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