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// Copyright 2016 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 <unordered_map>
#include <vector>
#include "base/macros.h"
#include "base/memory/singleton.h"
#include "base/observer_list.h"
enum class KeepAliveOrigin;
enum class KeepAliveRestartOption;
class KeepAliveStateObserver;
// Centralized registry that objects in the browser can use to
// express their requirements wrt the lifetime of the browser.
// Observers registered with it can then react as those requirements
// change.
// In particular, this is how the browser process knows when to stop
// or stay alive.
// Note: BrowserProcessImpl registers to react on changes.
// TestingBrowserProcess does not do it, meaning that the shutdown
// sequence does not happen during unit tests.
class KeepAliveRegistry {
static KeepAliveRegistry* GetInstance();
// Methods to query the state of the registry.
bool IsKeepingAlive() const;
bool IsKeepingAliveOnlyByBrowserOrigin() const;
bool IsRestartAllowed() const;
bool IsOriginRegistered(KeepAliveOrigin origin) const;
void AddObserver(KeepAliveStateObserver* observer);
void RemoveObserver(KeepAliveStateObserver* observer);
// Returns whether restart would be allowed if all the keep alives for the
// provided |origins| were not registered.
bool WouldRestartWithout(const std::vector<KeepAliveOrigin>& origins) const;
// Call when shutting down to ensure registering a new KeepAlive DCHECKs.
void SetIsShuttingDown(bool value = true);
friend struct base::DefaultSingletonTraits<KeepAliveRegistry>;
// Friend to be able to use Register/Unregister
friend class ScopedKeepAlive;
friend std::ostream& operator<<(std::ostream& out,
const KeepAliveRegistry& registry);
// TODO(dgn): Remove this when std::hash supports enums directly (c++14)
struct EnumClassHash {
std::size_t operator()(KeepAliveOrigin origin) const {
return static_cast<int>(origin);
using OriginMap = std::unordered_map<KeepAliveOrigin, int, EnumClassHash>;
// Add/Remove entries. Do not use directly, use ScopedKeepAlive instead.
void Register(KeepAliveOrigin origin, KeepAliveRestartOption restart);
void Unregister(KeepAliveOrigin origin, KeepAliveRestartOption restart);
// Methods called when a specific aspect of the state of the registry changes.
void OnKeepAliveStateChanged(bool new_keeping_alive);
void OnRestartAllowedChanged(bool new_restart_allowed);
// Unregisters one occurrence of the provided |origin| from |keep_alive_map|
void DecrementCount(KeepAliveOrigin origin, OriginMap* keep_alive_map);
// Tracks the registered KeepAlives, storing the origin and the number of
// registered KeepAlives for each.
OriginMap registered_keep_alives_;
// Tracks the registered KeepAlives that had KeepAliveRestartOption::ENABLED
// set, storing the origin and the number of restart allowed KeepAlives for
// each origin.
OriginMap restart_allowed_keep_alives_;
// Total number of registered KeepAlives
int registered_count_;
// Number of registered keep alives that have KeepAliveRestartOption::ENABLED.
int restart_allowed_count_;
// Used to guard against registering during shutdown.
bool is_shutting_down_ = false;
base::ObserverList<KeepAliveStateObserver> observers_;