NQE: Add accuracy histogram for external estimate provider

net/nqe/network_quality_estimator.cc

 // Copyright 2015 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 "net/nqe/network_quality_estimator.h"
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 #include <utility>
@@ skipping 499 matching lines @@
     if (!GetDownlinkThroughputKbpsEstimate(&downstream_throughput_kbps))
       downstream_throughput_kbps = nqe::internal::kInvalidThroughput;
 
     estimated_quality_at_last_main_frame_ = nqe::internal::NetworkQuality(
         estimated_http_rtt, estimated_transport_rtt,
         downstream_throughput_kbps);
     effective_connection_type_at_last_main_frame_ =
         GetEffectiveConnectionType();
 
     RecordMetricsOnMainFrameRequest();
+    MaybeQueryExternalEstimateProvider();
 
     // Post the tasks which will run in the future and record the estimation
     // accuracy based on the observations received between now and the time of
     // task execution. Posting the task at different intervals makes it
     // possible to measure the accuracy by comparing the estimate with the
     // observations received over intervals of varying durations.
     for (const base::TimeDelta& measuring_delay :
          GetAccuracyRecordingIntervals()) {
       base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
           FROM_HERE,
@@ skipping 125 matching lines @@
   if (effective_connection_type_at_last_main_frame_ !=
           EFFECTIVE_CONNECTION_TYPE_UNKNOWN &&
       recent_effective_connection_type != EFFECTIVE_CONNECTION_TYPE_UNKNOWN) {
     const int estimated_observed_diff =
         static_cast<int>(effective_connection_type_at_last_main_frame_) -
         static_cast<int>(recent_effective_connection_type);
 
     const std::string sign_suffix =
         estimated_observed_diff >= 0 ? "Positive." : "Negative.";
 
     base::HistogramBase* histogram = base::Histogram::FactoryGet(

[bengr, 2016/07/20 23:51:28]

You should have tests for histograms.

[tbansal1, 2016/07/21 22:00:50]

Done. I completely forgot that I already have harness for external estimate
provider in the tests.

         "NQE.Accuracy.EffectiveConnectionType.EstimatedObservedDiff." +
             sign_suffix + base::IntToString(measuring_duration.InSeconds()) +
             "." +
             GetNameForEffectiveConnectionType(recent_effective_connection_type),
         0, EFFECTIVE_CONNECTION_TYPE_LAST,
         EFFECTIVE_CONNECTION_TYPE_LAST /* Number of buckets */,
         base::HistogramBase::kUmaTargetedHistogramFlag);
     histogram->Add(std::abs(estimated_observed_diff));
   }
+
+  // Add histogram for accuracy of external estimate provider.

[bengr, 2016/07/20 23:51:28]

for -> to evaluate the 
of -> of the

[tbansal1, 2016/07/21 22:00:50]

Done.

+  if (external_estimate_provider_quality_.http_rtt() !=
+          nqe::internal::InvalidRTT() &&
+      recent_http_rtt != nqe::internal::InvalidRTT()) {
+    const int estimated_observed_diff_milliseconds =
+        external_estimate_provider_quality_.http_rtt().InMilliseconds() -
+        recent_http_rtt.InMilliseconds();
+
+    const std::string sign_suffix =
+        estimated_observed_diff_milliseconds >= 0 ? "Positive." : "Negative.";

[bengr, 2016/07/20 23:51:28]

You should probably create a helper called GetSignSuffix() and use it
everywhere.

[tbansal1, 2016/07/21 22:00:50]

Done.

+
+    base::HistogramBase* histogram = base::Histogram::FactoryGet(

[bengr, 2016/07/20 23:51:28]

You get similar histograms all over this method. Consider refactoring into a
helper.

[tbansal1, 2016/07/21 22:00:50]

Done.

+        "NQE.ExternalEstimateProvider.RTT.Accuracy."

[bengr, 2016/07/20 23:51:28]

Here and everywhere in this method, consider using StringPrintf.

[tbansal1, 2016/07/21 22:00:50]

Done.

+        "EstimatedObservedDiff." +
+            sign_suffix + base::IntToString(measuring_duration.InSeconds()) +
+            "." + GetHistogramSuffixObservedRTT(recent_http_rtt),
+        1, 10 * 1000 /* 10 seconds */, 50 /* Number of buckets */,
+        base::HistogramBase::kUmaTargetedHistogramFlag);
+    histogram->Add(std::abs(estimated_observed_diff_milliseconds));
+  }
 }
 
 void NetworkQualityEstimator::NotifyRequestCompleted(
     const URLRequest& request) {
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("net"),
                "NetworkQualityEstimator::NotifyRequestCompleted");
   DCHECK(thread_checker_.CalledOnValidThread());
 
   if (!RequestSchemeIsHTTPOrHTTPS(request))
     return;
@@ skipping 91 matching lines @@
         "NQE.CellularSignalStrengthAvailable",
         min_signal_strength_since_connection_change_ != INT32_MAX &&
             max_signal_strength_since_connection_change_ != INT32_MIN);
   }
 #endif  // OS_ANDROID
   min_signal_strength_since_connection_change_ = INT32_MAX;
   max_signal_strength_since_connection_change_ = INT32_MIN;
 
   current_network_id_ = GetCurrentNetworkID();
 
+  MaybeQueryExternalEstimateProvider();
+
+  // Read any cached estimates for the new network. If cached estimates are
+  // unavailable, add the default estimates.
+  if (!ReadCachedNetworkQualityEstimate())
+    AddDefaultEstimates();
+  estimated_quality_at_last_main_frame_ = nqe::internal::NetworkQuality();
+  throughput_analyzer_->OnConnectionTypeChanged();
+  MaybeRecomputeEffectiveConnectionType();
+  UpdateSignalStrength();
+}
+
+void NetworkQualityEstimator::MaybeQueryExternalEstimateProvider() const {
   // Query the external estimate provider on certain connection types. Once the
   // updated estimates are available, OnUpdatedEstimateAvailable will be called
   // by |external_estimate_provider_| with updated estimates.
   if (external_estimate_provider_ &&
       current_network_id_.type != NetworkChangeNotifier::CONNECTION_NONE &&
       current_network_id_.type != NetworkChangeNotifier::CONNECTION_UNKNOWN &&
       current_network_id_.type != NetworkChangeNotifier::CONNECTION_ETHERNET &&
       current_network_id_.type != NetworkChangeNotifier::CONNECTION_BLUETOOTH) {
     RecordExternalEstimateProviderMetrics(
         EXTERNAL_ESTIMATE_PROVIDER_STATUS_QUERIED);
     external_estimate_provider_->Update();
   }
-
-  // Read any cached estimates for the new network. If cached estimates are
-  // unavailable, add the default estimates.
-  if (!ReadCachedNetworkQualityEstimate())
-    AddDefaultEstimates();
-  estimated_quality_at_last_main_frame_ = nqe::internal::NetworkQuality();
-  throughput_analyzer_->OnConnectionTypeChanged();
-  MaybeRecomputeEffectiveConnectionType();
-  UpdateSignalStrength();
 }
 
 void NetworkQualityEstimator::UpdateSignalStrength() {
 #if defined(OS_ANDROID)
   int32_t signal_strength_dbm;
   if (!android::cellular_signal_strength::GetSignalStrengthDbm(
           &signal_strength_dbm)) {
     return;
   }
   min_signal_strength_since_connection_change_ = std::min(
@@ skipping 439 matching lines @@
 void NetworkQualityEstimator::OnUpdatedEstimateAvailable(
     const base::TimeDelta& rtt,
     int32_t downstream_throughput_kbps,
     int32_t upstream_throughput_kbps) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(external_estimate_provider_);
 
   RecordExternalEstimateProviderMetrics(
       EXTERNAL_ESTIMATE_PROVIDER_STATUS_CALLBACK);
 
+  external_estimate_provider_quality_ = nqe::internal::NetworkQuality();
+
   if (rtt > base::TimeDelta()) {
     RecordExternalEstimateProviderMetrics(
         EXTERNAL_ESTIMATE_PROVIDER_STATUS_RTT_AVAILABLE);
     UMA_HISTOGRAM_TIMES("NQE.ExternalEstimateProvider.RTT", rtt);
     rtt_observations_.AddObservation(
         RttObservation(rtt, tick_clock_->NowTicks(),
                        NETWORK_QUALITY_OBSERVATION_SOURCE_EXTERNAL_ESTIMATE));
+    external_estimate_provider_quality_.set_http_rtt(rtt);
   }
 
   if (downstream_throughput_kbps > 0) {
     RecordExternalEstimateProviderMetrics(
         EXTERNAL_ESTIMATE_PROVIDER_STATUS_DOWNLINK_BANDWIDTH_AVAILABLE);
     UMA_HISTOGRAM_COUNTS("NQE.ExternalEstimateProvider.DownlinkBandwidth",
                          downstream_throughput_kbps);
     downstream_throughput_kbps_observations_.AddObservation(
         ThroughputObservation(
             downstream_throughput_kbps, tick_clock_->NowTicks(),
             NETWORK_QUALITY_OBSERVATION_SOURCE_EXTERNAL_ESTIMATE));
+    external_estimate_provider_quality_.set_downstream_throughput_kbps(
+        downstream_throughput_kbps);
   }
 }
 
 // static
 const char* NetworkQualityEstimator::GetNameForEffectiveConnectionType(
     EffectiveConnectionType type) {
   switch (type) {
     case EFFECTIVE_CONNECTION_TYPE_UNKNOWN:
       return "Unknown";
     case EFFECTIVE_CONNECTION_TYPE_OFFLINE:
@@ skipping 178 matching lines @@
     NotifyObserversOfEffectiveConnectionTypeChanged() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   // TODO(tbansal): Add hysteresis in the notification.
   FOR_EACH_OBSERVER(
       EffectiveConnectionTypeObserver, effective_connection_type_observer_list_,
       OnEffectiveConnectionTypeChanged(effective_connection_type_));
 }
 
 }  // namespace net