Add an IsolateRunnable event to the service protocol. Improve service docs.

Closes #24140

R=johnmccutchan@google.com

Review URL: https://codereview.chromium.org//1293383011 .

runtime/observatory/lib/src/app/application.dart

@@ -89,6 +89,7 @@ class ObservatoryApplication extends Observable {
   void _onEvent(ServiceEvent event) {
     switch(event.kind) {
       case ServiceEvent.kIsolateStart:
+      case ServiceEvent.kIsolateRunnable:
       case ServiceEvent.kIsolateUpdate:
       case ServiceEvent.kBreakpointAdded:
       case ServiceEvent.kBreakpointResolved:

runtime/observatory/lib/src/elements/debugger.dart

@@ -1482,10 +1482,11 @@ class ObservatoryDebugger extends Debugger {
         }
         break;
 
-      case ServiceEvent.kIsolateStart:
+      case ServiceEvent.kIsolateRunnable:
       case ServiceEvent.kGraph:
       case ServiceEvent.kGC:
       case ServiceEvent.kInspect:
+        // Ignore.
         break;
 
       case ServiceEvent.kLogging:

runtime/observatory/lib/src/service/object.dart

@@ -1334,6 +1334,7 @@ class Isolate extends ServiceObjectOwner with Coverage {
   void _onEvent(ServiceEvent event) {
     switch(event.kind) {
       case ServiceEvent.kIsolateStart:
+      case ServiceEvent.kIsolateRunnable:
       case ServiceEvent.kIsolateExit:
       case ServiceEvent.kInspect:
         // Handled elsewhere.
@@ -1706,6 +1707,7 @@ Level _findLogLevel(int value) {
 class ServiceEvent extends ServiceObject {
   /// The possible 'kind' values.
   static const kIsolateStart           = 'IsolateStart';
+  static const kIsolateRunnable        = 'IsolateRunnable';
   static const kIsolateExit            = 'IsolateExit';
   static const kIsolateUpdate          = 'IsolateUpdate';
   static const kPauseStart             = 'PauseStart';

runtime/observatory/tests/service/isolate_lifecycle_test.dart

@@ -4,6 +4,7 @@
 // VMOptions=--error_on_bad_type --error_on_bad_override
 
 import 'dart:async';
+import 'dart:developer';
 import 'dart:isolate' as I;
 
 import 'package:observatory/service_io.dart';
@@ -18,7 +19,8 @@ final isolates = [];
 void spawnEntry(int i) {
 }
 
-Future before() async {
+Future during() async {
+  debugger();
   // Spawn spawnCount long lived isolates.
   for (var i = 0; i < spawnCount; i++) {
     var isolate = await I.Isolate.spawn(spawnEntry, i);
@@ -27,9 +29,6 @@ Future before() async {
   print('spawned all isolates');
 }
 
-Future during() async {
-}
-
 int numPaused(vm) {
   int paused = 0;
   for (var isolate in vm.isolates) {
@@ -41,21 +40,34 @@ int numPaused(vm) {
 }
 
 var tests = [
+  (VM vm) async {
+    expect(vm.isolates.length, 1);
+    await hasStoppedAtBreakpoint(vm.isolates[0]);
+  },
+
   (VM vm) async {
     Completer completer = new Completer();
     var stream = await vm.getEventStream(VM.kIsolateStream);
-    if (vm.isolates.length < spawnCount + 1) {
-      var subscription;
-      subscription = stream.listen((ServiceEvent event) {
-        if (event.kind == ServiceEvent.kIsolateStart) {
-          if (vm.isolates.length == (spawnCount + 1)) {
-            subscription.cancel();
-            completer.complete(null);
-          }
-        }
-      });
-      await completer.future;
-    }
+    var subscription;
+    int startCount = 0;
+    int runnableCount = 0;
+    subscription = stream.listen((ServiceEvent event) {
+      if (event.kind == ServiceEvent.kIsolateStart) {
+        startCount++;
+      }
+      if (event.kind == ServiceEvent.kIsolateRunnable) {
+        runnableCount++;
+      }
+      if (runnableCount == spawnCount) {
+        subscription.cancel();
+        completer.complete(null);
+      }
+    });
+    expect(vm.isolates.length, 1);
+    vm.isolates[0].resume();
+    await completer.future;
+    expect(startCount, spawnCount);
+    expect(runnableCount, spawnCount);
     expect(vm.isolates.length, spawnCount + 1);
   },
 
@@ -124,6 +136,5 @@ var tests = [
 ];
 
 main(args) async => runVMTests(args, tests,
-                               testeeBefore: before,
                                testeeConcurrent: during,
                                pause_on_exit: true);

runtime/vm/isolate.cc

@@ -1015,6 +1015,10 @@ bool Isolate::MakeRunnable() {
     event->Instant("Runnable");
     event->Complete();
   }
+  if (Service::isolate_stream.enabled()) {
+    ServiceEvent runnableEvent(this, ServiceEvent::kIsolateRunnable);
+    Service::HandleEvent(&runnableEvent);
+  }
   return true;
 }
 
@@ -1704,7 +1708,9 @@ void Isolate::PrintJSON(JSONStream* stream, bool ref) {
 
   const Library& lib =
       Library::Handle(object_store()->root_library());
-  jsobj.AddProperty("rootLib", lib);
+  if (!lib.IsNull()) {
+    jsobj.AddProperty("rootLib", lib);
+  }
 
   timer_list().PrintTimersToJSONProperty(&jsobj);
   {

runtime/vm/service/service.md

@@ -620,7 +620,7 @@ The _streamId_ parameter may have the following published values:
 
 streamId | event types provided
 -------- | -----------
-Isolate | IsolateStart, IsolateExit, IsolateUpdate
+Isolate | IsolateStart, IsolateRunnable, IsolateExit, IsolateUpdate
 Debug | PauseStart, PauseExit, PauseBreakpoint, PauseInterrupted, PauseException, Resume, BreakpointAdded, BreakpointResolved, BreakpointRemoved, Inspect
 GC | GC
 
@@ -1017,6 +1017,9 @@ enum EventKind {
   // Notification that a new isolate has started.
   IsolateStart,
 
+  // Notification that an isolate is ready to run.
+  IsolateRunnable,
+
   // Notification that an isolate has exited.
   IsolateExit,
 
@@ -1581,9 +1584,6 @@ class Isolate extends Response {
   // Suitable to pass to DateTime.fromMillisecondsSinceEpoch.
   int startTime;
 
-  // The entry function for this isolate.
-  @Function entry [optional];
-
   // The number of live ports for this isolate.
   int livePorts;
 
@@ -1594,17 +1594,26 @@ class Isolate extends Response {
   // running, this will be a resume event.
   Event pauseEvent;
 
-  // The error that is causing this isolate to exit, if applicable.
-  Error error [optional];
+  // The entry function for this isolate.
+  //
+  // Guaranteed to be initialized when the IsolateRunnable event fires.
+  @Function entry [optional];
 
   // The root library for this isolate.
-  @Library rootLib;
+  //
+  // Guaranteed to be initialized when the IsolateRunnable event fires.
+  @Library rootLib [optional];
 
   // A list of all libraries for this isolate.
+  //
+  // Guaranteed to be initialized when the IsolateRunnable event fires.
   @Library[] libraries;
 
   // A list of all breakpoints for this isolate.
   Breakpoint[] breakpoints;
+
+  // The error that is causing this isolate to exit, if applicable.
+  Error error [optional];
 }
 ```
 

runtime/vm/service_event.cc

@@ -62,6 +62,8 @@ const char* ServiceEvent::KindAsCString() const {
   switch (kind()) {
     case kIsolateStart:
       return "IsolateStart";
+    case kIsolateRunnable:
+      return "IsolateRunnable";
     case kIsolateExit:
       return "IsolateExit";
     case kIsolateUpdate:
@@ -106,6 +108,7 @@ const char* ServiceEvent::KindAsCString() const {
 const char* ServiceEvent::stream_id() const {
   switch (kind()) {
     case kIsolateStart:
+    case kIsolateRunnable:
     case kIsolateExit:
     case kIsolateUpdate:
       return Service::isolate_stream.id();

runtime/vm/service_event.h

@@ -15,6 +15,7 @@ class ServiceEvent {
  public:
   enum EventKind {
     kIsolateStart,       // New isolate has started
+    kIsolateRunnable,    // Isolate is ready to run
     kIsolateExit,        // Isolate has exited
     kIsolateUpdate,      // Isolate identity information has changed