content/child/scheduler/task_queue_selector.h

   1 // Copyright 2014 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 CONTENT_CHILD_SCHEDULER_TASK_QUEUE_SELECTOR_H_
   6 #define CONTENT_CHILD_SCHEDULER_TASK_QUEUE_SELECTOR_H_
   7
   8 #include <vector>
   9
  10 #include "base/basictypes.h"
  11 #include "content/common/content_export.h"
  12
  13 namespace base {
  14 class TaskQueue;
  15 namespace trace_event {
  16 class TracedValue;
  17 }  // namespace trace_event
  18 }  // namespace base
  19
  20 namespace content {
  21
  22 class TaskQueueSelector {
  23  public:
  24   virtual ~TaskQueueSelector() {}
  25
  26   // Called once to register the work queues to be selected from. This function
  27   // is called on the main thread.
  28   virtual void RegisterWorkQueues(
  29       const std::vector<const base::TaskQueue*>& work_queues) = 0;
  30
  31   class CONTENT_EXPORT Observer {
  32    public:
  33     virtual ~Observer() {}
  34
  35     // Called when a task queue transitions from disabled to enabled.
  36     virtual void OnTaskQueueEnabled() = 0;
  37   };
  38
  39   // Called once to set the Observer. This function is called
  40   // on the main thread. If |observer| is null, then no callbacks will occur.
  41   virtual void SetTaskQueueSelectorObserver(Observer* observer) = 0;
  42
  43   // Called to choose the work queue from which the next task should be taken
  44   // and run. Return true if |out_queue| indicates the queue to service or
  45   // false to avoid running any task.
  46   //
  47   // This function is called on the main thread.
  48   virtual bool SelectWorkQueueToService(size_t* out_queue_index) = 0;
  49
  50   // Serialize the selector state for tracing.
  51   virtual void AsValueInto(base::trace_event::TracedValue* state) const = 0;
  52 };
  53
  54 }  // namespace content
  55
  56 #endif  // CONTENT_CHILD_SCHEDULER_TASK_QUEUE_SELECTOR_H_