EQT: Record the max queueing time from navigation start to navigation away

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

Index: third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
diff --git a/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc b/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
index fa6a06c86d0821630db268290ca2b6f145301b08..f7c1b8dce2dd97692c42b0cd48c5bd2eb31988de 100644
--- a/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
+++ b/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
@@ -14,6 +14,7 @@
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
 #include "cc/output/begin_frame_args.h"
+#include "components/metrics/single_sample_metrics_factory_impl.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/scheduler/base/real_time_domain.h"
 #include "platform/scheduler/base/task_queue_impl.h"
@@ -219,6 +220,7 @@ RendererSchedulerImpl::MainThreadOnly::MainThreadOnly(
       in_idle_period_for_testing(false),
       use_virtual_time(false),
       is_audio_playing(false),
+      has_navigated(false),
       rail_mode_observer(nullptr),
       wake_up_budget_pool(nullptr),
       task_duration_per_queue_type_histogram(base::Histogram::FactoryGet(
@@ -1631,6 +1633,24 @@ void RendererSchedulerImpl::RemovePendingNavigation(NavigatingFrameType type) {
   }
 }
 
+void RendererSchedulerImpl::OnCommitProvisionalLoad() {
+  // Initialize |max_queueing_time_metric| as we need it so that

[tdresser, 2017/05/30 13:34:44]

I think "as we need it" -> "lazily" is a bit clearer.

[Liquan (Max) Gu, 2017/05/30 19:57:19]

Done.

+  // |SingleSampleMetricsFactory::SetFactory()| is called before
+  // |SingleSampleMetricsFactory::Get()|
+  if (!GetMainThreadOnly().max_queueing_time_metric) {
+    GetMainThreadOnly().max_queueing_time_metric = GetMaxQueueingTimeMetric();
+  }

[tdresser, 2017/05/30 13:34:44]

Do we need this? We reset it immediately below.
Don't we only need the lazy initialization in OnQueueingTimeForWindowEstimated?

[Liquan (Max) Gu, 2017/05/30 19:57:19]

Lazy init is not happened just from the beginning. Every time reset happen, it
needs to get the metric again.
Let's say NS is OnCommitProvisionalLoad, Q = OnQueueingTimeForWindowEstimated.
After resetting in NS, we need lazy init again, but there is chances for both NS
and Q to happen next, So that's why we need that in both places.

+  GetMainThreadOnly().max_queueing_time_metric.reset();
+  GetMainThreadOnly().max_queueing_time = base::TimeDelta();
+  GetMainThreadOnly().has_navigated = true;
+}
+
+std::unique_ptr<base::SingleSampleMetric>
+RendererSchedulerImpl::GetMaxQueueingTimeMetric() {

[tdresser, 2017/05/30 15:44:41]

GetOrCreate

[Liquan (Max) Gu, 2017/05/30 19:57:19]

Done.

+  return base::SingleSampleMetricsFactory::Get()->CreateCustomCountsMetric(
+      "RendererScheduler.MaxQueueingTime", 1, 10000, 50);
+}
+
 void RendererSchedulerImpl::OnNavigationStarted() {
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
                "RendererSchedulerImpl::OnNavigationStarted");
@@ -1907,6 +1927,17 @@ void RendererSchedulerImpl::RemoveTaskTimeObserver(
 void RendererSchedulerImpl::OnQueueingTimeForWindowEstimated(
     base::TimeDelta queueing_time,
     base::TimeTicks window_start_time) {
+  if (GetMainThreadOnly().has_navigated) {

[tdresser, 2017/05/30 13:34:44]

Can we get here when |has_navigated| is false?
If not, we can get rid of has_navigated.

[Liquan (Max) Gu, 2017/05/30 19:57:19]

Yes, the EQTEstimator starts to measure EQTs before navigation start.

+    if (GetMainThreadOnly().max_queueing_time < queueing_time) {
+      if (!GetMainThreadOnly().max_queueing_time_metric) {
+        GetMainThreadOnly().max_queueing_time_metric =
+            GetMaxQueueingTimeMetric();
+      }
+      GetMainThreadOnly().max_queueing_time_metric->SetSample(
+          queueing_time.InMilliseconds());
+      GetMainThreadOnly().max_queueing_time = queueing_time;
+    }
+  }
   // RendererScheduler reports the queueing time once per window's duration.
   //          |stepEQT|stepEQT|stepEQT|stepEQT|stepEQT|stepEQT|
   // Report:  |-------window EQT------|