[scheduler] Teach scheduler about audio state

third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc

 // 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.
 
 #include "platform/scheduler/renderer/renderer_scheduler_impl.h"
 
 #include "base/bind.h"
 #include "base/debug/stack_trace.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
 #include "cc/output/begin_frame_args.h"
+#include "platform/scheduler/base/real_time_domain.h"
 #include "platform/scheduler/base/task_queue_impl.h"
 #include "platform/scheduler/base/task_queue_selector.h"
 #include "platform/scheduler/base/virtual_time_domain.h"
 #include "platform/scheduler/child/scheduler_tqm_delegate.h"
 #include "platform/scheduler/renderer/auto_advancing_virtual_time_domain.h"
 #include "platform/scheduler/renderer/task_queue_throttler.h"
 #include "platform/scheduler/renderer/web_view_scheduler_impl.h"
 #include "platform/scheduler/renderer/webthread_impl_for_renderer_scheduler.h"
 
 namespace blink {
 namespace scheduler {
 namespace {
 // The run time of loading tasks is strongly bimodal.  The vast majority are
 // very cheap, but there are usually a handful of very expensive tasks (e.g ~1
 // second on a mobile device) so we take a very pessimistic view when estimating
 // the cost of loading tasks.
 const int kLoadingTaskEstimationSampleCount = 1000;
 const double kLoadingTaskEstimationPercentile = 99;
 const int kTimerTaskEstimationSampleCount = 1000;
 const double kTimerTaskEstimationPercentile = 99;
 const int kShortIdlePeriodDurationSampleCount = 10;
 const double kShortIdlePeriodDurationPercentile = 50;
 // Amount of idle time left in a frame (as a ratio of the vsync interval) above
 // which main thread compositing can be considered fast.
 const double kFastCompositingIdleTimeThreshold = .2;
+// We do not throttle anything while audio is played and shortly after that.
+const int kThrottlingDelayAfterAudioIsPlayedInSeconds = 5;
 
 void ReportForegroundRendererTaskLoad(base::TimeTicks time, double load) {
   int load_percentage = static_cast<int>(load * 100);
   UMA_HISTOGRAM_PERCENTAGE("RendererScheduler.ForegroundRendererMainThreadLoad",
                            load_percentage);
   TRACE_COUNTER1(TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
                  "RendererScheduler.ForegroundRendererLoad", load_percentage);
 }
 
 void ReportBackgroundRendererTaskLoad(base::TimeTicks time, double load) {
@@ skipping 101 matching lines @@
                           time_source,
                           kShortIdlePeriodDurationSampleCount,
                           kShortIdlePeriodDurationPercentile),
       background_main_thread_load_tracker(
           now,
           base::Bind(&ReportBackgroundRendererTaskLoad)),
       foreground_main_thread_load_tracker(
           now,
           base::Bind(&ReportForegroundRendererTaskLoad)),
       current_use_case(UseCase::NONE),
+      throttling_delay_after_audio_is_played(base::TimeDelta::FromSeconds(
+          kThrottlingDelayAfterAudioIsPlayedInSeconds)),
       timer_queue_suspend_count(0),
       navigation_task_expected_count(0),
       expensive_task_policy(ExpensiveTaskPolicy::RUN),
       renderer_hidden(false),
       renderer_backgrounded(false),
       renderer_suspended(false),
       timer_queue_suspension_when_backgrounded_enabled(false),
       timer_queue_suspended_when_backgrounded(false),
       was_shutdown(false),
       loading_tasks_seem_expensive(false),
@@ skipping 298 matching lines @@
   MainThreadOnly().renderer_suspended = false;
 
   base::TimeTicks now = tick_clock()->NowTicks();
   MainThreadOnly().foreground_main_thread_load_tracker.Resume(now);
   MainThreadOnly().background_main_thread_load_tracker.Pause(now);
 
   suspend_timers_when_backgrounded_closure_.Cancel();
   ResumeTimerQueueWhenForegrounded();
 }
 
+void RendererSchedulerImpl::OnAudioStateChanged(bool is_audio_playing) {
+  MainThreadOnly().last_audio_state_change =
+      helper_.scheduler_tqm_delegate()->NowTicks();
+  MainThreadOnly().is_audio_playing = is_audio_playing;
+
+  UpdatePolicy();
+}
+
 void RendererSchedulerImpl::SuspendRenderer() {
   helper_.CheckOnValidThread();
   DCHECK(MainThreadOnly().renderer_backgrounded);
   if (helper_.IsShutdown())
     return;
   suspend_timers_when_backgrounded_closure_.Cancel();
   // TODO(hajimehoshi): We might need to suspend not only timer queue but also
   // e.g. loading tasks or postMessage.
   MainThreadOnly().renderer_suspended = true;
   SuspendTimerQueueWhenBackgrounded();
@@ skipping 310 matching lines @@
   // The |new_policy_duration| is the minimum of |expected_use_case_duration|
   // and |touchstart_expected_flag_valid_for_duration| unless one is zero in
   // which case we choose the other.
   base::TimeDelta new_policy_duration = expected_use_case_duration;
   if (new_policy_duration.is_zero() ||
       (touchstart_expected_flag_valid_for_duration > base::TimeDelta() &&
        new_policy_duration > touchstart_expected_flag_valid_for_duration)) {
     new_policy_duration = touchstart_expected_flag_valid_for_duration;
   }
 
+  if (MainThreadOnly().last_audio_state_change &&

[alex clarke (OOO till 29th), 2016/09/30 10:33:46]

Please add a brief comment outlining why we do this.

[altimin, 2016/10/03 11:15:25]

Done.

+      !MainThreadOnly().is_audio_playing) {
+    base::TimeTicks audio_will_expire =
+        MainThreadOnly().last_audio_state_change.value() +
+        MainThreadOnly().throttling_delay_after_audio_is_played;
+
+    base::TimeDelta audio_will_expire_after = audio_will_expire - now;
+
+    if (audio_will_expire_after > base::TimeDelta()) {
+      if (new_policy_duration.is_zero()) {
+        new_policy_duration = audio_will_expire_after;
+      } else {
+        new_policy_duration =
+            std::min(new_policy_duration, audio_will_expire_after);
+      }
+    }
+  }
+
   if (new_policy_duration > base::TimeDelta()) {
     MainThreadOnly().current_policy_expiration_time = now + new_policy_duration;
     delayed_update_policy_runner_.SetDeadline(FROM_HERE, new_policy_duration,
                                               now);
   } else {
     MainThreadOnly().current_policy_expiration_time = base::TimeTicks();
   }
 
   // Avoid prioritizing main thread compositing (e.g., rAF) if it is extremely
   // slow, because that can cause starvation in other task sources.
@@ skipping 135 matching lines @@
   }
 
   if (MainThreadOnly().use_virtual_time) {
     new_policy.compositor_queue_policy.time_domain_type =
         TimeDomainType::VIRTUAL;
     new_policy.default_queue_policy.time_domain_type = TimeDomainType::VIRTUAL;
     new_policy.loading_queue_policy.time_domain_type = TimeDomainType::VIRTUAL;
     new_policy.timer_queue_policy.time_domain_type = TimeDomainType::VIRTUAL;
   }
 
+  new_policy.should_disable_throttling =
+      ShouldDisableThrottlingBecauseOfAudio(now) ||

[Sami, 2016/09/30 11:52:09]

By the way, this means that we might get more scroll jank on pages that play
audio, but those are most likely pretty rare.

[altimin, 2016/10/03 11:15:25]

How are throttling and scroll jank related? Are you talking about offscreen
iframes throttling?

[Sami, 2016/10/03 14:36:31]

Not just visibility-based throttling. Previously we would always throttle, e.g.,
long timer tasks when the user was trying to scroll. With this change we no
longer do that on pages that play audio. Things like games might be impacted,
but then again we already try to be very careful about throttling anything when
there is complicated input handling going on.

+      MainThreadOnly().use_virtual_time;
+
   // Tracing is done before the early out check, because it's quite possible we
   // will otherwise miss this information in traces.
   CreateTraceEventObjectSnapshotLocked();
   TRACE_COUNTER1(TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"), "use_case",
                  use_case);
   TRACE_COUNTER1(TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"), "rail_mode",
                  new_policy.rail_mode);
   TRACE_COUNTER1(TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
                  "touchstart_expected_soon",
                  MainThreadOnly().touchstart_expected_soon);
@@ skipping 35 matching lines @@
   // are mostly dispatched on the default queue) need to be preserved.
   ApplyTaskQueuePolicy(helper_.DefaultTaskRunner().get(),
                        MainThreadOnly().current_policy.default_queue_policy,
                        new_policy.default_queue_policy);
   if (MainThreadOnly().rail_mode_observer &&
       new_policy.rail_mode != MainThreadOnly().current_policy.rail_mode) {
     MainThreadOnly().rail_mode_observer->OnRAILModeChanged(
         new_policy.rail_mode);
   }
 
+  if (new_policy.should_disable_throttling !=
+      MainThreadOnly().current_policy.should_disable_throttling) {
+    if (new_policy.should_disable_throttling) {
+      task_queue_throttler()->DisableThrottling();
+    } else {
+      task_queue_throttler()->EnableThrottling();
+    }
+  }
+
   DCHECK(compositor_task_runner_->IsQueueEnabled());
   MainThreadOnly().current_policy = new_policy;
 }
 
 void RendererSchedulerImpl::ApplyTaskQueuePolicy(
     TaskQueue* task_queue,
     const TaskQueuePolicy& old_task_queue_policy,
     const TaskQueuePolicy& new_task_queue_policy) const {
   if (old_task_queue_policy.is_enabled != new_task_queue_policy.is_enabled) {
     task_queue_throttler_->SetQueueEnabled(task_queue,
@@ skipping 502 matching lines @@
 }
 
 void RendererSchedulerImpl::EnableVirtualTime() {
   MainThreadOnly().use_virtual_time = true;
 
   // The |unthrottled_task_runners_| are not actively managed by UpdatePolicy().
   AutoAdvancingVirtualTimeDomain* time_domain = GetVirtualTimeDomain();
   for (const scoped_refptr<TaskQueue>& task_queue : unthrottled_task_runners_)
     task_queue->SetTimeDomain(time_domain);
 
-  task_queue_throttler_->EnableVirtualTime();
+  ForceUpdatePolicy();
+}
 
-  ForceUpdatePolicy();
+bool RendererSchedulerImpl::ShouldDisableThrottlingBecauseOfAudio(
+    base::TimeTicks now) {
+  if (!MainThreadOnly().last_audio_state_change)
+    return false;
+
+  if (MainThreadOnly().is_audio_playing)
+    return true;
+
+  return MainThreadOnly().last_audio_state_change.value() +
+             MainThreadOnly().throttling_delay_after_audio_is_played >
+         now;
+}
+
+TimeDomain* RendererSchedulerImpl::GetActiveTimeDomain() {
+  if (MainThreadOnly().use_virtual_time) {
+    return GetVirtualTimeDomain();
+  } else {
+    return real_time_domain();
+  }
 }
 
 // static
 const char* RendererSchedulerImpl::UseCaseToString(UseCase use_case) {
   switch (use_case) {
     case UseCase::NONE:
       return "none";
     case UseCase::COMPOSITOR_GESTURE:
       return "compositor_gesture";
     case UseCase::MAIN_THREAD_CUSTOM_INPUT_HANDLING:
@@ skipping 24 matching lines @@
     case v8::PERFORMANCE_LOAD:
       return "load";
     default:
       NOTREACHED();
       return nullptr;
   }
 }
 
 }  // namespace scheduler
 }  // namespace blink