// Copyright 2018 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. #ifndef BASE_TASK_TASK_FEATURES_H_ #define BASE_TASK_TASK_FEATURES_H_ #include "base/base_export.h" #include "base/metrics/field_trial_params.h" #include "build/build_config.h" namespace base { struct Feature; // Under this feature, workers blocked with MayBlock are replaced immediately // instead of waiting for a threshold in the foreground thread group. extern const BASE_EXPORT Feature kMayBlockWithoutDelay; // Under this feature, ThreadPool::ShouldYield() always returns false extern const BASE_EXPORT Feature kDisableJobYield; // Under this feature, JobTaskSource doesn't use worker count in its sort key // such that worker threads are not distributed among running jobs equally. extern const BASE_EXPORT Feature kDisableFairJobScheduling; // Under this feature, priority update on Jobs is disabled. extern const BASE_EXPORT Feature kDisableJobUpdatePriority; // Under this feature, another WorkerThread is signaled only after the current // thread was assigned work. extern const BASE_EXPORT Feature kWakeUpAfterGetWork; // Strategy affecting how WorkerThreads are signaled to pick up pending work. enum class WakeUpStrategy { // A single thread scheduling new work signals all required WorkerThreads. kCentralizedWakeUps, // Each thread signals at most a single thread, either when scheduling new // work or picking up pending work. kSerializedWakeUps, // Each thread signals at most 2 threads, either when scheduling new // work or picking up pending work. kExponentialWakeUps, // Each thread signals as many threads as necessary, either when scheduling // new work or picking up pending work. kGreedyWakeUps, }; // Under this feature, a given WakeUpStrategy param is used. extern const BASE_EXPORT Feature kWakeUpStrategyFeature; extern const BASE_EXPORT base::FeatureParam kWakeUpStrategyParam; #if BUILDFLAG(IS_WIN) || BUILDFLAG(IS_APPLE) #define HAS_NATIVE_THREAD_POOL() 1 #else #define HAS_NATIVE_THREAD_POOL() 0 #endif #if HAS_NATIVE_THREAD_POOL() // Under this feature, ThreadPoolImpl will use a foreground ThreadGroup backed // by a native thread pool implementation. The Windows Thread Pool API and // libdispatch are used on Windows and macOS/iOS respectively. extern const BASE_EXPORT Feature kUseNativeThreadPool; // Under this feature, ThreadPoolImpl will use a background ThreadGroup backed // by a native thread pool implementation. extern const BASE_EXPORT Feature kUseBackgroundNativeThreadPool; #endif // Whether threads in the ThreadPool should be reclaimed after being idle for 5 // minutes, instead of 30 seconds. extern const BASE_EXPORT Feature kUseFiveMinutesThreadReclaimTime; // This feature controls whether wake ups are possible for canceled tasks. extern const BASE_EXPORT Feature kNoWakeUpsForCanceledTasks; // Controls whether or not canceled delayed tasks are removed from task queues. extern const BASE_EXPORT base::Feature kRemoveCanceledTasksInTaskQueue; // This feature controls whether or not the scheduled task is always abandoned // when a timer is stopped or reset. The re-use of the scheduled task is an // optimization that ensures a timer can not leave multiple canceled tasks in // the task queue. Meant to be used in conjunction with // kRemoveCanceledTasksInTaskQueue. extern const BASE_EXPORT base::Feature kAlwaysAbandonScheduledTask; // Under this feature, a non-zero leeway is added to delayed tasks. Along with // DelayPolicy, this affects the time at which a delayed task runs. extern const BASE_EXPORT Feature kAddTaskLeewayFeature; constexpr TimeDelta kDefaultLeeway = Milliseconds(8); extern const BASE_EXPORT base::FeatureParam kTaskLeewayParam; // Under this feature, wake ups are aligned at a 8ms boundary when allowed per // DelayPolicy. extern const BASE_EXPORT base::Feature kAlignWakeUps; // Under this feature, tasks that need high resolution timer are determined // based on explicit DelayPolicy rather than based on a threshold. extern const BASE_EXPORT base::Feature kExplicitHighResolutionTimerWin; // Feature to run tasks by batches before pumping out messages. extern const BASE_EXPORT base::Feature kRunTasksByBatches; BASE_EXPORT void InitializeTaskLeeway(); BASE_EXPORT TimeDelta GetTaskLeeway(); } // namespace base #endif // BASE_TASK_TASK_FEATURES_H_