From 53b3429c74fb15880bf831f50c743e716e3d008f Mon Sep 17 00:00:00 2001
From: emeric <itmfr@yahoo.fr>
Date: Sun, 16 Feb 2020 16:33:38 +0100
Subject: [PATCH] Atomatically reload recommendation engines

---
 src/libs/recommendation/impl/Engine.cpp | 19 ++++++++++---------
 src/libs/recommendation/impl/Engine.hpp |  4 +++-
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/src/libs/recommendation/impl/Engine.cpp b/src/libs/recommendation/impl/Engine.cpp
index 5b3d818f..2a4aa772 100644
--- a/src/libs/recommendation/impl/Engine.cpp
+++ b/src/libs/recommendation/impl/Engine.cpp
@@ -148,7 +148,7 @@ Engine::reload()
 {
 	using namespace Database;
 
-	LMS_LOG(RECOMMENDATION, DEBUG) << "Reloading recommendation engines...";
+	LMS_LOG(RECOMMENDATION, INFO) << "Reloading recommendation engines...";
 
 	const ScanSettings::RecommendationEngineType engineType {[&]()
 	{
@@ -157,21 +157,25 @@ Engine::reload()
 		return ScanSettings::get(_dbSession)->getRecommendationEngineType();
 	}()};
 
-	// TODO: just replace the classifier once it is ready
-	clearClassifiers();
+	std::map<ClassifierPriority, std::unique_ptr<IClassifier>> newClassifiers;
 
 	switch (engineType)
 	{
 		case ScanSettings::RecommendationEngineType::Features:
-//			addClassifier(createFeaturesClassifier(), 0); // higher priority
+//			newClassifiers.emplace_back(0, createFeaturesClassifier()); // higher priority
 //			[[fallthrough]];
 
 		case ScanSettings::RecommendationEngineType::Clusters:
-			addClassifier(createClustersClassifier(_dbSession), 1); // lower priority
+			newClassifiers.emplace(1, createClustersClassifier(_dbSession)); // lower priority
 			break;
 	}
 
-	LMS_LOG(RECOMMENDATION, DEBUG) << "Recommendation engines reloaded!";
+	{
+		std::unique_lock lock {_classifiersMutex};
+		_classifiers.swap(newClassifiers);
+	}
+
+	LMS_LOG(RECOMMENDATION, INFO) << "Recommendation engines reloaded!";
 
 	_sigReloaded.emit();
 }
@@ -180,9 +184,6 @@ Engine::reload()
 void
 Engine::clearClassifiers()
 {
-	std::unique_lock lock {_classifiersMutex};
-
-	_classifiers.clear();
 }
 
 void
diff --git a/src/libs/recommendation/impl/Engine.hpp b/src/libs/recommendation/impl/Engine.hpp
index bc6eea96..9fde430e 100644
--- a/src/libs/recommendation/impl/Engine.hpp
+++ b/src/libs/recommendation/impl/Engine.hpp
@@ -37,6 +37,8 @@ namespace Recommendation
 
 		private:
 
+			using ClassifierPriority = unsigned;
+
 			void start() override;
 			void stop() override;
 
@@ -59,7 +61,7 @@ namespace Recommendation
 			Wt::Signal<>		_sigReloaded;
 
 			std::shared_mutex	_classifiersMutex;
-			std::map<unsigned, std::unique_ptr<IClassifier>> _classifiers;
+			std::map<ClassifierPriority, std::unique_ptr<IClassifier>> _classifiers;
 	};
 
 } // ns Recommendation