Implement safepointing of threads

runtime/vm/os_thread.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_OS_THREAD_H_
 #define VM_OS_THREAD_H_
 
 #include "platform/globals.h"
 #include "vm/allocation.h"
 #include "vm/globals.h"
@@ skipping 219 matching lines @@
 
   // thread_list_lock_ cannot have a static lifetime because the order in which
   // destructors run is undefined. At the moment this lock cannot be deleted
   // either since otherwise, if a thread only begins to run after we have
   // started to run TLS destructors for a call to exit(), there will be a race
   // on its deletion in CreateOSThread().
   static Mutex* thread_list_lock_;
   static OSThread* thread_list_head_;
   static bool creation_enabled_;
 
+  friend class Isolate;  // to access set_thread(Thread*).
   friend class OSThreadIterator;
   friend class ThreadInterrupterWin;
-  friend class ThreadRegistry;
 };
 
 
 // Note that this takes the thread list lock, prohibiting threads from coming
 // on- or off-line.
 class OSThreadIterator : public ValueObject {
  public:
   OSThreadIterator();
   ~OSThreadIterator();
 
@@ skipping 79 matching lines @@
 #endif  // defined(DEBUG)
 
   DISALLOW_COPY_AND_ASSIGN(Monitor);
 };
 
 
 }  // namespace dart
 
 
 #endif  // VM_OS_THREAD_H_