org.mycore.backend.jpa.MCRSessionContext Maven / Gradle / Ivy
/*
* This file is part of *** M y C o R e ***
* See http://www.mycore.de/ for details.
*
* MyCoRe 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.
*
* MyCoRe 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 MyCoRe. If not, see .
*/
package org.mycore.backend.jpa;
import java.util.Optional;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.mycore.common.MCRSession;
import org.mycore.common.MCRSessionMgr;
import org.mycore.common.events.MCRSessionEvent;
import org.mycore.common.events.MCRSessionListener;
/**
* A helper class which scopes the notion of
* current session by the current {@link MCRSession}. This implementation allows a thread of a
* {@link MCRSession} to keep the {@link EntityManager} open for a long conversation.
*
* @author Thomas Scheffler (yagee)
*
* @version $Revision: 33146 $ $Date: 2011-04-05 10:52:04 +0200 (Di, 05 Apr
* 2011) $
* @since 2016.03
*/
class MCRSessionContext implements MCRSessionListener {
private static final Logger LOGGER = LogManager.getLogger();
private EntityManagerFactory factory;
private ThreadLocal context;
MCRSessionContext(EntityManagerFactory factory) {
this.factory = factory;
this.context = new ThreadLocal<>();
MCRSessionMgr.addSessionListener(this);
}
public void sessionEvent(MCRSessionEvent event) {
MCRSession mcrSession = event.getSession();
EntityManager currentEntityManager;
switch (event.getType()) {
case activated:
if (event.getConcurrentAccessors() <= 1) {
LOGGER.debug(() -> "First Thread to access " + mcrSession);
}
break;
case passivated:
currentEntityManager = unbind();
autoCloseSession(currentEntityManager);
break;
case destroyed:
currentEntityManager = unbind();
autoCloseSession(currentEntityManager);
break;
case created:
break;
default:
break;
}
}
private EntityManager unbind() {
EntityManager entityManager = context.get();
context.set(null);
return entityManager;
}
EntityManager getCurrentEntityManager() {
return Optional
.ofNullable(context.get())
.filter(EntityManager::isOpen)
.orElseGet(this::createEntityManagerInContext);
}
/**
* Closes Session if Session is still open.
*/
private void autoCloseSession(EntityManager currentEntityManager) {
if (currentEntityManager != null && currentEntityManager.isOpen()) {
LOGGER.debug("Autoclosing current JPA EntityManager");
currentEntityManager.close();
}
}
private EntityManager createEntityManagerInContext() {
// creates a new one
LOGGER.debug("Obtaining new entity manager.");
EntityManager entityManager = factory.createEntityManager();
LOGGER.debug(() -> "Returning entity manager with "
+ (entityManager.getTransaction().isActive() ? "active" : "non-active")
+ " transaction.");
context.set(entityManager);
return entityManager;
}
}