scheduler: Move the Blink scheduler into Blink

components/scheduler/child/scheduler_helper.h

-// Copyright 2015 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 COMPONENTS_SCHEDULER_CHILD_SCHEDULER_HELPER_H_
-#define COMPONENTS_SCHEDULER_CHILD_SCHEDULER_HELPER_H_
-
-#include <stddef.h>
-
-#include "base/macros.h"
-#include "base/time/tick_clock.h"
-#include "components/scheduler/base/task_queue_manager.h"
-#include "components/scheduler/base/task_queue_selector.h"
-#include "components/scheduler/scheduler_export.h"
-
-namespace base {
-class TickClock;
-}
-
-namespace scheduler {
-
-class SchedulerTqmDelegate;
-
-// Common scheduler functionality for default tasks.
-class SCHEDULER_EXPORT SchedulerHelper
-    : public TaskQueueManager::Observer {
- public:
-  // Category strings must have application lifetime (statics or
-  // literals). They may not include " chars.
-  SchedulerHelper(
-      scoped_refptr<SchedulerTqmDelegate> task_queue_manager_delegate,
-      const char* tracing_category,
-      const char* disabled_by_default_tracing_category,
-      const char* disabled_by_default_verbose_tracing_category);
-  ~SchedulerHelper() override;
-
-  // TaskQueueManager::Observer implementation:
-  void OnUnregisterTaskQueue(const scoped_refptr<TaskQueue>& queue) override;
-  void OnTriedToExecuteBlockedTask(const TaskQueue& queue,
-                                   const base::PendingTask& task) override;
-
-  // Returns the default task runner.
-  scoped_refptr<TaskQueue> DefaultTaskRunner();
-
-  // Returns the control task runner.  Tasks posted to this runner are executed
-  // with the highest priority. Care must be taken to avoid starvation of other
-  // task queues.
-  scoped_refptr<TaskQueue> ControlTaskRunner();
-
-  // Returns the control task after wakeup runner.  Tasks posted to this runner
-  // are executed with the highest priority but do not cause the scheduler to
-  // wake up. Care must be taken to avoid starvation of other task queues.
-  scoped_refptr<TaskQueue> ControlAfterWakeUpTaskRunner();
-
-  // Adds or removes a task observer from the scheduler. The observer will be
-  // notified before and after every executed task. These functions can only be
-  // called on the thread this class was created on.
-  void AddTaskObserver(base::MessageLoop::TaskObserver* task_observer);
-  void RemoveTaskObserver(base::MessageLoop::TaskObserver* task_observer);
-
-  void SetTaskTimeTracker(TaskTimeTracker* task_time_tracker) {
-    if (task_queue_manager_)
-      task_queue_manager_->SetTaskTimeTracker(task_time_tracker);
-  }
-
-  // Shuts down the scheduler by dropping any remaining pending work in the work
-  // queues. After this call any work posted to the task runners will be
-  // silently dropped.
-  void Shutdown();
-
-  // Returns true if Shutdown() has been called. Otherwise returns false.
-  bool IsShutdown() const { return !task_queue_manager_.get(); }
-
-  void CheckOnValidThread() const {
-    DCHECK(thread_checker_.CalledOnValidThread());
-  }
-
-  // Creates a new TaskQueue with the given |spec|.
-  scoped_refptr<TaskQueue> NewTaskQueue(const TaskQueue::Spec& spec);
-
-  class SCHEDULER_EXPORT Observer {
-   public:
-    virtual ~Observer() {}
-
-    // Called when |queue| is unregistered.
-    virtual void OnUnregisterTaskQueue(
-        const scoped_refptr<TaskQueue>& queue) = 0;
-
-    // Called when the scheduler tried to execute a task from a disabled
-    // queue. See TaskQueue::Spec::SetShouldReportWhenExecutionBlocked.
-    virtual void OnTriedToExecuteBlockedTask(const TaskQueue& queue,
-                                             const base::PendingTask& task) = 0;
-  };
-
-  // Called once to set the Observer. This function is called on the main
-  // thread. If |observer| is null, then no callbacks will occur.
-  // Note |observer| is expected to outlive the SchedulerHelper.
-  void SetObserver(Observer* observer);
-
-  // Accessor methods.
-  RealTimeDomain* real_time_domain() const;
-  void RegisterTimeDomain(TimeDomain* time_domain);
-  void UnregisterTimeDomain(TimeDomain* time_domain);
-  const scoped_refptr<SchedulerTqmDelegate>& scheduler_tqm_delegate() const;
-  bool GetAndClearSystemIsQuiescentBit();
-  TaskQueue* CurrentlyExecutingTaskQueue() const;
-
-  // Test helpers.
-  void SetWorkBatchSizeForTesting(size_t work_batch_size);
-  TaskQueueManager* GetTaskQueueManagerForTesting();
-
- private:
-  friend class SchedulerHelperTest;
-
-  base::ThreadChecker thread_checker_;
-  scoped_refptr<SchedulerTqmDelegate> task_queue_manager_delegate_;
-  std::unique_ptr<TaskQueueManager> task_queue_manager_;
-  scoped_refptr<TaskQueue> control_task_runner_;
-  scoped_refptr<TaskQueue> control_after_wakeup_task_runner_;
-  scoped_refptr<TaskQueue> default_task_runner_;
-
-  Observer* observer_;  // NOT OWNED
-  const char* tracing_category_;
-  const char* disabled_by_default_tracing_category_;
-
-  DISALLOW_COPY_AND_ASSIGN(SchedulerHelper);
-};
-
-}  // namespace scheduler
-
-#endif  // COMPONENTS_SCHEDULER_CHILD_SCHEDULER_HELPER_H_