net/base/network_quality_estimator.h

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef NET_BASE_NETWORK_QUALITY_ESTIMATOR_H_
   6 #define NET_BASE_NETWORK_QUALITY_ESTIMATOR_H_
   7
   8 #include <stdint.h>
   9
  10 #include "base/gtest_prod_util.h"
  11 #include "base/macros.h"
  12 #include "base/threading/thread_checker.h"
  13 #include "base/time/time.h"
  14 #include "net/base/network_change_notifier.h"
  15
  16 namespace net {
  17
  18 struct NetworkQuality;
  19
  20 // NetworkQualityEstimator provides network quality estimates (quality of the
  21 // full paths to all origins that have been connected to).
  22 // The estimates are based on the observed organic traffic.
  23 // A NetworkQualityEstimator instance is attached to URLRequestContexts and
  24 // observes the traffic of URLRequests spawned from the URLRequestContexts.
  25 // A single instance of NQE can be attached to multiple URLRequestContexts,
  26 // thereby increasing the single NQE instance's accuracy by providing more
  27 // observed traffic characteristics.
  28 class NET_EXPORT_PRIVATE NetworkQualityEstimator
  29     : public NetworkChangeNotifier::ConnectionTypeObserver {
  30  public:
  31   // Creates a new NetworkQualityEstimator.
  32   NetworkQualityEstimator();
  33
  34   ~NetworkQualityEstimator() override;
  35
  36   // Returns an estimate of the current network quality.
  37   // Virtualized for testing.
  38   virtual NetworkQuality GetEstimate() const;
  39
  40   // Notifies NetworkQualityEstimator that a response has been received.
  41   // |prefilter_bytes_read| is the count of the bytes received prior to
  42   // applying filters (e.g. decompression, SDCH) from request creation time
  43   // until now.
  44   void NotifyDataReceived(const URLRequest& request,
  45                           int64_t prefilter_bytes_read);
  46
  47  private:
  48   FRIEND_TEST_ALL_PREFIXES(NetworkQualityEstimatorTest,
  49                            TestPeakKbpsFastestRTTUpdates);
  50   FRIEND_TEST_ALL_PREFIXES(URLRequestTestHTTP, NetworkQualityEstimator);
  51
  52   // Tiny transfer sizes may give inaccurate throughput results.
  53   // Minimum size of the transfer over which the throughput is computed.
  54   static const int kMinTransferSizeInBytes = 10000;
  55
  56   // Minimum duration (in microseconds) of the transfer over which the
  57   // throughput is computed.
  58   static const int kMinRequestDurationMicroseconds = 1000;
  59
  60   // Construct a NetworkQualityEstimator instance allowing for test
  61   // configuration.
  62   // Registers for network type change notifications so estimates can be kept
  63   // network specific.
  64   // |allow_local_host_requests_for_tests| should only be true when testing
  65   // against local HTTP server and allows the requests to local host to be
  66   // used for network quality estimation.
  67   explicit NetworkQualityEstimator(bool allow_local_host_requests_for_tests);
  68
  69   // NetworkChangeNotifier::ConnectionTypeObserver implementation.
  70   void OnConnectionTypeChanged(
  71       NetworkChangeNotifier::ConnectionType type) override;
  72
  73   // Determines if the requests to local host can be used in estimating the
  74   // network quality. Set to true only for tests.
  75   const bool allow_localhost_requests_;
  76
  77   // Time when last connection change was observed.
  78   base::TimeTicks last_connection_change_;
  79
  80   // Last value passed to |OnConnectionTypeChanged|. This indicates the
  81   // current connection type.
  82   NetworkChangeNotifier::ConnectionType current_connection_type_;
  83
  84   // Set if any network data has been received since last connectivity change.
  85   bool bytes_read_since_last_connection_change_;
  86
  87   // Fastest round-trip-time (RTT) since last connectivity change. RTT measured
  88   // from URLRequest creation until first byte received.
  89   base::TimeDelta fastest_RTT_since_last_connection_change_;
  90
  91   // Rough measurement of downlink peak Kbps witnessed since last connectivity
  92   // change. The accuracy is decreased by ignoring these factors:
  93   // 1) Multiple URLRequests can occur concurrently.
  94   // 2) The transfer time includes at least one RTT while no bytes are read.
  95   uint64_t peak_kbps_since_last_connection_change_;
  96
  97   base::ThreadChecker thread_checker_;
  98
  99   DISALLOW_COPY_AND_ASSIGN(NetworkQualityEstimator);
 100 };
 101
 102 }  // namespace net
 103
 104 #endif  // NET_BASE_NETWORK_QUALITY_ESTIMATOR_H_