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// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_PERFORMANCE_MANAGER_SCENARIO_API_PERFORMANCE_SCENARIO_OBSERVER_H_
#define COMPONENTS_PERFORMANCE_MANAGER_SCENARIO_API_PERFORMANCE_SCENARIO_OBSERVER_H_
#include <array>
#include "base/component_export.h"
#include "base/location.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_refptr.h"
#include "base/observer_list_threadsafe.h"
#include "base/observer_list_types.h"
#include "base/scoped_observation_traits.h"
#include "base/sequence_checker.h"
#include "base/synchronization/lock.h"
#include "base/types/pass_key.h"
#include "components/performance_manager/scenario_api/performance_scenario_memory_forward.h"
#include "components/performance_manager/scenario_api/performance_scenarios.h"
namespace performance_scenarios {
class PerformanceScenarioObserverList;
// An observer that watches for changes to values held in
// ScopedReadOnlyScenarioMemory.
class COMPONENT_EXPORT(SCENARIO_API) PerformanceScenarioObserver
: public base::CheckedObserver {
public:
// Invoked whenever the given scenario changes for `scope`.
virtual void OnLoadingScenarioChanged(ScenarioScope scope,
LoadingScenario old_scenario,
LoadingScenario new_scenario) {}
virtual void OnInputScenarioChanged(ScenarioScope scope,
InputScenario old_scenario,
InputScenario new_scenario) {}
};
// An observer that watches for the scenario values held in
// ScopedReadOnlyScenarioMemory to start or stop matching a ScenarioPattern.
class COMPONENT_EXPORT(SCENARIO_API) MatchingScenarioObserver
: public base::CheckedObserver {
public:
explicit MatchingScenarioObserver(ScenarioPattern pattern);
~MatchingScenarioObserver() override;
MatchingScenarioObserver(const MatchingScenarioObserver&) = delete;
MatchingScenarioObserver& operator=(const MatchingScenarioObserver&) = delete;
// Returns the pattern that this observer matches.
ScenarioPattern scenario_pattern() const { return pattern_; }
// Invoked whenever the scenarios for `scope` change in a way that causes them
// to start or stop matching the ScenarioPattern. `matches_pattern` will be
// true if they now match the pattern, false otherwise.
virtual void OnScenarioMatchChanged(ScenarioScope scope,
bool matches_pattern) = 0;
// Allows PerformanceScenarioObserverList to notify of scenario changes. Will
// invoke OnScenarioMatchChanged if necessary.
void NotifyIfScenarioMatchChanged(ScenarioScope scope,
LoadingScenario loading_scenario,
InputScenario input_scenario);
private:
// Returns a reference into `last_match_notifications_` for `scope`.
bool& LastMatchNotification(ScenarioScope scope);
const ScenarioPattern pattern_;
// This will be bound to whichever sequence calls
// PerformanceScenarioObserverList::AddMatchingObserver, to validate that the
// observer list always accesses this class on that sequence.
SEQUENCE_CHECKER(sequence_checker_);
// The last match notification that was sent for each scope.
std::array<bool, ScenarioScopes::kValueCount> last_match_notifications_
GUARDED_BY_CONTEXT(sequence_checker_);
};
// Central list of PerformanceScenarioObservers for a scope, wrapping an
// ObserverListThreadSafe. The lifetime is managed by
// ScopedReadOnlyScenarioMemory on the main thread, but it's refcounted so
// GetForScope() can be called from any sequence. Callers on other sequences
// will extend the lifetime until they drop their reference.
//
// All methods can be called from any sequence.
class COMPONENT_EXPORT(SCENARIO_API) PerformanceScenarioObserverList
: public base::RefCountedThreadSafe<PerformanceScenarioObserverList> {
public:
// Returns the object that notifies observers for `scope`, or nullptr if no
// ScopedReadOnlyScenarioMemory exists for `scope`.
static scoped_refptr<PerformanceScenarioObserverList> GetForScope(
ScenarioScope scope);
PerformanceScenarioObserverList(const PerformanceScenarioObserverList&) =
delete;
PerformanceScenarioObserverList& operator=(
const PerformanceScenarioObserverList&) = delete;
// Adds `observer` to the list. The observer will be notified on the calling
// sequence.
void AddObserver(PerformanceScenarioObserver* observer);
// Removes `observer` from the list.
void RemoveObserver(PerformanceScenarioObserver* observer);
// Adds `matching_observer` to the list. The observer will be notified on the
// calling sequence.
void AddMatchingObserver(MatchingScenarioObserver* matching_observer);
// Removes `matching_observer` from the list.
void RemoveMatchingObserver(MatchingScenarioObserver* matching_observer);
// Notifies observers of scenarios that have changed for this scope since the
// last call.
void NotifyIfScenarioChanged(
base::Location location = base::Location::Current());
// Notifies observers for all scopes of scenarios that have changed since the
// last call.
static void NotifyAllScopes(
base::Location location = base::Location::Current());
// Lets ScopedReadOnlyScenarioMemory create and destroy the notifier for
// `scope`.
static void CreateForScope(base::PassKey<ScopedReadOnlyScenarioMemory>,
ScenarioScope scope);
static void DestroyForScope(base::PassKey<ScopedReadOnlyScenarioMemory>,
ScenarioScope scope);
private:
friend class base::RefCountedThreadSafe<PerformanceScenarioObserverList>;
explicit PerformanceScenarioObserverList(ScenarioScope scope);
~PerformanceScenarioObserverList();
const ScenarioScope scope_;
// The last scenario values that were notified.
base::Lock lock_;
LoadingScenario last_loading_scenario_ GUARDED_BY(lock_);
InputScenario last_input_scenario_ GUARDED_BY(lock_);
// kAddingSequenceOnly is safer than the default so use it for all lists.
template <typename T>
using ObserverList = base::ObserverListThreadSafe<
T,
base::RemoveObserverPolicy::kAddingSequenceOnly>;
// ObserverListThreadSafe must be held in a scoped_refptr because its
// destructor is private, but the pointer should never be reassigned.
const scoped_refptr<ObserverList<PerformanceScenarioObserver>> observers_ =
base::MakeRefCounted<ObserverList<PerformanceScenarioObserver>>();
const scoped_refptr<ObserverList<MatchingScenarioObserver>>
matching_observers_ =
base::MakeRefCounted<ObserverList<MatchingScenarioObserver>>();
};
} // namespace performance_scenarios
namespace base {
// Specialize ScopedObservation to invoke the correct add and remove methods for
// MatchingScenarioObserver. These must be in the same namespace as
// base::ScopedObservationTraits.
template <>
struct ScopedObservationTraits<
performance_scenarios::PerformanceScenarioObserverList,
performance_scenarios::MatchingScenarioObserver> {
static void AddObserver(
performance_scenarios::PerformanceScenarioObserverList* source,
performance_scenarios::MatchingScenarioObserver* observer) {
source->AddMatchingObserver(observer);
}
static void RemoveObserver(
performance_scenarios::PerformanceScenarioObserverList* source,
performance_scenarios::MatchingScenarioObserver* observer) {
source->RemoveMatchingObserver(observer);
}
};
} // namespace base
#endif // COMPONENTS_PERFORMANCE_MANAGER_SCENARIO_API_PERFORMANCE_SCENARIO_OBSERVER_H_
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