late field initialize.
+  (Isolate isolate) async {
+    // Call eval to get a class id.
+    var evalResult = await invoke(isolate, 'getDummyClass');
+    var id = "${evalResult['class']['id']}/field_inits/dummyLateVar";
+    var params = {
+      'objectId': id,
+    };
+    bool caughtException = false;
+    try {
+      await isolate.invokeRpcNoUpgrade('getObject', params);
+      expect(false, isTrue, reason: 'Unreachable');
+    } on ServerRpcException catch (e) {
+      caughtException = true;
+      expect(e.code, equals(ServerRpcException.kInvalidParams));
+      expect(
+          e.message, startsWith("getObject: invalid 'objectId' parameter: "));
+    }
+    expect(caughtException, isTrue);
+  },
+
   // field with guards
   (Isolate isolate) async {
     var result = await isolate.vm.invokeRpcNoUpgrade('getFlagList', {});

runtime/observatory/tests/service/get_version_rpc_test.dart

@@ -12,7 +12,7 @@ var tests = <VMTest>[
     final result = await vm.invokeRpcNoUpgrade('getVersion', {});
     expect(result['type'], 'Version');
     expect(result['major'], 3);
-    expect(result['minor'], 53);
+    expect(result['minor'], 54);
     expect(result['_privateMajor'], 0);
     expect(result['_privateMinor'], 0);
   },

runtime/observatory_2/tests/service_2/get_object_rpc_test.dart

@@ -14,8 +14,10 @@ import 'test_helper.dart';
 class _DummyClass {
   static var dummyVar = 11;
   final List<String> dummyList = new List<String>.filled(20, null);
+  static var dummyVarWithInit = foo();
   void dummyFunction(int a, [bool b = false]) {}
   void dummyGenericFunction<K, V>(K a, {V param}) {}
+  static List foo() => List<String>.filled(20, '');
 }
 
 class _DummySubClass extends _DummyClass {}
@@ -1014,6 +1016,34 @@ var tests = <IsolateTest>[
     expect(result['_guardLength'], equals('20'));
   },
 
+  // static field initializer
+  (Isolate isolate) async {
+    // Call eval to get a class id.
+    var evalResult = await invoke(isolate, 'getDummyClass');
+    var id = "${evalResult['class']['id']}/field_inits/dummyVarWithInit";
+    var params = {
+      'objectId': id,
+    };
+    var result = await isolate.invokeRpcNoUpgrade('getObject', params);
+    expect(result['type'], equals('Function'));
+    expect(result['id'], equals(id));
+    expect(result['name'], equals('dummyVarWithInit'));
+    expect(result['_kind'], equals('FieldInitializer'));
+    expect(result['static'], equals(true));
+    expect(result['const'], equals(false));
+    expect(result['implicit'], equals(false));
+    expect(result['signature']['typeParameters'], isNull);
+    expect(result['signature']['returnType'], isNotNull);
+    expect(result['signature']['parameters'].length, 0);
+    expect(result['location']['type'], equals('SourceLocation'));
+    expect(result['code']['type'], equals('@Code'));
+    expect(result['_optimizable'], equals(true));
+    expect(result['_inlinable'], equals(false));
+    expect(result['_usageCounter'], isZero);
+    expect(result['_optimizedCallSiteCount'], isZero);
+    expect(result['_deoptimizations'], isZero);
+  },
+
   // invalid field.
   (Isolate isolate) async {
     // Call eval to get a class id.

runtime/observatory_2/tests/service_2/get_version_rpc_test.dart

@@ -12,7 +12,7 @@ var tests = <VMTest>[
     final result = await vm.invokeRpcNoUpgrade('getVersion', {});
     expect(result['type'], equals('Version'));
     expect(result['major'], equals(3));
-    expect(result['minor'], equals(53));
+    expect(result['minor'], equals(54));
     expect(result['_privateMajor'], equals(0));
     expect(result['_privateMinor'], equals(0));
   },

runtime/vm/object.h

@@ -3702,6 +3702,9 @@ class Function : public Object {
   //   element 2 * i + 1 is coverage hit (zero meaning code was not hit)
   ArrayPtr GetCoverageArray() const;
 
+  // Outputs this function's service ID to the provided JSON object.
+  void AddFunctionServiceId(const JSONObject& obj) const;
+
   // Sets deopt reason in all ICData-s with given deopt_id.
   void SetDeoptReasonForAll(intptr_t deopt_id, ICData::DeoptReasonId reason);
 

runtime/vm/object_service.cc

@@ -248,22 +248,36 @@ void PatchClass::PrintJSONImpl(JSONStream* stream, bool ref) const {
   Object::PrintJSONImpl(stream, ref);
 }
 
-static void AddFunctionServiceId(const JSONObject& jsobj,
-                                 const Function& f,
-                                 const Class& cls) {
-  ASSERT(!cls.IsNull());
+void Function::AddFunctionServiceId(const JSONObject& jsobj) const {
+  Class& cls = Class::Handle(Owner());
   // Special kinds of functions use indices in their respective lists.
   intptr_t id = -1;
   const char* selector = NULL;
-  if (f.IsNonImplicitClosureFunction()) {
-    id = ClosureFunctionsCache::FindClosureIndex(f);
+  // Regular functions known to their owner use their name (percent-encoded).
+  String& name = String::Handle(this->name());
+
+  if (IsNonImplicitClosureFunction()) {
+    id = ClosureFunctionsCache::FindClosureIndex(*this);
     selector = "closures";
-  } else if (f.IsImplicitClosureFunction()) {
-    id = cls.FindImplicitClosureFunctionIndex(f);
+  } else if (IsImplicitClosureFunction()) {
+    id = cls.FindImplicitClosureFunctionIndex(*this);
     selector = "implicit_closures";
-  } else if (f.IsNoSuchMethodDispatcher() || f.IsInvokeFieldDispatcher()) {
-    id = cls.FindInvocationDispatcherFunctionIndex(f);
+  } else if (IsNoSuchMethodDispatcher() || IsInvokeFieldDispatcher()) {
+    id = cls.FindInvocationDispatcherFunctionIndex(*this);
     selector = "dispatchers";
+  } else if (IsFieldInitializer()) {
+    name ^= Field::NameFromInit(name);
+    const char* encoded_field_name = String::EncodeIRI(name);
+    if (cls.IsTopLevel()) {
+      const auto& library = Library::Handle(cls.library());
+      const auto& private_key = String::Handle(library.private_key());
+      jsobj.AddFixedServiceId("libraries/%s/field_inits/%s",
+                              private_key.ToCString(), encoded_field_name);
+    } else {
+      jsobj.AddFixedServiceId("classes/%" Pd "/field_inits/%s", cls.id(),
+                              encoded_field_name);
+    }
+    return;
   }
   if (id != -1) {
     ASSERT(selector != NULL);
@@ -278,10 +292,8 @@ static void AddFunctionServiceId(const JSONObject& jsobj,
     }
     return;
   }
-  // Regular functions known to their owner use their name (percent-encoded).
-  String& name = String::Handle(f.name());
   Thread* thread = Thread::Current();
-  if (Resolver::ResolveFunction(thread->zone(), cls, name) == f.ptr()) {
+  if (Resolver::ResolveFunction(thread->zone(), cls, name) == ptr()) {
     const char* encoded_name = String::EncodeIRI(name);
     if (cls.IsTopLevel()) {
       const auto& library = Library::Handle(cls.library());
@@ -297,7 +309,7 @@ static void AddFunctionServiceId(const JSONObject& jsobj,
   // Oddball functions (not known to their owner) fall back to use the object
   // id ring. Current known examples are signature functions of closures
   // and stubs like 'megamorphic_call_miss'.
-  jsobj.AddServiceId(f);
+  jsobj.AddServiceId(*this);
 }
 
 void Function::PrintJSONImpl(JSONStream* stream, bool ref) const {
@@ -308,7 +320,7 @@ void Function::PrintJSONImpl(JSONStream* stream, bool ref) const {
   ASSERT(err.IsNull());
   JSONObject jsobj(stream);
   AddCommonObjectProperties(&jsobj, "Function", ref);
-  AddFunctionServiceId(jsobj, *this, cls);
+  AddFunctionServiceId(jsobj);
   const char* user_name = UserVisibleNameCString();
   const String& vm_name = String::Handle(name());
   AddNameProperties(&jsobj, user_name, vm_name.ToCString());

runtime/vm/profiler.cc

@@ -250,7 +250,6 @@ void SampleBlockBuffer::ProcessCompletedBlocks() {
 ProcessedSampleBuffer* SampleBlockListProcessor::BuildProcessedSampleBuffer(
     SampleFilter* filter,
     ProcessedSampleBuffer* buffer) {
-  ASSERT(filter != NULL);
   Thread* thread = Thread::Current();
   Zone* zone = thread->zone();
 
@@ -267,7 +266,6 @@ ProcessedSampleBuffer* SampleBlockListProcessor::BuildProcessedSampleBuffer(
 ProcessedSampleBuffer* SampleBlockBuffer::BuildProcessedSampleBuffer(
     SampleFilter* filter,
     ProcessedSampleBuffer* buffer) {
-  ASSERT(filter != NULL);
   Thread* thread = Thread::Current();
   Zone* zone = thread->zone();
 

runtime/vm/profiler_service.cc

@@ -170,7 +170,19 @@ void ProfileFunction::PrintToJSONObject(JSONObject* func) {
   func->AddProperty("_kind", KindToCString(kind()));
 }
 
-void ProfileFunction::PrintToJSONArray(JSONArray* functions) {
+void ProfileFunction::PrintToJSONArray(JSONArray* functions,
+                                       bool print_only_ids) {
+  if (print_only_ids) {
+    JSONObject obj(functions);
+    if (kind() == kDartFunction) {
+      ASSERT(!function_.IsNull());
+      obj.AddProperty("type", "@Object");
+      function_.AddFunctionServiceId(obj);
+    } else {
+      PrintToJSONObject(&obj);
+    }
+    return;
+  }
   JSONObject obj(functions);
   obj.AddProperty("type", "ProfileFunction");
   obj.AddProperty("kind", KindToCString(kind()));
@@ -1728,10 +1740,16 @@ void Profile::PrintProfileJSON(JSONStream* stream, bool include_code_samples) {
   PrintProfileJSON(&obj, include_code_samples);
 }
 
-void Profile::PrintProfileJSON(JSONObject* obj, bool include_code_samples) {
+void Profile::PrintProfileJSON(JSONObject* obj,
+                               bool include_code_samples,
+                               bool is_event) {
   ScopeTimer sw("Profile::PrintProfileJSON", FLAG_trace_profiler);
   Thread* thread = Thread::Current();
-  obj->AddProperty("type", "CpuSamples");
+  if (is_event) {
+    obj->AddProperty("type", "CpuSamplesEvent");
+  } else {
+    obj->AddProperty("type", "CpuSamples");
+  }
   PrintHeaderJSON(obj);
   if (include_code_samples) {
     JSONArray codes(obj, "_codes");
@@ -1760,7 +1778,7 @@ void Profile::PrintProfileJSON(JSONObject* obj, bool include_code_samples) {
     for (intptr_t i = 0; i < functions_->length(); i++) {
       ProfileFunction* function = functions_->At(i);
       ASSERT(function != NULL);
-      function->PrintToJSONArray(&functions);
+      function->PrintToJSONArray(&functions, is_event);
       thread->CheckForSafepoint();
     }
   }

runtime/vm/profiler_service.h

@@ -171,7 +171,7 @@ class ProfileFunction : public ZoneAllocated {
 
   static const char* KindToCString(Kind kind);
 
-  void PrintToJSONArray(JSONArray* functions);
+  void PrintToJSONArray(JSONArray* functions, bool print_only_ids = false);
 
   // Returns true if the call was successful and |pfsp| is set.
   bool GetSinglePosition(ProfileFunctionSourcePosition* pfsp);
@@ -385,7 +385,9 @@ class Profile : public ValueObject {
   ProfileCode* GetCodeFromPC(uword pc, int64_t timestamp);
 
   void PrintProfileJSON(JSONStream* stream, bool include_code_samples);
-  void PrintProfileJSON(JSONObject* obj, bool include_code_samples);
+  void PrintProfileJSON(JSONObject* obj,
+                        bool include_code_samples,
+                        bool is_event = false);
 
   ProfileFunction* FindFunction(const Function& function);
 

runtime/vm/service.cc

@@ -1791,6 +1791,18 @@ static ObjectPtr LookupClassMembers(Thread* thread,
     }
     return field.ptr();
   }
+  if (strcmp(parts[2], "field_inits") == 0) {
+    // Field initializer ids look like: "classes/17/field_inits/name"
+    const auto& field = Field::Handle(klass.LookupField(id));
+    if (field.IsNull() || (field.is_late() && !field.has_initializer())) {
+      return Object::sentinel().ptr();
+    }
+    const auto& function = Function::Handle(field.EnsureInitializerFunction());
+    if (function.IsNull()) {
+      return Object::sentinel().ptr();
+    }
+    return function.ptr();
+  }
   if (strcmp(parts[2], "functions") == 0) {
     // Function ids look like: "classes/17/functions/name"
 
@@ -1883,6 +1895,10 @@ static ObjectPtr LookupHeapObjectLibraries(IsolateGroup* isolate_group,
     // Library field ids look like: "libraries/17/fields/name"
     return LookupClassMembers(Thread::Current(), klass, parts, num_parts);
   }
+  if (strcmp(parts[2], "field_inits") == 0) {
+    // Library field ids look like: "libraries/17/field_inits/name"
+    return LookupClassMembers(Thread::Current(), klass, parts, num_parts);
+  }
   if (strcmp(parts[2], "functions") == 0) {
     // Library function ids look like: "libraries/17/functions/name"
     return LookupClassMembers(Thread::Current(), klass, parts, num_parts);
@@ -1952,6 +1968,9 @@ static ObjectPtr LookupHeapObjectClasses(Thread* thread,
   if (strcmp(parts[2], "closures") == 0) {
     // Closure ids look like: "classes/17/closures/11"
     return LookupClassMembers(thread, cls, parts, num_parts);
+  } else if (strcmp(parts[2], "field_inits") == 0) {
+    // Field initializer ids look like: "classes/17/field_inits/name"
+    return LookupClassMembers(thread, cls, parts, num_parts);
   } else if (strcmp(parts[2], "fields") == 0) {
     // Field ids look like: "classes/17/fields/name"
     return LookupClassMembers(thread, cls, parts, num_parts);

runtime/vm/service.h

@@ -15,7 +15,7 @@
 namespace dart {
 
 #define SERVICE_PROTOCOL_MAJOR_VERSION 3
-#define SERVICE_PROTOCOL_MINOR_VERSION 53
+#define SERVICE_PROTOCOL_MINOR_VERSION 54
 
 class Array;
 class EmbedderServiceHandler;

runtime/vm/service/service.md

@@ -1,8 +1,8 @@
-# Dart VM Service Protocol 3.53
+# Dart VM Service Protocol 3.54
 
 > Please post feedback to the [observatory-discuss group][discuss-list]
 
-This document describes of _version 3.53_ of the Dart VM Service Protocol. This
+This document describes of _version 3.54_ of the Dart VM Service Protocol. This
 protocol is used to communicate with a running Dart Virtual Machine.
 
 To use the Service Protocol, start the VM with the *--observe* flag.
@@ -1987,6 +1987,46 @@ class CpuSamples extends Response {
 
 See [getCpuSamples](#getcpusamples) and [CpuSample](#cpusample).
 
+### CpuSamplesEvent
+
+```
+class CpuSamplesEvent {
+  // The sampling rate for the profiler in microseconds.
+  int samplePeriod;
+
+  // The maximum possible stack depth for samples.
+  int maxStackDepth;
+
+  // The number of samples returned.
+  int sampleCount;
+
+  // The timespan the set of returned samples covers, in microseconds (deprecated).
+  //
+  // Note: this property is deprecated and will always return -1. Use `timeExtentMicros`
+  // instead.
+  int timeSpan;
+
+  // The start of the period of time in which the returned samples were
+  // collected.
+  int timeOriginMicros;
+
+  // The duration of time covered by the returned samples.
+  int timeExtentMicros;
+
+  // The process ID for the VM.
+  int pid;
+
+  // A list of references to functions seen in the relevant samples. These references can
+  // be looked up using the indicies provided in a `CpuSample` `stack` to determine
+  // which function was on the stack.
+  (@Object|NativeFunction)[] functions;
+
+  // A list of samples collected in the range
+  // `[timeOriginMicros, timeOriginMicros + timeExtentMicros]`
+  CpuSample[] samples;
+}
+```
+
 ### CpuSample
 
 ```
@@ -2251,7 +2291,7 @@ class Event extends Response {
   string previousTag [optional];
 
   // A CPU profile containing recent samples.
-  CpuSamples cpuSamples [optional];
+  CpuSamplesEvent cpuSamples [optional];
 }
 ```
 
@@ -4263,4 +4303,6 @@ version | comments
 3.51 | Added optional `reportLines` parameter to `getSourceReport` RPC.
 3.52 | Added `lookupResolvedPackageUris` and `lookupPackageUris` RPCs and `UriList` type.
 3.53 | Added `setIsolatePauseMode` RPC.
+3.54 | Added `CpuSamplesEvent`, updated `cpuSamples` property on `Event` to have type `CpuSamplesEvent`.
+
 [discuss-list]: https://groups.google.com/a/dartlang.org/forum/#!forum/observatory-discuss

runtime/vm/service_event.cc

@@ -307,7 +307,8 @@ void ServiceEvent::PrintJSON(JSONStream* js) const {
 
   if (kind() == kCpuSamples) {
     JSONObject cpu_profile(&jsobj, "cpuSamples");
-    cpu_profile_->PrintProfileJSON(&cpu_profile, false);
+    cpu_profile_->PrintProfileJSON(&cpu_profile, /*include_code_samples=*/false,
+                                   /*is_event=*/true);
   }
 }