001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied. See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019 package org.apache.shiro.session.mgt.eis;
020
021 import org.apache.shiro.session.Session;
022 import org.apache.shiro.session.UnknownSessionException;
023 import org.apache.shiro.util.CollectionUtils;
024 import org.slf4j.Logger;
025 import org.slf4j.LoggerFactory;
026
027 import java.io.Serializable;
028 import java.util.Collection;
029 import java.util.Collections;
030 import java.util.concurrent.ConcurrentHashMap;
031 import java.util.concurrent.ConcurrentMap;
032
033
034 /**
035 * Simple memory-based implementation of the SessionDAO that stores all of its sessions in an in-memory
036 * {@link ConcurrentMap}. <b>This implementation does not page to disk and is therefore unsuitable for applications
037 * that could experience a large amount of sessions</b> and would therefore cause {@code OutOfMemoryException}s. It is
038 * <em>not</em> recommended for production use in most environments.
039 * <h2>Memory Restrictions</h2>
040 * If your application is expected to host many sessions beyond what can be stored in the
041 * memory available to the JVM, it is highly recommended to use a different {@code SessionDAO} implementation which
042 * uses a more expansive or permanent backing data store.
043 * <p/>
044 * In this case, it is recommended to instead use a custom
045 * {@link CachingSessionDAO} implementation that communicates with a higher-capacity data store of your choice
046 * (file system, database, etc).
047 * <h2>Changes in 1.0</h2>
048 * This implementation prior to 1.0 used to subclass the {@link CachingSessionDAO}, but this caused problems with many
049 * cache implementations that would expunge entries due to TTL settings, resulting in Sessions that would be randomly
050 * (and permanently) lost. The Shiro 1.0 release refactored this implementation to be 100% memory-based (without
051 * {@code Cache} usage to avoid this problem.
052 *
053 * @see CachingSessionDAO
054 * @since 0.1
055 */
056 public class MemorySessionDAO extends AbstractSessionDAO {
057
058 private static final Logger log = LoggerFactory.getLogger(MemorySessionDAO.class);
059
060 private ConcurrentMap<Serializable, Session> sessions;
061
062 public MemorySessionDAO() {
063 this.sessions = new ConcurrentHashMap<Serializable, Session>();
064 }
065
066 protected Serializable doCreate(Session session) {
067 Serializable sessionId = generateSessionId(session);
068 assignSessionId(session, sessionId);
069 storeSession(sessionId, session);
070 return sessionId;
071 }
072
073 protected Session storeSession(Serializable id, Session session) {
074 if (id == null) {
075 throw new NullPointerException("id argument cannot be null.");
076 }
077 return sessions.putIfAbsent(id, session);
078 }
079
080 protected Session doReadSession(Serializable sessionId) {
081 return sessions.get(sessionId);
082 }
083
084 public void update(Session session) throws UnknownSessionException {
085 storeSession(session.getId(), session);
086 }
087
088 public void delete(Session session) {
089 if (session == null) {
090 throw new NullPointerException("session argument cannot be null.");
091 }
092 Serializable id = session.getId();
093 if (id != null) {
094 sessions.remove(id);
095 }
096 }
097
098 public Collection<Session> getActiveSessions() {
099 Collection<Session> values = sessions.values();
100 if (CollectionUtils.isEmpty(values)) {
101 return Collections.emptySet();
102 } else {
103 return Collections.unmodifiableCollection(values);
104 }
105 }
106
107 }