Added a cache for track features, made the crossover ratio configurable, now using a fitness proportional selection

src/similarity/features/SimilarityFeaturesSearcher.cpp

@@ -36,43 +36,52 @@
 namespace Similarity {
 
 static
-std::optional<SOM::InputVector>
-getInputVectorFromTrack(Database::Session& session, Database::IdType trackId, const std::unordered_set<FeatureName>& featureNames, std::size_t nbDimensions)
+std::optional<FeatureValuesMap>
+getTrackFeatureValues(FeaturesSearcher::FeaturesFetchFunc func, Database::IdType trackId, const std::unordered_set<FeatureName>& featureNames)
 {
-	FeatureValuesMap featureValuesMap;
+	return func(trackId, featureNames);
+}
 
+static
+std::optional<FeatureValuesMap>
+getTrackFeatureValuesFromDb(Database::Session& session, Database::IdType trackId, const std::unordered_set<FeatureName>& featureNames)
+{
+	auto func = [&](Database::IdType trackId, const std::unordered_set<FeatureName>& featureNames)
 	{
+		std::optional<FeatureValuesMap> res;
+
 		auto transaction {session.createSharedTransaction()};
 
 		Database::Track::pointer track {Database::Track::getById(session, trackId)};
 		if (!track)
-			return std::nullopt;
+			return res;
 
-		featureValuesMap = track->getTrackFeatures()->getFeatureValuesMap(featureNames);
-		if (featureValuesMap.empty())
-			return std::nullopt;
-	}
+		res = track->getTrackFeatures()->getFeatureValuesMap(featureNames);
+		if (res->empty())
+			res.reset();
 
+		return res;
+	};
+
+	return getTrackFeatureValues(func, trackId, featureNames);
+}
+
+static
+std::optional<SOM::InputVector>
+convertFeatureValuesMapToInputVector(const FeatureValuesMap& featureValuesMap, std::size_t nbDimensions)
+{
 	std::size_t i {};
 	std::optional<SOM::InputVector> res {SOM::InputVector {nbDimensions}};
-	for (const auto& featureName : featureNames)
+	for (const auto& [featureName, values] : featureValuesMap)
 	{
-		const auto it {featureValuesMap.find(featureName)};
-		if (it == std::cend(featureValuesMap))
+		if (values.size() != getFeatureDef(featureName).nbDimensions)
 		{
-			LMS_LOG(SIMILARITY, WARNING) << "Cannot find feature '" << featureName << "' for track id'" << trackId << "'";
+			LMS_LOG(SIMILARITY, WARNING) << "Dimension mismatch for feature '" << featureName << "'. Expected " << getFeatureDef(featureName).nbDimensions << ", got " << values.size();
 			res.reset();
 			break;
 		}
 
-		if (it->second.size() != getFeatureDef(featureName).nbDimensions)
-		{
-			LMS_LOG(SIMILARITY, WARNING) << "Dimension mismatch for feature '" << featureName << "'. Expected " << getFeatureDef(featureName).nbDimensions << ", got " << it->second.size() << ", trackId = " << trackId;
-			res.reset();
-			break;
-		}
-
-		for (double val : it->second)
+		for (double val : values)
 			(*res)[i++] = val;
 	}
 
@@ -134,7 +143,17 @@ FeaturesSearcher::FeaturesSearcher(Database::Session& session,
 		if (stopRequested && stopRequested())
 			return;
 
-		std::optional<SOM::InputVector> inputVector {getInputVectorFromTrack(session, trackId, featureNames, nbDimensions)};
+		std::optional<FeatureValuesMap> featureValuesMap;
+
+		if (_featuresFetchFunc)
+			featureValuesMap = getTrackFeatureValues(_featuresFetchFunc, trackId, featureNames);
+		else
+			featureValuesMap = getTrackFeatureValuesFromDb(session, trackId, featureNames);
+
+		if (!featureValuesMap)
+			continue;
+
+		std::optional<SOM::InputVector> inputVector {convertFeatureValuesMapToInputVector(*featureValuesMap, nbDimensions)};
 		if (!inputVector)
 			continue;
 

src/similarity/features/SimilarityFeaturesSearcher.hpp

@@ -20,6 +20,7 @@
 #pragma once
 
 #include <map>
+#include <optional>
 #include <set>
 #include <string>
 
@@ -70,6 +71,11 @@ class FeaturesSearcher
 
 		FeaturesCache toCache() const;
 
+		using FeaturesFetchFunc = std::function<std::optional<std::unordered_map<std::string, std::vector<double>>>(Database::IdType /*trackId*/, const std::unordered_set<std::string>& /*features*/)>;
+		// Default is to retrieve the features from the database (may be slow).
+		// Use this only if you want to train different searchers with the same data
+		static void setFeaturesFetchFunc(FeaturesFetchFunc func) { _featuresFetchFunc = func; }
+
 	private:
 
 		using ObjectPositions = std::map<Database::IdType, std::set<SOM::Position>>;
@@ -96,6 +102,7 @@ class FeaturesSearcher
 		SOM::Matrix<std::set<Database::IdType>> 	_tracksMap;
 		ObjectPositions					_trackPositions;
 
+		static inline FeaturesFetchFunc _featuresFetchFunc;
 };
 
 } // ns Similarity

src/utils/Utils.cpp

@@ -176,10 +176,3 @@ RandGenerator& getRandGenerator()
 	return randGenerator;
 }
 
-int
-getRandom(int min, int max)
-{
-	std::uniform_int_distribution<> dist {min, max};
-	return dist (getRandGenerator());
-}
-

src/utils/Utils.hpp

@@ -113,8 +113,21 @@ constexpr T clamp(T v, T lo, T hi, Compare comp = {})
 using RandGenerator = std::mt19937;
 RandGenerator& getRandGenerator();
 
-int
-getRandom(int min, int max);
+template <typename T>
+T
+getRandom(T min, T max)
+{
+	std::uniform_int_distribution<> dist {min, max};
+	return dist (getRandGenerator());
+}
+
+template <typename T>
+T
+getRealRandom(T min, T max)
+{
+	std::uniform_real_distribution<> dist {min, max};
+	return dist (getRandGenerator());
+}
 
 template <typename Container>
 void