NQE: Record correlation metric in UMA

net/nqe/network_quality_estimator_unittest.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 <stddef.h>
 #include <stdint.h>
 
 #include <limits>
@@ skipping 59 matching lines @@
         effective_connection_type_(EFFECTIVE_CONNECTION_TYPE_UNKNOWN),
         recent_effective_connection_type_set_(false),
         recent_effective_connection_type_(EFFECTIVE_CONNECTION_TYPE_UNKNOWN),
         current_network_type_(NetworkChangeNotifier::CONNECTION_UNKNOWN),
         accuracy_recording_intervals_set_(false),
         http_rtt_set_(false),
         recent_http_rtt_set_(false),
         transport_rtt_set_(false),
         recent_transport_rtt_set_(false),
         downlink_throughput_kbps_set_(false),
-        recent_downlink_throughput_kbps_set_(false) {
+        recent_downlink_throughput_kbps_set_(false),
+        rand_double_(0.0) {
     // Set up embedded test server.
     embedded_test_server_.ServeFilesFromDirectory(
         base::FilePath(FILE_PATH_LITERAL("net/data/url_request_unittest")));
     EXPECT_TRUE(embedded_test_server_.Start());
     embedded_test_server_.RegisterRequestHandler(base::Bind(
         &TestNetworkQualityEstimator::HandleRequest, base::Unretained(this)));
   }
 
   explicit TestNetworkQualityEstimator(
       const std::map<std::string, std::string>& variation_params)
@@ skipping 165 matching lines @@
   }
 
   const std::vector<base::TimeDelta>& GetAccuracyRecordingIntervals()
       const override {
     if (accuracy_recording_intervals_set_)
       return accuracy_recording_intervals_;
 
     return NetworkQualityEstimator::GetAccuracyRecordingIntervals();
   }
 
+  void set_rand_double(double rand_double) { rand_double_ = rand_double; }
+
+  double RandDouble() const override { return rand_double_; }
+
   using NetworkQualityEstimator::SetTickClockForTesting;
   using NetworkQualityEstimator::ReadCachedNetworkQualityEstimate;
   using NetworkQualityEstimator::OnConnectionTypeChanged;
 
  private:
   // NetworkQualityEstimator implementation that returns the overridden
   // network
   // id (instead of invoking platform APIs).
   NetworkQualityEstimator::NetworkID GetCurrentNetworkID() const override {
     return NetworkQualityEstimator::NetworkID(current_network_type_,
@@ skipping 23 matching lines @@
 
   bool recent_transport_rtt_set_;
   base::TimeDelta recent_transport_rtt_;
 
   bool downlink_throughput_kbps_set_;
   int32_t downlink_throughput_kbps_;
 
   bool recent_downlink_throughput_kbps_set_;
   int32_t recent_downlink_throughput_kbps_;
 
+  double rand_double_;
+
   // Embedded server used for testing.
   EmbeddedTestServer embedded_test_server_;
 
   DISALLOW_COPY_AND_ASSIGN(TestNetworkQualityEstimator);
 };
 
 class TestEffectiveConnectionTypeObserver
     : public NetworkQualityEstimator::EffectiveConnectionTypeObserver {
  public:
   std::vector<NetworkQualityEstimator::EffectiveConnectionType>&
@@ skipping 1486 matching lines @@
     std::string connection_type_name =
         std::string(NetworkQualityEstimator::GetNameForEffectiveConnectionType(
             effective_connection_type));
     EXPECT_FALSE(connection_type_name.empty());
     EXPECT_EQ(effective_connection_type,
               NetworkQualityEstimator::GetEffectiveConnectionTypeForName(
                   connection_type_name));
   }
 }
 
+// Tests that the correlation histogram is recorded correctly based on
+// correlation logging probability set in the variation params.
+TEST(NetworkQualityEstimatorTest, CorrelationHistogram) {
+  // Match the values set in network_quality_estimator.cc.
+  static const int32_t kTrimBits = 5;
+  static const int32_t kBitsPerMetric = 7;
+
+  const struct {
+    double rand_double;
+    double correlation_logging_probability;
+    base::TimeDelta transport_rtt;
+    int32_t expected_transport_rtt_milliseconds;
+    base::TimeDelta http_rtt;
+    int32_t expected_http_rtt_milliseconds;
+    int32_t downstream_throughput_kbps;
+    int32_t expected_downstream_throughput_kbps;
+
+  } tests[] = {
+      {
+          // Verify that the metric is not recorded if the logging probability
+          // is set to 0.0.
+          0.5, 0.0, base::TimeDelta::FromSeconds(1), 1000 >> kTrimBits,
+          base::TimeDelta::FromSeconds(2), 2000 >> kTrimBits, 3000,
+          3000 >> kTrimBits,
+      },
+      {
+          // Verify that the metric is not recorded if the logging probability
+          // is lower than the value returned by the random number generator.
+          0.3, 0.1, base::TimeDelta::FromSeconds(1), 1000 >> kTrimBits,
+          base::TimeDelta::FromSeconds(2), 2000 >> kTrimBits, 3000,
+          3000 >> kTrimBits,
+      },
+      {
+          // Verify that the metric is recorded if the logging probability is
+          // higher than the value returned by the random number generator.
+          0.3, 0.4, base::TimeDelta::FromSeconds(1), 1000 >> kTrimBits,
+          base::TimeDelta::FromSeconds(2), 2000 >> kTrimBits, 3000,
+          3000 >> kTrimBits,
+      },
+      {
+          // Verify that the metric is recorded if the logging probability is
+          // set to 1.0.
+          0.5, 1.0, base::TimeDelta::FromSeconds(1), 1000 >> kTrimBits,
+          base::TimeDelta::FromSeconds(2), 2000 >> kTrimBits, 3000,
+          3000 >> kTrimBits,
+      },
+      {
+          // Verify that if the metric is larger than
+          // 2^(kBitsPerMetric + kTrimBits), it is rounded down to
+          // (2^(kBitsPerMetric + kTrimBits) - 1) >> kTrimBits.
+          0.5, 1.0, base::TimeDelta::FromSeconds(10), 4095 >> kTrimBits,
+          base::TimeDelta::FromSeconds(20), 4095 >> kTrimBits, 30000,
+          4095 >> kTrimBits,
+      },
+  };
+
+  for (const auto& test : tests) {
+    base::HistogramTester histogram_tester;
+
+    std::map<std::string, std::string> variation_params;
+    variation_params["correlation_logging_probability"] =
+        base::DoubleToString(test.correlation_logging_probability);
+    TestNetworkQualityEstimator estimator(variation_params);
+
+    estimator.set_transport_rtt(test.transport_rtt);
+    estimator.set_recent_transport_rtt(test.transport_rtt);
+    estimator.set_http_rtt(test.http_rtt);
+    estimator.set_recent_http_rtt(test.http_rtt);
+    estimator.set_downlink_throughput_kbps(test.downstream_throughput_kbps);
+    estimator.set_rand_double(test.rand_double);
+
+    TestDelegate test_delegate;
+    TestURLRequestContext context(true);
+    context.set_network_quality_estimator(&estimator);
+    context.Init();
+
+    // Start a main-frame request that should cause network quality estimator to
+    // record the network quality at the last main frame request.
+    std::unique_ptr<URLRequest> request_1(context.CreateRequest(
+        estimator.GetEchoURL(), DEFAULT_PRIORITY, &test_delegate));
+    request_1->SetLoadFlags(request_1->load_flags() | LOAD_MAIN_FRAME);
+    request_1->Start();
+    base::RunLoop().Run();
+    histogram_tester.ExpectTotalCount("NQE.Correlation.ResourceLoadTime", 0);
+
+    // Start another main-frame request which should cause network quality
+    // estimator to record the correlation UMA.
+    std::unique_ptr<URLRequest> request_2(context.CreateRequest(
+        estimator.GetEchoURL(), DEFAULT_PRIORITY, &test_delegate));
+    request_2->Start();
+    base::RunLoop().Run();
+
+    if (test.rand_double >= test.correlation_logging_probability) {
+      histogram_tester.ExpectTotalCount("NQE.Correlation.ResourceLoadTime", 0);
+      continue;
+    }
+    histogram_tester.ExpectTotalCount("NQE.Correlation.ResourceLoadTime", 1);
+    std::vector<base::Bucket> buckets =
+        histogram_tester.GetAllSamples("NQE.Correlation.ResourceLoadTime");
+    // Get the bits at index 0-10 which contain the transport RTT.
+    // 128 is 2^kBitsPerMetric.
+    EXPECT_EQ(test.expected_transport_rtt_milliseconds,
+              buckets.at(0).min >> kBitsPerMetric >> kBitsPerMetric >>
+                  kBitsPerMetric);
+    // Get the bits at index 11-17 which contain the HTTP RTT.
+    EXPECT_EQ(test.expected_http_rtt_milliseconds,
+              (buckets.at(0).min >> kBitsPerMetric >> kBitsPerMetric) % 128);
+    // Get the bits at index 18-24 which contain the downstream throughput.
+    EXPECT_EQ(test.expected_downstream_throughput_kbps,
+              (buckets.at(0).min >> kBitsPerMetric) % 128);
+    // Get the bits at index 25-31 which contain the resource fetch time.
+    EXPECT_LE(0, buckets.at(0).min % 128);
+  }
+}
+
 }  // namespace net