ConcurrentMap.java

/**
 * Copyright 2005-2014 Restlet
 * 
 * The contents of this file are subject to the terms of one of the following
 * open source licenses: Apache 2.0 or or EPL 1.0 (the "Licenses"). You can
 * select the license that you prefer but you may not use this file except in
 * compliance with one of these Licenses.
 * 
 * You can obtain a copy of the Apache 2.0 license at
 * http://www.opensource.org/licenses/apache-2.0
 * 
 * You can obtain a copy of the EPL 1.0 license at
 * http://www.opensource.org/licenses/eclipse-1.0
 * 
 * See the Licenses for the specific language governing permissions and
 * limitations under the Licenses.
 * 
 * Alternatively, you can obtain a royalty free commercial license with less
 * limitations, transferable or non-transferable, directly at
 * http://restlet.com/products/restlet-framework
 * 
 * Restlet is a registered trademark of Restlet S.A.S.
 */

package com.google.gwt.emul.java.util.concurrent;

import java.util.Map;

/**
 * Emulate the ConcurrentMap class, especially for the GWT module.
 * 
 * @author Thierry Boileau
 */
public interface ConcurrentMap<K, V> extends Map<K, V> {

    /**
     * If the specified key is not already associated with a value, associate it
     * with the given value.
     * 
     * @param key
     *            The key.
     * @param value
     *            The value
     */
    void putIfAbsent(K key, V value);

    /**
     * Remove entry for key only if currently mapped to given value.
     * 
     * @param key
     *            The key.
     * @param value
     *            The value.
     * @return True if the value was removed, false otherwise
     */
    boolean remove(Object key, Object value);

    /**
     * Replace entry for key only if currently mapped to some value.
     * 
     * @param key
     *            The key
     * @param value
     * @return Previous value associated with specified key, or null if there
     *         was no mapping for key. A null return can also indicate that the
     *         map previously associated null with the specified key, if the
     *         implementation supports null values.
     */
    V replace(K key, V value);

    /**
     * Replace entry for key only if currently mapped to given value.
     * 
     * @param key
     *            The key.
     * @param oldValue
     *            The current value.
     * @param newValue
     *            The new value.
     * @return True if the value was replaced
     */
    boolean replace(K key, V oldValue, V newValue);

}