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[chromium-blink-merge.git] / base / at_exit.h
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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.
5 #ifndef BASE_AT_EXIT_H_
6 #define BASE_AT_EXIT_H_
8 #include <stack>
10 #include "base/base_export.h"
11 #include "base/basictypes.h"
12 #include "base/callback.h"
13 #include "base/synchronization/lock.h"
15 namespace base {
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.
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;
27 // }
28 // When the exit_manager object goes out of scope, all the registered
29 // callbacks and singleton destructors will be called.
31 class BASE_EXPORT AtExitManager {
32 public:
33 typedef void (*AtExitCallbackType)(void*);
35 AtExitManager();
37 // The dtor calls all the registered callbacks. Do not try to register more
38 // callbacks after this point.
39 ~AtExitManager();
41 // Registers the specified function to be called at exit. The prototype of
42 // the callback function is void func(void*).
43 static void RegisterCallback(AtExitCallbackType func, void* param);
45 // Registers the specified task to be called at exit.
46 static void RegisterTask(base::Closure task);
48 // Calls the functions registered with RegisterCallback in LIFO order. It
49 // is possible to register new callbacks after calling this function.
50 static void ProcessCallbacksNow();
52 protected:
53 // This constructor will allow this instance of AtExitManager to be created
54 // even if one already exists. This should only be used for testing!
55 // AtExitManagers are kept on a global stack, and it will be removed during
56 // destruction. This allows you to shadow another AtExitManager.
57 explicit AtExitManager(bool shadow);
59 private:
60 base::Lock lock_;
61 std::stack<base::Closure> stack_;
62 AtExitManager* next_manager_; // Stack of managers to allow shadowing.
64 DISALLOW_COPY_AND_ASSIGN(AtExitManager);
67 #if defined(UNIT_TEST)
68 class ShadowingAtExitManager : public AtExitManager {
69 public:
70 ShadowingAtExitManager() : AtExitManager(true) {}
72 #endif // defined(UNIT_TEST)
74 } // namespace base
76 #endif // BASE_AT_EXIT_H_