NQE: Separate out params to a different file

net/nqe/network_quality_estimator_params.cc

+// Copyright 2016 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_params.h"
+
+#include "base/strings/string_number_conversions.h"
+#include "base/time/time.h"
+
+namespace {
+
+// Default value of the half life (in seconds) for computing time weighted
+// percentiles. Every half life, the weight of all observations reduces by
+// half. Lowering the half life would reduce the weight of older values faster.
+const int kDefaultHalfLifeSeconds = 60;
+
+// Name of the variation parameter that holds the value of the half life (in
+// seconds) of the observations.
+const char kHalfLifeSecondsParamName[] = "HalfLifeSeconds";
+
+// Suffix of the name of the variation parameter that contains the default RTT
+// observation (in milliseconds). Complete name of the variation parameter
+// would be |ConnectionType|.|kDefaultRTTMsecObservationSuffix| where
+// |ConnectionType| is from |kConnectionTypeNames|. For example, variation
+// parameter for Wi-Fi would be "WiFi.DefaultMedianRTTMsec".
+const char kDefaultRTTMsecObservationSuffix[] = ".DefaultMedianRTTMsec";
+
+// Suffix of the name of the variation parameter that contains the default
+// downstream throughput observation (in Kbps).  Complete name of the variation
+// parameter would be |ConnectionType|.|kDefaultKbpsObservationSuffix| where
+// |ConnectionType| is from |kConnectionTypeNames|. For example, variation
+// parameter for Wi-Fi would be "WiFi.DefaultMedianKbps".
+const char kDefaultKbpsObservationSuffix[] = ".DefaultMedianKbps";
+
+// Suffix of the name of the variation parameter that contains the threshold
+// HTTP RTTs (in milliseconds) for different effective connection types.
+// Complete name of the variation parameter would be
+// |EffectiveConnectionType|.|kThresholdURLRTTMsecSuffix|.
+const char kThresholdURLRTTMsecSuffix[] = ".ThresholdMedianHttpRTTMsec";
+
+// Suffix of the name of the variation parameter that contains the threshold
+// transport RTTs (in milliseconds) for different effective connection types.
+// Complete name of the variation parameter would be
+// |EffectiveConnectionType|.|kThresholdTransportRTTMsecSuffix|.
+const char kThresholdTransportRTTMsecSuffix[] =
+    ".ThresholdMedianTransportRTTMsec";
+
+// Suffix of the name of the variation parameter that contains the threshold
+// downlink throughput (in kbps) for different effective connection types.
+// Complete name of the variation parameter would be
+// |EffectiveConnectionType|.|kThresholdKbpsSuffix|.
+const char kThresholdKbpsSuffix[] = ".ThresholdMedianKbps";
+
+// Minimum valid value of the variation parameter that holds RTT (in
+// milliseconds) values.
+static const int kMinimumRTTVariationParameterMsec = 1;
+
+// Minimum valid value of the variation parameter that holds throughput (in
+// kilobits per second) values.
+static const int kMinimumThroughputVariationParameterKbps = 1;
+
+// Sets |variations_value| to the value of |parameter_name| read from
+// |variation_params|. If the value is unavailable from |variation_params|, then
+// |variations_value| is set to |default_value|.
+void GetValueForVariationParam(

[RyanSturm, 2016/10/18 23:29:04]

Return an int64_t instead of void and an out param?

[tbansal1, 2016/10/20 01:02:15]

Done.

+    const std::map<std::string, std::string>& variation_params,
+    const std::string& parameter_name,
+    int64_t default_value,
+    int64_t* variations_value) {
+  const auto it = variation_params.find(parameter_name);
+  if (it != variation_params.end() &&
+      base::StringToInt64(it->second, variations_value)) {
+    return;
+  }
+  *variations_value = default_value;
+}
+
+// Returns the variation value for |parameter_name|. If the value is
+// unavailable, |default_value| is returned.
+double GetDoubleValueForVariationParamWithDefaultValue(
+    const std::map<std::string, std::string>& variation_params,
+    const std::string& parameter_name,
+    double default_value) {
+  const auto it = variation_params.find(parameter_name);
+  if (it == variation_params.end())
+    return default_value;
+
+  double variations_value = default_value;

[RyanSturm, 2016/10/18 23:29:04]

why define this as default_value?

[tbansal1, 2016/10/20 01:02:15]

Done.

[RyanSturm, 2016/10/20 17:29:59]

I guess I was asking why variations_value = default_value; is done here. If
StringToDouble succeeds variations_value will be set, and if it fails, it will
return default_value, so there is no need to set it initially.

Same thing on line 70 now.

[tbansal1, 2016/10/20 17:32:14]

Windows compiler complains otherwise. Look at the trybots log from PS 3. I
thought I had added a comment here explaining this, but I forgot.

[RyanSturm, 2016/10/20 17:40:21]

If you're feeling curious, I bet that switching the return statements and
removing the ! Will fix it on windows compilers, but that is just a hunch.

+  if (!base::StringToDouble(it->second, &variations_value))
+    return default_value;
+  return variations_value;
+}
+
+// Returns the variation value for |parameter_name|. If the value is
+// unavailable, |default_value| is returned.
+std::string GetStringValueForVariationParamWithDefaultValue(
+    const std::map<std::string, std::string>& variation_params,
+    const std::string& parameter_name,
+    const std::string& default_value) {
+  const auto it = variation_params.find(parameter_name);
+  if (it == variation_params.end())
+    return default_value;
+  return it->second;
+}
+
+}  // namespace
+
+namespace net {
+
+namespace nqe {
+
+namespace internal {
+
+std::string GetEffectiveConnectionTypeAlgorithm(
+    const std::map<std::string, std::string>& variation_params) {
+  const auto it = variation_params.find("effective_connection_type_algorithm");
+  if (it == variation_params.end())
+    return std::string();
+  return it->second;
+}
+
+double GetWeightMultiplierPerSecond(
+    const std::map<std::string, std::string>& variation_params) {
+  static_assert(kDefaultHalfLifeSeconds > 0,
+                "Default half life duration must be > 0");
+
+  int half_life_seconds = kDefaultHalfLifeSeconds;
+  int32_t variations_value = 0;
+  auto it = variation_params.find(kHalfLifeSecondsParamName);
+  if (it != variation_params.end() &&
+      base::StringToInt(it->second, &variations_value) &&
+      variations_value >= 1) {
+    half_life_seconds = variations_value;
+  }
+  DCHECK_GT(half_life_seconds, 0);
+  return exp(log(0.5) / half_life_seconds);

[RyanSturm, 2016/10/18 23:29:04]

nit: I think this would be more readable as pow(.5, 1.0 / half_life_seconds). To
me, that reads as "If I raise the returned value to the |half_life_seconds|, I
will get .5". WDYT? I would doubt there are performance implications either way.

[tbansal1, 2016/10/20 01:02:15]

Done.

+}
+
+const char* GetNameForConnectionType(
+    net::NetworkChangeNotifier::ConnectionType connection_type) {
+  switch (connection_type) {
+    case net::NetworkChangeNotifier::CONNECTION_UNKNOWN:
+      return "Unknown";
+    case net::NetworkChangeNotifier::CONNECTION_ETHERNET:
+      return "Ethernet";
+    case net::NetworkChangeNotifier::CONNECTION_WIFI:
+      return "WiFi";
+    case net::NetworkChangeNotifier::CONNECTION_2G:
+      return "2G";
+    case net::NetworkChangeNotifier::CONNECTION_3G:
+      return "3G";
+    case net::NetworkChangeNotifier::CONNECTION_4G:
+      return "4G";
+    case net::NetworkChangeNotifier::CONNECTION_NONE:
+      return "None";
+    case net::NetworkChangeNotifier::CONNECTION_BLUETOOTH:
+      return "Bluetooth";
+    default:
+      NOTREACHED();
+      break;
+  }
+  return "";
+}
+
+void ObtainDefaultObservations(
+    const std::map<std::string, std::string>& variation_params,
+    nqe::internal::NetworkQuality default_observations[]) {

[RyanSturm, 2016/10/18 23:29:04]

I don't think you should pass this as an array, but rather a pointer and access
it the same way. I don't particularly like the use of array here because array
doesn't carry a size with it. Maybe you should switch to a vector?

[tbansal1, 2016/10/20 01:02:15]

The size of the array has to always match the number of ECTs. So, the size is
known (although out of band) at the compile time, and the size never changes.

[RyanSturm, 2016/10/20 17:29:59]

Acknowledged.

+  for (size_t i = 0; i <= NetworkChangeNotifier::CONNECTION_LAST; ++i) {
+    NetworkChangeNotifier::ConnectionType type =
+        static_cast<NetworkChangeNotifier::ConnectionType>(i);
+    DCHECK_EQ(nqe::internal::InvalidRTT(), default_observations[i].http_rtt());
+    DCHECK_EQ(nqe::internal::InvalidRTT(),
+              default_observations[i].transport_rtt());
+    DCHECK_EQ(nqe::internal::kInvalidThroughput,
+              default_observations[i].downstream_throughput_kbps());
+
+    base::TimeDelta default_rtt = net::nqe::internal::InvalidRTT();
+    int32_t variations_value = kMinimumRTTVariationParameterMsec - 1;
+    std::string parameter_name = std::string(GetNameForConnectionType(type))
+                                     .append(kDefaultRTTMsecObservationSuffix);
+    auto it = variation_params.find(parameter_name);
+
+    if (it != variation_params.end() &&
+        base::StringToInt(it->second, &variations_value) &&
+        variations_value >= kMinimumRTTVariationParameterMsec) {
+      default_rtt = base::TimeDelta::FromMilliseconds(variations_value);
+    }
+
+    int32_t downstream_throughput_kbps = net::nqe::internal::kInvalidThroughput;
+    variations_value = kMinimumThroughputVariationParameterKbps - 1;
+    parameter_name = std::string(GetNameForConnectionType(type))
+                         .append(kDefaultKbpsObservationSuffix);
+    it = variation_params.find(parameter_name);
+
+    if (it != variation_params.end() &&
+        base::StringToInt(it->second, &variations_value) &&
+        variations_value >= kMinimumThroughputVariationParameterKbps) {
+      downstream_throughput_kbps = variations_value;
+    }
+
+    default_observations[i] = nqe::internal::NetworkQuality(
+        default_rtt, default_observations[i].transport_rtt(),
+        downstream_throughput_kbps);
+  }
+}
+
+void ObtainEffectiveConnectionTypeModelParams(
+    const std::map<std::string, std::string>& variation_params,
+    nqe::internal::NetworkQuality connection_thresholds[]) {

[RyanSturm, 2016/10/18 23:29:04]

same as comment above.

[tbansal1, 2016/10/20 01:02:15]

See the reply above.

+  // First set the default thresholds.
+  nqe::internal::NetworkQuality default_effective_connection_type_thresholds
+      [EffectiveConnectionType::EFFECTIVE_CONNECTION_TYPE_LAST];
+
+  default_effective_connection_type_thresholds
+      [EFFECTIVE_CONNECTION_TYPE_SLOW_2G] = nqe::internal::NetworkQuality(
+          // Set to 2010 milliseconds, which corresponds to the 33rd percentile
+          // of 2G HTTP RTT observations on Android.
+          base::TimeDelta::FromMilliseconds(2010),
+          // Set to 1870 milliseconds, which corresponds to the 33rd percentile
+          // of 2G transport RTT observations on Android.
+          base::TimeDelta::FromMilliseconds(1870),
+          nqe::internal::kInvalidThroughput);
+
+  default_effective_connection_type_thresholds[EFFECTIVE_CONNECTION_TYPE_2G] =
+      nqe::internal::NetworkQuality(
+          // Set to 1420 milliseconds, which corresponds to 50th percentile of
+          // 2G
+          // HTTP RTT observations on Android.
+          base::TimeDelta::FromMilliseconds(1420),
+          // Set to 1280 milliseconds, which corresponds to 50th percentile of
+          // 2G
+          // transport RTT observations on Android.
+          base::TimeDelta::FromMilliseconds(1280),
+          nqe::internal::kInvalidThroughput);
+
+  default_effective_connection_type_thresholds[EFFECTIVE_CONNECTION_TYPE_3G] =
+      nqe::internal::NetworkQuality(
+          // Set to 273 milliseconds, which corresponds to 50th percentile of
+          // 3G HTTP RTT observations on Android.
+          base::TimeDelta::FromMilliseconds(273),
+          // Set to 204 milliseconds, which corresponds to 50th percentile of
+          // 3G transport RTT observations on Android.
+          base::TimeDelta::FromMilliseconds(204),
+          nqe::internal::kInvalidThroughput);
+
+  for (size_t i = 0; i < EFFECTIVE_CONNECTION_TYPE_LAST; ++i) {
+    EffectiveConnectionType effective_connection_type =
+        static_cast<EffectiveConnectionType>(i);
+    DCHECK_EQ(nqe::internal::InvalidRTT(), connection_thresholds[i].http_rtt());
+    DCHECK_EQ(nqe::internal::InvalidRTT(),
+              connection_thresholds[i].transport_rtt());
+    DCHECK_EQ(nqe::internal::kInvalidThroughput,
+              connection_thresholds[i].downstream_throughput_kbps());
+    if (effective_connection_type == EFFECTIVE_CONNECTION_TYPE_UNKNOWN)
+      continue;
+
+    std::string connection_type_name = std::string(
+        GetNameForEffectiveConnectionType(effective_connection_type));
+
+    int64_t variations_value;
+    GetValueForVariationParam(variation_params,
+                              connection_type_name + kThresholdURLRTTMsecSuffix,
+                              default_effective_connection_type_thresholds[i]
+                                  .http_rtt()
+                                  .InMilliseconds(),
+                              &variations_value);
+    connection_thresholds[i].set_http_rtt(
+        base::TimeDelta::FromMilliseconds(variations_value));
+
+    GetValueForVariationParam(
+        variation_params,
+        connection_type_name + kThresholdTransportRTTMsecSuffix,
+        default_effective_connection_type_thresholds[i]
+            .transport_rtt()
+            .InMilliseconds(),
+        &variations_value);
+    connection_thresholds[i].set_transport_rtt(
+        base::TimeDelta::FromMilliseconds(variations_value));
+
+    GetValueForVariationParam(variation_params,
+                              connection_type_name + kThresholdKbpsSuffix,
+                              default_effective_connection_type_thresholds[i]
+                                  .downstream_throughput_kbps(),
+                              &variations_value);
+    connection_thresholds[i].set_downstream_throughput_kbps(variations_value);
+    DCHECK(i == 0 ||
+           connection_thresholds[i].IsFaster(connection_thresholds[i - 1]));
+  }
+}
+
+double correlation_uma_logging_probability(
+    const std::map<std::string, std::string>& variation_params) {
+  double correlation_uma_logging_probability =
+      GetDoubleValueForVariationParamWithDefaultValue(
+          variation_params, "correlation_logging_probability", 0.0);
+  DCHECK_LE(0.0, correlation_uma_logging_probability);
+  DCHECK_GE(1.0, correlation_uma_logging_probability);
+  return correlation_uma_logging_probability;
+}
+
+bool forced_effective_connection_type_set(
+    const std::map<std::string, std::string>& variation_params) {
+  return !GetStringValueForVariationParamWithDefaultValue(
+              variation_params, "force_effective_connection_type", "")
+              .empty();
+}
+
+EffectiveConnectionType forced_effective_connection_type(
+    const std::map<std::string, std::string>& variation_params) {
+  EffectiveConnectionType forced_effective_connection_type =
+      EFFECTIVE_CONNECTION_TYPE_UNKNOWN;
+  std::string forced_value = GetStringValueForVariationParamWithDefaultValue(
+      variation_params, "force_effective_connection_type",
+      GetNameForEffectiveConnectionType(EFFECTIVE_CONNECTION_TYPE_UNKNOWN));
+  DCHECK(!forced_value.empty());
+  bool effective_connection_type_available = GetEffectiveConnectionTypeForName(
+      forced_value, &forced_effective_connection_type);
+  DCHECK(effective_connection_type_available);
+
+  // Silence unused variable warning in release builds.
+  (void)effective_connection_type_available;
+
+  return forced_effective_connection_type;
+}
+
+}  // namespace internal
+
+}  // namespace nqe
+
+}  // namespace net