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The Adobe Experience Manager SDK
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// 
// ========================================================================
// Copyright (c) 1995-2022 Mort Bay Consulting Pty Ltd and others.
// ------------------------------------------------------------------------
// 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;

import java.util.Set;
import org.eclipse.jetty.util.component.ContainerLifeCycle;
import org.eclipse.jetty.util.log.Log;
import org.eclipse.jetty.util.log.Logger;

/**
 *  CachingSessionDataStore
 *
 *  A SessionDataStore is a mechanism for (persistently) storing data associated with sessions.
 *  This implementation delegates to a pluggable SessionDataStore for actually storing the
 *  session data. It also uses a pluggable cache implementation in front of the
 *  delegate SessionDataStore to improve performance: accessing most persistent store
 *  technology can be expensive time-wise, so introducing a fronting cache
 *  can increase performance. The cache implementation can either be a local cache,
 *  a remote cache, or a clustered cache.
 *
 *  The implementation here will try to read first from the cache and fallback to
 *  reading from the SessionDataStore if the session key is not found. On writes, the
 *  session data is written first to the SessionDataStore, and then to the cache. On
 *  deletes, the data is deleted first from the SessionDataStore, and then from the
 *  cache. There is no transaction manager ensuring atomic operations, so it is
 *  possible that failures can result in cache inconsistency.
 *
 * @deprecated The Eclipse Jetty and Apache Felix Http Jetty packages are no longer supported.
 */
@Deprecated(since = "2021-05-27")
public class CachingSessionDataStore extends ContainerLifeCycle implements SessionDataStore {

    private static final Logger LOG = Log.getLogger("org.eclipse.jetty.server.session");

    /**
     * The actual store for the session data
     */
    protected SessionDataStore _store;

    /**
     * The fronting cache
     */
    protected SessionDataMap _cache;

    /**
     * @param cache the front cache to use
     * @param store the actual store for the the session data
     */
    public CachingSessionDataStore(SessionDataMap cache, SessionDataStore store) {
        _cache = cache;
        addBean(_cache, true);
        _store = store;
        addBean(_store, true);
    }

    /**
     * @return the delegate session store
     */
    public SessionDataStore getSessionStore() {
        return _store;
    }

    /**
     * @return the fronting cache for session data
     */
    public SessionDataMap getSessionDataMap() {
        return _cache;
    }

    /**
     * @see org.eclipse.jetty.server.session.SessionDataStore#load(java.lang.String)
     */
    @Override
    public SessionData load(String id) throws Exception {
        SessionData d = null;
        try {
            // check to see if the session data is already in the cache
            d = _cache.load(id);
        } catch (Exception e) {
            LOG.warn(e);
        }
        if (d != null)
            // cache hit
            return d;
        // cache miss - go get it from the store
        d = _store.load(id);
        return d;
    }

    /**
     * @see org.eclipse.jetty.server.session.SessionDataStore#delete(java.lang.String)
     */
    @Override
    public boolean delete(String id) throws Exception {
        // delete from the store
        boolean deleted = _store.delete(id);
        // and from the cache
        _cache.delete(id);
        return deleted;
    }

    /**
     * @see org.eclipse.jetty.server.session.SessionDataStore#getExpired(Set)
     */
    @Override
    public Set getExpired(Set candidates) {
        // pass thru to the delegate store
        return _store.getExpired(candidates);
    }

    /**
     * @see org.eclipse.jetty.server.session.SessionDataStore#store(java.lang.String, org.eclipse.jetty.server.session.SessionData)
     */
    @Override
    public void store(String id, SessionData data) throws Exception {
        long lastSaved = data.getLastSaved();
        // write to the SessionDataStore first
        _store.store(id, data);
        // if the store saved it, then update the cache too
        if (data.getLastSaved() != lastSaved)
            _cache.store(id, data);
    }

    @Override
    protected void doStart() throws Exception {
        super.doStart();
    }

    @Override
    protected void doStop() throws Exception {
        super.doStop();
    }

    /**
     * @see org.eclipse.jetty.server.session.SessionDataStore#isPassivating()
     */
    @Override
    public boolean isPassivating() {
        return _store.isPassivating();
    }

    /**
     * @see org.eclipse.jetty.server.session.SessionDataStore#exists(java.lang.String)
     */
    @Override
    public boolean exists(String id) throws Exception {
        try {
            // check the cache first
            SessionData data = _cache.load(id);
            if (data != null)
                return true;
        } catch (Exception e) {
            LOG.warn(e);
        }
        // then the delegate store
        return _store.exists(id);
    }

    /**
     * @see org.eclipse.jetty.server.session.SessionDataStore#initialize(org.eclipse.jetty.server.session.SessionContext)
     */
    @Override
    public void initialize(SessionContext context) throws Exception {
        // pass through
        _store.initialize(context);
        _cache.initialize(context);
    }

    /**
     * @see org.eclipse.jetty.server.session.SessionDataStore#newSessionData(java.lang.String, long, long, long, long)
     */
    @Override
    public SessionData newSessionData(String id, long created, long accessed, long lastAccessed, long maxInactiveMs) {
        return _store.newSessionData(id, created, accessed, lastAccessed, maxInactiveMs);
    }
}