[ VM / Service ] Add UserTag support to C-API and send UserTagChanged

events on Developer stream.

Also removes intrinsic implementations for UserTag_makeCurrent to allow
for service events to be sent on UserTag change.

TEST=DartAPI_UserTags,pkg/vm_service/test/user_tag_changed_test.dart

Change-Id: I5dc9ee77c0048590d3c6e33a652eee5bc3bf522a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/204440
Commit-Queue: Ben Konyi <bkonyi@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>

pkg/vm_service/example/vm_service_assert.dart

@@ -159,6 +159,7 @@ String assertEventKind(String obj) {
   if (obj == "ServiceUnregistered") return obj;
   if (obj == "TimelineEvents") return obj;
   if (obj == "TimelineStreamSubscriptionsUpdate") return obj;
+  if (obj == "UserTagChanged") return obj;
   if (obj == "VMFlagUpdate") return obj;
   if (obj == "VMUpdate") return obj;
   if (obj == "WriteEvent") return obj;

pkg/vm_service/java/version.properties

@@ -1 +1 @@
-version=3.47
+version=3.48

pkg/vm_service/lib/src/vm_service.dart

@@ -26,7 +26,7 @@ export 'snapshot_graph.dart'
         HeapSnapshotObjectNoData,
         HeapSnapshotObjectNullData;
 
-const String vmServiceVersion = '3.47.0';
+const String vmServiceVersion = '3.48.0';
 
 /// @optional
 const String optional = 'optional';
@@ -1150,6 +1150,7 @@ abstract class VmServiceInterface {
   /// Debug | PauseStart, PauseExit, PauseBreakpoint, PauseInterrupted,
   /// PauseException, PausePostRequest, Resume, BreakpointAdded,
   /// BreakpointResolved, BreakpointRemoved, BreakpointUpdated, Inspect, None
+  /// Profiler | UserTagChanged
   /// GC | GC
   /// Extension | Extension
   /// Timeline | TimelineEvents, TimelineStreamsSubscriptionUpdate
@@ -1690,6 +1691,9 @@ class VmService implements VmServiceInterface {
   // PauseStart, PauseExit, PauseBreakpoint, PauseInterrupted, PauseException, PausePostRequest, Resume, BreakpointAdded, BreakpointResolved, BreakpointRemoved, BreakpointUpdated, Inspect, None
   Stream<Event> get onDebugEvent => _getEventController('Debug').stream;
 
+  // UserTagChanged
+  Stream<Event> get onProfilerEvent => _getEventController('Profiler').stream;
+
   // GC
   Stream<Event> get onGCEvent => _getEventController('GC').stream;
 
@@ -2384,6 +2388,7 @@ class EventStreams {
   static const String kVM = 'VM';
   static const String kIsolate = 'Isolate';
   static const String kDebug = 'Debug';
+  static const String kProfiler = 'Profiler';
   static const String kGC = 'GC';
   static const String kExtension = 'Extension';
   static const String kTimeline = 'Timeline';
@@ -2496,6 +2501,9 @@ class EventKind {
   /// Notification that a Service has been removed from the Service Protocol
   /// from another client.
   static const String kServiceUnregistered = 'ServiceUnregistered';
+
+  /// Notification that the UserTag for an isolate has been changed.
+  static const String kUserTagChanged = 'UserTagChanged';
 }
 
 /// Adding new values to `InstanceKind` is considered a backwards compatible
@@ -3885,6 +3893,14 @@ class Event extends Response {
   @optional
   bool? last;
 
+  /// The current UserTag label.
+  @optional
+  String? updatedTag;
+
+  /// The previous UserTag label.
+  @optional
+  String? previousTag;
+
   /// Binary data associated with the event.
   ///
   /// This is provided for the event kinds:
@@ -3917,6 +3933,8 @@ class Event extends Response {
     this.flag,
     this.newValue,
     this.last,
+    this.updatedTag,
+    this.previousTag,
     this.data,
   });
 
@@ -3959,6 +3977,8 @@ class Event extends Response {
     flag = json['flag'];
     newValue = json['newValue'];
     last = json['last'];
+    updatedTag = json['updatedTag'];
+    previousTag = json['previousTag'];
     data = json['data'];
   }
 
@@ -3998,6 +4018,8 @@ class Event extends Response {
     _setIfNotNull(json, 'flag', flag);
     _setIfNotNull(json, 'newValue', newValue);
     _setIfNotNull(json, 'last', last);
+    _setIfNotNull(json, 'updatedTag', updatedTag);
+    _setIfNotNull(json, 'previousTag', previousTag);
     _setIfNotNull(json, 'data', data);
     return json;
   }

pkg/vm_service/test/common/test_helper.dart

@@ -346,7 +346,7 @@ class _ServiceTesterRunner {
       completer!.complete(vmIsolates.first);
       completer = null;
     }
-    return await (completer!.future as FutureOr<IsolateRef>);
+    return (await completer!.future) as IsolateRef;
   }
 }
 

pkg/vm_service/test/user_tag_changed_test.dart

@@ -0,0 +1,62 @@
+// Copyright (c) 2021, 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 'dart:developer';
+
+import 'package:async/async.dart';
+import 'package:test/test.dart';
+import 'package:vm_service/vm_service.dart';
+
+import 'common/service_test_common.dart';
+import 'common/test_helper.dart';
+
+void testMain() {
+  final tag = UserTag('Foo');
+  final origTag = tag.makeCurrent();
+  origTag.makeCurrent();
+}
+
+late StreamQueue<Event> stream;
+
+var tests = <IsolateTest>[
+  hasPausedAtStart,
+  (VmService service, IsolateRef isolate) async {
+    await service.streamListen(EventStreams.kProfiler);
+    stream = StreamQueue(
+      service.onProfilerEvent.transform(
+        SingleSubscriptionTransformer<Event, Event>(),
+      ),
+    );
+  },
+  resumeIsolate,
+  hasStoppedAtExit,
+  (VmService service, IsolateRef isolate) async {
+    await service.streamCancel(EventStreams.kProfiler);
+    expect(await stream.hasNext, true);
+
+    var event = await stream.next;
+    expect(event.kind, EventKind.kUserTagChanged);
+    expect(event.updatedTag, 'Foo');
+    expect(event.previousTag, 'Default');
+
+    expect(await stream.hasNext, true);
+    event = await stream.next;
+    expect(event.kind, EventKind.kUserTagChanged);
+    expect(event.updatedTag, 'Default');
+    expect(event.previousTag, 'Foo');
+  },
+  resumeIsolate,
+  (VmService service, IsolateRef isolate) async {
+    expect(await stream.hasNext, false);
+  }
+];
+
+main([args = const <String>[]]) async => await runIsolateTests(
+      args,
+      tests,
+      'user_tag_changed_test.dart',
+      pause_on_start: true,
+      pause_on_exit: true,
+      testeeConcurrent: testMain,
+    );

runtime/include/dart_tools_api.h

@@ -496,4 +496,53 @@ Dart_IsolateRunnableLatencyMetric(Dart_Isolate isolate);  // Microsecond
 DART_EXPORT int64_t
 Dart_IsolateRunnableHeapSizeMetric(Dart_Isolate isolate);  // Byte
 
+/*
+ * ========
+ * UserTags
+ * ========
+ */
+
+/*
+ * Gets the current isolate's currently set UserTag instance.
+ *
+ * \return The currently set UserTag instance.
+ */
+DART_EXPORT Dart_Handle Dart_GetCurrentUserTag();
+
+/*
+ * Gets the current isolate's default UserTag instance.
+ *
+ * \return The default UserTag with label 'Default'
+ */
+DART_EXPORT Dart_Handle Dart_GetDefaultUserTag();
+
+/*
+ * Creates a new UserTag instance.
+ *
+ * \param label The name of the new UserTag.
+ *
+ * \return The newly created UserTag instance or an error handle.
+ */
+DART_EXPORT Dart_Handle Dart_NewUserTag(const char* label);
+
+/*
+ * Updates the current isolate's UserTag to a new value.
+ *
+ * \param user_tag The UserTag to be set as the current UserTag.
+ *
+ * \return The previously set UserTag instance or an error handle.
+ */
+DART_EXPORT Dart_Handle Dart_SetCurrentUserTag(Dart_Handle user_tag);
+
+/*
+ * Returns the label of a given UserTag instance.
+ *
+ * \param user_tag The UserTag from which the label will be retrieved.
+ *
+ * \return The UserTag's label. NULL if the user_tag is invalid. The caller is
+ *   responsible for freeing the returned label.
+ */
+DART_WARN_UNUSED_RESULT DART_EXPORT char* Dart_GetUserTagLabel(
+    Dart_Handle user_tag);
+
 #endif  // RUNTIME_INCLUDE_DART_TOOLS_API_H_

runtime/lib/profiler.cc

@@ -29,12 +29,7 @@ DEFINE_NATIVE_ENTRY(UserTag_label, 0, 1) {
 
 DEFINE_NATIVE_ENTRY(UserTag_makeCurrent, 0, 1) {
   const UserTag& self = UserTag::CheckedHandle(zone, arguments->NativeArgAt(0));
-  if (FLAG_trace_intrinsified_natives) {
-    OS::PrintErr("UserTag_makeCurrent: %s\n", self.ToCString());
-  }
-  const UserTag& old = UserTag::Handle(zone, isolate->current_tag());
-  self.MakeActive();
-  return old.ptr();
+  return self.MakeActive();
 }
 
 DEFINE_NATIVE_ENTRY(UserTag_defaultTag, 0, 0) {

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'], 47);
+    expect(result['minor'], 48);
     expect(result['_privateMajor'], 0);
     expect(result['_privateMinor'], 0);
   },

runtime/observatory_2/tests/service_2/get_version_rpc_test.dart

@@ -9,10 +9,10 @@ import 'test_helper.dart';
 
 var tests = <VMTest>[
   (VM vm) async {
-    var result = await vm.invokeRpcNoUpgrade('getVersion', {});
+    final result = await vm.invokeRpcNoUpgrade('getVersion', {});
     expect(result['type'], equals('Version'));
     expect(result['major'], equals(3));
-    expect(result['minor'], equals(47));
+    expect(result['minor'], equals(48));
     expect(result['_privateMajor'], equals(0));
     expect(result['_privateMinor'], equals(0));
   },

runtime/vm/compiler/asm_intrinsifier_arm.cc

@@ -2020,24 +2020,6 @@ void AsmIntrinsifier::IntrinsifyRegExpExecuteMatch(Assembler* assembler,
   __ Branch(FieldAddress(R0, target::Function::entry_point_offset()));
 }
 
-// On stack: user tag (+0).
-void AsmIntrinsifier::UserTag_makeCurrent(Assembler* assembler,
-                                          Label* normal_ir_body) {
-  // R1: Isolate.
-  __ LoadIsolate(R1);
-  // R0: Current user tag.
-  __ ldr(R0, Address(R1, target::Isolate::current_tag_offset()));
-  // R2: UserTag.
-  __ ldr(R2, Address(SP, +0 * target::kWordSize));
-  // Set target::Isolate::current_tag_.
-  __ str(R2, Address(R1, target::Isolate::current_tag_offset()));
-  // R2: UserTag's tag.
-  __ ldr(R2, FieldAddress(R2, target::UserTag::tag_offset()));
-  // Set target::Isolate::user_tag_.
-  __ str(R2, Address(R1, target::Isolate::user_tag_offset()));
-  __ Ret();
-}
-
 void AsmIntrinsifier::UserTag_defaultTag(Assembler* assembler,
                                          Label* normal_ir_body) {
   __ LoadIsolate(R0);

runtime/vm/compiler/asm_intrinsifier_arm64.cc

@@ -2224,24 +2224,6 @@ void AsmIntrinsifier::IntrinsifyRegExpExecuteMatch(Assembler* assembler,
   __ br(R1);
 }
 
-// On stack: user tag (+0).
-void AsmIntrinsifier::UserTag_makeCurrent(Assembler* assembler,
-                                          Label* normal_ir_body) {
-  // R1: Isolate.
-  __ LoadIsolate(R1);
-  // R0: Current user tag.
-  __ ldr(R0, Address(R1, target::Isolate::current_tag_offset()));
-  // R2: UserTag.
-  __ ldr(R2, Address(SP, +0 * target::kWordSize));
-  // Set target::Isolate::current_tag_.
-  __ str(R2, Address(R1, target::Isolate::current_tag_offset()));
-  // R2: UserTag's tag.
-  __ ldr(R2, FieldAddress(R2, target::UserTag::tag_offset()));
-  // Set target::Isolate::user_tag_.
-  __ str(R2, Address(R1, target::Isolate::user_tag_offset()));
-  __ ret();
-}
-
 void AsmIntrinsifier::UserTag_defaultTag(Assembler* assembler,
                                          Label* normal_ir_body) {
   __ LoadIsolate(R0);

runtime/vm/compiler/asm_intrinsifier_ia32.cc

@@ -2009,24 +2009,6 @@ void AsmIntrinsifier::IntrinsifyRegExpExecuteMatch(Assembler* assembler,
   __ jmp(FieldAddress(EAX, target::Function::entry_point_offset()));
 }
 
-// On stack: user tag (+1), return-address (+0).
-void AsmIntrinsifier::UserTag_makeCurrent(Assembler* assembler,
-                                          Label* normal_ir_body) {
-  // EDI: Isolate.
-  __ LoadIsolate(EDI);
-  // EAX: Current user tag.
-  __ movl(EAX, Address(EDI, target::Isolate::current_tag_offset()));
-  // EAX: UserTag.
-  __ movl(EBX, Address(ESP, +1 * target::kWordSize));
-  // Set target::Isolate::current_tag_.
-  __ movl(Address(EDI, target::Isolate::current_tag_offset()), EBX);
-  // EAX: UserTag's tag.
-  __ movl(EBX, FieldAddress(EBX, target::UserTag::tag_offset()));
-  // Set target::Isolate::user_tag_.
-  __ movl(Address(EDI, target::Isolate::user_tag_offset()), EBX);
-  __ ret();
-}
-
 void AsmIntrinsifier::UserTag_defaultTag(Assembler* assembler,
                                          Label* normal_ir_body) {
   __ LoadIsolate(EAX);

runtime/vm/compiler/asm_intrinsifier_x64.cc

@@ -2086,24 +2086,6 @@ void AsmIntrinsifier::IntrinsifyRegExpExecuteMatch(Assembler* assembler,
   __ jmp(RDI);
 }
 
-// On stack: user tag (+1), return-address (+0).
-void AsmIntrinsifier::UserTag_makeCurrent(Assembler* assembler,
-                                          Label* normal_ir_body) {
-  // RBX: Isolate.
-  __ LoadIsolate(RBX);
-  // RAX: Current user tag.
-  __ movq(RAX, Address(RBX, target::Isolate::current_tag_offset()));
-  // R10: UserTag.
-  __ movq(R10, Address(RSP, +1 * target::kWordSize));
-  // Set Isolate::current_tag_.
-  __ movq(Address(RBX, target::Isolate::current_tag_offset()), R10);
-  // R10: UserTag's tag.
-  __ movq(R10, FieldAddress(R10, target::UserTag::tag_offset()));
-  // Set Isolate::user_tag_.
-  __ movq(Address(RBX, target::Isolate::user_tag_offset()), R10);
-  __ ret();
-}
-
 void AsmIntrinsifier::UserTag_defaultTag(Assembler* assembler,
                                          Label* normal_ir_body) {
   __ LoadIsolate(RAX);

runtime/vm/compiler/recognized_methods_list.h

@@ -377,7 +377,6 @@ namespace dart {
   GRAPH_MATH_LIB_INTRINSIC_LIST(V)                                             \
 
 #define DEVELOPER_LIB_INTRINSIC_LIST(V)                                        \
-  V(_UserTag, makeCurrent, UserTag_makeCurrent, 0x5bd9b88e)                    \
   V(::, _getDefaultTag, UserTag_defaultTag, 0x6c19c8a5)                        \
   V(::, _getCurrentTag, Profiler_getCurrentTag, 0x70ead08e)                    \
   V(::, _isDartStreamEnabled, Timeline_isDartStreamEnabled, 0xc97aafb3)        \

runtime/vm/dart_api_impl.cc

@@ -7011,4 +7011,53 @@ DART_EXPORT void Dart_PrepareToAbort() {
   OS::PrepareToAbort();
 }
 
+DART_EXPORT Dart_Handle Dart_GetCurrentUserTag() {
+  Thread* thread = Thread::Current();
+  CHECK_ISOLATE(thread->isolate());
+  DARTSCOPE(thread);
+  Isolate* isolate = thread->isolate();
+  return Api::NewHandle(thread, isolate->current_tag());
+}
+
+DART_EXPORT Dart_Handle Dart_GetDefaultUserTag() {
+  Thread* thread = Thread::Current();
+  CHECK_ISOLATE(thread->isolate());
+  DARTSCOPE(thread);
+  Isolate* isolate = thread->isolate();
+  return Api::NewHandle(thread, isolate->default_tag());
+}
+
+DART_EXPORT Dart_Handle Dart_NewUserTag(const char* label) {
+  Thread* thread = Thread::Current();
+  CHECK_ISOLATE(thread->isolate());
+  DARTSCOPE(thread);
+  if (label == nullptr) {
+    return Api::NewError(
+        "Dart_NewUserTag expects argument 'label' to be non-null");
+  }
+  const String& value = String::Handle(String::New(label));
+  return Api::NewHandle(thread, UserTag::New(value));
+}
+
+DART_EXPORT Dart_Handle Dart_SetCurrentUserTag(Dart_Handle user_tag) {
+  Thread* thread = Thread::Current();
+  CHECK_ISOLATE(thread->isolate());
+  DARTSCOPE(thread);
+  const UserTag& tag = Api::UnwrapUserTagHandle(Z, user_tag);
+  if (tag.IsNull()) {
+    RETURN_TYPE_ERROR(Z, user_tag, UserTag);
+  }
+  return Api::NewHandle(thread, tag.MakeActive());
+}
+
+DART_EXPORT char* Dart_GetUserTagLabel(Dart_Handle user_tag) {
+  DARTSCOPE(Thread::Current());
+  const UserTag& tag = Api::UnwrapUserTagHandle(Z, user_tag);
+  if (tag.IsNull()) {
+    return nullptr;
+  }
+  const String& label = String::Handle(Z, tag.label());
+  return Utils::StrDup(label.ToCString());
+}
+
 }  // namespace dart

runtime/vm/dart_api_impl_test.cc

@@ -9363,6 +9363,52 @@ TEST_CASE(Dart_SetFfiNativeResolver_DoesNotResolve) {
       "Invalid argument(s): Couldn't resolve function: 'DoesNotResolve'");
 }
 
+TEST_CASE(DartAPI_UserTags) {
+  Dart_Handle default_tag = Dart_GetDefaultUserTag();
+  EXPECT_VALID(default_tag);
+
+  auto default_label =
+      Utils::CStringUniquePtr(Dart_GetUserTagLabel(default_tag), std::free);
+  EXPECT_STREQ(default_label.get(), "Default");
+
+  Dart_Handle current_tag = Dart_GetCurrentUserTag();
+  EXPECT(Dart_IdentityEquals(default_tag, current_tag));
+
+  auto current_label =
+      Utils::CStringUniquePtr(Dart_GetUserTagLabel(current_tag), std::free);
+  EXPECT_STREQ(default_label.get(), current_label.get());
+
+  Dart_Handle new_tag = Dart_NewUserTag("Foo");
+  EXPECT_VALID(new_tag);
+
+  auto new_tag_label =
+      Utils::CStringUniquePtr(Dart_GetUserTagLabel(new_tag), std::free);
+  EXPECT_STREQ(new_tag_label.get(), "Foo");
+
+  Dart_Handle old_tag = Dart_SetCurrentUserTag(new_tag);
+  EXPECT_VALID(old_tag);
+
+  auto old_label =
+      Utils::CStringUniquePtr(Dart_GetUserTagLabel(old_tag), std::free);
+  EXPECT_STREQ(old_label.get(), default_label.get());
+
+  current_tag = Dart_GetCurrentUserTag();
+  EXPECT(Dart_IdentityEquals(new_tag, current_tag));
+
+  current_label =
+      Utils::CStringUniquePtr(Dart_GetUserTagLabel(current_tag), std::free);
+  EXPECT_STREQ(current_label.get(), new_tag_label.get());
+
+  EXPECT(Dart_GetUserTagLabel(Dart_Null()) == nullptr);
+
+  EXPECT_ERROR(Dart_NewUserTag(nullptr),
+               "Dart_NewUserTag expects argument 'label' to be non-null");
+
+  EXPECT_ERROR(
+      Dart_SetCurrentUserTag(Dart_Null()),
+      "Dart_SetCurrentUserTag expects argument 'user_tag' to be non-null");
+}
+
 #endif  // !PRODUCT
 
 }  // namespace dart

runtime/vm/object.cc

@@ -25690,10 +25690,25 @@ const char* MirrorReference::ToCString() const {
   return "_MirrorReference";
 }
 
-void UserTag::MakeActive() const {
+UserTagPtr UserTag::MakeActive() const {
   Isolate* isolate = Isolate::Current();
   ASSERT(isolate != NULL);
+  UserTag& old = UserTag::Handle(isolate->current_tag());
   isolate->set_current_tag(*this);
+
+#if !defined(PRODUCT)
+  // Notify VM service clients that the current UserTag has changed.
+  if (Service::profiler_stream.enabled()) {
+    ServiceEvent event(ServiceEvent::kUserTagChanged);
+    String& name = String::Handle(old.label());
+    event.set_previous_tag(name.ToCString());
+    name ^= label();
+    event.set_updated_tag(name.ToCString());
+    Service::HandleEvent(&event);
+  }
+#endif  // !defined(PRODUCT)
+
+  return old.ptr();
 }
 
 UserTagPtr UserTag::New(const String& label, Heap::Space space) {

runtime/vm/object.h

@@ -11559,7 +11559,7 @@ class UserTag : public Instance {
 
   StringPtr label() const { return untag()->label(); }
 
-  void MakeActive() const;
+  UserTagPtr MakeActive() const;
 
   static intptr_t InstanceSize() {
     return RoundedAllocationSize(sizeof(UntaggedUserTag));

runtime/vm/object_test.cc

@@ -4605,7 +4605,7 @@ ISOLATE_UNIT_TEST_CASE(PrintJSONPrimitives) {
         "vmName\":\"\",\"location\":{\"type\":\"SourceLocation\",\"script\":{"
         "\"type\":\"@Script\",\"fixedId\":true,\"id\":\"\",\"uri\":\"dart:"
         "developer-patch\\/profiler.dart\",\"_kind\":\"kernel\"},\"tokenPos\":"
-        "414,\"endTokenPos\":672},\"library\":{\"type\":\"@Library\","
+        "414,\"endTokenPos\":628},\"library\":{\"type\":\"@Library\","
         "\"fixedId\":true,\"id\":\"\",\"name\":\"dart.developer\",\"uri\":"
         "\"dart:developer\"}},"
         // Handle non-zero identity hash.

runtime/vm/service.cc

@@ -128,16 +128,18 @@ StreamInfo Service::heapsnapshot_stream("HeapSnapshot");
 StreamInfo Service::logging_stream("Logging");
 StreamInfo Service::extension_stream("Extension");
 StreamInfo Service::timeline_stream("Timeline");
+StreamInfo Service::profiler_stream("Profiler");
 
 const uint8_t* Service::dart_library_kernel_ = NULL;
 intptr_t Service::dart_library_kernel_len_ = 0;
 
 static StreamInfo* const streams_[] = {
-    &Service::vm_stream,      &Service::isolate_stream,
-    &Service::debug_stream,   &Service::gc_stream,
-    &Service::echo_stream,    &Service::heapsnapshot_stream,
-    &Service::logging_stream, &Service::extension_stream,
-    &Service::timeline_stream};
+    &Service::vm_stream,       &Service::isolate_stream,
+    &Service::debug_stream,    &Service::gc_stream,
+    &Service::echo_stream,     &Service::heapsnapshot_stream,
+    &Service::logging_stream,  &Service::extension_stream,
+    &Service::timeline_stream, &Service::profiler_stream,
+};
 
 bool Service::ListenStream(const char* stream_id) {
   if (FLAG_trace_service) {

runtime/vm/service.h

@@ -15,7 +15,7 @@
 namespace dart {
 
 #define SERVICE_PROTOCOL_MAJOR_VERSION 3
-#define SERVICE_PROTOCOL_MINOR_VERSION 47
+#define SERVICE_PROTOCOL_MINOR_VERSION 48
 
 class Array;
 class EmbedderServiceHandler;
@@ -171,6 +171,7 @@ class Service : public AllStatic {
   static StreamInfo logging_stream;
   static StreamInfo extension_stream;
   static StreamInfo timeline_stream;
+  static StreamInfo profiler_stream;
 
   static bool ListenStream(const char* stream_id);
   static void CancelStream(const char* stream_id);

runtime/vm/service/service.md

@@ -1,8 +1,8 @@
-# Dart VM Service Protocol 3.47
+# Dart VM Service Protocol 3.48
 
 > Please post feedback to the [observatory-discuss group][discuss-list]
 
-This document describes of _version 3.47_ of the Dart VM Service Protocol. This
+This document describes of _version 3.48_ 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.
@@ -1477,6 +1477,7 @@ streamId | event types provided
 VM | VMUpdate, VMFlagUpdate
 Isolate | IsolateStart, IsolateRunnable, IsolateExit, IsolateUpdate, IsolateReload, ServiceExtensionAdded
 Debug | PauseStart, PauseExit, PauseBreakpoint, PauseInterrupted, PauseException, PausePostRequest, Resume, BreakpointAdded, BreakpointResolved, BreakpointRemoved, BreakpointUpdated, Inspect, None
+Profiler | UserTagChanged
 GC | GC
 Extension | Extension
 Timeline | TimelineEvents, TimelineStreamsSubscriptionUpdate
@@ -2154,6 +2155,12 @@ class Event extends Response {
   // This is provided for the event kinds:
   //   HeapSnapshot
   bool last [optional];
+
+  // The current UserTag label.
+  string updatedTag [optional];
+
+  // The previous UserTag label.
+  string previousTag [optional];
 }
 ```
 
@@ -2264,6 +2271,9 @@ enum EventKind {
   // Notification that a Service has been removed from the Service Protocol
   // from another client.
   ServiceUnregistered,
+
+  // Notification that the UserTag for an isolate has been changed.
+  UserTagChanged,
 }
 ```
 
@@ -4058,5 +4068,6 @@ version | comments
 3.45 | Added `setBreakpointState` RPC and `BreakpointUpdated` event kind.
 3.46 | Moved `sourceLocation` property into reference types for `Class`, `Field`, and `Function`.
 3.47 | Added `shows` and `hides` properties to `LibraryDependency`.
+3.48 | Added `Profiler` stream, `UserTagChanged` event kind, and `updatedTag` and `previousTag` properties to `Event`.
 
 [discuss-list]: https://groups.google.com/a/dartlang.org/forum/#!forum/observatory-discuss

runtime/vm/service_event.cc

@@ -28,22 +28,24 @@ ServiceEvent::ServiceEvent(IsolateGroup* isolate_group,
     : isolate_(isolate),
       isolate_group_(isolate_group),
       kind_(event_kind),
-      flag_name_(NULL),
-      flag_new_value_(NULL),
-      embedder_kind_(NULL),
-      embedder_stream_id_(NULL),
-      breakpoint_(NULL),
-      top_frame_(NULL),
-      timeline_event_block_(NULL),
-      extension_rpc_(NULL),
-      exception_(NULL),
-      reload_error_(NULL),
-      spawn_token_(NULL),
-      spawn_error_(NULL),
+      flag_name_(nullptr),
+      flag_new_value_(nullptr),
+      previous_tag_(nullptr),
+      updated_tag_(nullptr),
+      embedder_kind_(nullptr),
+      embedder_stream_id_(nullptr),
+      breakpoint_(nullptr),
+      top_frame_(nullptr),
+      timeline_event_block_(nullptr),
+      extension_rpc_(nullptr),
+      exception_(nullptr),
+      reload_error_(nullptr),
+      spawn_token_(nullptr),
+      spawn_error_(nullptr),
       at_async_jump_(false),
-      inspectee_(NULL),
-      gc_stats_(NULL),
-      bytes_(NULL),
+      inspectee_(nullptr),
+      gc_stats_(nullptr),
+      bytes_(nullptr),
       bytes_length_(0),
       timestamp_(OS::GetCurrentTimeMillis()) {
   // We should never generate events for the vm isolate as it is never reported
@@ -137,6 +139,8 @@ const char* ServiceEvent::KindAsCString() const {
       return "TimelineEvents";
     case kTimelineStreamSubscriptionsUpdate:
       return "TimelineStreamSubscriptionsUpdate";
+    case kUserTagChanged:
+      return "UserTagChanged";
     default:
       UNREACHABLE();
       return "Unknown";
@@ -187,11 +191,14 @@ const StreamInfo* ServiceEvent::stream_info() const {
       return &Service::timeline_stream;
 
     case kEmbedder:
-      return NULL;
+      return nullptr;
+
+    case kUserTagChanged:
+      return &Service::profiler_stream;
 
     default:
       UNREACHABLE();
-      return NULL;
+      return nullptr;
   }
 }
 
@@ -213,6 +220,10 @@ void ServiceEvent::PrintJSON(JSONStream* js) const {
     // For backwards compatibility, "new_value" is also provided.
     jsobj.AddProperty("newValue", flag_new_value());
   }
+  if (kind() == kUserTagChanged) {
+    jsobj.AddProperty("previousTag", previous_tag());
+    jsobj.AddProperty("updatedTag", updated_tag());
+  }
   if (kind() == kIsolateReload) {
     if (reload_error_ == NULL) {
       jsobj.AddProperty("status", "success");

runtime/vm/service_event.h

@@ -60,6 +60,8 @@ class ServiceEvent {
     // Sent when SetVMTimelineFlags is called.
     kTimelineStreamSubscriptionsUpdate,
 
+    kUserTagChanged,
+
     kIllegal,
   };
 
@@ -111,6 +113,14 @@ class ServiceEvent {
   const char* flag_new_value() const { return flag_new_value_; }
   void set_flag_new_value(const char* value) { flag_new_value_ = value; }
 
+  const char* previous_tag() const { return previous_tag_; }
+  void set_previous_tag(const char* previous_tag) {
+    previous_tag_ = previous_tag;
+  }
+
+  const char* updated_tag() const { return updated_tag_; }
+  void set_updated_tag(const char* updated_tag) { updated_tag_ = updated_tag; }
+
   const char* embedder_kind() const { return embedder_kind_; }
 
   const char* KindAsCString() const;
@@ -217,6 +227,8 @@ class ServiceEvent {
   EventKind kind_;
   const char* flag_name_;
   const char* flag_new_value_;
+  const char* previous_tag_;
+  const char* updated_tag_;
   const char* embedder_kind_;
   const char* embedder_stream_id_;
   Breakpoint* breakpoint_;

sdk/lib/_internal/vm/lib/profiler.dart

@@ -18,7 +18,6 @@ class UserTag {
 class _UserTag implements UserTag {
   factory _UserTag(String label) native "UserTag_new";
   String get label native "UserTag_label";
-  @pragma("vm:recognized", "asm-intrinsic")
   UserTag makeCurrent() native "UserTag_makeCurrent";
 }