Add locker support to DebugMessageDispatchHandler

src/v8threads.h

Index: src/v8threads.h
diff --git a/src/v8threads.h b/src/v8threads.h
index 06840532812ee9133e1d8160a14492e64d9d04db..9fa6f0eaf91f8ec3e61914e5b5926e0fda077dea 100644
--- a/src/v8threads.h
+++ b/src/v8threads.h
@@ -29,6 +29,11 @@
 #define V8_V8THREADS_H_
 
 namespace v8 {
+
+struct LockParameters {
+  bool successfully_relaied;
+};
+
 namespace internal {
 
 
@@ -78,12 +83,43 @@ class ThreadState {
   static ThreadState* in_use_anchor_;
 };
 
+#ifdef ENABLE_DEBUGGER_SUPPORT
+
+struct Promises {
+  bool promise_to_process_debug_commands;
+  void Reset() {
+    promise_to_process_debug_commands = false;
+  }
+};
+
+// This mutex has an additional feature: you may try acquire it if it's free or
+// ASK someone who owns it right now to do a particular chore for you before
+// releasing it. The current owner is guaranteed to NOTICE your ask.
+class MutexWithResponsibilities {
+ public:
+  MutexWithResponsibilities();
+  ~MutexWithResponsibilities();
+  void Lock();
+  bool LockOrAsk(bool Promises::* promise);
+  void Unlock();
+
+ private:
+  Mutex* flag_mutex_;
+  Semaphore* sem_;
+  bool locked_;
+  bool has_promises_;
+  Promises promises_;
+};
+#endif
 
 class ThreadManager : public AllStatic {
  public:
   static void Lock();
   static void Unlock();
 
+#ifdef ENABLE_DEBUGGER_SUPPORT
+  static bool LockOrAsk(bool Promises::* promise);
+#endif
   static void ArchiveThread();
   static bool RestoreThread();
   static void FreeThreadResources();
@@ -105,7 +141,11 @@ class ThreadManager : public AllStatic {
   static void EagerlyArchiveThread();
 
   static int last_id_;  // V8 threads are identified through an integer.
+#ifdef ENABLE_DEBUGGER_SUPPORT
+  static MutexWithResponsibilities* mutex_;
+#else
   static Mutex* mutex_;
+#endif
   static ThreadHandle mutex_owner_;
   static ThreadHandle lazily_archived_thread_;
   static ThreadState* lazily_archived_thread_state_;