NQE: Allow algorithm to be set using variation params

net/nqe/network_quality_estimator.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 <algorithm>
 #include <cmath>
 #include <limits>
 #include <utility>
@@ skipping 122 matching lines @@
 
 bool GetValueForVariationParam(
     const std::map<std::string, std::string>& variation_params,
     const std::string& parameter_name,
     int32_t* variations_value) {
   auto it = variation_params.find(parameter_name);
   return it != variation_params.end() &&
          base::StringToInt(it->second, variations_value);
 }
 
+// Returns the value of the |parameter_name| in |variation_params|. If
+// |parameter_name| is not set in |variation_params|, then |default_value| is
+// returned.
+int32_t GetValueForVariationParamWithDefaultValue(
+    const std::map<std::string, std::string>& variation_params,
+    const std::string& parameter_name,
+    int32_t default_value) {
+  int32_t variations_value;
+  return GetValueForVariationParam(variation_params, parameter_name,
+                                   &variations_value)
+             ? variations_value
+             : default_value;
+}
+
 net::NetworkQualityObservationSource ProtocolSourceToObservationSource(
     net::SocketPerformanceWatcherFactory::Protocol protocol) {
   switch (protocol) {
     case net::SocketPerformanceWatcherFactory::PROTOCOL_TCP:
       return net::NETWORK_QUALITY_OBSERVATION_SOURCE_TCP;
     case net::SocketPerformanceWatcherFactory::PROTOCOL_QUIC:
       return net::NETWORK_QUALITY_OBSERVATION_SOURCE_QUIC;
   }
   NOTREACHED();
   return net::NETWORK_QUALITY_OBSERVATION_SOURCE_TCP;
@@ skipping 93 matching lines @@
 
 NetworkQualityEstimator::NetworkQualityEstimator(
     std::unique_ptr<ExternalEstimateProvider> external_estimates_provider,
     const std::map<std::string, std::string>& variation_params,
     bool use_local_host_requests_for_tests,
     bool use_smaller_responses_for_tests)
     : use_localhost_requests_(use_local_host_requests_for_tests),
       use_small_responses_(use_smaller_responses_for_tests),
       weight_multiplier_per_second_(
           GetWeightMultiplierPerSecond(variation_params)),
+      algorithm_(GetValueForVariationParamWithDefaultValue(variation_params,

[bengr, 2016/06/02 22:59:43]

You should add a comment somewhere that you default to algorithm 0 if you do not
have a valid variations param.

[tbansal1, 2016/06/03 00:50:10]

Done.

+                                                           "algorithm",
+                                                           0)),
       tick_clock_(new base::DefaultTickClock()),
       effective_connection_type_recomputation_interval_(
           base::TimeDelta::FromSeconds(15)),
       last_connection_change_(tick_clock_->NowTicks()),
       current_network_id_(
           NetworkID(NetworkChangeNotifier::ConnectionType::CONNECTION_UNKNOWN,
                     std::string())),
       downstream_throughput_kbps_observations_(weight_multiplier_per_second_),
       rtt_observations_(weight_multiplier_per_second_),
       external_estimate_provider_(std::move(external_estimates_provider)),
       effective_connection_type_(EFFECTIVE_CONNECTION_TYPE_UNKNOWN),
       weak_ptr_factory_(this) {
   static_assert(kDefaultHalfLifeSeconds > 0,
                 "Default half life duration must be > 0");
   static_assert(kMaximumNetworkQualityCacheSize > 0,
                 "Size of the network quality cache must be > 0");
   // This limit should not be increased unless the logic for removing the
   // oldest cache entry is rewritten to use a doubly-linked-list LRU queue.
   static_assert(kMaximumNetworkQualityCacheSize <= 10,
                 "Size of the network quality cache must <= 10");
+  DCHECK_GE(algorithm_, 0);

[bengr, 2016/06/02 22:59:43]

Shouldn't this be DCHECK_EQ? algorithm_ should be greater than or equal to zero,
but no greater than the maximum supported algorithm number. You might also want
to introduce a constant that contains the maximum supported algorithm number.

[tbansal1, 2016/06/03 00:50:10]

I removed it since with strings it does not really work. Also, I added
NOTREACHED() in GetRecentEffectiveConnectionType, so this is covered there.

 
   ObtainOperatingParams(variation_params);
   ObtainEffectiveConnectionTypeModelParams(variation_params);
   NetworkChangeNotifier::AddConnectionTypeObserver(this);
   if (external_estimate_provider_) {
     RecordExternalEstimateProviderMetrics(
         EXTERNAL_ESTIMATE_PROVIDER_STATUS_AVAILABLE);
     external_estimate_provider_->SetUpdatedEstimateDelegate(this);
   } else {
     RecordExternalEstimateProviderMetrics(
@@ skipping 462 matching lines @@
 NetworkQualityEstimator::GetEffectiveConnectionType() const {
   DCHECK(thread_checker_.CalledOnValidThread());
   return GetRecentEffectiveConnectionType(base::TimeTicks());
 }
 
 NetworkQualityEstimator::EffectiveConnectionType
 NetworkQualityEstimator::GetRecentEffectiveConnectionType(
     const base::TimeTicks& start_time) const {
   DCHECK(thread_checker_.CalledOnValidThread());
 
+  switch (algorithm_) {
+    case 0:
+      return GetRecentEffectiveConnectionTypeAlgorithm0(start_time);
+    default:
+      NOTREACHED();
+  }
+  return GetRecentEffectiveConnectionTypeAlgorithm0(start_time);
+}
+
+NetworkQualityEstimator::EffectiveConnectionType
+NetworkQualityEstimator::GetRecentEffectiveConnectionTypeAlgorithm0(
+    const base::TimeTicks& start_time) const {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK_EQ(0, algorithm_);
+
   // If the device is currently offline, then return
   // EFFECTIVE_CONNECTION_TYPE_OFFLINE.
   if (GetCurrentNetworkID().type == NetworkChangeNotifier::CONNECTION_NONE)
     return EFFECTIVE_CONNECTION_TYPE_OFFLINE;
 
   base::TimeDelta http_rtt = nqe::internal::InvalidRTT();
   if (!GetRecentHttpRTTMedian(start_time, &http_rtt))
     http_rtt = nqe::internal::InvalidRTT();
 
   int32_t kbps = nqe::internal::kInvalidThroughput;
   if (!GetRecentMedianDownlinkThroughputKbps(start_time, &kbps))
     kbps = nqe::internal::kInvalidThroughput;
 
-  if (http_rtt == nqe::internal::InvalidRTT() &&
+  if (http_rtt == nqe::internal::InvalidRTT() ||
       kbps == nqe::internal::kInvalidThroughput) {
     // Quality of the current network is unknown.
     return EFFECTIVE_CONNECTION_TYPE_UNKNOWN;
   }
 
   // Search from the slowest connection type to the fastest to find the
   // EffectiveConnectionType that best matches the current connection's
   // performance. The match is done by comparing RTT and throughput.
   for (size_t i = 0; i < EFFECTIVE_CONNECTION_TYPE_LAST; ++i) {
     EffectiveConnectionType type = static_cast<EffectiveConnectionType>(i);
@@ skipping 408 matching lines @@
     NotifyObserversOfEffectiveConnectionTypeChanged() {
   DCHECK(thread_checker_.CalledOnValidThread());
 
   // TODO(tbansal): Add hysteresis in the notification.
   FOR_EACH_OBSERVER(
       EffectiveConnectionTypeObserver, effective_connection_type_observer_list_,
       OnEffectiveConnectionTypeChanged(effective_connection_type_));
 }
 
 }  // namespace net