- Add assertions in MutexLocker/MonitorLocker to ensure that the code enclosed

runtime/vm/os_thread_win.cc

 // 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.
 
 #include "platform/globals.h"  // NOLINT
 #if defined(TARGET_OS_WINDOWS)
 
 #include "vm/growable_array.h"
 #include "vm/os_thread.h"
 
@@ skipping 287 matching lines @@
 #if defined(DEBUG)
   // When running with assertions enabled we track the owner.
   ASSERT(owner_ == OSThread::kInvalidThreadId);
 #endif  // defined(DEBUG)
 
   DeleteCriticalSection(&data_.cs_);
   DeleteCriticalSection(&data_.waiters_cs_);
 }
 
 
+bool Mutex::TryEnter() {
+  // Attempt to pass the semaphore but return immediately.
+  BOOL result = TryEnterCriticalSection(&data_.cs_);
+  if (!result) {
+    return false;
+  }
+#if defined(DEBUG)
+  // When running with assertions enabled we do track the owner.
+  ASSERT(owner_ == OSThread::kInvalidThreadId);
+  owner_ = OSThread::GetCurrentThreadId();
+#endif  // defined(DEBUG)
+  return true;
+}
+
+
 void Monitor::Enter() {
   EnterCriticalSection(&data_.cs_);
 
 #if defined(DEBUG)
   // When running with assertions enabled we track the owner.
   ASSERT(owner_ == OSThread::kInvalidThreadId);
   owner_ = OSThread::GetCurrentThreadId();
 #endif  // defined(DEBUG)
 }
 
@@ skipping 380 matching lines @@
 #pragma data_seg(".CRT$XLB")
 PIMAGE_TLS_CALLBACK p_thread_callback_dart = OnDartThreadExit;
 
 // Reset the default section.
 #pragma data_seg()
 
 #endif  // _WIN64
 }  // extern "C"
 
 #endif  // defined(TARGET_OS_WINDOWS)