[content]: Add support for long idle times in the Blink Scheduler.

content/renderer/scheduler/renderer_scheduler_impl.h

 // Copyright 2014 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 CONTENT_RENDERER_SCHEDULER_RENDERER_SCHEDULER_IMPL_H_
 #define CONTENT_RENDERER_SCHEDULER_RENDERER_SCHEDULER_IMPL_H_
 
 #include "base/atomicops.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread_checker.h"
@@ skipping 34 matching lines @@
   void DidAnimateForInputOnCompositorThread() override;
   bool IsHighPriorityWorkAnticipated() override;
   bool ShouldYieldForHighPriorityWork() override;
   void AddTaskObserver(base::MessageLoop::TaskObserver* task_observer) override;
   void RemoveTaskObserver(
       base::MessageLoop::TaskObserver* task_observer) override;
   void Shutdown() override;
 
   void SetTimeSourceForTesting(scoped_refptr<cc::TestNowSource> time_source);
   void SetWorkBatchSizeForTesting(size_t work_batch_size);
+  // TODO(rmcilroy): Remove this when http://crbug.com/467655 is fixed.
+  void SetLongIdlePeriodsEnabledForTesting(bool long_idle_periods_enabled);
 
  private:
   friend class RendererSchedulerImplTest;
   friend class RendererSchedulerImplForTest;
 
   // Keep RendererSchedulerImpl::TaskQueueIdToString in sync with this enum.
   enum QueueId {
     DEFAULT_TASK_QUEUE,
     COMPOSITOR_TASK_QUEUE,
     LOADING_TASK_QUEUE,
     IDLE_TASK_QUEUE,
     CONTROL_TASK_QUEUE,
     CONTROL_TASK_AFTER_WAKEUP_QUEUE,
     // Must be the last entry.
     TASK_QUEUE_COUNT,
   };
 
+  // Keep RendererSchedulerImpl::PolicyToString in sync with this enum.
   enum class Policy {
     NORMAL,
     COMPOSITOR_PRIORITY,
     TOUCHSTART_PRIORITY,
   };
 
+  // Keep RendererSchedulerImpl::InputStreamStateToString in sync with this
+  // enum.
   enum class InputStreamState {
     INACTIVE,
     ACTIVE,
     ACTIVE_AND_AWAITING_TOUCHSTART_RESPONSE
   };
 
+  // Keep RendererSchedulerImpl::IdlePeriodStateToString in sync with this enum.
+  enum class IdlePeriodState {
+    NOT_IN_IDLE_PERIOD,
+    IN_SHORT_IDLE_PERIOD,
+    IN_LONG_IDLE_PERIOD,
+    IN_LONG_IDLE_PERIOD_WITH_MAX_DEADLINE,
+    ENDING_LONG_IDLE_PERIOD
+  };
+
   class PollableNeedsUpdateFlag {
    public:
     PollableNeedsUpdateFlag(base::Lock* write_lock);
     ~PollableNeedsUpdateFlag();
 
     // Set the flag. May only be called if |write_lock| is held.
     void SetWhileLocked(bool value);
 
     // Returns true iff the flag is set to true.
     bool IsSet() const;
 
    private:
     base::subtle::Atomic32 flag_;
     base::Lock* write_lock_;  // Not owned.
 
     DISALLOW_COPY_AND_ASSIGN(PollableNeedsUpdateFlag);
   };
 
   // Returns the serialized scheduler state for tracing.
   scoped_refptr<base::trace_event::ConvertableToTraceFormat> AsValueLocked(
       base::TimeTicks optional_now) const;
   static const char* TaskQueueIdToString(QueueId queue_id);
   static const char* PolicyToString(Policy policy);
   static const char* InputStreamStateToString(InputStreamState state);
+  static const char* IdlePeriodStateToString(IdlePeriodState state);
 
   static InputStreamState ComputeNewInputStreamState(
       InputStreamState current_state,
       blink::WebInputEvent::Type new_input_event,
       blink::WebInputEvent::Type last_input_event);
 
   // The time we should stay in a priority-escalated mode after an input event.
   static const int kPriorityEscalationAfterInputMillis = 100;
 
+  // The maximum length of an idle period.
+  static const int kMaximumIdlePeriodMillis = 50;
+
+  // The minimum delay to wait between retrying to initiate a long idle time.
+  static const int kRetryInitiateLongIdlePeriodDelayMillis = 1;
+
   // IdleTaskDeadlineSupplier Implementation:
   void CurrentIdleTaskDeadlineCallback(base::TimeTicks* deadline_out) const;
 
   // Returns the current scheduler policy. Must be called from the main thread.
   Policy SchedulerPolicy() const;
 
   // Schedules an immediate PolicyUpdate, if there isn't one already pending and
   // sets |policy_may_need_update_|. Note |incoming_signals_lock_| must be
   // locked.
   void EnsureUrgentPolicyUpdatePostedOnMainThread(
       const tracked_objects::Location& from_here);
 
   // Update the policy if a new signal has arrived. Must be called from the main
   // thread.
   void MaybeUpdatePolicy();
 
   // Locks |incoming_signals_lock_| and updates the scheduler policy.
   // Must be called from the main thread.
   void UpdatePolicy();
   virtual void UpdatePolicyLocked();
 
+  // Returns the amount of time left in the current input escalated priority
+  // policy.
+  base::TimeDelta TimeLeftInInputEscalatedPolicy(base::TimeTicks now) const;
+
   // Helper for computing the new policy. |new_policy_duration| will be filled
   // with the amount of time after which the policy should be updated again. If
   // the duration is zero, a new policy update will not be scheduled. Must be
   // called with |incoming_signals_lock_| held.
   Policy ComputeNewPolicy(base::TimeTicks now,
                           base::TimeDelta* new_policy_duration);
 
   // An input event of some sort happened, the policy may need updating.
   void UpdateForInputEvent(blink::WebInputEvent::Type type);
 
   // Called when a previously queued input event was processed.
   // |begin_frame_time|, if non-zero, identifies the frame time at which the
   // input was processed.
   void DidProcessInputEvent(base::TimeTicks begin_frame_time);
 
+  // Returns the new idle period state for the next long idle period. Fills in
+  // |next_long_idle_period_delay_out| with the next time we should try to
+  // initiate the next idle period.
+  IdlePeriodState ComputeNewLongIdlePeriodState(
+      const base::TimeTicks now,
+      base::TimeDelta* next_long_idle_period_delay_out);
+
+  // Initiate a long idle period.
+  void InitiateLongIdlePeriod();
+  void InitiateLongIdlePeriodAfterWakeup();
+
   // Start and end an idle period.
-  void StartIdlePeriod();
+  void StartIdlePeriod(IdlePeriodState new_idle_period_state);
   void EndIdlePeriod();
 
+  // Returns true if |state| represents being within an idle period state.
+  static bool IsInIdlePeriod(IdlePeriodState state);
+
   base::TimeTicks Now() const;
 
   base::ThreadChecker main_thread_checker_;
   scoped_ptr<RendererTaskQueueSelector> renderer_task_queue_selector_;
   scoped_ptr<TaskQueueManager> task_queue_manager_;
   scoped_refptr<base::SingleThreadTaskRunner> control_task_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> control_task_after_wakeup_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> default_task_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> compositor_task_runner_;
   scoped_refptr<base::SingleThreadTaskRunner> loading_task_runner_;
   scoped_refptr<SingleThreadIdleTaskRunner> idle_task_runner_;
 
   base::Closure update_policy_closure_;
   DeadlineTaskRunner delayed_update_policy_runner_;
   CancelableClosureHolder end_idle_period_closure_;
+  CancelableClosureHolder initiate_next_long_idle_period_closure_;
+  CancelableClosureHolder initiate_next_long_idle_period_after_wakeup_closure_;
 
   // Don't access current_policy_ directly, instead use SchedulerPolicy().
   Policy current_policy_;
+  IdlePeriodState idle_period_state_;
+
+    // TODO(rmcilroy): Remove this when http://crbug.com/467655 is fixed.
+  bool long_idle_periods_enabled_;
 
   base::TimeTicks estimated_next_frame_begin_;
+  base::TimeTicks current_policy_expiration_time_;
 
   // The incoming_signals_lock_ mutex protects access to all variables in the
   // (contiguous) block below.
   base::Lock incoming_signals_lock_;
   base::TimeTicks last_input_receipt_time_on_compositor_;
   base::TimeTicks last_input_process_time_on_main_;
   blink::WebInputEvent::Type last_input_type_;
   InputStreamState input_stream_state_;
   PollableNeedsUpdateFlag policy_may_need_update_;
 
   scoped_refptr<cc::TestNowSource> time_source_;
 
   base::WeakPtr<RendererSchedulerImpl> weak_renderer_scheduler_ptr_;
   base::WeakPtrFactory<RendererSchedulerImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RendererSchedulerImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_SCHEDULER_RENDERER_SCHEDULER_IMPL_H_