TaskScheduler [13] TaskSchedulerImpl

base/task_scheduler/task_scheduler_impl.h

+// 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_IMPL_H_
+#define BASE_TASK_SCHEDULER_TASK_SCHEDULER_IMPL_H_
+
+#include <memory>
+
+#include "base/base_export.h"
+#include "base/logging.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/synchronization/waitable_event.h"
+#include "base/task_runner.h"
+#include "base/task_scheduler/delayed_task_manager.h"
+#include "base/task_scheduler/scheduler_thread_pool_impl.h"
+#include "base/task_scheduler/sequence.h"
+#include "base/task_scheduler/task_scheduler.h"
+#include "base/task_scheduler/task_tracker.h"
+#include "base/task_scheduler/task_traits.h"
+
+namespace base {
+namespace internal {
+
+// Default TaskScheduler implementation. This class is thread-safe.
+class BASE_EXPORT TaskSchedulerImpl : public TaskScheduler {
+ public:
+  // Creates and returns an initialized TaskSchedulerImpl. CHECKs on failure to
+  // do so (never returns null).
+  static std::unique_ptr<TaskSchedulerImpl> Create();
+
+  // Destroying a TaskSchedulerImpl is not allowed in production; it is always
+  // leaked. In tests, it can only be destroyed after JoinForTesting() has
+  // returned.
+  ~TaskSchedulerImpl() override;
+
+  // TaskScheduler:
+  void PostTaskWithTraits(const tracked_objects::Location& from_here,
+                          const TaskTraits& traits,
+                          const Closure& task) override;
+  scoped_refptr<TaskRunner> CreateTaskRunnerWithTraits(
+      const TaskTraits& traits,
+      ExecutionMode execution_mode) override;
+  void Shutdown() override;
+
+  // Joins all threads of this scheduler. Tasks that are already running are
+  // allowed to complete their execution. This can only be called once.
+  void JoinForTesting();
+
+ private:
+  TaskSchedulerImpl();
+
+  void Initialize();
+
+  // Returns the thread pool that runs Tasks with |traits|.
+  SchedulerThreadPool* GetThreadPoolForTraits(const TaskTraits& traits);
+
+  // Callback invoked when a non-single-thread |sequence| isn't empty after a
+  // worker thread pops a Task from it.
+  void ReEnqueueSequenceCallback(scoped_refptr<Sequence> sequence);
+
+  TaskTracker task_tracker_;
+  DelayedTaskManager delayed_task_manager_;
+
+  // Thread pool for BACKGROUND Tasks without file I/O.
+  std::unique_ptr<SchedulerThreadPoolImpl> background_thread_pool_;
+
+  // Thread pool for BACKGROUND Tasks with file I/O.
+  std::unique_ptr<SchedulerThreadPoolImpl> background_file_io_thread_pool_;
+
+  // Thread pool for USER_VISIBLE and USER_BLOCKING Tasks without file I/O.
+  std::unique_ptr<SchedulerThreadPoolImpl> normal_thread_pool_;
+
+  // Thread pool for USER_VISIBLE and USER_BLOCKING Tasks with file I/O.
+  std::unique_ptr<SchedulerThreadPoolImpl> normal_file_io_thread_pool_;
+
+#if DCHECK_IS_ON()
+  // Signaled once JoinForTesting() has returned.
+  WaitableEvent join_for_testing_returned_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(TaskSchedulerImpl);
+};
+
+}  // namespace internal
+}  // namespace base
+
+#endif  // BASE_TASK_SCHEDULER_TASK_SCHEDULER_IMPL_H_