| // 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_ |