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Groovy: A powerful, dynamic language for the JVM
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.codehaus.groovy.util;
import java.util.concurrent.ConcurrentHashMap;
/**
* This is a basic implementation of a map able to forget its values. This
* map uses internally a ConcurrentHashMap, thus should be save for concurrency.
* hashcode and equals are used to find the entries and should thus be implemented
* properly for the keys. This map does not support null keys.
* @author Jochen "blackdrag" Theodorou
*
* @param the key type
* @param the value type
*/
public class ManagedConcurrentValueMap {
private final ConcurrentHashMap> internalMap;
private ReferenceBundle bundle;
public ManagedConcurrentValueMap(ReferenceBundle bundle){
this.bundle = bundle;
internalMap = new ConcurrentHashMap>();
}
/**
* Sets a new bundle used for reference creation. Be warned that
* older entries will not be changed by this
* @param bundle - the ReferenceBundle
*/
public void setBundle(ReferenceBundle bundle) {
this.bundle = bundle;
}
/**
* Returns the value stored for the given key at the point of call.
* @param key a non null key
* @return the value stored in the map for the given key
*/
public V get(K key) {
ManagedReference ref = internalMap.get(key);
if (ref!=null) return ref.get();
return null;
}
/**
* Sets a new value for a given key. an older value is overwritten.
* @param key a non null key
* @param value the new value
*/
public void put(final K key, V value) {
ManagedReference ref = new ManagedReference(bundle, value) {
@Override
public void finalizeReference() {
super.finalizeReference();
internalMap.remove(key, get());
}
};
internalMap.put(key, ref);
}
}