Add isolate tag-profile and better handling of errors

runtime/vm/isolate.cc

Index: runtime/vm/isolate.cc
diff --git a/runtime/vm/isolate.cc b/runtime/vm/isolate.cc
index 673fa0b72f1f76797b4c546e470f302248403245..b95c4c35deb365959f595aef5f1103d3bb7fd7fe 100644
--- a/runtime/vm/isolate.cc
+++ b/runtime/vm/isolate.cc
@@ -368,9 +368,11 @@ void Isolate::SetCurrent(Isolate* current) {
   if (old_current != NULL) {
     old_current->set_thread_state(NULL);
     Profiler::EndExecution(old_current);
+    old_current->set_vm_tag(VMTag::kIdleTagId);
   }
   Thread::SetThreadLocal(isolate_key, reinterpret_cast<uword>(current));
   if (current != NULL) {
+    current->set_vm_tag(VMTag::kVMTagId);
     ASSERT(current->thread_state() == NULL);
     InterruptableThreadState* thread_state =
         ThreadInterrupter::GetCurrentThreadState();
@@ -923,6 +925,12 @@ void Isolate::PrintToJSONStream(JSONStream* stream, bool ref) {
 
   timer_list().PrintTimersToJSONProperty(&jsobj);
 
+  if (object_store()->sticky_error() != Object::null()) {
+    Error& error = Error::Handle(this, object_store()->sticky_error());
+    ASSERT(!error.IsNull());
+    jsobj.AddProperty("stickyError", error, false);

[turnidge, 2014/03/24 20:22:13]

rename to "error"?

[Cutch, 2014/03/25 14:39:06]

Done.

+  }
+
   {
     JSONObject typeargsRef(&jsobj, "canonicalTypeArguments");
     typeargsRef.AddProperty("type", "@TypeArgumentsList");
@@ -932,6 +940,23 @@ void Isolate::PrintToJSONStream(JSONStream* stream, bool ref) {
 }
 
 
+void Isolate::ProfileInterrupt() {
+  InterruptableThreadState* state = thread_state();
+  if (state == NULL) {
+    // Isolate is not scheduled on a thread.
+    ProfileIdle();
+    return;
+  }
+  ASSERT(state->id != Thread::kInvalidThreadId);
+  ThreadInterrupter::InterruptThread(state);
+}
+
+
+void Isolate::ProfileIdle() {
+  vm_tag_counters_.Increment(vm_tag());

[turnidge, 2014/03/24 20:22:13]

Is the vm_tag always the kIdleTagId here?  Or are there other possibilities?

[Cutch, 2014/03/25 14:39:06]

It will always be kIdleTagId or kVMTagId (there is a race because we update the
tag without taking any locks).

+}
+
+
 void Isolate::VisitIsolates(IsolateVisitor* visitor) {
   if (visitor == NULL) {
     return;