components/scheduler/child/scheduler_helper.h

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef COMPONENTS_SCHEDULER_CHILD_SCHEDULER_HELPER_H_
   6 #define COMPONENTS_SCHEDULER_CHILD_SCHEDULER_HELPER_H_
   7
   8 #include "components/scheduler/child/task_queue_manager.h"
   9 #include "components/scheduler/child/task_queue_selector.h"
  10 #include "components/scheduler/scheduler_export.h"
  11
  12 namespace base {
  13 class TickClock;
  14 }
  15
  16 namespace scheduler {
  17
  18 class SchedulerTaskRunnerDelegate;
  19
  20 // Common scheduler functionality for default tasks.
  21 class SCHEDULER_EXPORT SchedulerHelper {
  22  public:
  23   // Category strings must have application lifetime (statics or
  24   // literals). They may not include " chars.
  25   SchedulerHelper(scoped_refptr<SchedulerTaskRunnerDelegate> main_task_runner,
  26                   const char* tracing_category,
  27                   const char* disabled_by_default_tracing_category,
  28                   const char* disabled_by_default_verbose_tracing_category);
  29   ~SchedulerHelper();
  30
  31   // Returns the default task runner.
  32   scoped_refptr<TaskQueue> DefaultTaskRunner();
  33
  34   // Returns the control task runner.  Tasks posted to this runner are executed
  35   // with the highest priority. Care must be taken to avoid starvation of other
  36   // task queues.
  37   scoped_refptr<TaskQueue> ControlTaskRunner();
  38
  39   // Returns the control task after wakeup runner.  Tasks posted to this runner
  40   // are executed with the highest priority but do not cause the scheduler to
  41   // wake up. Care must be taken to avoid starvation of other task queues.
  42   scoped_refptr<TaskQueue> ControlAfterWakeUpTaskRunner();
  43
  44   // Adds or removes a task observer from the scheduler. The observer will be
  45   // notified before and after every executed task. These functions can only be
  46   // called on the thread this class was created on.
  47   void AddTaskObserver(base::MessageLoop::TaskObserver* task_observer);
  48   void RemoveTaskObserver(base::MessageLoop::TaskObserver* task_observer);
  49
  50   // Shuts down the scheduler by dropping any remaining pending work in the work
  51   // queues. After this call any work posted to the task runners will be
  52   // silently dropped.
  53   void Shutdown();
  54
  55   // Returns true if Shutdown() has been called. Otherwise returns false.
  56   bool IsShutdown() const { return !task_queue_manager_.get(); }
  57
  58   void CheckOnValidThread() const {
  59     DCHECK(thread_checker_.CalledOnValidThread());
  60   }
  61
  62   // Creates a new TaskQueue with the given |spec|.
  63   scoped_refptr<TaskQueue> NewTaskQueue(const TaskQueue::Spec& spec);
  64
  65   // Accessor methods.
  66   base::TimeTicks Now() const;
  67   base::TimeTicks NextPendingDelayedTaskRunTime() const;
  68   bool GetAndClearSystemIsQuiescentBit();
  69
  70   // Test helpers.
  71   void SetTimeSourceForTesting(scoped_ptr<base::TickClock> time_source);
  72   void SetWorkBatchSizeForTesting(size_t work_batch_size);
  73   TaskQueueManager* GetTaskQueueManagerForTesting();
  74
  75  private:
  76   friend class SchedulerHelperTest;
  77
  78   base::ThreadChecker thread_checker_;
  79   scoped_refptr<SchedulerTaskRunnerDelegate> main_task_runner_;
  80   scoped_ptr<TaskQueueManager> task_queue_manager_;
  81   scoped_refptr<TaskQueue> control_task_runner_;
  82   scoped_refptr<TaskQueue> control_after_wakeup_task_runner_;
  83   scoped_refptr<TaskQueue> default_task_runner_;
  84
  85   scoped_ptr<base::TickClock> time_source_;
  86
  87   const char* tracing_category_;
  88   const char* disabled_by_default_tracing_category_;
  89
  90   DISALLOW_COPY_AND_ASSIGN(SchedulerHelper);
  91 };
  92
  93 }  // namespace scheduler
  94
  95 #endif  // COMPONENTS_SCHEDULER_CHILD_SCHEDULER_HELPER_H_