| // 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. |
| |
| #ifndef BASE_TASK_SCHEDULER_TASK_SCHEDULER_H_ |
| #define BASE_TASK_SCHEDULER_TASK_SCHEDULER_H_ |
| |
| #include <memory> |
| |
| #include "base/base_export.h" |
| #include "base/callback_forward.h" |
| #include "base/memory/ref_counted.h" |
| #include "base/task_runner.h" |
| #include "base/task_scheduler/task_traits.h" |
| |
| namespace tracked_objects { |
| class Location; |
| } |
| |
| namespace base { |
| |
| // Interface for a task scheduler and static methods to manage the instance used |
| // by the post_task.h API. |
| class BASE_EXPORT TaskScheduler { |
| public: |
| virtual ~TaskScheduler() = default; |
| |
| // Posts |task| with specific |traits|. |
| // For one off tasks that don't require a TaskRunner. |
| virtual void PostTaskWithTraits(const tracked_objects::Location& from_here, |
| const TaskTraits& traits, |
| const Closure& task) = 0; |
| |
| // Returns a TaskRunner whose PostTask invocations will result in scheduling |
| // Tasks with |traits| which will be executed according to |execution_mode|. |
| virtual scoped_refptr<TaskRunner> CreateTaskRunnerWithTraits( |
| const TaskTraits& traits, |
| ExecutionMode execution_mode) = 0; |
| |
| // Synchronously shuts down the scheduler. Once this is called, only tasks |
| // posted with the BLOCK_SHUTDOWN behavior will be run. When this returns: |
| // - All SKIP_ON_SHUTDOWN tasks that were already running have completed their |
| // execution. |
| // - All posted BLOCK_SHUTDOWN tasks have completed their execution. |
| // - CONTINUE_ON_SHUTDOWN tasks might still be running. |
| // Note that an implementation can keep threads and other resources alive to |
| // support running CONTINUE_ON_SHUTDOWN after this returns. This can only be |
| // called once. |
| virtual void Shutdown() = 0; |
| |
| // Registers |task_scheduler| to handle tasks posted through the post_task.h |
| // API for this process. The registered TaskScheduler will only be deleted |
| // when a new TaskScheduler is registered (i.e. otherwise leaked on shutdown). |
| // This must not be called when TaskRunners created by the previous |
| // TaskScheduler are still alive. This method is not thread-safe; proper |
| // synchronization is required to use the post_task.h API after registering a |
| // new TaskScheduler. |
| static void SetInstance(std::unique_ptr<TaskScheduler> task_scheduler); |
| |
| // Retrieve the TaskScheduler set via SetInstance(). This should be used very |
| // rarely; most users of TaskScheduler should use the post_task.h API. |
| static TaskScheduler* GetInstance(); |
| }; |
| |
| } // namespace base |
| |
| #endif // BASE_TASK_SCHEDULER_TASK_SCHEDULER_H_ |