Compute effective connection type dynamically

net/nqe/network_quality_estimator.h

 // 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.
 
 #ifndef NET_NQE_NETWORK_QUALITY_ESTIMATOR_H_
 #define NET_NQE_NETWORK_QUALITY_ESTIMATOR_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 277 matching lines @@
   virtual const std::vector<base::TimeDelta>& GetAccuracyRecordingIntervals()
       const;
 
   // Overrides the tick clock used by |this| for testing.
   void SetTickClockForTesting(std::unique_ptr<base::TickClock> tick_clock);
 
   // Returns a random double in the range [0.0, 1.0). Virtualized for testing.
   virtual double RandDouble() const;
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
+                           AdaptiveRecomputationEffectiveConnectionType);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, StoreObservations);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, TestAddObservation);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, ObtainOperatingParams);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
                            ObtainAlgorithmToUseFromParams);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, HalfLifeParam);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, ComputedPercentiles);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, TestGetMetricsSince);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
                            TestExternalEstimateProviderMergeEstimates);
+  FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
+                           UnknownEffectiveConnectionType);
 
   // Value of round trip time observations is in base::TimeDelta.
   typedef nqe::internal::Observation<base::TimeDelta> RttObservation;
   typedef nqe::internal::ObservationBuffer<base::TimeDelta>
       RttObservationBuffer;
 
   // Value of throughput observations is in kilobits per second.
   typedef nqe::internal::Observation<int32_t> ThroughputObservation;
   typedef nqe::internal::ObservationBuffer<int32_t> ThroughputObservationBuffer;
 
@@ skipping 183 matching lines @@
 
   // Algorithm to use for computing effective connection type. The value is
   // obtained from field trial parameters. If the value from field trial
   // parameters is unavailable, it is set to
   // kDefaultEffectiveConnectionTypeAlgorithm.
   const EffectiveConnectionTypeAlgorithm effective_connection_type_algorithm_;
 
   // Tick clock used by the network quality estimator.
   std::unique_ptr<base::TickClock> tick_clock_;
 
-  // Minimum duration between two consecutive computations of effective
-  // connection type. Set to non-zero value as a performance optimization.
-  const base::TimeDelta effective_connection_type_recomputation_interval_;
-
-  // Time when the effective connection type was last computed.
-  base::TimeTicks last_effective_connection_type_computation_;
-
   // Intervals after the main frame request arrives at which accuracy of network
   // quality prediction is recorded.
   std::vector<base::TimeDelta> accuracy_recording_intervals_;
 
   // Time when last connection change was observed.
   base::TimeTicks last_connection_change_;
 
   // ID of the current network.
   nqe::internal::NetworkID current_network_id_;
 
@@ skipping 56 matching lines @@
   base::ObserverList<ThroughputObserver> throughput_observer_list_;
 
   std::unique_ptr<SocketPerformanceWatcherFactory> watcher_factory_;
 
   // Takes throughput measurements, and passes them back to |this| through the
   // provided callback. |this| stores the throughput observations in
   // |downstream_throughput_kbps_observations_|, which are later used for
   // estimating the throughput.
   std::unique_ptr<nqe::internal::ThroughputAnalyzer> throughput_analyzer_;
 
+  // Minimum duration between two consecutive computations of effective
+  // connection type. Set to non-zero value as a performance optimization.
+  const base::TimeDelta effective_connection_type_recomputation_interval_;
+
+  // Time when the effective connection type was last computed.
+  base::TimeTicks last_effective_connection_type_computation_;
+
+  // Number of RTT and bandwidth samples available when effective connection
+  // type was last recomputed.
+  size_t number_of_rtt_samples_at_last_ect_computation_;
+  size_t number_of_bandwidth_samples_at_last_ect_computation_;

[RyanSturm, 2016/08/08 23:57:01]

nit: The naming of this variable is mouthful and has nothing in common with
downstream_throughput_kbps_observations_, which makes it confusing. I think that
the number_of_ part is unnecessary.

Maybe, throughput_observations_size_at_last_ect_computation_? If you want to
refactor the observations buffer name to bandwidth, that also works.

If you do decide to change this, make the rtt consistent with that change.

[tbansal1, 2016/08/09 18:00:56]

Done.

+
   // Current effective connection type. It is updated on connection change
   // events. It is also updated every time there is network traffic (provided
   // the last computation was more than
   // |effective_connection_type_recomputation_interval_| ago).
   EffectiveConnectionType effective_connection_type_;
 
   // Minimum and Maximum signal strength (in dbM) observed since last connection
   // change. Updated on connection change and main frame requests.
   int32_t min_signal_strength_since_connection_change_;
   int32_t max_signal_strength_since_connection_change_;
@@ skipping 11 matching lines @@
   base::ThreadChecker thread_checker_;
 
   base::WeakPtrFactory<NetworkQualityEstimator> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkQualityEstimator);
 };
 
 }  // namespace net
 
 #endif  // NET_NQE_NETWORK_QUALITY_ESTIMATOR_H_