package org.hibernate.context;
import org.hibernate.classic.Session;
import org.hibernate.HibernateException;
import org.hibernate.SessionFactory;
import org.hibernate.engine.SessionFactoryImplementor;
import java.util.Map;
import java.util.HashMap;
/**
* Represents a {@link CurrentSessionContext} the notion of a contextual session
* is managed by some external entity (generally some form of interceptor, etc).
* This external manager is responsible for scoping these contextual sessions
* appropriately binding/unbinding them here for exposure to the application
* through {@link SessionFactory#getCurrentSession} calls.
* <p/>
* Basically exposes two interfaces. <ul>
* <li>First is the implementation of CurrentSessionContext which is then used
* by the {@link SessionFactory#getCurrentSession()} calls. This
* portion is instance-based specific to the session factory owning the given
* instance of this impl (there will be one instance of this per each session
* factory using this strategy).
* <li>Second is the externally facing methods {@link #hasBind}, {@link #bind},
* and {@link #unbind} used by the external thing to manage exposure of the
* current session it is scoping. This portion is static to allow easy
* reference from that external thing.
* </ul>
* The underlying storage of the current sessions here is a static
* {@link ThreadLocal}-based map where the sessions are keyed by the
* the owning session factory.
*
* @author Steve Ebersole
*/
public class ManagedSessionContext implements CurrentSessionContext {
private static final ThreadLocal context = new ThreadLocal();
private final SessionFactoryImplementor factory;
public ManagedSessionContext(SessionFactoryImplementor factory) {
this.factory = factory;
}
/**
* @see CurrentSessionContext#currentSession
*/
public Session currentSession() {
Session current = existingSession( factory );
if ( current == null ) {
throw new HibernateException( "No session currently bound to execution context" );
}
return current;
}
/**
* Check to see if there is already a session associated with the current
* thread for the given session factory.
*
* @param factory The factory against which to check for a given session
* within the current thread.
* @return True if there is currently a session bound.
*/
public static boolean hasBind(SessionFactory factory) {
return existingSession( factory ) != null;
}
/**
* Binds the given session to the current context for its session factory.
*
* @param session The session to be bound.
* @return Any previously bound session (should be null in most cases).
*/
public static Session bind(Session session) {
return ( Session ) sessionMap( true ).put( session.getSessionFactory(), session );
}
/**
* Unbinds the session (if one) current associated with the context for the
* given session.
*
* @param factory The factory for which to unbind the current session.
* @return The bound session if one, else null.
*/
public static Session unbind(SessionFactory factory) {
Session existing = null;
Map sessionMap = sessionMap();
if ( sessionMap != null ) {
existing = ( Session ) sessionMap.remove( factory );
doCleanup();
}
return existing;
}
private static Session existingSession(SessionFactory factory) {
Map sessionMap = sessionMap();
if ( sessionMap == null ) {
return null;
}
else {
return ( Session ) sessionMap.get( factory );
}
}
protected static Map sessionMap() {
return sessionMap( false );
}
private static synchronized Map sessionMap(boolean createMap) {
Map sessionMap = ( Map ) context.get();
if ( sessionMap == null && createMap ) {
sessionMap = new HashMap();
context.set( sessionMap );
}
return sessionMap;
}
private static synchronized void doCleanup() {
Map sessionMap = sessionMap( false );
if ( sessionMap != null ) {
if ( sessionMap.isEmpty() ) {
context.set( null );
}
}
}
}