Notify NQE of TCP RTT values

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 <stddef.h>
 #include <stdint.h>
 
 #include <deque>
 #include <map>
 #include <string>
 #include <tuple>
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
 #include "base/observer_list.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"
 #include "net/base/socket_performance_watcher.h"
 #include "net/base/socket_performance_watcher_factory.h"
 
 namespace net {
 
+class NetworkQualityEstimatorWatcherFactory;
 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 SocketPerformanceWatcherFactory {
+      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:
   enum ObservationSource {
     // The observation was taken at the request layer, e.g., a round trip time
     // is recorded as the time between the request being sent and the first byte
     // being received.
     URL_REQUEST,
@@ skipping 99 matching lines @@
                                   base::TimeDelta* rtt) const;
 
   // Returns true if median downstream throughput is available and sets |kbps|
   // to the median of downstream throughput (in kilobits per second)
   // observations since |begin_timestamp|. Virtualized for testing. |kbps|
   // should not be null.
   virtual bool GetRecentMedianDownlinkThroughputKbps(
       const base::TimeTicks& begin_timestamp,
       int32_t* kbps) const;
 
-  // SocketPerformanceWatcherFactory implementation:
-  scoped_ptr<SocketPerformanceWatcher> CreateSocketPerformanceWatcher(
-      const Protocol protocol) override;
-  void OnUpdatedRTTAvailable(const Protocol protocol,
-                             const base::TimeDelta& rtt) override;
-
   // Adds |rtt_observer| to the list of round trip time observers. Must be
   // called on the IO thread.
   void AddRTTObserver(RTTObserver* rtt_observer);
 
   // Removes |rtt_observer| from the list of round trip time observers if it
   // is on the list of observers. Must be called on the IO thread.
   void RemoveRTTObserver(RTTObserver* rtt_observer);
 
   // Adds |throughput_observer| to the list of throughput observers. Must be
   // called on the IO thread.
   void AddThroughputObserver(ThroughputObserver* throughput_observer);
 
   // Removes |throughput_observer| from the list of throughput observers if it
   // is on the list of observers. Must be called on the IO thread.
   void RemoveThroughputObserver(ThroughputObserver* throughput_observer);
 
+  // Virtualized for testing.
+  virtual SocketPerformanceWatcherFactory* GetSocketPerformanceWatcherFactory();
+
  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 28 matching lines @@
   // Returns true if the cached network quality estimate was successfully read.
   bool ReadCachedNetworkQualityEstimate();
 
   // NetworkChangeNotifier::ConnectionTypeObserver implementation:
   void OnConnectionTypeChanged(
       NetworkChangeNotifier::ConnectionType type) override;
 
   // ExternalEstimateProvider::UpdatedEstimateObserver implementation.
   void OnUpdatedEstimateAvailable() override;
 
+  // Called by |socket_performance_watcher_factory_| every time it receives a
+  // notification from a socket performance watcher.

[Ryan Sleevi, 2016/03/25 01:45:34]

This comment is leaking the abstraction details into the header; it's especially
at conflict with the comments on 180-182 (which implies a different factory can
be set, which may not call this method)

+  void OnUpdatedRTTAvailable(SocketPerformanceWatcherFactory::Protocol protocol,
+                             const base::TimeDelta& rtt);
+  void OnWatcherReset();
+
  private:
+  // Allows |NetworkQualityEstimatorWatcherFactory| to call protected functions.

[Ryan Sleevi, 2016/03/25 01:45:34]

You can drop this comment. Per
https://google.github.io/styleguide/cppguide.html#Implementation_Comments , this
is the "Do not state the obvious" aspect, as that's given to a reader who
understands C++ well.

+  friend class NetworkQualityEstimatorWatcherFactory;
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, StoreObservations);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, TestKbpsRTTUpdates);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, TestAddObservation);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, ObtainOperatingParams);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, HalfLifeParam);
   FRIEND_TEST_ALL_PREFIXES(URLRequestTestHTTP, NetworkQualityEstimator);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
                            PercentileSameTimestamps);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
                            PercentileDifferentTimestamps);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, ComputedPercentiles);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, TestCaching);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
                            TestLRUCacheMaximumSize);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, TestGetMedianRTTSince);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
                            TestExternalEstimateProvider);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
                            TestExternalEstimateProviderMergeEstimates);
   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, TestObservers);
+  FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest, TestTcpSocketRtt);
 
   // NetworkQuality is used to cache the quality of a network connection.
   class NET_EXPORT_PRIVATE NetworkQuality {
    public:
     NetworkQuality();
     // |rtt| is the estimate of the round trip time.
     // |downstream_throughput_kbps| is the estimate of the downstream
     // throughput in kilobits per second.
     NetworkQuality(const base::TimeDelta& rtt,
                    int32_t downstream_throughput_kbps);
@@ skipping 248 matching lines @@
   // Virtualized for testing.
   virtual NetworkID GetCurrentNetworkID() const;
 
   // Writes the estimated quality of the current network to the cache.
   void CacheNetworkQualityEstimate();
 
   void NotifyObserversOfRTT(const RttObservation& observation);
 
   void NotifyObserversOfThroughput(const ThroughputObservation& observation);
 
+  // For use by SocketPerformanceWatcher.
+  base::WeakPtr<NetworkQualityEstimator> GetWeakPtr();
+
   // 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;
 
   // Values of external estimate provider status. This enum must remain
@@ skipping 55 matching lines @@
   NetworkQuality estimated_median_network_quality_;
 
   // ExternalEstimateProvider that provides network quality using operating
   // system APIs. May be NULL.
   const scoped_ptr<ExternalEstimateProvider> external_estimate_provider_;
 
   // Observer lists for round trip times and throughput measurements.
   base::ObserverList<RTTObserver> rtt_observer_list_;
   base::ObserverList<ThroughputObserver> throughput_observer_list_;
 
+  scoped_ptr<SocketPerformanceWatcherFactory>
+      socket_performance_watcher_factory_;
+
   base::ThreadChecker thread_checker_;
 
+  base::WeakPtrFactory<NetworkQualityEstimator> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(NetworkQualityEstimator);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_NETWORK_QUALITY_ESTIMATOR_H_