Endless thread safe timeline recorder

runtime/vm/thread.h

Index: runtime/vm/thread.h
diff --git a/runtime/vm/thread.h b/runtime/vm/thread.h
index 746d25ee616f16fa13d8e80eef71ce316c0f5d7e..c0721d9b1daf4ae688e686beb97e07b602d2af62 100644
--- a/runtime/vm/thread.h
+++ b/runtime/vm/thread.h
@@ -20,6 +20,7 @@ class Object;
 class RawBool;
 class RawObject;
 class StackResource;
+class TimelineEventBlock;
 class Zone;
 
 
@@ -197,6 +198,7 @@ class Thread {
     Zone* zone;
     uword top_exit_frame_info;
     StackResource* top_resource;
+    TimelineEventBlock* timeline_block;
     // TODO(koda): Migrate individual fields of InterruptableThreadState.
     InterruptableThreadState* thread_state;
 #if defined(DEBUG)
@@ -216,6 +218,14 @@ CACHED_CONSTANTS_LIST(DEFINE_OFFSET_METHOD)
   static bool CanLoadFromThread(const Object& object);
   static intptr_t OffsetFromThread(const Object& object);
 
+  TimelineEventBlock* timeline_block() const {
+    return state_.timeline_block;
+  }
+
+  void set_timeline_block(TimelineEventBlock* block) {
+    state_.timeline_block = block;
+  }
+
  private:
   static ThreadLocalKey thread_key_;