NQE: Store the current network quality in a single variable

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 371 matching lines @@
           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(10)),
       rtt_observations_size_at_last_ect_computation_(0),
       throughput_observations_size_at_last_ect_computation_(0),
-      http_rtt_(nqe::internal::InvalidRTT()),
-      transport_rtt_(nqe::internal::InvalidRTT()),
-      downstream_throughput_kbps_(nqe::internal::kInvalidThroughput),
       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)),
       forced_effective_connection_type_set_(
           !GetStringValueForVariationParamWithDefaultValue(
@@ skipping 349 matching lines @@
   // 2. This can happen if the task is executed much later than its scheduled
   // time. Returning here ensures that we do not take inaccurate readings.
   if (now - last_main_frame_request_ > 2 * measuring_duration)
     return;
 
   // Do not record accuracy if there was a connection change since the last main
   // frame request.
   if (last_main_frame_request_ <= last_connection_change_)
     return;
 
-  base::TimeDelta recent_http_rtt;
+  base::TimeDelta recent_http_rtt = nqe::internal::InvalidRTT();

[RyanSturm, 2016/10/31 19:22:10]

nit: Is this part necessary? If GetRecentHttpRTT returns true this will be set,
if it returns false, it will get set on line 763.

Side-note: this change is to support line 821, and is more or less changing
nothing else?

[tbansal1, 2016/10/31 21:34:51]

Done.

+  if (!GetRecentHttpRTT(last_main_frame_request_, &recent_http_rtt))
+    recent_http_rtt = nqe::internal::InvalidRTT();
+
   if (estimated_quality_at_last_main_frame_.http_rtt() !=
           nqe::internal::InvalidRTT() &&
-      GetRecentHttpRTT(last_main_frame_request_, &recent_http_rtt)) {
+      recent_http_rtt != nqe::internal::InvalidRTT()) {
     const int estimated_observed_diff_milliseconds =
         estimated_quality_at_last_main_frame_.http_rtt().InMilliseconds() -
         recent_http_rtt.InMilliseconds();
 
     RecordRTTAccuracy("NQE.Accuracy.HttpRTT",
                       estimated_observed_diff_milliseconds, measuring_duration,
                       recent_http_rtt);
   }
 
   base::TimeDelta recent_transport_rtt;
@@ skipping 242 matching lines @@
 }
 
 void NetworkQualityEstimator::OnConnectionTypeChanged(
     NetworkChangeNotifier::ConnectionType type) {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   RecordMetricsOnConnectionTypeChanged();
 
   // Write the estimates of the previous network to the cache.
   network_quality_store_->Add(
-      current_network_id_,
-      nqe::internal::CachedNetworkQuality(
-          last_effective_connection_type_computation_,
-          estimated_quality_at_last_main_frame_, effective_connection_type_));
+      current_network_id_, nqe::internal::CachedNetworkQuality(
+                               last_effective_connection_type_computation_,
+                               network_quality_, effective_connection_type_));
 
   // Clear the local state.
   last_connection_change_ = tick_clock_->NowTicks();
   peak_network_quality_ = nqe::internal::NetworkQuality();
   downstream_throughput_kbps_observations_.Clear();
   rtt_observations_.Clear();
 
 #if defined(OS_ANDROID)
   if (NetworkChangeNotifier::IsConnectionCellular(current_network_id_.type)) {
     UMA_HISTOGRAM_BOOLEAN(
         "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;
-  estimated_quality_at_last_main_frame_ = nqe::internal::NetworkQuality();
-  http_rtt_ = nqe::internal::InvalidRTT();
-  transport_rtt_ = nqe::internal::InvalidRTT();
-  downstream_throughput_kbps_ = nqe::internal::kInvalidThroughput;
+  network_quality_ = nqe::internal::NetworkQuality();
   effective_connection_type_ = EFFECTIVE_CONNECTION_TYPE_UNKNOWN;
   effective_connection_type_at_last_main_frame_ =
       EFFECTIVE_CONNECTION_TYPE_UNKNOWN;
 
   // Update the local state as part of preparation for the new connection.
   current_network_id_ = GetCurrentNetworkID();
   RecordNetworkIDAvailability();
 
   MaybeQueryExternalEstimateProvider();
 
@@ skipping 166 matching lines @@
 }
 
 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;
 
+  base::TimeDelta http_rtt = nqe::internal::InvalidRTT();
+  base::TimeDelta transport_rtt = nqe::internal::InvalidRTT();
+  int32_t downstream_throughput_kbps = nqe::internal::kInvalidThroughput;
+
   effective_connection_type_ =
       GetRecentEffectiveConnectionTypeAndNetworkQuality(
-          base::TimeTicks(), &http_rtt_, &transport_rtt_,
-          &downstream_throughput_kbps_);
+          base::TimeTicks(), &http_rtt, &transport_rtt,
+          &downstream_throughput_kbps);
+
+  network_quality_ = nqe::internal::NetworkQuality(http_rtt, transport_rtt,
+                                                   downstream_throughput_kbps);
+
   NotifyObserversOfRTTOrThroughputComputed();
 
   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 effective_connection_type_;
 }
 
 EffectiveConnectionType
 NetworkQualityEstimator::GetRecentEffectiveConnectionType(
     const base::TimeTicks& start_time) const {
   DCHECK(thread_checker_.CalledOnValidThread());
 
-  base::TimeDelta http_rtt;
-  base::TimeDelta transport_rtt;
-  int32_t downstream_throughput_kbps;
+  base::TimeDelta http_rtt = nqe::internal::InvalidRTT();
+  base::TimeDelta transport_rtt = nqe::internal::InvalidRTT();
+  int32_t downstream_throughput_kbps = nqe::internal::kInvalidThroughput;
 
   return GetRecentEffectiveConnectionTypeAndNetworkQuality(
       start_time, &http_rtt, &transport_rtt, &downstream_throughput_kbps);
 }
 
 EffectiveConnectionType
 NetworkQualityEstimator::GetRecentEffectiveConnectionTypeAndNetworkQuality(
     const base::TimeTicks& start_time,
     base::TimeDelta* http_rtt,
     base::TimeDelta* transport_rtt,
@@ skipping 312 matching lines @@
                         cached_estimate_available);
 
   if (!cached_estimate_available)
     return false;
 
   const base::TimeTicks now = tick_clock_->NowTicks();
 
   if (effective_connection_type_ == EFFECTIVE_CONNECTION_TYPE_UNKNOWN) {
     // Read the effective connection type from the cached estimate.
     last_effective_connection_type_computation_ = now;
-    http_rtt_ = cached_network_quality.network_quality().http_rtt();
-    transport_rtt_ = cached_network_quality.network_quality().transport_rtt();
-    downstream_throughput_kbps_ =
-        cached_network_quality.network_quality().downstream_throughput_kbps();
+    network_quality_ = cached_network_quality.network_quality();
     effective_connection_type_ =
         cached_network_quality.effective_connection_type();
 
     if (effective_connection_type_ != EFFECTIVE_CONNECTION_TYPE_UNKNOWN)
       NotifyObserversOfEffectiveConnectionTypeChanged();
   }
 
   if (cached_network_quality.network_quality().downstream_throughput_kbps() !=
       nqe::internal::kInvalidThroughput) {
     ThroughputObservation througphput_observation(
@@ skipping 157 matching lines @@
     NotifyObserversOfEffectiveConnectionTypeChanged() {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK_NE(EFFECTIVE_CONNECTION_TYPE_LAST, effective_connection_type_);
 
   // TODO(tbansal): Add hysteresis in the notification.
   for (auto& observer : effective_connection_type_observer_list_)
     observer.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_));
+    network_quality_store_->Add(current_network_id_,
+                                nqe::internal::CachedNetworkQuality(
+                                    tick_clock_->NowTicks(), network_quality_,
+                                    effective_connection_type_));
   }
 }
 
 void NetworkQualityEstimator::NotifyObserversOfRTTOrThroughputComputed() const {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   // TODO(tbansal): Add hysteresis in the notification.
   for (auto& observer : rtt_and_throughput_estimates_observer_list_) {
-    observer.OnRTTOrThroughputEstimatesComputed(http_rtt_, transport_rtt_,
-                                                downstream_throughput_kbps_);
+    observer.OnRTTOrThroughputEstimatesComputed(
+        network_quality_.http_rtt(), network_quality_.transport_rtt(),
+        network_quality_.downstream_throughput_kbps());
   }
 }
 
 void NetworkQualityEstimator::AddNetworkQualitiesCacheObserver(
     nqe::internal::NetworkQualityStore::NetworkQualitiesCacheObserver*
         observer) {
   DCHECK(thread_checker_.CalledOnValidThread());
   network_quality_store_->AddNetworkQualitiesCacheObserver(observer);
 }
 
 void NetworkQualityEstimator::RemoveNetworkQualitiesCacheObserver(
     nqe::internal::NetworkQualityStore::NetworkQualitiesCacheObserver*
         observer) {
   DCHECK(thread_checker_.CalledOnValidThread());
   network_quality_store_->RemoveNetworkQualitiesCacheObserver(observer);
 }
 
 void NetworkQualityEstimator::OnPrefsRead(
     const std::map<nqe::internal::NetworkID,
                    nqe::internal::CachedNetworkQuality> read_prefs) {
   DCHECK(thread_checker_.CalledOnValidThread());
   UMA_HISTOGRAM_COUNTS("NQE.Prefs.ReadSize", read_prefs.size());
   // TODO(tbansal): crbug.com/490870. Incorporate the network quality into the
   // current estimates.
 }
 
 }  // namespace net