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// Copyright 2025 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_ANDROID_BACKGROUND_THREAD_POOL_FIELD_TRIAL_H_
#define BASE_ANDROID_BACKGROUND_THREAD_POOL_FIELD_TRIAL_H_
#include <optional>
#include <string_view>
#include "base/auto_reset.h"
#include "base/base_export.h"
#include "base/synchronization/synchronization_buildflags.h"
namespace base::android {
class BASE_EXPORT BackgroundThreadPoolFieldTrial {
public:
static void Initialize();
// Returns true if the background thread pool field trial is active and has
// requested the use of priority-inheritance locks.
static bool ShouldUsePriorityInheritanceLocks();
// Returns true if the background thread pool field trial is active and has
// requested the use of background thread pool.
static bool ShouldUseBackgroundThreadPool();
struct BASE_EXPORT TrialInfo {
std::string trial_name;
std::string group_name;
};
// Returns a non-null TrialInfo struct if the trial is active.
static std::optional<TrialInfo> GetTrialInfo();
protected:
// The configuration value dictates the trial and group currently active. It
// is
// set by the server-side config and applied on the next browser launch.
enum class Configuration : int {
// |kDisabled|: No trial is currently active.
kDisabled = 0,
// The PI supported trial groups requires the kernel to support priority
// inheritance futexes. It is intended
// to measure the effect of PI-locks along with the background thread pool.
kPISupportedTrialControl = 1,
kPISupportedTrialEnabledPILocksOnly = 2,
kPISupportedTrialEnabledBGThreadPoolOnly = 3,
kPISupportedTrialEnabledBoth = 4,
// The general trial does not require any special kernel support and is
// meant
// to measure the effect of
// using a background thread pool unconditionally.
kGeneralTrialControl = 5,
kGeneralTrialEnabledBGThreadPool = 6,
// |kConfigurationMax|: The maximum integer value of the configuration.
kConfigurationMax = kGeneralTrialEnabledBGThreadPool,
};
friend class ScopedUsePriorityInheritanceLocksForTesting;
static std::optional<Configuration> s_configuration_;
private:
static Configuration ReadConfigurationFromCommandLine();
static Configuration GetConfiguration();
static TrialInfo GetGeneralTrialInfo();
#if BUILDFLAG(ENABLE_MUTEX_PRIORITY_INHERITANCE)
static TrialInfo GetPISupportedTrialInfo();
#endif // BUILDFLAG(ENABLE_MUTEX_PRIORITY_INHERITANCE)
};
#if BUILDFLAG(ENABLE_MUTEX_PRIORITY_INHERITANCE)
class BASE_EXPORT ScopedUsePriorityInheritanceLocksForTesting {
public:
ScopedUsePriorityInheritanceLocksForTesting();
~ScopedUsePriorityInheritanceLocksForTesting();
private:
base::AutoReset<std::optional<BackgroundThreadPoolFieldTrial::Configuration>>
reset_config_value_;
};
#endif // BUILDFLAG(ENABLE_MUTEX_PRIORITY_INHERITANCE)
} // namespace base::android
#endif // BASE_ANDROID_BACKGROUND_THREAD_POOL_FIELD_TRIAL_H_
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