Make service protocol respect isolate lifecycle

runtime/vm/isolate.cc

Index: runtime/vm/isolate.cc
diff --git a/runtime/vm/isolate.cc b/runtime/vm/isolate.cc
index 4172327255161565a66b914e5e0008df5877e423..52c3c4553772e7b09d12d5a01e8b1140c798cc2b 100644
--- a/runtime/vm/isolate.cc
+++ b/runtime/vm/isolate.cc
@@ -1995,11 +1995,22 @@ void Isolate::PrintJSON(JSONStream* stream, bool ref) {
     ASSERT((debugger() == NULL) || (debugger()->PauseEvent() == NULL));
     ServiceEvent pause_event(this, ServiceEvent::kNone);
     jsobj.AddProperty("pauseEvent", &pause_event);
-  } else if (message_handler()->is_paused_on_start() ||
-             message_handler()->should_pause_on_start()) {
-    ASSERT((debugger() == NULL) || (debugger()->PauseEvent() == NULL));
-    ServiceEvent pause_event(this, ServiceEvent::kPauseStart);
-    jsobj.AddProperty("pauseEvent", &pause_event);
+  } else if (message_handler()->should_pause_on_start()) {
+    if (message_handler()->is_paused_on_start()) {

[siva, 2017/08/30 23:56:30]

Access to should_pause_on_start and is_paused_on_start still seem racy but I
guess you made sure the state shown is an earlier state which is safer than
showing a newer state.

+      ASSERT((debugger() == NULL) || (debugger()->PauseEvent() == NULL));
+      ServiceEvent pause_event(this, ServiceEvent::kPauseStart);
+      jsobj.AddProperty("pauseEvent", &pause_event);
+    } else {
+      // Isolate is runnable but not paused on start.
+      // Some service clients get confused if they see:
+      // NotRunnable -> Runnable -> PausedAtStart
+      // Treat Runnable+ShouldPauseOnStart as NotRunnable so they see:
+      // NonRunnable -> PausedAtStart
+      // The should_pause_on_start flag is set to false after resume.
+      ASSERT((debugger() == NULL) || (debugger()->PauseEvent() == NULL));
+      ServiceEvent pause_event(this, ServiceEvent::kNone);
+      jsobj.AddProperty("pauseEvent", &pause_event);
+    }
   } else if (message_handler()->is_paused_on_exit() &&
              ((debugger() == NULL) || (debugger()->PauseEvent() == NULL))) {
     ServiceEvent pause_event(this, ServiceEvent::kPauseExit);