1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef BASE_AT_EXIT_H_ 6 #define BASE_AT_EXIT_H_ 7 #pragma once 8 9 #include <stack> 10 11 #include "base/base_api.h" 12 #include "base/basictypes.h" 13 #include "base/synchronization/lock.h" 14 15 namespace base { 16 17 // This class provides a facility similar to the CRT atexit(), except that 18 // we control when the callbacks are executed. Under Windows for a DLL they 19 // happen at a really bad time and under the loader lock. This facility is 20 // mostly used by base::Singleton. 21 // 22 // The usage is simple. Early in the main() or WinMain() scope create an 23 // AtExitManager object on the stack: 24 // int main(...) { 25 // base::AtExitManager exit_manager; 26 // 27 // } 28 // When the exit_manager object goes out of scope, all the registered 29 // callbacks and singleton destructors will be called. 30 31 class BASE_API AtExitManager { 32 public: 33 typedef void (*AtExitCallbackType)(void*); 34 35 AtExitManager(); 36 37 // The dtor calls all the registered callbacks. Do not try to register more 38 // callbacks after this point. 39 ~AtExitManager(); 40 41 // Registers the specified function to be called at exit. The prototype of 42 // the callback function is void func(). 43 static void RegisterCallback(AtExitCallbackType func, void* param); 44 45 // Calls the functions registered with RegisterCallback in LIFO order. It 46 // is possible to register new callbacks after calling this function. 47 static void ProcessCallbacksNow(); 48 49 protected: 50 // This constructor will allow this instance of AtExitManager to be created 51 // even if one already exists. This should only be used for testing! 52 // AtExitManagers are kept on a global stack, and it will be removed during 53 // destruction. This allows you to shadow another AtExitManager. 54 explicit AtExitManager(bool shadow); 55 56 private: 57 struct CallbackAndParam { CallbackAndParamCallbackAndParam58 CallbackAndParam(AtExitCallbackType func, void* param) 59 : func_(func), param_(param) { } 60 AtExitCallbackType func_; 61 void* param_; 62 }; 63 64 base::Lock lock_; 65 std::stack<CallbackAndParam> stack_; 66 AtExitManager* next_manager_; // Stack of managers to allow shadowing. 67 68 DISALLOW_COPY_AND_ASSIGN(AtExitManager); 69 }; 70 71 #if defined(UNIT_TEST) 72 class ShadowingAtExitManager : public AtExitManager { 73 public: ShadowingAtExitManager()74 ShadowingAtExitManager() : AtExitManager(true) {} 75 }; 76 #endif // defined(UNIT_TEST) 77 78 } // namespace base 79 80 #endif // BASE_AT_EXIT_H_ 81