Added Network Quality Estimator Real-time interface to Cronet

net/base/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_BASE_NETWORK_QUALITY_ESTIMATOR_H_
 #define NET_BASE_NETWORK_QUALITY_ESTIMATOR_H_
 
 #include <stdint.h>
 
 #include <deque>
 #include <map>
 #include <string>
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
+#include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/observer_list_threadsafe.h"
 #include "base/threading/thread_checker.h"
 #include "base/time/time.h"
 #include "net/base/external_estimate_provider.h"
 #include "net/base/net_export.h"
 #include "net/base/network_change_notifier.h"
 
 namespace net {
 
 class URLRequest;
 
 // NetworkQualityEstimator provides network quality estimates (quality of the
 // full paths to all origins that have been connected to).
 // The estimates are based on the observed organic traffic.
 // A NetworkQualityEstimator instance is attached to URLRequestContexts and
 // observes the traffic of URLRequests spawned from the URLRequestContexts.
 // A single instance of NQE can be attached to multiple URLRequestContexts,
 // thereby increasing the single NQE instance's accuracy by providing more
 // observed traffic characteristics.
 class NET_EXPORT_PRIVATE NetworkQualityEstimator
     : public NetworkChangeNotifier::ConnectionTypeObserver,
       public ExternalEstimateProvider::UpdatedEstimateDelegate {
  public:
+  // On Android, a Java counterpart will be generated for this enum.
+  // GENERATED_JAVA_ENUM_PACKAGE: org.chromium.net
+  // GENERATED_JAVA_CLASS_NAME_OVERRIDE: NetworkQualityObservationSource
+  // GENERATED_JAVA_PREFIX_TO_STRIP: OBSERVATION_SOURCE_
+  enum ObservationSource {
+    OBSERVATION_SOURCE_URL_REQUEST,
+    OBSERVATION_SOURCE_TCP,
+    OBSERVATION_SOURCE_QUIC,
+    OBSERVATION_SOURCE_CACHED_ESTIMATE,
+    OBSERVATION_SOURCE_DEFAULT_FROM_PLATFORM,
+    OBSERVATION_SOURCE_EXTERNAL_ESTIMATE
+  };
+
+  // Observes measurements of round trip time.
+  class NET_EXPORT_PRIVATE RTTObserver {
+   public:
+    // Will be called when a new RTT observation is available. The round trip
+    // times is specified in milliseconds.
+    virtual void OnRTTObservation(int32_t rtt_ms,
+                                  const base::TimeTicks& timestamp,
+                                  ObservationSource source) = 0;
+
+   protected:
+    RTTObserver() {}
+    virtual ~RTTObserver() {}
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(RTTObserver);
+  };
+
+  // Observes measurements of throughput.
+  class NET_EXPORT_PRIVATE ThroughputObserver {
+   public:
+    // Will be called when a new throughput observation is available.
+    // Throughput is specified in kilobits per second.
+    virtual void OnThroughputObservation(int32_t throughput_kbps,
+                                         const base::TimeTicks& timestamp,
+                                         ObservationSource source) = 0;
+
+   protected:
+    ThroughputObserver() {}
+    virtual ~ThroughputObserver() {}
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(ThroughputObserver);
+  };
+
   // Creates a new NetworkQualityEstimator.
   // |variation_params| is the map containing all field trial parameters
   // related to NetworkQualityEstimator field trial.
   // |external_estimates_provider| may be NULL.
   NetworkQualityEstimator(
       scoped_ptr<ExternalEstimateProvider> external_estimates_provider,
       const std::map<std::string, std::string>& variation_params);
 
   ~NetworkQualityEstimator() override;
 
@@ skipping 20 matching lines @@
   virtual bool GetRecentMedianRTT(const base::TimeTicks& begin_timestamp,
                                   base::TimeDelta* rtt) const;
 
   // Returns true if median downstream throughput is available and sets |kbps|
   // to the median of downstream Kbps observations since |begin_timestamp|.
   // Virtualized for testing. |kbps| should not be null.
   virtual bool GetRecentMedianDownlinkThroughputKbps(
       const base::TimeTicks& begin_timestamp,
       int32_t* kbps) const;
 
+  void AddRTTObserver(RTTObserver* rtt_observer);

[pauljensen, 2015/09/01 10:59:10]

These functions need comments, esp with regard to threading.

[bengr, 2015/09/01 23:07:39]

Done.

+  void RemoveRTTObserver(RTTObserver* rtt_observer);
+  void AddThroughputObserver(ThroughputObserver* throughput_observer);
+  void RemoveThroughputObserver(ThroughputObserver* throughput_observer);
+
+  void Configure(bool allow_local_host_requests, bool allow_smaller_responses);
+
  protected:
   // NetworkID is used to uniquely identify a network.
   // For the purpose of network quality estimation and caching, a network is
   // uniquely identified by a combination of |type| and
   // |id|. This approach is unable to distinguish networks with
   // same name (e.g., different Wi-Fi networks with same SSID).
   // This is a protected member to expose it to tests.
   struct NET_EXPORT_PRIVATE NetworkID {
     NetworkID(NetworkChangeNotifier::ConnectionType type, const std::string& id)
         : type(type), id(id) {}
@@ skipping 117 matching lines @@
     const base::TimeTicks last_update_time_;
 
     // Quality of this cached network.
     const NetworkQuality network_quality_;
 
    private:
     DISALLOW_ASSIGN(CachedNetworkQuality);
   };
 
   // Records the round trip time or throughput observation, along with the time
-  // the observation was made.
+  // the observation was made. The units of value are type specific. For round
+  // trip time observations, the value is in milliseconds. For throughput,
+  // the value is in kilobits per second. Observations can be made at several
+  // places in the network stack, thus the observation source is provided as
+  // well.
   struct NET_EXPORT_PRIVATE Observation {
-    Observation(int32_t value, base::TimeTicks timestamp);
+    Observation(int32_t value,
+                base::TimeTicks timestamp,
+                ObservationSource source);
     ~Observation();
 
     // Value of the observation.
     const int32_t value;
 
     // Time when the observation was taken.
     const base::TimeTicks timestamp;
+
+    // The source of the observation.
+    ObservationSource source;

[pauljensen, 2015/09/01 10:59:10]

const

[bengr, 2015/09/01 23:07:39]

Done.

   };
 
   // Holds an observation and its weight.
   struct NET_EXPORT_PRIVATE WeightedObservation {
     WeightedObservation(int32_t value, double weight)
         : value(value), weight(weight) {}
     WeightedObservation(const WeightedObservation& other)
         : WeightedObservation(other.value, other.weight) {}
 
     WeightedObservation& operator=(const WeightedObservation& other) {
@@ skipping 135 matching lines @@
       const base::TimeTicks& begin_timestamp,
       int percentile) const;
 
   // Returns the current network ID checking by calling the platform APIs.
   // Virtualized for testing.
   virtual NetworkID GetCurrentNetworkID() const;
 
   // Writes the estimated quality of the current network to the cache.
   void CacheNetworkQualityEstimate();
 
+  void NotifyObserversOfRTT(const Observation& observation);
+
+  void NotifyObserversOfThroughput(const Observation& observation);
+
   // Records the UMA related to RTT.
   void RecordRTTUMA(int32_t estimated_value_msec,
                     int32_t actual_value_msec) const;
 
   // Returns true only if |request| can be used for network quality estimation.
   // Only the requests that go over network are considered to provide useful
   // observations.
   bool RequestProvidesUsefulObservations(const URLRequest& request) const;
 
   // Determines if the requests to local host can be used in estimating the
   // network quality. Set to true only for tests.
-  const bool allow_localhost_requests_;
+  bool allow_localhost_requests_;

[pauljensen, 2015/09/01 10:59:10]

why are you removing the const and adding Configure()?

[bengr, 2015/09/01 23:07:39]

For tests.

[pauljensen, 2015/09/02 16:54:47]

Configure() seems unused.  Can we go back to const and no Configure()?

 
   // Determines if the responses smaller than |kMinTransferSizeInBytes|
   // or shorter than |kMinTransferSizeInBytes| can be used in estimating the
   // network quality. Set to true only for tests.
-  const bool allow_small_responses_;
+  bool allow_small_responses_;
 
   // Time when last connection change was observed.
   base::TimeTicks last_connection_change_;
 
   // ID of the current network.
   NetworkID current_network_id_;
 
   // Peak network quality (fastest round-trip-time (RTT) and highest
   // downstream throughput) measured since last connectivity change. RTT is
   // measured from time the request is sent until the first byte received.
@@ skipping 17 matching lines @@
   NetworkQuality
       default_observations_[NetworkChangeNotifier::CONNECTION_LAST + 1];
 
   // Estimated network quality. Updated on mainframe requests.
   NetworkQuality estimated_median_network_quality_;
 
   // ExternalEstimateProvider that provides network quality using operating
   // system APIs. May be NULL.
   const scoped_ptr<ExternalEstimateProvider> external_estimates_provider_;
 
+  // Observer lists for round trip times and throughput measurements.
+  scoped_refptr<base::ObserverListThreadSafe<RTTObserver>> rtt_observer_list_;

[pauljensen, 2015/09/01 10:59:10]

const

[pauljensen, 2015/09/01 10:59:10]

why do these need to be ThreadSafe?  can we instead guarantee they're only
accessed on the network thread?

[bengr, 2015/09/01 23:07:39]

Acknowledged.

[bengr, 2015/09/01 23:07:39]

Funny. I fixed this before I saw your comment. Glad we're on the same page.

+  scoped_refptr<base::ObserverListThreadSafe<ThroughputObserver>>
+      throughput_observer_list_;
+
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkQualityEstimator);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_NETWORK_QUALITY_ESTIMATOR_H_