gremlin-groovy/src/main/java/org/apache/tinkerpop/gremlin/groovy/jsr223/ManagedConcurrentValueMap.java

/*
 * 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.apache.tinkerpop.gremlin.groovy.jsr223;

import org.codehaus.groovy.util.ManagedReference;
import org.codehaus.groovy.util.ReferenceBundle;

import java.util.concurrent.ConcurrentHashMap;

/**
 * Expanded from the original {@code ManagedConcurrentHashMap} in groovy-core.
 *
 * @author Stephen Mallette (http://stephen.genoprime.com)
 */
class ManagedConcurrentValueMap<K, V> {
    private final ConcurrentHashMap<K, ManagedReference<V>> internalMap;
    private ReferenceBundle bundle;

    public ManagedConcurrentValueMap(final 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(final 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(final K key) {
        final ManagedReference<V> 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, final V value) {
        final ManagedReference<V> ref = new ManagedReference<V>(bundle, value) {
            @Override
            public void finalizeReference() {
                super.finalizeReference();
                internalMap.remove(key, get());
            }
        };
        internalMap.put(key, ref);
    }

    public void remove(final K key) {
        internalMap.remove(key);
    }

    /**
     * Clear the map.
     */
    public void clear() {
        internalMap.clear();
    }
}