Bring more diversity in the radio mode. fixes #54

2022-10-19 13:56:32 +02:00
parent b85553af34
commit c816b0db45
21 changed files with 750 additions and 104 deletions
@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2022 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 "PlaylistGeneratorService.hpp"
+
+#include "services/database/Db.hpp"
+#include "services/database/Session.hpp"
+#include "services/database/Track.hpp"
+#include "services/recommendation/IRecommendationService.hpp"
+#include "playlist-constraints/ConsecutiveArtists.hpp"
+#include "playlist-constraints/ConsecutiveReleases.hpp"
+#include "playlist-constraints/DuplicateTracks.hpp"
+#include "utils/Logger.hpp"
+
+namespace Recommendation
+{
+	using namespace Database;
+
+	std::unique_ptr<IPlaylistGeneratorService>
+	createPlaylistGeneratorService(Db& db, Recommendation::IRecommendationService& recommendationService)
+	{
+		return std::make_unique<PlaylistGeneratorService>(db, recommendationService);
+	}
+
+	PlaylistGeneratorService::PlaylistGeneratorService(Db& db, Recommendation::IRecommendationService& recommendationService)
+		: _db {db}
+	, _recommendationService {recommendationService}
+	{
+		_constraints.push_back(std::make_unique<PlaylistGeneratorConstraint::ConsecutiveArtists>(_db));
+		_constraints.push_back(std::make_unique<PlaylistGeneratorConstraint::ConsecutiveReleases>(_db));
+		_constraints.push_back(std::make_unique<PlaylistGeneratorConstraint::DuplicateTracks>());
+	}
+
+	std::vector<TrackId>
+	PlaylistGeneratorService::extendPlaylist(TrackListId tracklistId, std::size_t maxCount) const
+	{
+		LMS_LOG(RECOMMENDATION, DEBUG) << "Requested to extend playlist by " << maxCount << " similar tracks";
+
+		// supposed to be ordered from most similar to least similar
+		std::vector<TrackId> similarTracks {_recommendationService.findSimilarTracks(tracklistId, maxCount * 2)}; // ask for more tracks than we need as it will be easier to respect constraints
+
+		const std::vector<TrackId> startingTracks {getTracksFromTrackList(tracklistId)};
+
+		std::vector<TrackId> finalResult = startingTracks;
+		finalResult.reserve(startingTracks.size() + maxCount);
+
+		std::vector<float> scores;
+		for (std::size_t i {}; i < maxCount; ++i)
+		{
+			if (similarTracks.empty())
+				break;
+
+			scores.resize(similarTracks.size(), {});
+
+			// select the similar track that has the best score
+			for (std::size_t trackIndex {}; trackIndex < similarTracks.size(); ++trackIndex)
+			{
+				using namespace Database::Debug;
+
+				finalResult.push_back(similarTracks[trackIndex]);
+
+				scores[trackIndex] = 0;
+				for (const auto& constraint : _constraints)
+					scores[trackIndex] += constraint->computeScore(finalResult, finalResult.size() - 1);
+
+				finalResult.pop_back();
+
+				// early exit if we consider we found a track with no constraint violation (since similarTracks sorted from most to least similar)
+				if (scores[trackIndex] < 0.01)
+					break;
+			}
+
+			// get the best score
+			const std::size_t bestScoreIndex {static_cast<std::size_t>(std::distance(std::cbegin(scores), std::min_element(std::cbegin(scores), std::cend(scores))))};
+
+			finalResult.push_back(similarTracks[bestScoreIndex]);
+			similarTracks.erase(std::begin(similarTracks) + bestScoreIndex);
+		}
+
+		// for now, just get some more similar tracks
+		return std::vector(std::cbegin(finalResult) + startingTracks.size(), std::cend(finalResult));
+	}
+
+	TrackContainer
+	PlaylistGeneratorService::getTracksFromTrackList(Database::TrackListId tracklistId) const
+	{
+		TrackContainer tracks;
+
+		Session& dbSession {_db.getTLSSession()};
+		auto transaction {dbSession.createSharedTransaction()};
+
+		Track::FindParameters params;
+		params.setTrackList(tracklistId);
+		params.setSortMethod(TrackSortMethod::TrackList);
+		params.setDistinct(false);
+
+		for (const TrackId trackId : Track::find(dbSession, params).results)
+			tracks.push_back(trackId);
+
+		return tracks;
+	}
+}