content/child/scheduler/worker_scheduler.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 CONTENT_CHILD_SCHEDULER_WORKER_SCHEDULER_H_
   6 #define CONTENT_CHILD_SCHEDULER_WORKER_SCHEDULER_H_
   7
   8 #include "base/message_loop/message_loop.h"
   9 #include "content/child/scheduler/single_thread_idle_task_runner.h"
  10 #include "content/common/content_export.h"
  11
  12 namespace base {
  13 class MessageLoop;
  14 }
  15
  16 namespace content {
  17
  18 class CONTENT_EXPORT WorkerScheduler {
  19  public:
  20   virtual ~WorkerScheduler();
  21   static scoped_ptr<WorkerScheduler> Create(base::MessageLoop* message_loop);
  22
  23   // Must be called before the scheduler can be used. Does any post construction
  24   // initialization needed such as initializing idle period detection.
  25   virtual void Init() = 0;
  26
  27   // Returns the default task runner.
  28   virtual scoped_refptr<base::SingleThreadTaskRunner> DefaultTaskRunner() = 0;
  29
  30   // Returns the idle task runner. Tasks posted to this runner may be reordered
  31   // relative to other task types and may be starved for an arbitrarily long
  32   // time if no idle time is available.
  33   virtual scoped_refptr<SingleThreadIdleTaskRunner> IdleTaskRunner() = 0;
  34
  35   // Returns true if a currently running idle task could exceed its deadline
  36   // without impacting user experience too much. This should only be used if
  37   // there is a task which cannot be pre-empted and is likely to take longer
  38   // than the largest expected idle task deadline. It should NOT be polled to
  39   // check whether more work can be performed on the current idle task after
  40   // its deadline has expired - post a new idle task for the continuation of the
  41   // work in this case.
  42   // Must be called from the worker's thread.
  43   virtual bool CanExceedIdleDeadlineIfRequired() const = 0;
  44
  45   // Adds or removes a task observer from the scheduler. The observer will be
  46   // notified before and after every executed task. These functions can only be
  47   // called on the main thread.
  48   virtual void AddTaskObserver(
  49       base::MessageLoop::TaskObserver* task_observer) = 0;
  50   virtual void RemoveTaskObserver(
  51       base::MessageLoop::TaskObserver* task_observer) = 0;
  52
  53   // Shuts down the scheduler by dropping any remaining pending work in the work
  54   // queues. After this call any work posted to the task runners will be
  55   // silently dropped.
  56   virtual void Shutdown() = 0;
  57
  58  protected:
  59   WorkerScheduler();
  60   DISALLOW_COPY_AND_ASSIGN(WorkerScheduler);
  61 };
  62
  63 }  // namespace content
  64
  65 #endif  // CONTENT_CHILD_SCHEDULER_WORKER_SCHEDULER_H_