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

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.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/threading/thread_task_runner_handle.h"
 #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"
 #include "platform/scheduler/base/task_queue_selector.h"
 #include "platform/scheduler/base/time_converter.h"
 #include "platform/scheduler/base/trace_helper.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"
@@ skipping 185 matching lines @@
       timer_tasks_seem_expensive(false),
       touchstart_expected_soon(false),
       have_seen_a_begin_main_frame(false),
       have_reported_blocking_intervention_in_current_policy(false),
       have_reported_blocking_intervention_since_navigation(false),
       has_visible_render_widget_with_touch_handler(false),
       begin_frame_not_expected_soon(false),
       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(
           "RendererScheduler.TaskDurationPerQueueType2",
           1,
           static_cast<int>(TaskQueue::QueueType::COUNT),
           static_cast<int>(TaskQueue::QueueType::COUNT) + 1,
           base::HistogramBase::kUmaTargetedHistogramFlag)) {
   foreground_main_thread_load_tracker.Resume(now);
 }
@@ skipping 1392 matching lines @@
 void RendererSchedulerImpl::RemovePendingNavigation(NavigatingFrameType type) {
   helper_.CheckOnValidThread();
   DCHECK_GT(GetMainThreadOnly().navigation_task_expected_count, 0);
   if (type == NavigatingFrameType::kMainFrame &&
       GetMainThreadOnly().navigation_task_expected_count > 0) {
     GetMainThreadOnly().navigation_task_expected_count--;
     UpdatePolicy();
   }
 }
 
+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");
   base::AutoLock lock(any_thread_lock_);
   ResetForNavigationLocked();
 }
 
 void RendererSchedulerImpl::OnFirstMeaningfulPaint() {
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
                "RendererSchedulerImpl::OnFirstMeaningfulPaint");
@@ skipping 256 matching lines @@
 }
 
 void RendererSchedulerImpl::RemoveTaskTimeObserver(
     TaskTimeObserver* task_time_observer) {
   helper_.RemoveTaskTimeObserver(task_time_observer);
 }
 
 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------|
   // Discard:         |-------window EQT------|
   // Discard:                 |-------window EQT------|
   // Report:                          |-------window EQT------|
   if (window_start_time -
           GetMainThreadOnly().uma_last_queueing_time_report_window_start_time <
       kQueueingTimeWindowDuration) {
     return;
@@ skipping 137 matching lines @@
     case TimeDomainType::VIRTUAL:
       return "virtual";
     default:
       NOTREACHED();
       return nullptr;
   }
 }
 
 }  // namespace scheduler
 }  // namespace blink