michael@0: // Copyright (c) 2011 The Chromium Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: 
michael@0: #ifndef BASE_AT_EXIT_H_
michael@0: #define BASE_AT_EXIT_H_
michael@0: 
michael@0: #include <stack>
michael@0: 
michael@0: #include "base/base_export.h"
michael@0: #include "base/basictypes.h"
michael@0: #include "base/callback.h"
michael@0: #include "base/synchronization/lock.h"
michael@0: 
michael@0: namespace base {
michael@0: 
michael@0: // This class provides a facility similar to the CRT atexit(), except that
michael@0: // we control when the callbacks are executed. Under Windows for a DLL they
michael@0: // happen at a really bad time and under the loader lock. This facility is
michael@0: // mostly used by base::Singleton.
michael@0: //
michael@0: // The usage is simple. Early in the main() or WinMain() scope create an
michael@0: // AtExitManager object on the stack:
michael@0: // int main(...) {
michael@0: //    base::AtExitManager exit_manager;
michael@0: //
michael@0: // }
michael@0: // When the exit_manager object goes out of scope, all the registered
michael@0: // callbacks and singleton destructors will be called.
michael@0: 
michael@0: class BASE_EXPORT AtExitManager {
michael@0:  public:
michael@0:   typedef void (*AtExitCallbackType)(void*);
michael@0: 
michael@0:   AtExitManager();
michael@0: 
michael@0:   // The dtor calls all the registered callbacks. Do not try to register more
michael@0:   // callbacks after this point.
michael@0:   ~AtExitManager();
michael@0: 
michael@0:   // Registers the specified function to be called at exit. The prototype of
michael@0:   // the callback function is void func(void*).
michael@0:   static void RegisterCallback(AtExitCallbackType func, void* param);
michael@0: 
michael@0:   // Registers the specified task to be called at exit.
michael@0:   static void RegisterTask(base::Closure task);
michael@0: 
michael@0:   // Calls the functions registered with RegisterCallback in LIFO order. It
michael@0:   // is possible to register new callbacks after calling this function.
michael@0:   static void ProcessCallbacksNow();
michael@0: 
michael@0:  protected:
michael@0:   // This constructor will allow this instance of AtExitManager to be created
michael@0:   // even if one already exists.  This should only be used for testing!
michael@0:   // AtExitManagers are kept on a global stack, and it will be removed during
michael@0:   // destruction.  This allows you to shadow another AtExitManager.
michael@0:   explicit AtExitManager(bool shadow);
michael@0: 
michael@0:  private:
michael@0:   base::Lock lock_;
michael@0:   std::stack<base::Closure> stack_;
michael@0:   AtExitManager* next_manager_;  // Stack of managers to allow shadowing.
michael@0: 
michael@0:   DISALLOW_COPY_AND_ASSIGN(AtExitManager);
michael@0: };
michael@0: 
michael@0: #if defined(UNIT_TEST)
michael@0: class ShadowingAtExitManager : public AtExitManager {
michael@0:  public:
michael@0:   ShadowingAtExitManager() : AtExitManager(true) {}
michael@0: };
michael@0: #endif  // defined(UNIT_TEST)
michael@0: 
michael@0: }  // namespace base
michael@0: 
michael@0: #endif  // BASE_AT_EXIT_H_