Reimplement Windows Monitors.

runtime/platform/thread_win.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 PLATFORM_THREAD_WIN_H_
 #define PLATFORM_THREAD_WIN_H_
 
 #if !defined(PLATFORM_THREAD_H_)
 #error Do not include thread_win.h directly; use thread.h instead.
 #endif
@@ skipping 30 matching lines @@
 
   HANDLE semaphore_;
 
   friend class Mutex;
 
   DISALLOW_ALLOCATION();
   DISALLOW_COPY_AND_ASSIGN(MutexData);
 };
 
 
+class MonitorWaitData {
+ private:
+  explicit MonitorWaitData(HANDLE event) : event_(event), next_(NULL) {}
+
+  // ThreadLocalKey used to fetch and store the MonitorWaitData object
+  // for a given thread.
+  static ThreadLocalKey monitor_wait_data_key_;
+
+  // Auto-reset event used for waiting.
+  HANDLE event_;
+  // Link to next element in the singly-linked list of waiters.
+  MonitorWaitData* next_;
+
+  friend class Monitor;
+  friend class MonitorData;
+
+  DISALLOW_COPY_AND_ASSIGN(MonitorWaitData);
+};
+
+
 class MonitorData {
  private:
   MonitorData() {}
   ~MonitorData() {}
 
+  // Helper methods to manipulate the list of waiters for this
+  // monitor.
+  void AddWaiter(MonitorWaitData* wait_data);
+  void RemoveWaiter(MonitorWaitData* wait_data);
+  void SignalAndRemoveFirstWaiter();
+  void SignalAndRemoveAllWaiters();
+  MonitorWaitData* GetMonitorWaitDataForThread();
+
+  // The external critical section for the monitor.
   CRITICAL_SECTION cs_;
 
   // Condition variables are only available since Windows Vista. To
   // support at least Windows XP, we implement our own condition
   // variables using SetEvent on Event objects.
 
-  // The notify_event_ is an auto-reset event which means that
-  // SetEvent only wakes up one waiter.
-  HANDLE notify_event_;
-
-  // The notify_all_event_ is a manual-reset event which means that
-  // SetEvent wakes up all waiters.
-  HANDLE notify_all_event_;
-
-  // Counter with protection used to determine the right time to reset
-  // the notify_all_event_.
+  // Singly-linked list of event objects, one for each thread waiting
+  // on this monitor. New waiters are added at the end of the list.
+  // Notify signals the first element of the list (FIFO
+  // order). NotifyAll, signals all the elements of the list.
   CRITICAL_SECTION waiters_cs_;
-  intptr_t waiters_;
+  MonitorWaitData* waiters_head_;
+  MonitorWaitData* waiters_tail_;
 
   friend class Monitor;
 
   DISALLOW_ALLOCATION();
   DISALLOW_COPY_AND_ASSIGN(MonitorData);
 };
 
 }  // namespace dart
 
 #endif  // PLATFORM_THREAD_WIN_H_