at_exit.h (2444B)
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_