001 package org.apache.fulcrum.yaafi.framework.tls;
002
003 /*
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements. See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership. The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License. You may obtain a copy of the License at
011 *
012 * http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing,
015 * software distributed under the License is distributed on an
016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 * KIND, either express or implied. See the License for the
018 * specific language governing permissions and limitations
019 * under the License.
020 */
021
022 import java.util.HashMap;
023 import java.util.Map;
024
025 /**
026 * Implementation of {@link org.apache.fulcrum.yaafi.framework.tls.ThreadLocalStorage}.
027 *
028 * The code was pasted from the Hivemnind container written by
029 * Howard Lewis Ship and Harish Krishnaswamy
030 *
031 * @author <a href="mailto:siegfried.goeschl@it20one.at">Siegfried Goeschl</a>
032 */
033
034 public class ThreadLocalStorageImpl implements ThreadLocalStorage
035 {
036 private static final String INITIALIZED_KEY =
037 "$org.apache.fulcrum.yaafi.framework.tls.ThreadLocalStorageImpl#initialized$";
038
039 private CleanableThreadLocal local = new CleanableThreadLocal();
040
041 private static class CleanableThreadLocal extends ThreadLocal
042 {
043 /**
044 * <p>
045 * Intializes the variable with a HashMap containing a single Boolean flag to denote the
046 * initialization of the variable.
047 */
048 protected Object initialValue()
049 {
050 // NOTE: This is a workaround to circumvent the ThreadLocal behavior.
051 // It would be easier if the implementation of ThreadLocal.get() checked for
052 // the existence of the thread local map, after initialValue() is evaluated,
053 // and used it instead of creating a new map always after initialization (possibly
054 // overwriting any variables created from within ThreadLocal.initialValue()).
055
056 Map map = new HashMap();
057 map.put(INITIALIZED_KEY, Boolean.TRUE);
058
059 return map;
060 }
061 }
062
063 /**
064 * Gets the thread local variable and registers the listener with ThreadEventNotifier
065 * if the thread local variable has been initialized. The registration cannot be done from
066 * within {@link CleanableThreadLocal#initialValue()} because the notifier's thread local
067 * variable will be overwritten and the listeners for the thread will be lost.
068 */
069 private Map getThreadLocalVariable()
070 {
071 Map map = (Map) local.get();
072 return map;
073 }
074
075 public Object get(String key)
076 {
077 Map map = getThreadLocalVariable();
078
079 return map.get(key);
080 }
081
082 public void put(String key, Object value)
083 {
084 Map map = getThreadLocalVariable();
085
086 map.put(key, value);
087 }
088
089 public boolean containsKey(String key)
090 {
091 Map map = getThreadLocalVariable();
092
093 return map.containsKey(key);
094 }
095
096 public void clear()
097 {
098 Map map = (Map) local.get();
099
100 if (map != null)
101 {
102 map.clear();
103 }
104 }
105 }