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- // Copyright (c) 2011 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #include "base/at_exit.h"
- #include <stddef.h>
- #include <ostream>
- #include <utility>
- #include "base/bind.h"
- #include "base/callback.h"
- #include "base/check_op.h"
- #include "base/notreached.h"
- namespace base {
- // Keep a stack of registered AtExitManagers. We always operate on the most
- // recent, and we should never have more than one outside of testing (for a
- // statically linked version of this library). Testing may use the shadow
- // version of the constructor, and if we are building a dynamic library we may
- // end up with multiple AtExitManagers on the same process. We don't protect
- // this for thread-safe access, since it will only be modified in testing.
- static AtExitManager* g_top_manager = nullptr;
- static bool g_disable_managers = false;
- AtExitManager::AtExitManager() : next_manager_(g_top_manager) {
- // If multiple modules instantiate AtExitManagers they'll end up living in this
- // module... they have to coexist.
- #if !defined(COMPONENT_BUILD)
- DCHECK(!g_top_manager);
- #endif
- g_top_manager = this;
- }
- AtExitManager::~AtExitManager() {
- if (!g_top_manager) {
- NOTREACHED() << "Tried to ~AtExitManager without an AtExitManager";
- return;
- }
- DCHECK_EQ(this, g_top_manager);
- if (!g_disable_managers)
- ProcessCallbacksNow();
- g_top_manager = next_manager_;
- }
- // static
- void AtExitManager::RegisterCallback(AtExitCallbackType func, void* param) {
- DCHECK(func);
- RegisterTask(base::BindOnce(func, param));
- }
- // static
- void AtExitManager::RegisterTask(base::OnceClosure task) {
- if (!g_top_manager) {
- NOTREACHED() << "Tried to RegisterCallback without an AtExitManager";
- return;
- }
- AutoLock lock(g_top_manager->lock_);
- #if DCHECK_IS_ON()
- DCHECK(!g_top_manager->processing_callbacks_);
- #endif
- g_top_manager->stack_.push(std::move(task));
- }
- // static
- void AtExitManager::ProcessCallbacksNow() {
- if (!g_top_manager) {
- NOTREACHED() << "Tried to ProcessCallbacksNow without an AtExitManager";
- return;
- }
- // Callbacks may try to add new callbacks, so run them without holding
- // |lock_|. This is an error and caught by the DCHECK in RegisterTask(), but
- // handle it gracefully in release builds so we don't deadlock.
- base::stack<base::OnceClosure> tasks;
- {
- AutoLock lock(g_top_manager->lock_);
- tasks.swap(g_top_manager->stack_);
- #if DCHECK_IS_ON()
- g_top_manager->processing_callbacks_ = true;
- #endif
- }
- // Relax the cross-thread access restriction to non-thread-safe RefCount.
- // It's safe since all other threads should be terminated at this point.
- ScopedAllowCrossThreadRefCountAccess allow_cross_thread_ref_count_access;
- while (!tasks.empty()) {
- std::move(tasks.top()).Run();
- tasks.pop();
- }
- #if DCHECK_IS_ON()
- AutoLock lock(g_top_manager->lock_);
- // Expect that all callbacks have been run.
- DCHECK(g_top_manager->stack_.empty());
- g_top_manager->processing_callbacks_ = false;
- #endif
- }
- void AtExitManager::DisableAllAtExitManagers() {
- AutoLock lock(g_top_manager->lock_);
- g_disable_managers = true;
- }
- AtExitManager::AtExitManager(bool shadow) : next_manager_(g_top_manager) {
- DCHECK(shadow || !g_top_manager);
- g_top_manager = this;
- }
- } // namespace base
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