Only add User session container if container was not found

code/moya-beans/ejbModule/fi/codecrew/moya/beans/SessionMgmtBean.java

@@ -28,6 +28,8 @@ import javax.annotation.security.RolesAllowed;
 import javax.ejb.ConcurrencyManagement;
 import javax.ejb.ConcurrencyManagementType;
 import javax.ejb.LocalBean;
+import javax.ejb.Lock;
+import javax.ejb.LockType;
 import javax.ejb.Singleton;
 import javax.ejb.TransactionAttribute;
 import javax.ejb.TransactionAttributeType;
@@ -47,26 +49,26 @@ import fi.codecrew.moya.enums.apps.UserPermission;
 @ConcurrencyManagement(ConcurrencyManagementType.BEAN)
 @TransactionAttribute(TransactionAttributeType.SUPPORTS)
 @DeclareRoles({ UserPermission.S_MANAGE_HTTP_SESSION })
+@Lock(LockType.READ)
 public class SessionMgmtBean implements SessionMgmtBeanLocal {
 
-	/**
-	 * Default constructor.
-	 */
-	public SessionMgmtBean() {
-		// TODO Auto-generated constructor stub
-	}
-
 	private final ConcurrentHashMap<String, UserContainer> sessionUsers = new ConcurrentHashMap<>();
 	private final Set<HttpSession> sessions = Collections.newSetFromMap(new ConcurrentHashMap<HttpSession, Boolean>());
 
 	@SuppressWarnings("unused")
 	private static final Logger logger = LoggerFactory.getLogger(SessionMgmtBean.class);
 
+	/**
+	 * Default constructor.
+	 */
+	public SessionMgmtBean() {
+	}
+
 	@Override
 	public void updateSessionUser(String sessionId, String user) {
 
 		if (!sessionUsers.containsKey(sessionId)) {
-			sessionUsers.put(sessionId, new UserContainer(BortalLocalContextHolder.getHostname(), user));
+			sessionUsers.putIfAbsent(sessionId, new UserContainer(BortalLocalContextHolder.getHostname(), user));
 		}
 	}