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// Copyright 2011 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_AT_EXIT_H_
#define BASE_AT_EXIT_H_
#include "base/base_export.h"
#include "base/containers/stack.h"
#include "base/dcheck_is_on.h"
#include "base/functional/callback.h"
#include "base/memory/raw_ptr.h"
#include "base/synchronization/lock.h"
#include "base/thread_annotations.h"
namespace base {
// This class provides a facility similar to the CRT atexit(), except that
// we control when the callbacks are executed. Under Windows for a DLL they
// happen at a really bad time and under the loader lock. This facility is
// mostly used by base::Singleton.
//
// The usage is simple. Early in the main() or WinMain() scope create an
// AtExitManager object on the stack:
// int main(...) {
// base::AtExitManager exit_manager;
//
// }
// When the exit_manager object goes out of scope, all the registered
// callbacks and singleton destructors will be called.
class BASE_EXPORT AtExitManager {
public:
typedef void (*AtExitCallbackType)(void*);
AtExitManager();
AtExitManager(const AtExitManager&) = delete;
AtExitManager& operator=(const AtExitManager&) = delete;
// The dtor calls all the registered callbacks. Do not try to register more
// callbacks after this point.
~AtExitManager();
// Registers the specified function to be called at exit. The prototype of
// the callback function is void func(void*).
static void RegisterCallback(AtExitCallbackType func, void* param);
// Registers the specified task to be called at exit.
static void RegisterTask(base::OnceClosure task);
// Calls the functions registered with RegisterCallback in LIFO order. It
// is possible to register new callbacks after calling this function.
static void ProcessCallbacksNow();
// Disable all registered at-exit callbacks. This is used only in a single-
// process mode.
static void DisableAllAtExitManagers();
protected:
// This constructor will allow this instance of AtExitManager to be created
// even if one already exists. This should only be used for testing!
// AtExitManagers are kept on a global stack, and it will be removed during
// destruction. This allows you to shadow another AtExitManager.
explicit AtExitManager(bool shadow);
private:
base::Lock lock_;
base::stack<base::OnceClosure> stack_ GUARDED_BY(lock_);
#if DCHECK_IS_ON()
bool processing_callbacks_ GUARDED_BY(lock_) = false;
#endif
// Stack of managers to allow shadowing.
const raw_ptr<AtExitManager, DanglingUntriaged> next_manager_;
};
#if defined(UNIT_TEST)
class ShadowingAtExitManager : public AtExitManager {
public:
ShadowingAtExitManager() : AtExitManager(true) {}
};
#endif // defined(UNIT_TEST)
} // namespace base
#endif // BASE_AT_EXIT_H_
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