ipc/chromium/src/base/at_exit.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
   4 // Use of this source code is governed by a BSD-style license that can be
   5 // found in the LICENSE file.
   6
   7 #ifndef BASE_AT_EXIT_H_
   8 #define BASE_AT_EXIT_H_
   9
  10 #include <stack>
  11
  12 #include "base/basictypes.h"
  13
  14 #include "mozilla/Mutex.h"
  15
  16 namespace base {
  17
  18 // This class provides a facility similar to the CRT atexit(), except that
  19 // we control when the callbacks are executed. Under Windows for a DLL they
  20 // happen at a really bad time and under the loader lock. This facility is
  21 // mostly used by base::Singleton.
  22 //
  23 // The usage is simple. Early in the main() or WinMain() scope create an
  24 // AtExitManager object on the stack:
  25 // int main(...) {
  26 //    base::AtExitManager exit_manager;
  27 //
  28 // }
  29 // When the exit_manager object goes out of scope, all the registered
  30 // callbacks and singleton destructors will be called.
  31
  32 class AtExitManager {
  33  protected:
  34   // This constructor will allow this instance of AtExitManager to be created
  35   // even if one already exists.  This should only be used for testing!
  36   // AtExitManagers are kept on a global stack, and it will be removed during
  37   // destruction.  This allows you to shadow another AtExitManager.
  38   explicit AtExitManager(bool shadow);
  39
  40  public:
  41   typedef void (*AtExitCallbackType)(void*);
  42
  43   AtExitManager();
  44
  45   // The dtor calls all the registered callbacks. Do not try to register more
  46   // callbacks after this point.
  47   ~AtExitManager();
  48
  49   // Registers the specified function to be called at exit. The prototype of
  50   // the callback function is void func().
  51   static void RegisterCallback(AtExitCallbackType func, void* param);
  52
  53   // Calls the functions registered with RegisterCallback in LIFO order. It
  54   // is possible to register new callbacks after calling this function.
  55   static void ProcessCallbacksNow();
  56
  57   static bool AlreadyRegistered();
  58
  59  private:
  60   struct CallbackAndParam {
  61     CallbackAndParam(AtExitCallbackType func, void* param)
  62         : func_(func), param_(param) {}
  63     AtExitCallbackType func_;
  64     void* param_;
  65   };
  66
  67   mozilla::Mutex lock_;
  68   std::stack<CallbackAndParam> stack_ MOZ_GUARDED_BY(lock_);
  69   AtExitManager* next_manager_;  // Stack of managers to allow shadowing.
  70
  71   DISALLOW_COPY_AND_ASSIGN(AtExitManager);
  72 };
  73
  74 }  // namespace base
  75
  76 #endif  // BASE_AT_EXIT_H_