NQE: Change GetEffectiveConnectionType to return last ECT

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 368 matching lines @@
       last_connection_change_(tick_clock_->NowTicks()),
       current_network_id_(nqe::internal::NetworkID(
           NetworkChangeNotifier::ConnectionType::CONNECTION_UNKNOWN,
           std::string())),
       downstream_throughput_kbps_observations_(weight_multiplier_per_second_),
       rtt_observations_(weight_multiplier_per_second_),
       effective_connection_type_at_last_main_frame_(
           EFFECTIVE_CONNECTION_TYPE_UNKNOWN),
       external_estimate_provider_(std::move(external_estimates_provider)),
       effective_connection_type_recomputation_interval_(
-          base::TimeDelta::FromSeconds(15)),
+          base::TimeDelta::FromSeconds(10)),
       rtt_observations_size_at_last_ect_computation_(0),
       throughput_observations_size_at_last_ect_computation_(0),
       effective_connection_type_(EFFECTIVE_CONNECTION_TYPE_UNKNOWN),
       min_signal_strength_since_connection_change_(INT32_MAX),
       max_signal_strength_since_connection_change_(INT32_MIN),
       correlation_uma_logging_probability_(
           GetDoubleValueForVariationParamWithDefaultValue(
               variation_params,
               "correlation_logging_probability",
               0.0)),
@@ skipping 254 matching lines @@
     if (!GetTransportRTT(&estimated_transport_rtt))
       estimated_transport_rtt = nqe::internal::InvalidRTT();
 
     int32_t downstream_throughput_kbps;
     if (!GetDownlinkThroughputKbps(&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);
+
+    ComputeEffectiveConnectionType();
     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
@@ skipping 355 matching lines @@
   RecordNetworkIDAvailability();
 
   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();
+  MaybeComputeEffectiveConnectionType();
   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 &&
@@ skipping 134 matching lines @@
       base::Histogram::FactoryGet(
           std::string("NQE.MainFrame.EffectiveConnectionType.") +
               GetNameForConnectionType(current_network_id_.type),
           0, EFFECTIVE_CONNECTION_TYPE_LAST,
           EFFECTIVE_CONNECTION_TYPE_LAST /* Number of buckets */,
           base::HistogramBase::kUmaTargetedHistogramFlag);
 
   effective_connection_type_histogram->Add(effective_connection_type);
 }
 
+void NetworkQualityEstimator::ComputeEffectiveConnectionType() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  const base::TimeTicks now = tick_clock_->NowTicks();
+
+  const EffectiveConnectionType past_type = effective_connection_type_;
+  last_effective_connection_type_computation_ = now;
+
+  effective_connection_type_ =
+      GetRecentEffectiveConnectionType(base::TimeTicks());
+
+  if (past_type != effective_connection_type_)
+    NotifyObserversOfEffectiveConnectionTypeChanged();
+
+  rtt_observations_size_at_last_ect_computation_ = rtt_observations_.Size();
+  throughput_observations_size_at_last_ect_computation_ =
+      downstream_throughput_kbps_observations_.Size();
+}
+
 EffectiveConnectionType NetworkQualityEstimator::GetEffectiveConnectionType()
     const {
   DCHECK(thread_checker_.CalledOnValidThread());
-  return GetRecentEffectiveConnectionType(base::TimeTicks());
+  return effective_connection_type_;
 }
 
 EffectiveConnectionType
 NetworkQualityEstimator::GetRecentEffectiveConnectionType(
     const base::TimeTicks& start_time) const {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   if (effective_connection_type_algorithm_ ==
       EffectiveConnectionTypeAlgorithm::HTTP_RTT_AND_DOWNSTREAM_THROUGHOUT) {
     return GetRecentEffectiveConnectionTypeUsingMetrics(
@@ skipping 390 matching lines @@
   rtt_observations_.AddObservation(observation);
 }
 
 void NetworkQualityEstimator::NotifyObserversOfRTT(
     const RttObservation& observation) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK_NE(nqe::internal::InvalidRTT(), observation.value);
 
   // Maybe recompute the effective connection type since a new RTT observation
   // is available.
-  MaybeRecomputeEffectiveConnectionType();
+  MaybeComputeEffectiveConnectionType();
   FOR_EACH_OBSERVER(
       RTTObserver, rtt_observer_list_,
       OnRTTObservation(observation.value.InMilliseconds(),
                        observation.timestamp, observation.source));
 }
 
 void NetworkQualityEstimator::NotifyObserversOfThroughput(
     const ThroughputObservation& observation) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK_NE(nqe::internal::kInvalidThroughput, observation.value);
 
   // Maybe recompute the effective connection type since a new throughput
   // observation is available.
-  MaybeRecomputeEffectiveConnectionType();
+  MaybeComputeEffectiveConnectionType();
   FOR_EACH_OBSERVER(
       ThroughputObserver, throughput_observer_list_,
       OnThroughputObservation(observation.value, observation.timestamp,
                               observation.source));
 }
 
 void NetworkQualityEstimator::OnNewThroughputObservationAvailable(
     int32_t downstream_kbps) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   if (downstream_kbps == 0)
     return;
 
   DCHECK_NE(nqe::internal::kInvalidThroughput, downstream_kbps);
 
   if (downstream_kbps > peak_network_quality_.downstream_throughput_kbps()) {
     peak_network_quality_ = nqe::internal::NetworkQuality(
         peak_network_quality_.http_rtt(), peak_network_quality_.transport_rtt(),
         downstream_kbps);
   }
   ThroughputObservation throughput_observation(
       downstream_kbps, tick_clock_->NowTicks(),
       NETWORK_QUALITY_OBSERVATION_SOURCE_URL_REQUEST);
   downstream_throughput_kbps_observations_.AddObservation(
       throughput_observation);
   NotifyObserversOfThroughput(throughput_observation);
 }
 
-void NetworkQualityEstimator::MaybeRecomputeEffectiveConnectionType() {
+void NetworkQualityEstimator::MaybeComputeEffectiveConnectionType() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   const base::TimeTicks now = tick_clock_->NowTicks();
   // Recompute effective connection type only if
   // |effective_connection_type_recomputation_interval_| has passed since it was
   // last computed or a connection change event was observed since the last
   // computation. Strict inequalities are used to ensure that effective
   // connection type is recomputed on connection change events even if the clock
   // has not updated.
   if (now - last_effective_connection_type_computation_ <
           effective_connection_type_recomputation_interval_ &&
       last_connection_change_ < last_effective_connection_type_computation_ &&
       // Recompute the effective connection type if the previously computed
       // effective connection type was unknown.
       effective_connection_type_ != EFFECTIVE_CONNECTION_TYPE_UNKNOWN &&
       // Recompute the effective connection type if the number of samples
-      // available now are more than twice in count than the number of
-      // samples that were available when the effective connection type was
-      // last computed.
-      rtt_observations_size_at_last_ect_computation_ * 2 >=
+      // available now are 50% more than the number of samples that were
+      // available when the effective connection type was last computed.
+      rtt_observations_size_at_last_ect_computation_ * 1.5 >=
           rtt_observations_.Size() &&
-      throughput_observations_size_at_last_ect_computation_ * 2 >=
+      throughput_observations_size_at_last_ect_computation_ * 1.5 >=
           downstream_throughput_kbps_observations_.Size()) {
     return;
   }
-
-  const EffectiveConnectionType past_type = effective_connection_type_;
-  last_effective_connection_type_computation_ = now;
-  effective_connection_type_ = GetEffectiveConnectionType();
-
-  if (past_type != effective_connection_type_)
-    NotifyObserversOfEffectiveConnectionTypeChanged();
-
-  rtt_observations_size_at_last_ect_computation_ = rtt_observations_.Size();
-  throughput_observations_size_at_last_ect_computation_ =
-      downstream_throughput_kbps_observations_.Size();
+  ComputeEffectiveConnectionType();
 }
 
 void NetworkQualityEstimator::
     NotifyObserversOfEffectiveConnectionTypeChanged() {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK_NE(EFFECTIVE_CONNECTION_TYPE_LAST, effective_connection_type_);
 
   // TODO(tbansal): Add hysteresis in the notification.
   FOR_EACH_OBSERVER(
       EffectiveConnectionTypeObserver, effective_connection_type_observer_list_,
       OnEffectiveConnectionTypeChanged(effective_connection_type_));
 
   // Add the estimates of the current network to the cache store.
   if (effective_connection_type_ != EFFECTIVE_CONNECTION_TYPE_UNKNOWN) {
     network_quality_store_->Add(
         current_network_id_,
         nqe::internal::CachedNetworkQuality(
             tick_clock_->NowTicks(), estimated_quality_at_last_main_frame_,
             effective_connection_type_));
   }
 }
 
 }  // namespace net