Index: chrome_frame/scoped_initialization_manager.h |
diff --git a/chrome_frame/scoped_initialization_manager.h b/chrome_frame/scoped_initialization_manager.h |
new file mode 100644 |
index 0000000000000000000000000000000000000000..0a22f4ffedd5e04a396ef76dcb411fd69f69da54 |
--- /dev/null |
+++ b/chrome_frame/scoped_initialization_manager.h |
@@ -0,0 +1,54 @@ |
+// Copyright 2013 The Chromium Authors. All rights reserved. |
+// Use of this source code is governed by a BSD-style license that can be |
+// found in the LICENSE file. |
+ |
+#ifndef CHROME_FRAME_SCOPED_INITIALIZATION_MANAGER_H_ |
+#define CHROME_FRAME_SCOPED_INITIALIZATION_MANAGER_H_ |
+ |
+#include "base/basictypes.h" |
+#include "base/lazy_instance.h" |
+#include "base/synchronization/lock.h" |
+ |
+namespace chrome_frame { |
+ |
+// A class intended to be instantiated on the stack in a dyanmically loaded |
+// shared object to initialize and shutdown the object's dependencies. |Traits| |
+// must be a type with two public static void(void) functions named Initialize |
+// and Shutdown. Traits::Initialize will be invoked when the first instance of |
+// this class is created and Traits::Shutdown will be invoked when the last one |
+// is destroyed. |
+template<class Traits> |
+class ScopedInitializationManager { |
+ public: |
+ ScopedInitializationManager() { AddRef(); } |
+ ~ScopedInitializationManager() { Release(); } |
+ |
+ private: |
+ static void AddRef() { |
+ base::AutoLock auto_lock(lock_.Get()); |
+ DCHECK_LT(ref_count_, kuint32max); |
+ if (++ref_count_ == 1) |
+ Traits::Initialize(); |
+ } |
+ |
+ static void Release() { |
+ base::AutoLock auto_lock(lock_.Get()); |
+ DCHECK_GT(ref_count_, 0U); |
+ if (--ref_count_ == 0) |
+ Traits::Shutdown(); |
+ } |
+ |
+ static base::LazyInstance<base::Lock>::Leaky lock_; |
+ static uint32 ref_count_; |
+ DISALLOW_COPY_AND_ASSIGN(ScopedInitializationManager); |
+}; |
+ |
+template<class Traits> base::LazyInstance<base::Lock>::Leaky |
+ ScopedInitializationManager<Traits>::lock_ = LAZY_INSTANCE_INITIALIZER; |
+ |
+template<class Traits> uint32 |
+ ScopedInitializationManager<Traits>::ref_count_ = 0; |
+ |
+} // namespace chrome_frame |
+ |
+#endif // CHROME_FRAME_SCOPED_INITIALIZATION_MANAGER_H_ |