Corrected multithreading issue

src/main/main.cpp

@@ -122,7 +122,7 @@ int main(int argc, char* argv[])
 		// Initializing a connection pool to the database that will be shared along services
 		auto connectionPool = Database::Handler::createConnectionPool(Config::instance().getPath("working-dir") / "lms.db");
 
-		UserInterface::LmsApplicationGroups appGroups;
+		UserInterface::LmsApplicationGroupContainer appGroups;
 		Scanner::MediaScanner scanner(*connectionPool);
 
 		// bind entry point

src/ui/LmsApplication.cpp

@@ -50,7 +50,7 @@
 namespace UserInterface {
 
 std::unique_ptr<Wt::WApplication>
-LmsApplication::create(const Wt::WEnvironment& env, Wt::Dbo::SqlConnectionPool& connectionPool, LmsApplicationGroups& appGroups, Scanner::MediaScanner& scanner)
+LmsApplication::create(const Wt::WEnvironment& env, Wt::Dbo::SqlConnectionPool& connectionPool, LmsApplicationGroupContainer& appGroups, Scanner::MediaScanner& scanner)
 {
 	/*
 	 * You could read information from the environment to decide whether
@@ -71,7 +71,7 @@ LmsApplication::instance()
  * constructor so it is typically also an argument for your custom
  * application constructor.
 */
-LmsApplication::LmsApplication(const Wt::WEnvironment& env, Wt::Dbo::SqlConnectionPool& connectionPool, LmsApplicationGroups& appGroups, Scanner::MediaScanner& scanner)
+LmsApplication::LmsApplication(const Wt::WEnvironment& env, Wt::Dbo::SqlConnectionPool& connectionPool, LmsApplicationGroupContainer& appGroups, Scanner::MediaScanner& scanner)
 : Wt::WApplication(env),
   _db(connectionPool),
   _appGroups(appGroups),
@@ -254,7 +254,7 @@ handlePathChange(Wt::WStackedWidget* stack, bool isAdmin)
 LmsApplicationGroup&
 LmsApplication::getApplicationGroup()
 {
-	return _appGroups[_userIdentity];
+	return _appGroups.get(_userIdentity);
 }
 
 void

src/ui/LmsApplication.hpp

@@ -47,11 +47,11 @@ struct GroupEvents
 class LmsApplication : public Wt::WApplication
 {
 	public:
-		LmsApplication(const Wt::WEnvironment& env, Wt::Dbo::SqlConnectionPool& connectionPool, LmsApplicationGroups& appGroups, Scanner::MediaScanner& scanner);
+		LmsApplication(const Wt::WEnvironment& env, Wt::Dbo::SqlConnectionPool& connectionPool, LmsApplicationGroupContainer& appGroups, Scanner::MediaScanner& scanner);
 		~LmsApplication();
 
 		static std::unique_ptr<Wt::WApplication> create(const Wt::WEnvironment& env,
-				Wt::Dbo::SqlConnectionPool& connectionPool, LmsApplicationGroups& appGroups, Scanner::MediaScanner& scanner);
+				Wt::Dbo::SqlConnectionPool& connectionPool, LmsApplicationGroupContainer& appGroups, Scanner::MediaScanner& scanner);
 		static LmsApplication* instance();
 
 		// Session application data
@@ -88,7 +88,7 @@ class LmsApplication : public Wt::WApplication
 		void createHome();
 
 		Database::Handler	_db;
-		LmsApplicationGroups&   _appGroups;
+		LmsApplicationGroupContainer&   _appGroups;
 		GroupEvents		_groupEvents;
 		Wt::WString		_userIdentity;
 		Auth*			_auth;

src/ui/LmsApplicationGroup.cpp

@@ -37,6 +37,7 @@ LmsApplicationInfo::fromEnvironment(const Wt::WEnvironment& env)
 void
 LmsApplicationGroup::join(LmsApplicationInfo info)
 {
+	std::lock_guard<std::mutex> lock(_mutex);
 
 	_apps.emplace(wApp->sessionId(), std::move(info));
 }
@@ -52,6 +53,7 @@ LmsApplicationGroup::getOtherSessionIds() const
 {
 	std::vector<std::string> res;
 
+	std::lock_guard<std::mutex> lock(_mutex);
 	for (auto const& app : _apps)
 	{
 		if (app.first != wApp->sessionId())
@@ -74,5 +76,12 @@ LmsApplicationGroup::postOthers(std::function<void()> func) const
 	}
 }
 
+LmsApplicationGroup&
+LmsApplicationGroupContainer::get(Wt::WString identity)
+{
+	std::lock_guard<std::mutex> lock(_mutex);
+
+	return _apps[identity];
+}
 
 } // UserInterface

src/ui/LmsApplicationGroup.hpp

@@ -20,6 +20,7 @@
 #pragma once
 
 #include <map>
+#include <mutex>
 
 #include <Wt/WSignal.h>
 #include <Wt/WEnvironment.h>
@@ -41,17 +42,25 @@ class LmsApplicationGroup
 		void join(LmsApplicationInfo info);
 		void leave();
 
-		std::vector<LmsApplicationInfo> list() const;
-
 		void postOthers(std::function<void()> func) const;
 
 	private:
 
+		mutable std::mutex _mutex;
+
 		std::vector<std::string>  getOtherSessionIds() const;
 
 		std::map<std::string, LmsApplicationInfo> _apps;
 };
 
-using LmsApplicationGroups = std::map<Wt::WString, LmsApplicationGroup>;
+class LmsApplicationGroupContainer
+{
+	public:
+		LmsApplicationGroup& get(Wt::WString identity);
+
+	private:
+		std::map<Wt::WString, LmsApplicationGroup> _apps;
+		std::mutex _mutex;
+};
 
 } // UserInterface