Add factory for a SessionStore with a fronting cache.

Not finished, initial checkin.

jetty-server/src/main/java/org/eclipse/jetty/server/session/CachingSessionStoreFactory.java

@@ -0,0 +1,57 @@
+//
+//  ========================================================================
+//  Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
+//  ------------------------------------------------------------------------
+//  All rights reserved. This program and the accompanying materials
+//  are made available under the terms of the Eclipse Public License v1.0
+//  and Apache License v2.0 which accompanies this distribution.
+//
+//      The Eclipse Public License is available at
+//      http://www.eclipse.org/legal/epl-v10.html
+//
+//      The Apache License v2.0 is available at
+//      http://www.opensource.org/licenses/apache2.0.php
+//
+//  You may elect to redistribute this code under either of these licenses.
+//  ========================================================================
+//
+
+
+package org.eclipse.jetty.server.session;
+
+/**
+ * CachingSessionStoreFactory
+ *
+ *
+ */
+public class CachingSessionStoreFactory extends AbstractSessionStoreFactory
+{
+
+    /**
+     * The SessionStore that will store session data.
+     */
+    protected  SessionStoreFactory _backingSessionStoreFactory;
+    
+    
+    
+    
+    /**
+     * @param factory The factory for the actual SessionStore that the
+     * CachingSessionStore will delegate to
+     */
+    public void setBackingSessionStoreFactory (SessionStoreFactory factory)
+    {
+        _backingSessionStoreFactory = factory;
+    }
+    
+    /** 
+     * @see org.eclipse.jetty.server.session.SessionStoreFactory#getSessionStore(org.eclipse.jetty.server.session.SessionHandler)
+     */
+    @Override
+    public SessionStore getSessionStore(SessionHandler handler) throws Exception
+    {
+        // TODO configure and create a cache!
+        return new CachingSessionStore(null, _backingSessionStoreFactory.getSessionStore(handler));    
+    }
+
+}