tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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at_exit.h (2857B)

      1 // Copyright 2011 The Chromium Authors
      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 
      8 #include "base/base_export.h"
      9 #include "base/containers/stack.h"
     10 #include "base/dcheck_is_on.h"
     11 #include "base/functional/callback.h"
     12 #include "base/memory/raw_ptr.h"
     13 #include "base/synchronization/lock.h"
     14 #include "base/thread_annotations.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 BASE_EXPORT AtExitManager {
     33 public:
     34  typedef void (*AtExitCallbackType)(void*);
     35 
     36  AtExitManager();
     37  AtExitManager(const AtExitManager&) = delete;
     38  AtExitManager& operator=(const AtExitManager&) = delete;
     39 
     40  // The dtor calls all the registered callbacks. Do not try to register more
     41  // callbacks after this point.
     42  ~AtExitManager();
     43 
     44  // Registers the specified function to be called at exit. The prototype of
     45  // the callback function is void func(void*).
     46  static void RegisterCallback(AtExitCallbackType func, void* param);
     47 
     48  // Registers the specified task to be called at exit.
     49  static void RegisterTask(base::OnceClosure task);
     50 
     51  // Calls the functions registered with RegisterCallback in LIFO order. It
     52  // is possible to register new callbacks after calling this function.
     53  static void ProcessCallbacksNow();
     54 
     55  // Disable all registered at-exit callbacks. This is used only in a single-
     56  // process mode.
     57  static void DisableAllAtExitManagers();
     58 
     59 protected:
     60  // This constructor will allow this instance of AtExitManager to be created
     61  // even if one already exists.  This should only be used for testing!
     62  // AtExitManagers are kept on a global stack, and it will be removed during
     63  // destruction.  This allows you to shadow another AtExitManager.
     64  explicit AtExitManager(bool shadow);
     65 
     66 private:
     67  base::Lock lock_;
     68 
     69  base::stack<base::OnceClosure> stack_ GUARDED_BY(lock_);
     70 
     71 #if DCHECK_IS_ON()
     72  bool processing_callbacks_ GUARDED_BY(lock_) = false;
     73 #endif
     74 
     75  // Stack of managers to allow shadowing.
     76  const raw_ptr<AtExitManager, DanglingUntriaged> next_manager_;
     77 };
     78 
     79 #if defined(UNIT_TEST)
     80 class ShadowingAtExitManager : public AtExitManager {
     81 public:
     82  ShadowingAtExitManager() : AtExitManager(true) {}
     83 };
     84 #endif  // defined(UNIT_TEST)
     85 
     86 }  // namespace base
     87 
     88 #endif  // BASE_AT_EXIT_H_