Finished clean on recommendation engines

src/libs/database/impl/Artist.cpp

@@ -66,6 +66,13 @@ Artist::getById(Session& session, ArtistId id)
 	return session.getDboSession().find<Artist>().where("id = ?").bind(id).resultValue();
 }
 
+bool
+Artist::exists(Session& session, ArtistId id)
+{
+	session.checkSharedLocked();
+	return session.getDboSession().query<int>("SELECT 1 FROM artist").where("id = ?").bind(id).resultValue() == 1;
+}
+
 Artist::pointer
 Artist::create(Session& session, const std::string& name, const std::optional<UUID>& MBID)
 {

src/libs/database/impl/Release.cpp

@@ -114,6 +114,13 @@ Release::getById(Session& session, ReleaseId id)
 					.resultValue();
 }
 
+bool
+Release::exists(Session& session, ReleaseId id)
+{
+	session.checkSharedLocked();
+	return session.getDboSession().query<int>("SELECT 1 FROM release").where("id = ?").bind(id).resultValue() == 1;
+}
+
 Release::pointer
 Release::create(Session& session, const std::string& name, const std::optional<UUID>& MBID)
 {

src/libs/database/impl/Track.cpp

@@ -156,6 +156,14 @@ Track::getById(Session& session, TrackId id)
 		.resultValue();
 }
 
+bool
+Track::exists(Session& session, TrackId id)
+{
+	session.checkSharedLocked();
+
+	return session.getDboSession().query<int>("SELECT 1 from track").where("id = ?").bind(id).resultValue() == 1;
+}
+
 std::vector<Track::pointer>
 Track::getByRecordingMBID(Session& session, const UUID& mbid)
 {

src/libs/database/include/database/Artist.hpp

@@ -58,8 +58,9 @@ class Artist : public Object<Artist, ArtistId>
 		// Accessors
 		static pointer			getByMBID(Session& session, const UUID& MBID);
 		static pointer			getById(Session& session, ArtistId id);
+		static bool				exists(Session& session, ArtistId id);
 		static std::vector<pointer>	getByName(Session& session, const std::string& name);		// exact match on name field
-		static std::vector<pointer> 	getByClusters(Session& session,
+		static std::vector<pointer> getByClusters(Session& session,
 								const std::vector<ClusterId>& clusters,		// at least one track that belongs to  these clusters
 								SortMethod sortMethod
 								);

src/libs/database/include/database/Release.hpp

@@ -50,6 +50,7 @@ class Release : public Object<Release, ReleaseId>
 		static pointer			getByMBID(Session& session, const UUID& MBID);
 		static std::vector<pointer>	getByName(Session& session, const std::string& name);
 		static pointer			getById(Session& session, ReleaseId id);
+		static bool				exists(Session& session, ReleaseId id);
 		static std::vector<pointer>	getAllOrphans(Session& session); // no track related
 		static std::vector<pointer>	getAll(Session& session, std::optional<Range> range = std::nullopt);
 		static std::vector<ReleaseId>	getAllIds(Session& session);

src/libs/database/include/database/Track.hpp

@@ -56,9 +56,10 @@ class Track : public Object<Track, TrackId>
 		Track(const std::filesystem::path& p);
 
 		// Find utility functions
-		static std::size_t getCount(Session& session);
-		static pointer getByPath(Session& session, const std::filesystem::path& p);
-		static pointer getById(Session& session, TrackId id);
+		static std::size_t			getCount(Session& session);
+		static pointer				getByPath(Session& session, const std::filesystem::path& p);
+		static pointer 				getById(Session& session, TrackId id);
+		static bool					exists(Session& session, TrackId id);
 		static std::vector<pointer> getByRecordingMBID(Session& session, const UUID& MBID);
 		static std::vector<pointer>	getSimilarTracks(Session& session,
 							const std::vector<TrackId>& trackIds,

src/libs/database/test/Artist.cpp

@@ -23,6 +23,13 @@ using namespace Database;
 
 TEST_F(DatabaseFixture, SingleArtist)
 {
+	{
+		auto transaction {session.createSharedTransaction()};
+		EXPECT_FALSE(Artist::exists(session, 35));
+		EXPECT_FALSE(Artist::exists(session, 0));
+		EXPECT_FALSE(Artist::exists(session, 1));
+	}
+
 	ScopedArtist artist {session, "MyArtist"};
 
 	{
@@ -31,6 +38,8 @@ TEST_F(DatabaseFixture, SingleArtist)
 		EXPECT_TRUE(artist.get());
 		EXPECT_FALSE(!artist.get());
 		EXPECT_EQ(artist.get()->getId(), artist.getId());
+
+		EXPECT_TRUE(Artist::exists(session, artist.getId()));
 	}
 
 	{

src/libs/database/test/Release.cpp

@@ -23,11 +23,20 @@ using namespace Database;
 
 TEST_F(DatabaseFixture, SingleRelease)
 {
+	{
+		auto transaction {session.createSharedTransaction()};
+
+		EXPECT_FALSE(Release::exists(session, 0));
+		EXPECT_FALSE(Release::exists(session, 1));
+	}
+
 	ScopedRelease release {session, "MyRelease"};
 
 	{
 		auto transaction {session.createSharedTransaction()};
 
+		EXPECT_TRUE(Release::exists(session, release.getId()));
+
 		auto releases {Release::getAllOrphans(session)};
 		ASSERT_EQ(releases.size(), 1);
 		EXPECT_EQ(releases.front()->getId(), release.getId());

src/libs/database/test/Track.cpp

@@ -28,6 +28,7 @@ TEST_F(DatabaseFixture, SingleTrack)
 	{
 		auto transaction {session.createSharedTransaction()};
 		EXPECT_EQ(Track::getCount(session), 0);
+		EXPECT_FALSE(Track::exists(session, 0));
 	}
 
 	ScopedTrack track {session, "MyTrackFile"};
@@ -37,6 +38,10 @@ TEST_F(DatabaseFixture, SingleTrack)
 
 		EXPECT_EQ(Track::getAll(session).size(), 1);
 		EXPECT_EQ(Track::getCount(session), 1);
+		EXPECT_TRUE(Track::exists(session, track.getId()));
+		auto myTrack {Track::getById(session, track.getId())};
+		ASSERT_TRUE(myTrack);
+		EXPECT_EQ(myTrack->getId(), track.getId());
 	}
 }
 

src/libs/recommendation/CMakeLists.txt

@@ -1,6 +1,6 @@
 
 add_library(lmsrecommendation SHARED
-	impl/clusters/ClustersClassifier.cpp
+	impl/clusters/ClustersEngine.cpp
 	impl/features/FeaturesEngineCache.cpp
 	impl/features/FeaturesEngine.cpp
 	impl/features/FeaturesDefs.cpp

src/libs/recommendation/impl/ClustersEngineCreator.hpp

@@ -21,10 +21,14 @@
 
 #include <memory>
 
-namespace Recommendation
+namespace Database
 {
-	class IClassifier;
-
-	std::unique_ptr<IClassifier> createClustersClassifier();
+	class Db;
+}
+
+namespace Recommendation
+{
+	class IEngine;
+	std::unique_ptr<IEngine> createClustersEngine(Database::Db& db);
 }
 

src/libs/recommendation/impl/Engine.cpp

@@ -22,7 +22,7 @@
 #include <unordered_map>
 #include <vector>
 
-#include "ClustersClassifierCreator.hpp"
+#include "ClustersEngineCreator.hpp"
 #include "FeaturesEngineCreator.hpp"
 
 #include "database/Db.hpp"
@@ -31,260 +31,229 @@
 #include "utils/Exception.hpp"
 #include "utils/Logger.hpp"
 
-namespace Recommendation {
-
-
-static
-std::unique_ptr<IClassifier>
-createClassifier(ClassifierType type)
+namespace Recommendation
 {
-	switch (type)
+
+	static
+	std::string_view
+	engineTypeToString(EngineType engineType)
 	{
-		case ClassifierType::Clusters:
-			return createClustersClassifier();
-			break;
-
-		case ClassifierType::Features:
-			return createFeaturesEngine();
-			break;
-	}
-
-	return {};
-}
-
-std::unique_ptr<IEngine>
-createEngine(Database::Db& db)
-{
-	return std::make_unique<Engine>(db);
-}
-
-Engine::Engine(Database::Db& db)
-: _db {db}
-{
-}
-
-Engine::TrackContainer
-Engine::getSimilarTracksFromTrackList(Database::Session& session, Database::TrackListId trackListId, std::size_t maxCount)
-{
-	TrackContainer res;
-
-	std::shared_lock lock {_classifiersMutex};
-	for (const auto& classifierName : _classifierPriorities)
-	{
-		auto itClassifier {_classifiers.find(classifierName)};
-		if (itClassifier == std::cend(_classifiers))
-			continue;
-
-		res = itClassifier->second->getSimilarTracksFromTrackList(session, trackListId, maxCount);
-		if (!res.empty())
-			break;
-	}
-
-	return res;
-}
-
-Engine::TrackContainer
-Engine::getSimilarTracks(Database::Session& dbSession, const std::vector<Database::TrackId>& trackIds, std::size_t maxCount)
-{
-	TrackContainer res;
-
-	std::shared_lock lock {_classifiersMutex};
-	for (ClassifierType classifierType : _classifierPriorities)
-	{
-		auto itClassifier {_classifiers.find(classifierType)};
-		if (itClassifier == std::cend(_classifiers))
-			continue;
-
-		const IClassifier& classifier {*itClassifier->second};
-		res = classifier.getSimilarTracks(dbSession, trackIds, maxCount);
-		if (!res.empty())
+		switch (engineType)
 		{
-			LMS_LOG(RECOMMENDATION, DEBUG) << "Got " << res.size() << " similar tracks using classifier '" << classifier.getName() << "'";
-			break;
+			case EngineType::Clusters: return "clusters";
+			case EngineType::Features: return "features";
+		}
+
+		throw LmsException {"Internal error"};
+	}
+
+	std::unique_ptr<IEngine>
+	createEngine(Database::Db& db)
+	{
+		return std::make_unique<Engine>(db);
+	}
+
+	Engine::Engine(Database::Db& db)
+		: _db {db}
+	{
+	}
+
+	Engine::TrackContainer
+	Engine::getSimilarTracksFromTrackList(Database::TrackListId trackListId, std::size_t maxCount) const
+	{
+		TrackContainer res;
+
+		std::shared_lock lock {_enginesMutex};
+		for (const auto& engineType : _enginePriorities)
+		{
+			auto itEngine {_engines.find(engineType)};
+			if (itEngine == std::cend(_engines))
+				continue;
+
+			res = itEngine->second->getSimilarTracksFromTrackList(trackListId, maxCount);
+			if (!res.empty())
+				break;
+		}
+
+		return res;
+	}
+
+	Engine::TrackContainer
+	Engine::getSimilarTracks(const std::vector<Database::TrackId>& trackIds, std::size_t maxCount) const
+	{
+		TrackContainer res;
+
+		std::shared_lock lock {_enginesMutex};
+		for (EngineType engineType : _enginePriorities)
+		{
+			auto itEngine {_engines.find(engineType)};
+			if (itEngine == std::cend(_engines))
+				continue;
+
+			const IEngine& engine {*itEngine->second};
+			res = engine.getSimilarTracks(trackIds, maxCount);
+			if (!res.empty())
+			{
+				LMS_LOG(RECOMMENDATION, DEBUG) << "Got " << res.size() << " similar tracks using engine '" << engineTypeToString(engineType) << "'";
+				break;
+			}
+		}
+
+		return res;
+	}
+
+	Engine::ReleaseContainer
+	Engine::getSimilarReleases(Database::ReleaseId releaseId, std::size_t maxCount) const
+	{
+		ReleaseContainer res;
+
+		std::shared_lock lock {_enginesMutex};
+		for (EngineType engineType : _enginePriorities)
+		{
+			auto itEngine {_engines.find(engineType)};
+			if (itEngine == std::cend(_engines))
+				continue;
+
+			const IEngine& engine {*itEngine->second};
+			res = engine.getSimilarReleases(releaseId, maxCount);
+			if (!res.empty())
+			{
+				LMS_LOG(RECOMMENDATION, DEBUG) << "Got " << res.size() << " similar releases using engine '" << engineTypeToString(engineType) << "'";
+				break;
+			}
+
+			LMS_LOG(RECOMMENDATION, DEBUG) << "No result using engine '" << engineTypeToString(engineType) << "'";
+		}
+
+		return res;
+	}
+
+	Engine::ArtistContainer
+	Engine::getSimilarArtists(Database::ArtistId artistId, EnumSet<Database::TrackArtistLinkType> linkTypes, std::size_t maxCount) const
+	{
+		ArtistContainer res;
+
+		std::shared_lock lock {_enginesMutex};
+		for (EngineType engineType : _enginePriorities)
+		{
+			auto itEngine {_engines.find(engineType)};
+			if (itEngine == std::cend(_engines))
+				continue;
+
+			const IEngine& engine {*itEngine->second};
+			res = engine.getSimilarArtists(artistId, linkTypes, maxCount);
+			if (!res.empty())
+			{
+				LMS_LOG(RECOMMENDATION, DEBUG) << "Got " << res.size() << " similar artists using engine '" << engineTypeToString(engineType) << "'";
+				return res;
+			}
+		}
+
+		return res;
+	}
+
+	static
+	Database::ScanSettings::RecommendationEngineType
+	getRecommendationEngineType(Database::Session& session)
+	{
+		auto transaction {session.createSharedTransaction()};
+
+		return Database::ScanSettings::get(session)->getRecommendationEngineType();
+	}
+
+	void
+	Engine::load(bool forceReload, const ProgressCallback& progressCallback)
+	{
+		using namespace Database;
+
+		LMS_LOG(RECOMMENDATION, INFO) << "Reloading recommendation engines...";
+
+		EngineContainer enginesToLoad;
+
+		{
+			std::unique_lock controlLock {_controlMutex};
+
+			{
+				std::unique_lock lock {_enginesMutex};
+				_engines.clear();
+			}
+
+			switch (getRecommendationEngineType(_db.getTLSSession()))
+			{
+				case ScanSettings::RecommendationEngineType::Clusters:
+					_enginePriorities = {EngineType::Clusters};
+					enginesToLoad.try_emplace(EngineType::Clusters, createClustersEngine(_db));
+					break;
+
+				case ScanSettings::RecommendationEngineType::Features:
+					_enginePriorities = {EngineType::Features, EngineType::Clusters};
+
+					// not same order since clusters is faster to load
+					enginesToLoad.try_emplace(EngineType::Clusters, createClustersEngine(_db));
+					enginesToLoad.try_emplace(EngineType::Features, createFeaturesEngine(_db));
+					break;
+			}
+
+			assert(_pendingEngines.empty());
+			for (auto& [engineType, engine] : enginesToLoad)
+				_pendingEngines.push_back(engine.get());
+		}
+
+		for (auto& [engineType, engine] : enginesToLoad)
+			loadPendingEngine(engineType, std::move(engine), forceReload, progressCallback);
+
+		_pendingEnginesCondvar.notify_all();
+
+		LMS_LOG(RECOMMENDATION, INFO) << "Recommendation engines loaded!";
+	}
+
+	void
+	Engine::loadPendingEngine(EngineType engineType, std::unique_ptr<IEngine> engine, bool forceReload, const ProgressCallback& progressCallback)
+	{
+		if (!_loadCancelled)
+		{
+			LMS_LOG(RECOMMENDATION, INFO) << "Initializing engine '" << engineTypeToString(engineType) << "'...";
+
+			auto progress {[&](const IEngine::Progress& progress)
+			{
+				progressCallback(progress);
+			}};
+
+			engine->load(forceReload, progressCallback ? progress : IEngine::ProgressCallback {});
+
+			{
+				std::scoped_lock lock {_controlMutex};
+				_pendingEngines.erase(std::find(std::begin(_pendingEngines), std::end(_pendingEngines), engine.get()));
+			}
+			LMS_LOG(RECOMMENDATION, INFO) << "Initializing engine '" << engineTypeToString(engineType) << "': " << (_loadCancelled ? "aborted" : "complete");
+		}
+
+		if (!_loadCancelled)
+		{
+			std::unique_lock lock {_enginesMutex};
+			_engines.emplace(engineType, std::move(engine));
 		}
 	}
 
-	return res;
-}
-
-Engine::ReleaseContainer
-Engine::getSimilarReleases(Database::Session& dbSession, Database::ReleaseId releaseId, std::size_t maxCount)
-{
-	ReleaseContainer res;
-
-	std::shared_lock lock {_classifiersMutex};
-	for (ClassifierType classifierType : _classifierPriorities)
+	void
+	Engine::cancelLoad()
 	{
-		auto itClassifier {_classifiers.find(classifierType)};
-		if (itClassifier == std::cend(_classifiers))
-			continue;
+		LMS_LOG(RECOMMENDATION, DEBUG) << "Cancelling loading...";
 
-		const IClassifier& classifier {*itClassifier->second};
-		res = classifier.getSimilarReleases(dbSession, releaseId, maxCount);
-		if (!res.empty())
-		{
-			LMS_LOG(RECOMMENDATION, DEBUG) << "Got " << res.size() << " similar releases using classifier '" << classifier.getName() << "'";
-			break;
-		}
+		std::unique_lock controlLock {_controlMutex};
+
+		assert(!_loadCancelled);
+		_loadCancelled = true;
+
+		LMS_LOG(RECOMMENDATION, DEBUG) << "Still " <<  _pendingEngines.size() << " pending engines!";
+
+		for (IEngine* engine : _pendingEngines)
+			engine->requestCancelLoad();
+
+		_pendingEnginesCondvar.wait(controlLock, [this] {return _pendingEngines.empty();});
+		_loadCancelled = false;
+
+		LMS_LOG(RECOMMENDATION, DEBUG) << "Cancelling loading DONE";
 	}
 
-	return res;
-}
-
-Engine::ArtistContainer
-Engine::getSimilarArtists(Database::Session& dbSession, Database::ArtistId artistId, EnumSet<Database::TrackArtistLinkType> linkTypes, std::size_t maxCount)
-{
-	ArtistContainer res;
-
-	std::shared_lock lock {_classifiersMutex};
-	for (ClassifierType classifierType : _classifierPriorities)
-	{
-		auto itClassifier {_classifiers.find(classifierType)};
-		if (itClassifier == std::cend(_classifiers))
-			continue;
-
-		const IClassifier& classifier {*itClassifier->second};
-		res = classifier.getSimilarArtists(dbSession, artistId, linkTypes, maxCount);
-		if (!res.empty())
-		{
-			LMS_LOG(RECOMMENDATION, DEBUG) << "Got " << res.size() << " similar artists using classifier '" << classifier.getName() << "'";
-			return res;
-		}
-	}
-
-	return res;
-}
-
-static
-Database::ScanSettings::RecommendationEngineType
-getRecommendationEngineType(Database::Session& session)
-{
-	auto transaction {session.createSharedTransaction()};
-
-	return Database::ScanSettings::get(session)->getRecommendationEngineType();
-}
-
-void
-Engine::load(bool forceReload, const ProgressCallback& progressCallback)
-{
-	using namespace Database;
-
-	LMS_LOG(RECOMMENDATION, INFO) << "Reloading recommendation engines...";
-	struct ClassifierWithType
-	{
-		ClassifierType type;
-		std::unique_ptr<IClassifier> classifier;
-	};
-
-	std::vector<ClassifierWithType> classifiers;
-	auto addClassifier {[&](ClassifierType type)
-	{
-		classifiers.emplace_back(ClassifierWithType {type, createClassifier(type)});
-	}};
-
-	switch (getRecommendationEngineType(_db.getTLSSession()))
-	{
-		case ScanSettings::RecommendationEngineType::Clusters:
-			setClassifierPriorities({ClassifierType::Clusters});
-			addClassifier(ClassifierType::Clusters);
-			break;
-		case ScanSettings::RecommendationEngineType::Features:
-			setClassifierPriorities({ClassifierType::Features, ClassifierType::Clusters});
-			// not same order since clusters is faster to load
-			addClassifier(ClassifierType::Clusters);
-			addClassifier(ClassifierType::Features);
-			break;
-	}
-
-	assert(_pendingClassifiers.empty());
-	clearClassifiers();
-
-	{
-		std::scoped_lock lock {_controlMutex};
-
-		std::transform(std::cbegin(classifiers), std::cend(classifiers), std::inserter(_pendingClassifiers, std::end(_pendingClassifiers)),
-				[](auto& classifier) { return classifier.classifier.get(); });
-	}
-
-	for (ClassifierWithType& classifier : classifiers)
-		loadClassifier(std::move(classifier.classifier), classifier.type, forceReload, progressCallback);
-
-	LMS_LOG(RECOMMENDATION, INFO) << "Recommendation engines loaded!";
-}
-
-void
-Engine::setClassifierPriorities(const std::vector<ClassifierType>& classifierPriorities)
-{
-	std::unique_lock<std::shared_mutex> lock {_classifiersMutex};
-
-	_classifierPriorities = classifierPriorities;
-}
-
-void
-Engine::clearClassifiers()
-{
-	std::unique_lock lock {_classifiersMutex};
-
-	_classifiers.clear();
-}
-
-void
-Engine::loadClassifier(std::unique_ptr<IClassifier> classifier,
-		ClassifierType classifierType,
-		bool forceReload,
-		const ProgressCallback& progressCallback)
-{
-	IClassifier* rawClassifier {classifier.get()};
-
-	bool res {};
-	if (!_loadCancelled)
-	{
-		LMS_LOG(RECOMMENDATION, INFO) << "Initializing classifier '" << classifier->getName() << "'...";
-
-		auto progress {[&](IClassifier::Progress progress)
-		{
-			progressCallback(Progress {progress.processedElems, progress.totalElems});
-		}};
-
-		res = classifier->load(_db.getTLSSession(), forceReload, progressCallback ? progress : IClassifier::ProgressCallback {});
-
-		LMS_LOG(RECOMMENDATION, INFO) << "Initializing classifier '" << classifier->getName() << "': " << (res ? "SUCCESS" : "FAILURE");
-	}
-
-	if (res)
-	{
-		std::unique_lock lock {_classifiersMutex};
-
-		_classifiers.emplace(classifierType, std::move(classifier));
-	}
-
-	{
-		std::scoped_lock lock {_controlMutex};
-
-		_pendingClassifiers.erase(rawClassifier);
-	}
-
-	_pendingClassifiersCondvar.notify_one();
-}
-
-void
-Engine::cancelLoad()
-{
-	LMS_LOG(RECOMMENDATION, DEBUG) << "Cancelling loading...";
-
-	std::unique_lock lock {_controlMutex};
-
-	LMS_LOG(RECOMMENDATION, DEBUG) << "Still " <<  _pendingClassifiers.size() << " pending classifiers!";
-
-	_loadCancelled = true;
-
-	for (IClassifier* classifier : _pendingClassifiers)
-		classifier->requestCancelLoad();
-
-    _pendingClassifiersCondvar.wait(lock, [this] {return _pendingClassifiers.empty();});
-	_loadCancelled = false;
-
-	LMS_LOG(RECOMMENDATION, DEBUG) << "Cancelling loading DONE";
-}
-
 } // ns Similarity

src/libs/recommendation/impl/Engine.hpp

@@ -20,13 +20,12 @@
 #pragma once
 
 #include <condition_variable>
+#include <mutex>
 #include <shared_mutex>
 #include <unordered_map>
-#include <unordered_set>
 #include <vector>
 
 #include "recommendation/IEngine.hpp"
-#include "IClassifier.hpp"
 
 namespace Database
 {
@@ -35,7 +34,7 @@ namespace Database
 
 namespace Recommendation
 {
-	enum class ClassifierType
+	enum class EngineType
 	{
 		Clusters,
 		Features,
@@ -57,29 +56,29 @@ namespace Recommendation
 			void	cancelLoad() override;
 			void	requestCancelLoad() override {};
 
-			ResultContainer<Database::TrackId> getSimilarTracksFromTrackList(Database::Session& session, Database::TrackListId tracklistId, std::size_t maxCount) override;
-			ResultContainer<Database::TrackId> getSimilarTracks(Database::Session& session, const std::vector<Database::TrackId>& tracksId, std::size_t maxCount) override;
-			ResultContainer<Database::ReleaseId> getSimilarReleases(Database::Session& session, Database::ReleaseId releaseId, std::size_t maxCount) override;
-			ResultContainer<Database::ArtistId> getSimilarArtists(Database::Session& session,
-					Database::ArtistId artistId,
-					EnumSet<Database::TrackArtistLinkType> linkTypes,
-					std::size_t maxCount) override;
+			TrackContainer getSimilarTracksFromTrackList(Database::TrackListId tracklistId, std::size_t maxCount) const override;
+			TrackContainer getSimilarTracks(const std::vector<Database::TrackId>& tracksId, std::size_t maxCount) const override;
+			ReleaseContainer getSimilarReleases(Database::ReleaseId releaseId, std::size_t maxCount) const override;
+			ArtistContainer getSimilarArtists(Database::ArtistId artistId, EnumSet<Database::TrackArtistLinkType> linkTypes, std::size_t maxCount) const override;
 
-			void setClassifierPriorities(const std::vector<ClassifierType>& classifierTypes);
-			void clearClassifiers();
-			void loadClassifier(std::unique_ptr<IClassifier> classifier, ClassifierType classifierType, bool forceReload, const ProgressCallback& progressCallback);
+			void setEnginePriorities(const std::vector<EngineType>& engineTypes);
+			void clearEngines();
+			void loadPendingEngine(EngineType engineType, std::unique_ptr<IEngine> engine, bool forceReload, const ProgressCallback& progressCallback);
 
 			Database::Db&				_db;
 
-			std::mutex							_controlMutex;
-			bool								_loadCancelled {};
-			std::condition_variable 			_pendingClassifiersCondvar;
-			std::unordered_set<IClassifier*>	_pendingClassifiers;
+			std::mutex					_controlMutex;
+			bool						_loadCancelled {};
 
-			std::shared_mutex			_classifiersMutex;
-			using ClassifierContainer = std::unordered_map<ClassifierType, std::unique_ptr<IClassifier>>;
-			ClassifierContainer			_classifiers;
-			std::vector<ClassifierType>	_classifierPriorities; // ordered by priority
+			using EngineContainer = std::unordered_map<EngineType, std::unique_ptr<IEngine>>;
+			EngineContainer				_engines;
+			mutable std::shared_mutex	_enginesMutex;
+
+			std::vector<IEngine*>		_pendingEngines;
+			std::shared_mutex			_pendingEnginesMutex;
+			std::condition_variable 	_pendingEnginesCondvar;
+
+			std::vector<EngineType>		_enginePriorities; // ordered by priority
 	};
 
 } // ns Recommendation

src/libs/recommendation/impl/FeaturesEngineCreator.hpp

@@ -20,10 +20,15 @@
 #pragma once
 
 #include <memory>
-#include "IClassifier.hpp"
+#include "recommendation/IEngine.hpp"
+
+namespace Database
+{
+	class Db;
+}
 
 namespace Recommendation
 {
-	std::unique_ptr<IClassifier> createFeaturesEngine();
+	std::unique_ptr<IEngine> createFeaturesEngine(Database::Db& db);
 }
 

src/libs/recommendation/impl/IClassifier.hpp

@@ -1,65 +0,0 @@
-/*
- * Copyright (C) 2020 Emeric Poupon
- *
- * This file is part of LMS.
- *
- * LMS is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * LMS is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with LMS.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-#pragma once
-
-#include <functional>
-#include <string_view>
-#include <vector>
-
-#include "database/Types.hpp"
-#include "recommendation/IRecommendation.hpp"
-#include "utils/EnumSet.hpp"
-
-namespace Database
-{
-	class Session;
-}
-
-namespace Recommendation
-{
-
-	class IClassifier : public IRecommendation
-	{
-		public:
-			virtual ~IClassifier() = default;
-
-			virtual std::string_view getName() const = 0;
-
-			struct Progress
-			{
-				std::size_t totalElems {};
-				std::size_t	processedElems {};
-			};
-			using ProgressCallback = std::function<void(const Progress&)>;
-			virtual bool load(Database::Session& session, bool forceReload, const ProgressCallback& progressCallback) = 0;
-			virtual void requestCancelLoad() = 0;
-
-			template <typename IdType>
-			using ResultContainer = std::vector<IdType>;
-
-			virtual ResultContainer<Database::TrackId> getSimilarTracksFromTrackList(Database::Session& session, Database::TrackListId tracklistId, std::size_t maxCount) const = 0;
-			virtual ResultContainer<Database::TrackId> getSimilarTracks(Database::Session& session, const std::vector<Database::TrackId>& tracksId, std::size_t maxCount) const = 0;
-			virtual ResultContainer<Database::ReleaseId> getSimilarReleases(Database::Session& session, Database::ReleaseId releaseId, std::size_t maxCount) const = 0;
-			virtual ResultContainer<Database::ArtistId> getSimilarArtists(Database::Session& session,
-					Database::ArtistId artistId,
-					EnumSet<Database::TrackArtistLinkType> linkTypes, std::size_t maxCount) const = 0;
-	};
-
-} // ns Recommendation

src/libs/recommendation/impl/clusters/ClustersClassifier.cpp

@@ -1,103 +0,0 @@
-/*
- * Copyright (C) 2018 Emeric Poupon
- *
- * This file is part of LMS.
- *
- * LMS is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * LMS is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with LMS.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-#include "ClustersClassifier.hpp"
-
-#include "database/Artist.hpp"
-#include "database/Cluster.hpp"
-#include "database/Release.hpp"
-#include "database/Session.hpp"
-#include "database/Track.hpp"
-#include "database/TrackList.hpp"
-
-namespace Recommendation {
-
-std::unique_ptr<IClassifier> createClustersClassifier()
-{
-	return std::make_unique<ClusterClassifier>();
-}
-
-IClassifier::ResultContainer<Database::TrackId>
-ClusterClassifier::getSimilarTracks(Database::Session& dbSession, const std::vector<Database::TrackId>& trackIds, std::size_t maxCount) const
-{
-	ResultContainer<Database::TrackId> res;
-
-	auto transaction {dbSession.createSharedTransaction()};
-
-	const auto tracks {Database::Track::getSimilarTracks(dbSession, trackIds, 0, maxCount)};
-	std::transform(std::cbegin(tracks), std::cend(tracks), std::back_inserter(res), [](const auto& track) { return track->getId(); });
-
-	return res;
-}
-
-IClassifier::ResultContainer<Database::TrackId>
-ClusterClassifier::getSimilarTracksFromTrackList(Database::Session& session, Database::TrackListId tracklistId, std::size_t maxCount) const
-{
-	ResultContainer<Database::TrackId> res;
-
-	auto transaction {session.createSharedTransaction()};
-
-	const Database::TrackList::pointer trackList {Database::TrackList::getById(session, tracklistId)};
-	if (!trackList)
-		return res;
-
-	const auto tracks {trackList->getSimilarTracks(0, maxCount)};
-	std::transform(std::cbegin(tracks), std::cend(tracks), std::back_inserter(res), [](const auto& track) { return track->getId(); });
-
-	return res;
-}
-
-IClassifier::ResultContainer<Database::ReleaseId>
-ClusterClassifier::getSimilarReleases(Database::Session& dbSession, Database::ReleaseId releaseId, std::size_t maxCount) const
-{
-	ResultContainer<Database::ReleaseId> res;
-
-	auto transaction {dbSession.createSharedTransaction()};
-
-	auto release {Database::Release::getById(dbSession, releaseId)};
-	if (!release)
-		return res;
-
-	const auto releases {release->getSimilarReleases(0, maxCount)};
-	std::transform(std::cbegin(releases), std::cend(releases), std::back_inserter(res), [](const auto& release) { return release->getId(); });
-
-	return res;
-}
-
-IClassifier::ResultContainer<Database::ArtistId>
-ClusterClassifier::getSimilarArtists(Database::Session& dbSession,
-		Database::ArtistId artistId,
-		EnumSet<Database::TrackArtistLinkType> artistLinkTypes,
-		std::size_t maxCount) const
-{
-	ResultContainer<Database::ArtistId> res;
-
-	auto transaction {dbSession.createSharedTransaction()};
-
-	auto artist {Database::Artist::getById(dbSession, artistId)};
-	if (!artist)
-		return res;
-
-	const auto artists {artist->getSimilarArtists(artistLinkTypes, Database::Range {0, maxCount})};
-	std::transform(std::cbegin(artists), std::cend(artists), std::back_inserter(res), [](const auto& artist) { return artist->getId(); });
-
-	return res;
-}
-
-} // namespace Recommendation

src/libs/recommendation/impl/clusters/ClustersClassifier.hpp

@@ -1,53 +0,0 @@
-/*
- * Copyright (C) 2018 Emeric Poupon
- *
- * This file is part of LMS.
- *
- * LMS is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * LMS is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with LMS.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-#pragma once
-
-#include "IClassifier.hpp"
-
-namespace Recommendation
-{
-
-	class ClusterClassifier : public IClassifier
-	{
-		public:
-			ClusterClassifier() = default;
-			ClusterClassifier(const ClusterClassifier&) = delete;
-			ClusterClassifier(ClusterClassifier&&) = delete;
-			ClusterClassifier& operator=(const ClusterClassifier&) = delete;
-			ClusterClassifier& operator=(ClusterClassifier&&) = delete;
-
-		private:
-
-			std::string_view getName() const override { return "Clusters"; }
-
-			bool load(Database::Session&, bool, const ProgressCallback&) override { return true; }
-			void requestCancelLoad() override {}
-
-			ResultContainer<Database::TrackId> getSimilarTracksFromTrackList(Database::Session& session, Database::TrackListId tracklistId, std::size_t maxCount) const override;
-			ResultContainer<Database::TrackId> getSimilarTracks(Database::Session& session, const std::vector<Database::TrackId>& tracksId, std::size_t maxCount) const override;
-			ResultContainer<Database::ReleaseId> getSimilarReleases(Database::Session& session, Database::ReleaseId releaseId, std::size_t maxCount) const override;
-			ResultContainer<Database::ArtistId> getSimilarArtists(Database::Session& session,
-					Database::ArtistId artistId,
-					EnumSet<Database::TrackArtistLinkType> linkTypes,
-					std::size_t maxCount) const override;
-};
-
-} // namespace Recommendation
-

src/libs/recommendation/impl/clusters/ClustersEngine.cpp

@@ -0,0 +1,119 @@
+/*
+ * Copyright (C) 2018 Emeric Poupon
+ *
+ * This file is part of LMS.
+ *
+ * LMS is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * LMS is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with LMS.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "ClustersEngine.hpp"
+
+#include "database/Artist.hpp"
+#include "database/Cluster.hpp"
+#include "database/Db.hpp"
+#include "database/Release.hpp"
+#include "database/Session.hpp"
+#include "database/Track.hpp"
+#include "database/TrackList.hpp"
+
+namespace Recommendation {
+
+std::unique_ptr<IEngine> createClustersEngine(Database::Db& db)
+{
+	return std::make_unique<ClusterEngine>(db);
+}
+
+IEngine::TrackContainer
+ClusterEngine::getSimilarTracks(const std::vector<Database::TrackId>& trackIds, std::size_t maxCount) const
+{
+	Database::Session& dbSession {_db.getTLSSession()};
+
+	TrackContainer res;
+
+	{
+		auto transaction {dbSession.createSharedTransaction()};
+
+		const auto tracks {Database::Track::getSimilarTracks(dbSession, trackIds, 0, maxCount)};
+		res.reserve(tracks.size());
+		std::transform(std::cbegin(tracks), std::cend(tracks), std::back_inserter(res), [](const auto& track) { return track->getId(); });
+	}
+
+	return res;
+}
+
+IEngine::ResultContainer<Database::TrackId>
+ClusterEngine::getSimilarTracksFromTrackList(Database::TrackListId tracklistId, std::size_t maxCount) const
+{
+	Database::Session& dbSession {_db.getTLSSession()};
+
+	TrackContainer res;
+
+	{
+		auto transaction {dbSession.createSharedTransaction()};
+
+		const Database::TrackList::pointer trackList {Database::TrackList::getById(dbSession, tracklistId)};
+		if (!trackList)
+			return res;
+
+		const auto tracks {trackList->getSimilarTracks(0, maxCount)};
+		res.reserve(tracks.size());
+		std::transform(std::cbegin(tracks), std::cend(tracks), std::back_inserter(res), [](const auto& track) { return track->getId(); });
+	}
+
+	return res;
+}
+
+IEngine::ResultContainer<Database::ReleaseId>
+ClusterEngine::getSimilarReleases(Database::ReleaseId releaseId, std::size_t maxCount) const
+{
+	Database::Session& dbSession {_db.getTLSSession()};
+
+	ReleaseContainer res;
+	{
+		auto transaction {dbSession.createSharedTransaction()};
+
+		auto release {Database::Release::getById(dbSession, releaseId)};
+		if (!release)
+			return res;
+
+		const auto releases {release->getSimilarReleases(0, maxCount)};
+		res.reserve(releases.size());
+		std::transform(std::cbegin(releases), std::cend(releases), std::back_inserter(res), [](const auto& release) { return release->getId(); });
+	}
+
+	return res;
+}
+
+IEngine::ResultContainer<Database::ArtistId>
+ClusterEngine::getSimilarArtists(Database::ArtistId artistId, EnumSet<Database::TrackArtistLinkType> artistLinkTypes, std::size_t maxCount) const
+{
+	Database::Session& dbSession {_db.getTLSSession()};
+
+	ResultContainer<Database::ArtistId> res;
+	{
+		auto transaction {dbSession.createSharedTransaction()};
+
+		auto artist {Database::Artist::getById(dbSession, artistId)};
+		if (!artist)
+			return res;
+
+		const auto artists {artist->getSimilarArtists(artistLinkTypes, Database::Range {0, maxCount})};
+		res.reserve(artists.size());
+		std::transform(std::cbegin(artists), std::cend(artists), std::back_inserter(res), [](const auto& artist) { return artist->getId(); });
+	}
+
+	return res;
+}
+
+} // namespace Recommendation

src/libs/recommendation/impl/clusters/ClustersEngine.hpp

@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2018 Emeric Poupon
+ *
+ * This file is part of LMS.
+ *
+ * LMS is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * LMS is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with LMS.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "recommendation/IEngine.hpp"
+
+namespace Recommendation
+{
+
+	class ClusterEngine : public IEngine
+	{
+		public:
+			ClusterEngine(Database::Db& db) : _db {db} {}
+
+			ClusterEngine(const ClusterEngine&) = delete;
+			ClusterEngine(ClusterEngine&&) = delete;
+			ClusterEngine& operator=(const ClusterEngine&) = delete;
+			ClusterEngine& operator=(ClusterEngine&&) = delete;
+
+		private:
+			void load(bool, const ProgressCallback&) override {}
+			void requestCancelLoad() override {}
+			void cancelLoad() {}
+
+			TrackContainer		getSimilarTracksFromTrackList(Database::TrackListId tracklistId, std::size_t maxCount) const override;
+			TrackContainer		getSimilarTracks(const std::vector<Database::TrackId>& tracksId, std::size_t maxCount) const override;
+			ReleaseContainer	getSimilarReleases(Database::ReleaseId releaseId, std::size_t maxCount) const override;
+			ArtistContainer		getSimilarArtists(Database::ArtistId artistId, EnumSet<Database::TrackArtistLinkType> linkTypes, std::size_t maxCount) const override;
+
+			Database::Db& _db;
+	};
+
+} // namespace Recommendation
+

src/libs/recommendation/impl/features/FeaturesEngine.cpp

@@ -22,6 +22,7 @@
 #include <numeric>
 
 #include "database/Artist.hpp"
+#include "database/Db.hpp"
 #include "database/Release.hpp"
 #include "database/Session.hpp"
 #include "database/Track.hpp"
@@ -35,9 +36,9 @@
 
 namespace Recommendation {
 
-std::unique_ptr<IClassifier> createFeaturesEngine()
+std::unique_ptr<IEngine> createFeaturesEngine(Database::Db& db)
 {
-	return std::make_unique<FeaturesEngine>();
+	return std::make_unique<FeaturesEngine>(db);
 }
 
 const FeatureSettingsMap&
@@ -127,8 +128,8 @@ getInputVectorWeights(const FeatureSettingsMap& featureSettingsMap, std::size_t
 	return weights;
 }
 
-bool
-FeaturesEngine::loadFromTraining(Database::Session& session, const TrainSettings& trainSettings, const ProgressCallback& progressCallback)
+void
+FeaturesEngine::loadFromTraining(const TrainSettings& trainSettings, const ProgressCallback& progressCallback)
 {
 	LMS_LOG(RECOMMENDATION, INFO) << "Constructing features classifier...";
 
@@ -141,6 +142,8 @@ FeaturesEngine::loadFromTraining(Database::Session& session, const TrainSettings
 
 	LMS_LOG(RECOMMENDATION, DEBUG) << "Features dimension = " << nbDimensions;
 
+	Database::Session& session {_db.getTLSSession()};
+
 	std::vector<Database::TrackId> trackIds;
 	{
 		auto transaction {session.createSharedTransaction()};
@@ -160,7 +163,7 @@ FeaturesEngine::loadFromTraining(Database::Session& session, const TrainSettings
 	for (Database::TrackId trackId : trackIds)
 	{
 		if (_loadCancelled)
-			return false;
+			return;
 
 		std::optional<FeatureValuesMap> featureValuesMap;
 
@@ -184,7 +187,7 @@ FeaturesEngine::loadFromTraining(Database::Session& session, const TrainSettings
 	if (samples.empty())
 	{
 		LMS_LOG(RECOMMENDATION, INFO) << "Nothing to classify!";
-		return false;
+		return;
 	}
 
 	LMS_LOG(RECOMMENDATION, DEBUG) << "Normalizing data...";
@@ -219,15 +222,13 @@ FeaturesEngine::loadFromTraining(Database::Session& session, const TrainSettings
 			[this] { return _loadCancelled; });
 	LMS_LOG(RECOMMENDATION, DEBUG) << "Training network DONE";
 
-	if (_loadCancelled)
-		return false;
 
 	LMS_LOG(RECOMMENDATION, DEBUG) << "Classifying tracks...";
 	TrackPositions trackPositions;
 	for (std::size_t i {}; i < samples.size(); ++i)
 	{
 		if (_loadCancelled)
-			return false;
+			return;
 
 		const SOM::Position position {network.getClosestRefVectorPosition(samples[i])};
 
@@ -236,23 +237,25 @@ FeaturesEngine::loadFromTraining(Database::Session& session, const TrainSettings
 
 	LMS_LOG(RECOMMENDATION, DEBUG) << "Classifying tracks DONE";
 
-	return load(session, std::move(network), std::move(trackPositions));
+	load(std::move(network), std::move(trackPositions));
 }
 
-bool
-FeaturesEngine::loadFromCache(Database::Session& session, const FeaturesEngineCache& cache)
+void
+FeaturesEngine::loadFromCache(FeaturesEngineCache cache)
 {
 	LMS_LOG(RECOMMENDATION, INFO) << "Constructing features classifier from cache...";
 
-	return load(session, std::move(cache._network), cache._trackPositions);
+	load(std::move(cache._network), cache._trackPositions);
 }
 
-IClassifier::ResultContainer<Database::TrackId>
-FeaturesEngine::getSimilarTracksFromTrackList(Database::Session& session, Database::TrackListId trackListId, std::size_t maxCount) const
+IEngine::TrackContainer
+FeaturesEngine::getSimilarTracksFromTrackList(Database::TrackListId trackListId, std::size_t maxCount) const
 {
-	const std::vector<Database::TrackId> trackIds {[&]
+	const TrackContainer trackIds {[&]
 	{
-		std::vector<Database::TrackId> res;
+		TrackContainer res;
+
+		Database::Session& session {_db.getTLSSession()};
 
 		auto transaction {session.createSharedTransaction()};
 
@@ -263,14 +266,16 @@ FeaturesEngine::getSimilarTracksFromTrackList(Database::Session& session, Databa
 		return res;
 	}()};
 
-	return getSimilarTracks(session, trackIds, maxCount);
+	return getSimilarTracks(trackIds, maxCount);
 }
 
-std::vector<Database::TrackId>
-FeaturesEngine::getSimilarTracks(Database::Session& session, const std::vector<Database::TrackId>& tracksIds, std::size_t maxCount) const
+IEngine::TrackContainer
+FeaturesEngine::getSimilarTracks(const std::vector<Database::TrackId>& tracksIds, std::size_t maxCount) const
 {
 	auto similarTrackIds {getSimilarObjects(tracksIds, _trackMatrix, _trackPositions, maxCount)};
 
+	Database::Session& session {_db.getTLSSession()};
+
 	{
 		// Report only existing ids, as tracks may have been removed a long time ago (refreshing the SOM takes some time)
 		auto transaction {session.createSharedTransaction()};
@@ -278,18 +283,21 @@ FeaturesEngine::getSimilarTracks(Database::Session& session, const std::vector<D
 		similarTrackIds.erase(std::remove_if(std::begin(similarTrackIds), std::end(similarTrackIds),
 			[&](Database::TrackId trackId)
 			{
-				return Database::Track::getById(session, trackId); // TODO exists
+				return !Database::Track::exists(session, trackId);
 			}), std::end(similarTrackIds));
 	}
 
 	return similarTrackIds;
 }
 
-std::vector<Database::ReleaseId>
-FeaturesEngine::getSimilarReleases(Database::Session& session, Database::ReleaseId releaseId, std::size_t maxCount) const
+IEngine::ReleaseContainer
+FeaturesEngine::getSimilarReleases(Database::ReleaseId releaseId, std::size_t maxCount) const
 {
-	auto similarReleaseIds {getSimilarObjects<Database::ReleaseId>({releaseId}, _releaseMatrix, _releasePositions, maxCount)};
+	auto similarReleaseIds {getSimilarObjects({releaseId}, _releaseMatrix, _releasePositions, maxCount)};
 
+	Database::Session& session {_db.getTLSSession()};
+
+	if (!similarReleaseIds.empty())
 	{
 		// Report only existing ids
 		auto transaction {session.createSharedTransaction()};
@@ -297,7 +305,7 @@ FeaturesEngine::getSimilarReleases(Database::Session& session, Database::Release
 		similarReleaseIds.erase(std::remove_if(std::begin(similarReleaseIds), std::end(similarReleaseIds),
 			[&](Database::ReleaseId releaseId)
 			{
-				return Database::Release::getById(session, releaseId); // TODO exists
+				return !Database::Release::exists(session, releaseId);
 			}), std::end(similarReleaseIds));
 	}
 
@@ -305,10 +313,7 @@ FeaturesEngine::getSimilarReleases(Database::Session& session, Database::Release
 }
 
 std::vector<Database::ArtistId>
-FeaturesEngine::getSimilarArtists(Database::Session& session,
-		Database::ArtistId artistId,
-		EnumSet<Database::TrackArtistLinkType> linkTypes,
-		std::size_t maxCount) const
+FeaturesEngine::getSimilarArtists(Database::ArtistId artistId, EnumSet<Database::TrackArtistLinkType> linkTypes, std::size_t maxCount) const
 {
 	auto getSimilarArtistIdsForLinkType {[&] (Database::TrackArtistLinkType linkType)
 	{
@@ -333,15 +338,16 @@ FeaturesEngine::getSimilarArtists(Database::Session& session,
 
 	std::vector<Database::ArtistId> res(std::cbegin(similarArtistIds), std::cend(similarArtistIds));
 
+	Database::Session& session {_db.getTLSSession()};
 	{
 		// Report only existing ids
 		auto transaction {session.createSharedTransaction()};
 
 		res.erase(std::remove_if(std::begin(res), std::end(res),
-				[&](Database::ArtistId artistId)
-				{
-					return Database::Artist::getById(session, artistId); // TODO exists
-				}), std::end(res));
+			[&](Database::ArtistId artistId)
+			{
+				return !Database::Artist::exists(session, artistId);
+			}), std::end(res));
 	}
 
 	while (res.size() > maxCount)
@@ -356,29 +362,25 @@ FeaturesEngine::toCache() const
 	return FeaturesEngineCache {*_network, _trackPositions};
 }
 
-bool
-FeaturesEngine::load(Database::Session& session, bool forceReload, const ProgressCallback& progressCallback)
+void
+FeaturesEngine::load(bool forceReload, const ProgressCallback& progressCallback)
 {
 	if (forceReload)
-
 	{
 		FeaturesEngineCache::invalidate();
 	}
-	else
+	else if (const std::optional<FeaturesEngineCache> cache {FeaturesEngineCache::read()})
 	{
-		const std::optional<FeaturesEngineCache> cache {FeaturesEngineCache::read()};
-		if (cache)
-			return loadFromCache(session, *cache);
+		loadFromCache(*cache);
+		return;
 	}
 
 	TrainSettings trainSettings;
 	trainSettings.featureSettingsMap = getDefaultTrainFeatureSettings();
 
-	const bool res {loadFromTraining(session, trainSettings, progressCallback)};
-	if (res)
+	loadFromTraining(trainSettings, progressCallback);
+	if (!_loadCancelled)
 		toCache().write();
-
-	return res;
 }
 
 void
@@ -388,10 +390,8 @@ FeaturesEngine::requestCancelLoad()
 	_loadCancelled = true;
 }
 
-bool
-FeaturesEngine::load(Database::Session& session,
-			SOM::Network network,
-			const TrackPositions& trackPositions)
+void
+FeaturesEngine::load(const SOM::Network& network, const TrackPositions& trackPositions)
 {
 	using namespace Database;
 
@@ -406,10 +406,12 @@ FeaturesEngine::load(Database::Session& session,
 
 	LMS_LOG(RECOMMENDATION, DEBUG) << "Constructing maps...";
 
+	Database::Session& session {_db.getTLSSession()};
+
 	for (const auto& [trackId, positions] : trackPositions)
 	{
 		if (_loadCancelled)
-			return false;
+			return;
 
 		auto transaction {session.createSharedTransaction()};
 
@@ -445,11 +447,9 @@ FeaturesEngine::load(Database::Session& session,
 		}
 	}
 
-	_network = std::make_unique<SOM::Network>(std::move(network));
+	_network = std::make_unique<SOM::Network>(network);
 
 	LMS_LOG(RECOMMENDATION, INFO) << "Classifier successfully loaded!";
-
-	return true;
 }
 
 } // ns Recommendation

src/libs/recommendation/impl/features/FeaturesEngine.hpp

@@ -26,12 +26,12 @@
 #include <string>
 #include <vector>
 
+#include "recommendation/IEngine.hpp"
 #include "som/DataNormalizer.hpp"
 #include "som/Network.hpp"
 #include "utils/Utils.hpp"
 #include "FeaturesEngineCache.hpp"
 #include "FeaturesDefs.hpp"
-#include "IClassifier.hpp"
 
 namespace Database
 {
@@ -42,10 +42,11 @@ namespace Recommendation {
 
 using FeatureWeight = double;
 
-class FeaturesEngine : public IClassifier
+class FeaturesEngine : public IEngine
 {
 	public:
-		FeaturesEngine() = default;
+		FeaturesEngine(Database::Db& db) : _db {db} {}
+
 		FeaturesEngine(const FeaturesEngine&) = delete;
 		FeaturesEngine(FeaturesEngine&&) = delete;
 		FeaturesEngine& operator=(const FeaturesEngine&) = delete;
@@ -59,21 +60,16 @@ class FeaturesEngine : public IClassifier
 		static const FeatureSettingsMap& getDefaultTrainFeatureSettings();
 
 	private:
-
-		std::string_view getName() const override { return "Features"; }
-
-		bool load(Database::Session& session, bool forceReload, const ProgressCallback& progressCallback) override;
+		void load(bool forceReload, const ProgressCallback& progressCallback) override;
 		void requestCancelLoad() override;
+		void cancelLoad() override {}
 
-		ResultContainer<Database::TrackId> getSimilarTracksFromTrackList(Database::Session& session, Database::TrackListId tracklistId, std::size_t maxCount) const override;
-		ResultContainer<Database::TrackId> getSimilarTracks(Database::Session& session, const std::vector<Database::TrackId>& tracksId, std::size_t maxCount) const override;
-		ResultContainer<Database::ReleaseId> getSimilarReleases(Database::Session& session, Database::ReleaseId releaseId, std::size_t maxCount) const override;
-		ResultContainer<Database::ArtistId> getSimilarArtists(Database::Session& session,
-				Database::ArtistId artistId,
-				EnumSet<Database::TrackArtistLinkType> linkTypes,
-				std::size_t maxCount) const override;
+		TrackContainer getSimilarTracksFromTrackList(Database::TrackListId tracklistId, std::size_t maxCount) const override;
+		TrackContainer getSimilarTracks(const std::vector<Database::TrackId>& tracksId, std::size_t maxCount) const override;
+		ReleaseContainer getSimilarReleases(Database::ReleaseId releaseId, std::size_t maxCount) const override;
+		ArtistContainer getSimilarArtists(Database::ArtistId artistId, EnumSet<Database::TrackArtistLinkType> linkTypes, std::size_t maxCount) const override;
 
-		bool loadFromCache(Database::Session& session, const FeaturesEngineCache& cache);
+		void loadFromCache(FeaturesEngineCache cache);
 
 		// Use training (may be very slow)
 		struct TrainSettings
@@ -82,7 +78,7 @@ class FeaturesEngine : public IClassifier
 			float sampleCountPerNeuron {4};
 			FeatureSettingsMap featureSettingsMap;
 		};
-		bool loadFromTraining(Database::Session& session, const TrainSettings& trainSettings, const ProgressCallback& progressCallback);
+		void loadFromTraining(const TrainSettings& trainSettings, const ProgressCallback& progressCallback);
 
 		template <typename IdType>
 		using ObjectPositions = std::unordered_map<IdType, std::vector<SOM::Position>>;
@@ -97,7 +93,7 @@ class FeaturesEngine : public IClassifier
 		using ReleaseMatrix = ObjectMatrix<Database::ReleaseId>;
 		using TrackMatrix = ObjectMatrix<Database::TrackId>;
 
-		bool load(Database::Session& session, SOM::Network network, const TrackPositions& tracksPosition);
+		void load(const SOM::Network& network, const TrackPositions& tracksPosition);
 
 		FeaturesEngineCache toCache() const;
 
@@ -113,6 +109,7 @@ class FeaturesEngine : public IClassifier
 				const ObjectPositions<IdType>& objectPositions,
 				std::size_t maxCount) const;
 
+		Database::Db&		_db;
 		bool				_loadCancelled {};
 		std::unique_ptr<SOM::Network>	_network;
 		double				_networkRefVectorsDistanceMedian {};

src/libs/recommendation/include/recommendation/IEngine.hpp

@@ -21,13 +21,13 @@
 
 #include <functional>
 #include <memory>
+#include <string_view>
 #include "database/Types.hpp"
 #include "utils/EnumSet.hpp"
 
 namespace Database
 {
 	class Db;
-	class Session;
 }
 
 namespace Recommendation
@@ -44,7 +44,8 @@ namespace Recommendation
 			};
 			using ProgressCallback = std::function<void(const Progress&)>;
 			virtual void load(bool forceReload, const ProgressCallback& progressCallback = {}) = 0;
-			virtual void cancelLoad() = 0;
+			virtual void cancelLoad() = 0;  // wait for cancel done
+			virtual void requestCancelLoad() = 0;
 
 			template <typename IdType>
 			using ResultContainer = std::vector<IdType>;
@@ -53,13 +54,10 @@ namespace Recommendation
 			using ReleaseContainer = ResultContainer<Database::ReleaseId>;
 			using TrackContainer = ResultContainer<Database::TrackId>;
 
-			virtual TrackContainer getSimilarTracksFromTrackList(Database::Session& session, Database::TrackListId tracklistId, std::size_t maxCount) = 0;
-			virtual TrackContainer getSimilarTracks(Database::Session& session, const std::vector<Database::TrackId>& tracksId, std::size_t maxCount) = 0;
-			virtual ReleaseContainer getSimilarReleases(Database::Session& session, Database::ReleaseId releaseId, std::size_t maxCount) = 0;
-			virtual ArtistContainer getSimilarArtists(Database::Session& session, Database::ArtistId artistId, EnumSet<Database::TrackArtistLinkType> linkTypes, std::size_t maxCount) = 0;
-
-		protected:
-			virtual void requestCancelLoad() = 0;
+			virtual TrackContainer getSimilarTracksFromTrackList(Database::TrackListId tracklistId, std::size_t maxCount) const = 0;
+			virtual TrackContainer getSimilarTracks(const std::vector<Database::TrackId>& tracksId, std::size_t maxCount) const = 0;
+			virtual ReleaseContainer getSimilarReleases(Database::ReleaseId releaseId, std::size_t maxCount) const = 0;
+			virtual ArtistContainer getSimilarArtists(Database::ArtistId artistId, EnumSet<Database::TrackArtistLinkType> linkTypes, std::size_t maxCount) const = 0;
 	};
 
 	std::unique_ptr<IEngine> createEngine(Database::Db& db);

src/libs/recommendation/include/recommendation/IRecommendation.hpp

@@ -1,38 +0,0 @@
-/*
- * Copyright (C) 2021 Emeric Poupon
- *
- * This file is part of LMS.
- *
- * LMS is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * LMS is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with LMS.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-#pragma once
-
-#include "database/Types.hpp"
-#include "utils/EnumSet.hpp"
-
-namespace Database
-{
-	class Db;
-	class Session;
-}
-
-namespace Recommendation
-{
-	class IRecommendation
-	{
-	};
-
-} // ns Recommendation
-

src/libs/scrobbling/impl/listenbrainz/FeedbackSynchronizer.hpp

@@ -0,0 +1,92 @@
+/*
+ * Copyright (C) 2021 Emeric Poupon
+ *
+ * This file is part of LMS.
+ *
+ * LMS is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * LMS is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with LMS.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/io_context_strand.hpp>
+#include <boost/asio/steady_timer.hpp>
+#include <Wt/Dbo/Dbo.h>
+
+#include "SendQueue.hpp"
+
+namespace Database
+{
+	class Db;
+	class Session;
+	class User;
+}
+
+namespace Scrobbling::ListenBrainz
+{
+	class ListensSynchronizer
+	{
+		public:
+			FeedbackSynchronizer(boost::asio::io_context& ioContext, Database::Db& db, SendQueue& sendQueue);
+
+			// void updateFeedback(const TimedListen& listen);
+
+		private:
+			struct UserContext
+			{
+				UserContext(Database::UserId id) : userId {id} {}
+
+				UserContext(const UserContext&) = delete;
+				UserContext(UserContext&&) = delete;
+				UserContext& operator=(const UserContext&) = delete;
+				UserContext& operator=(UserContext&&) = delete;
+
+				const Database::UserId	userId;
+				bool					fetching {};
+				std::optional<std::size_t> listenCount {};
+
+				// resetted at each fetch
+				std::string		listenBrainzUserName; // need to be resolved first
+				Wt::WDateTime	maxDateTime;
+				std::size_t		fetchedListenCount{};
+				std::size_t		matchedListenCount{};
+				std::size_t		importedListenCount{};
+			};
+
+			UserContext& getUserContext(Database::UserId userId);
+			bool isFetching() const;
+			void scheduleGetListens(std::chrono::seconds fromNow);
+			void startGetListens();
+			void startGetListens(UserContext& context);
+			void onGetListensEnded(UserContext& context);
+			void enqueValidateToken(UserContext& context);
+			void enqueGetListenCount(UserContext& context);
+			void enqueGetListens(UserContext& context);
+			std::optional<SendQueue::RequestData>	createValidateTokenRequestData(Database::UserId userId);
+			std::optional<SendQueue::RequestData>	createGetListensRequestData(std::string_view listenBrainzUserName, const Wt::WDateTime& maxDateTime);
+			void									processGetListensResponse(std::string_view body, UserContext& context);
+
+			boost::asio::io_context&		_ioContext;
+			boost::asio::io_context::strand	_strand {_ioContext};
+			Database::Db&					_db;
+			SendQueue&						_sendQueue;
+			boost::asio::steady_timer		_getListensTimer {_ioContext};
+
+			std::unordered_map<Database::UserId, UserContext> _userContexts;
+
+			const std::size_t			_maxSyncFeedbackCount;
+			const std::chrono::hours	_syncFeedbackPeriod;
+	};
+} // Scrobbling::ListenBrainz
+

src/libs/subsonic/impl/SubsonicResource.cpp

@@ -896,10 +896,7 @@ handleGetArtistInfoRequestCommon(RequestContext& context, bool id3)
 			artistInfoNode.createChild("musicBrainzId").setValue(artistMBID->getAsString());
 	}
 
-	auto similarArtistsId {Service<Recommendation::IEngine>::get()->getSimilarArtists(context.dbSession,
-			id,
-			{TrackArtistLinkType::Artist, TrackArtistLinkType::ReleaseArtist},
-			count)};
+	auto similarArtistsId {Service<Recommendation::IEngine>::get()->getSimilarArtists(id, {TrackArtistLinkType::Artist, TrackArtistLinkType::ReleaseArtist}, count)};
 
 	{
 		auto transaction {context.dbSession.createSharedTransaction()};
@@ -1135,10 +1132,7 @@ handleGetSimilarSongsRequestCommon(RequestContext& context, bool id3)
 	// Optional params
 	std::size_t count {getParameterAs<std::size_t>(context.parameters, "count").value_or(50)};
 
-	const auto similarArtistIds {Service<Recommendation::IEngine>::get()->getSimilarArtists(context.dbSession,
-			artistId,
-			{TrackArtistLinkType::Artist, TrackArtistLinkType::ReleaseArtist},
-			5)};
+	const auto similarArtistIds {Service<Recommendation::IEngine>::get()->getSimilarArtists(artistId, {TrackArtistLinkType::Artist, TrackArtistLinkType::ReleaseArtist}, 5)};
 
 	auto transaction {context.dbSession.createSharedTransaction()};
 

src/lms/ui/PlayQueue.cpp

@@ -520,7 +520,7 @@ PlayQueue::addEntry(const Database::TrackListEntry::pointer& tracklistEntry)
 void
 PlayQueue::enqueueRadioTracks()
 {
-	const auto similarTrackIds {Service<Recommendation::IEngine>::get()->getSimilarTracksFromTrackList(LmsApp->getDbSession(), _tracklistId, 3)};
+	const auto similarTrackIds {Service<Recommendation::IEngine>::get()->getSimilarTracksFromTrackList(_tracklistId, 3)};
 
 	std::vector<Database::TrackId> trackToAddIds(std::cbegin(similarTrackIds), std::cend(similarTrackIds));
 	Random::shuffleContainer(trackToAddIds);

src/lms/ui/explore/ArtistView.cpp

@@ -102,10 +102,7 @@ Artist::refreshView()
 	if (!artistId)
 		throw ArtistNotFoundException {};
 
-	const auto similarArtistIds {Service<Recommendation::IEngine>::get()->getSimilarArtists(LmsApp->getDbSession(),
-			*artistId,
-			{TrackArtistLinkType::Artist, TrackArtistLinkType::ReleaseArtist},
-			5)};
+	const auto similarArtistIds {Service<Recommendation::IEngine>::get()->getSimilarArtists(*artistId, {TrackArtistLinkType::Artist, TrackArtistLinkType::ReleaseArtist}, 5)};
 
     auto transaction {LmsApp->getDbSession().createSharedTransaction()};
 

src/lms/ui/explore/ReleaseView.cpp

@@ -101,7 +101,7 @@ Release::refreshView()
 	if (!releaseId)
 		throw ReleaseNotFoundException {};
 
-	auto similarReleasesIds {Service<Recommendation::IEngine>::get()->getSimilarReleases(LmsApp->getDbSession(), *releaseId, 6)};
+	auto similarReleasesIds {Service<Recommendation::IEngine>::get()->getSimilarReleases(*releaseId, 6)};
 
     auto transaction {LmsApp->getDbSession().createSharedTransaction()};
 

src/tools/recommendation/LmsRecommendation.cpp

@@ -66,7 +66,7 @@ dumpTracksRecommendation(Database::Session session, Recommendation::IEngine& eng
 		};
 
 		std::cout << "Processing track '" << trackToString(trackId) << std::endl;
-		for (Database::TrackId similarTrackId : engine.getSimilarTracks(session, {trackId}, maxSimilarityCount))
+		for (Database::TrackId similarTrackId : engine.getSimilarTracks({trackId}, maxSimilarityCount))
 			std::cout << "\t- Similar track '" << trackToString(similarTrackId) << std::endl;
 	}
 }
@@ -84,7 +84,7 @@ dumpReleasesRecommendation(Database::Session session, Recommendation::IEngine& e
 	std::cout << "*** Releases ***" << std::endl;
 	for (Database::ReleaseId releaseId : releaseIds)
 	{
-		auto releaseToString = [&](Database::ReleaseId releaseId)
+		auto releaseToString = [&](Database::ReleaseId releaseId) -> std::string
 		{
 			auto transaction {session.createSharedTransaction()};
 
@@ -93,7 +93,7 @@ dumpReleasesRecommendation(Database::Session session, Recommendation::IEngine& e
 		};
 
 		std::cout << "Processing release '" << releaseToString(releaseId) << "'" << std::endl;
-		for (Database::ReleaseId similarReleaseId : engine.getSimilarReleases(session, releaseId, maxSimilarityCount))
+		for (Database::ReleaseId similarReleaseId : engine.getSimilarReleases(releaseId, maxSimilarityCount))
 			std::cout << "\t- Similar release '" << releaseToString(similarReleaseId) << "'" << std::endl;
 	}
 }
@@ -120,7 +120,7 @@ dumpArtistsRecommendation(Database::Session session, Recommendation::IEngine& en
 		};
 
 		std::cout << "Processing artist '" << artistToString(artistId) << "'" << std::endl;
-		for (Database::ArtistId similarArtistId : engine.getSimilarArtists(session, artistId, {Database::TrackArtistLinkType::Artist, Database::TrackArtistLinkType::ReleaseArtist}, maxSimilarityCount))
+		for (Database::ArtistId similarArtistId : engine.getSimilarArtists(artistId, {Database::TrackArtistLinkType::Artist, Database::TrackArtistLinkType::ReleaseArtist}, maxSimilarityCount))
 		{
 			std::cout << "\t- Similar artist '" << artistToString(similarArtistId) << "'" << std::endl;
 		}