NQE: Allow algorithm to be set using variation params

net/nqe/network_quality_estimator.cc

Index: net/nqe/network_quality_estimator.cc
diff --git a/net/nqe/network_quality_estimator.cc b/net/nqe/network_quality_estimator.cc
index f2247f048b1195104c95a750623e9433d1e09c92..5fabb8178bf4c14c6451e25245cfd1d23a9aa946 100644
--- a/net/nqe/network_quality_estimator.cc
+++ b/net/nqe/network_quality_estimator.cc
@@ -140,6 +140,20 @@ bool GetValueForVariationParam(
          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) {
@@ -253,6 +267,9 @@ NetworkQualityEstimator::NetworkQualityEstimator(
       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)),
@@ -273,6 +290,7 @@ NetworkQualityEstimator::NetworkQualityEstimator(
   // 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);
@@ -755,6 +773,21 @@ 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)
@@ -768,7 +801,7 @@ NetworkQualityEstimator::GetRecentEffectiveConnectionType(
   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;