// Copyright 2008, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//    * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//    * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//    * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifndef BASE_AT_EXIT_H__
#define BASE_AT_EXIT_H__

#include <stack>

#include "base/basictypes.h"
#include "base/lock.h"

namespace base {

typedef void (*AtExitCallbackType)();

// This class provides a facility similar to the CRT atexit(), except that
// we control when the callbacks are executed. Under Windows for a DLL they
// happen at a really bad time and under the loader lock. This facility is
// mostly used by base::Singleton.
//
// The usage is simple. Early in the main() or WinMain() scope create an
// AtExitManager object on the stack:
// int main(...) {
//    base::AtExitManager exit_manager;
//   
// }
// When the exit_manager object goes out of scope, all the registered
// callbacks and singleton destructors will be called.

class AtExitManager {
 public:
  AtExitManager();

  // The dtor calls all the registered callbacks. Do not try to register more
  // callbacks after this point.
  ~AtExitManager();

  // Registers the specified function to be called at exit. The prototype of
  // the callback function is void func().
  static void RegisterCallback(AtExitCallbackType func);

  // Calls the functions registered with RegisterCallback in LIFO order. It
  // is possible to register new callbacks after calling this function.
  static void ProcessCallbacksNow();

 private:
  Lock lock_;
  std::stack<base::AtExitCallbackType> atexit_queue_;
  DISALLOW_EVIL_CONSTRUCTORS(AtExitManager);
};

}  // namespace base

#endif // BASE_AT_EXIT_H__