components/scheduler/renderer/renderer_scheduler_impl.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 COMPONENTS_SCHEDULER_RENDERER_RENDERER_SCHEDULER_IMPL_H_
   6 #define COMPONENTS_SCHEDULER_RENDERER_RENDERER_SCHEDULER_IMPL_H_
   7
   8 #include "base/atomicops.h"
   9 #include "base/synchronization/lock.h"
  10 #include "components/scheduler/child/idle_helper.h"
  11 #include "components/scheduler/child/pollable_thread_safe_flag.h"
  12 #include "components/scheduler/child/scheduler_helper.h"
  13 #include "components/scheduler/renderer/deadline_task_runner.h"
  14 #include "components/scheduler/renderer/renderer_scheduler.h"
  15 #include "components/scheduler/renderer/task_cost_estimator.h"
  16 #include "components/scheduler/scheduler_export.h"
  17
  18 namespace base {
  19 namespace trace_event {
  20 class ConvertableToTraceFormat;
  21 }
  22 }
  23
  24 namespace scheduler {
  25
  26 class SCHEDULER_EXPORT RendererSchedulerImpl : public RendererScheduler,
  27                                                public IdleHelper::Delegate {
  28  public:
  29   RendererSchedulerImpl(
  30       scoped_refptr<SchedulerTaskRunnerDelegate> main_task_runner);
  31   ~RendererSchedulerImpl() override;
  32
  33   // RendererScheduler implementation:
  34   scoped_refptr<TaskQueue> DefaultTaskRunner() override;
  35   scoped_refptr<SingleThreadIdleTaskRunner> IdleTaskRunner() override;
  36   scoped_refptr<base::SingleThreadTaskRunner> CompositorTaskRunner() override;
  37   scoped_refptr<base::SingleThreadTaskRunner> LoadingTaskRunner() override;
  38   scoped_refptr<TaskQueue> TimerTaskRunner() override;
  39   void WillBeginFrame(const cc::BeginFrameArgs& args) override;
  40   void BeginFrameNotExpectedSoon() override;
  41   void DidCommitFrameToCompositor() override;
  42   void DidHandleInputEventOnCompositorThread(
  43       const blink::WebInputEvent& web_input_event,
  44       InputEventState event_state) override;
  45   void DidHandleInputEventOnMainThread(
  46       const blink::WebInputEvent& web_input_event) override;
  47   void DidAnimateForInputOnCompositorThread() override;
  48   void OnRendererHidden() override;
  49   void OnRendererVisible() override;
  50   void OnPageLoadStarted() override;
  51   bool IsHighPriorityWorkAnticipated() override;
  52   bool ShouldYieldForHighPriorityWork() override;
  53   bool CanExceedIdleDeadlineIfRequired() const override;
  54   void AddTaskObserver(base::MessageLoop::TaskObserver* task_observer) override;
  55   void RemoveTaskObserver(
  56       base::MessageLoop::TaskObserver* task_observer) override;
  57   void Shutdown() override;
  58   void SuspendTimerQueue() override;
  59   void ResumeTimerQueue() override;
  60
  61   SchedulerHelper* GetSchedulerHelperForTesting();
  62   base::TimeTicks CurrentIdleTaskDeadlineForTesting() const;
  63
  64  private:
  65   friend class RendererSchedulerImplTest;
  66   friend class RendererSchedulerImplForTest;
  67
  68   // Keep RendererSchedulerImpl::PolicyToString in sync with this enum.
  69   enum class Policy {
  70     NORMAL,
  71     COMPOSITOR_PRIORITY,
  72     COMPOSITOR_CRITICAL_PATH_PRIORITY,
  73     TOUCHSTART_PRIORITY,
  74     LOADING_PRIORITY,
  75     // Must be the last entry.
  76     POLICY_COUNT,
  77     FIRST_POLICY = NORMAL,
  78   };
  79
  80   class PollableNeedsUpdateFlag {
  81    public:
  82     PollableNeedsUpdateFlag(base::Lock* write_lock);
  83     ~PollableNeedsUpdateFlag();
  84
  85     // Set the flag. May only be called if |write_lock| is held.
  86     void SetWhileLocked(bool value);
  87
  88     // Returns true iff the flag is set to true.
  89     bool IsSet() const;
  90
  91    private:
  92     base::subtle::Atomic32 flag_;
  93     base::Lock* write_lock_;  // Not owned.
  94
  95     DISALLOW_COPY_AND_ASSIGN(PollableNeedsUpdateFlag);
  96   };
  97
  98   // IdleHelper::Delegate implementation:
  99   bool CanEnterLongIdlePeriod(
 100       base::TimeTicks now,
 101       base::TimeDelta* next_long_idle_period_delay_out) override;
 102   void IsNotQuiescent() override {}
 103   void OnIdlePeriodStarted() override;
 104   void OnIdlePeriodEnded() override;
 105
 106   void EndIdlePeriod();
 107
 108   // Returns the serialized scheduler state for tracing.
 109   scoped_refptr<base::trace_event::ConvertableToTraceFormat> AsValue(
 110       base::TimeTicks optional_now) const;
 111   scoped_refptr<base::trace_event::ConvertableToTraceFormat> AsValueLocked(
 112       base::TimeTicks optional_now) const;
 113   static const char* PolicyToString(Policy policy);
 114
 115   static bool ShouldPrioritizeInputEvent(
 116       const blink::WebInputEvent& web_input_event);
 117
 118   // The time we should stay in a priority-escalated mode after an input event.
 119   static const int kPriorityEscalationAfterInputMillis = 100;
 120
 121   // The amount of time which idle periods can continue being scheduled when the
 122   // renderer has been hidden, before going to sleep for good.
 123   static const int kEndIdleWhenHiddenDelayMillis = 10000;
 124
 125   // The amount of time for which loading tasks will be prioritized over
 126   // other tasks during the initial page load.
 127   static const int kRailsInitialLoadingPrioritizationMillis = 1000;
 128
 129   // For the purposes of deciding whether or not it's safe to turn timers and
 130   // loading tasks on only in idle periods, we regard the system as being as
 131   // being "idle period" starved if there hasn't been an idle period in the last
 132   // 10 seconds. This was chosen to be long enough to cover most anticipated
 133   // user gestures.
 134   static const int kIdlePeriodStarvationThresholdMillis = 10000;
 135
 136   // Schedules an immediate PolicyUpdate, if there isn't one already pending and
 137   // sets |policy_may_need_update_|. Note |any_thread_lock_| must be
 138   // locked.
 139   void EnsureUrgentPolicyUpdatePostedOnMainThread(
 140       const tracked_objects::Location& from_here);
 141
 142   // Update the policy if a new signal has arrived. Must be called from the main
 143   // thread.
 144   void MaybeUpdatePolicy();
 145
 146   // Locks |any_thread_lock_| and updates the scheduler policy.  May early
 147   // out if the policy is unchanged. Must be called from the main thread.
 148   void UpdatePolicy();
 149
 150   // Like UpdatePolicy, except it doesn't early out.
 151   void ForceUpdatePolicy();
 152
 153   enum class UpdateType {
 154     MAY_EARLY_OUT_IF_POLICY_UNCHANGED,
 155     FORCE_UPDATE,
 156   };
 157
 158   // The implelemtation of UpdatePolicy & ForceUpdatePolicy.  It is allowed to
 159   // early out if |update_type| is MAY_EARLY_OUT_IF_POLICY_UNCHANGED.
 160   virtual void UpdatePolicyLocked(UpdateType update_type);
 161
 162   // Returns the amount of time left in the current input escalated priority
 163   // policy.  Can be called from any thread.
 164   base::TimeDelta TimeLeftInInputEscalatedPolicy(base::TimeTicks now) const;
 165
 166   // Helper for computing the new policy. |new_policy_duration| will be filled
 167   // with the amount of time after which the policy should be updated again. If
 168   // the duration is zero, a new policy update will not be scheduled. Must be
 169   // called with |any_thread_lock_| held. Can be called from any thread.
 170   Policy ComputeNewPolicy(base::TimeTicks now,
 171                           base::TimeDelta* new_policy_duration) const;
 172
 173   // Works out if compositor tasks would be prioritized based on the current
 174   // input signals.  Can be called from any thread.
 175   bool InputSignalsSuggestCompositorPriority(base::TimeTicks now) const;
 176
 177   // An input event of some sort happened, the policy may need updating.
 178   void UpdateForInputEventOnCompositorThread(blink::WebInputEvent::Type type,
 179                                              InputEventState input_event_state);
 180
 181   // Returns true if there has been at least one idle period in the last
 182   // |kIdlePeriodStarvationThresholdMillis|.
 183   bool HadAnIdlePeriodRecently(base::TimeTicks now) const;
 184
 185   SchedulerHelper helper_;
 186   IdleHelper idle_helper_;
 187
 188   const scoped_refptr<TaskQueue> control_task_runner_;
 189   const scoped_refptr<TaskQueue> compositor_task_runner_;
 190   const scoped_refptr<TaskQueue> loading_task_runner_;
 191   const scoped_refptr<TaskQueue> timer_task_runner_;
 192
 193   base::Closure update_policy_closure_;
 194   DeadlineTaskRunner delayed_update_policy_runner_;
 195   CancelableClosureHolder end_renderer_hidden_idle_period_closure_;
 196
 197   // We have decided to improve thread safety at the cost of some boilerplate
 198   // (the accessors) for the following data members.
 199
 200   struct MainThreadOnly {
 201     MainThreadOnly();
 202     ~MainThreadOnly();
 203
 204     TaskCostEstimator timer_task_cost_estimator_;
 205     cc::RollingTimeDeltaHistory short_idle_period_duration_;
 206     Policy current_policy_;
 207     base::TimeTicks current_policy_expiration_time_;
 208     base::TimeTicks estimated_next_frame_begin_;
 209     base::TimeDelta expected_short_idle_period_duration_;
 210     int timer_queue_suspend_count_;  // TIMER_TASK_QUEUE suspended if non-zero.
 211     bool renderer_hidden_;
 212     bool was_shutdown_;
 213   };
 214
 215   struct AnyThread {
 216     AnyThread();
 217
 218     base::TimeTicks last_input_signal_time_;
 219     base::TimeTicks last_idle_period_end_time_;
 220     base::TimeTicks rails_loading_priority_deadline_;
 221     int pending_main_thread_input_event_count_;
 222     bool awaiting_touch_start_response_;
 223     bool in_idle_period_;
 224     bool begin_main_frame_on_critical_path_;
 225     bool timer_tasks_seem_expensive_;
 226   };
 227
 228   struct CompositorThreadOnly {
 229     CompositorThreadOnly();
 230     ~CompositorThreadOnly();
 231
 232     blink::WebInputEvent::Type last_input_type_;
 233     scoped_ptr<base::ThreadChecker> compositor_thread_checker_;
 234
 235     void CheckOnValidThread() {
 236 #if DCHECK_IS_ON()
 237       // We don't actually care which thread this called from, just so long as
 238       // its consistent.
 239       if (!compositor_thread_checker_)
 240         compositor_thread_checker_.reset(new base::ThreadChecker());
 241       DCHECK(compositor_thread_checker_->CalledOnValidThread());
 242 #endif
 243     }
 244   };
 245
 246   // Don't access main_thread_only_, instead use MainThreadOnly().
 247   MainThreadOnly main_thread_only_;
 248   MainThreadOnly& MainThreadOnly() {
 249     helper_.CheckOnValidThread();
 250     return main_thread_only_;
 251   }
 252   const struct MainThreadOnly& MainThreadOnly() const {
 253     helper_.CheckOnValidThread();
 254     return main_thread_only_;
 255   }
 256
 257   mutable base::Lock any_thread_lock_;
 258   // Don't access any_thread_, instead use AnyThread().
 259   AnyThread any_thread_;
 260   AnyThread& AnyThread() {
 261     any_thread_lock_.AssertAcquired();
 262     return any_thread_;
 263   }
 264   const struct AnyThread& AnyThread() const {
 265     any_thread_lock_.AssertAcquired();
 266     return any_thread_;
 267   }
 268
 269   // Don't access compositor_thread_only_, instead use CompositorThreadOnly().
 270   CompositorThreadOnly compositor_thread_only_;
 271   CompositorThreadOnly& CompositorThreadOnly() {
 272     compositor_thread_only_.CheckOnValidThread();
 273     return compositor_thread_only_;
 274   }
 275
 276   PollableThreadSafeFlag policy_may_need_update_;
 277   base::WeakPtrFactory<RendererSchedulerImpl> weak_factory_;
 278
 279   DISALLOW_COPY_AND_ASSIGN(RendererSchedulerImpl);
 280 };
 281
 282 }  // namespace scheduler
 283
 284 #endif  // COMPONENTS_SCHEDULER_RENDERER_RENDERER_SCHEDULER_IMPL_H_