| /* |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| /* |
| * This file is available under and governed by the GNU General Public |
| * License version 2 only, as published by the Free Software Foundation. |
| * However, the following notice accompanied the original version of this |
| * file: |
| * |
| * Written by Doug Lea with assistance from members of JCP JSR-166 |
| * Expert Group and released to the public domain, as explained at |
| * http://creativecommons.org/licenses/publicdomain |
| */ |
| |
| package java.util.concurrent; |
| import java.util.Map; |
| |
| /** |
| * A {@link java.util.Map} providing additional atomic |
| * <tt>putIfAbsent</tt>, <tt>remove</tt>, and <tt>replace</tt> methods. |
| * |
| * <p>Memory consistency effects: As with other concurrent |
| * collections, actions in a thread prior to placing an object into a |
| * {@code ConcurrentMap} as a key or value |
| * <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a> |
| * actions subsequent to the access or removal of that object from |
| * the {@code ConcurrentMap} in another thread. |
| * |
| * <p>This interface is a member of the |
| * <a href="{@docRoot}/../technotes/guides/collections/index.html"> |
| * Java Collections Framework</a>. |
| * |
| * @since 1.5 |
| * @author Doug Lea |
| * @param <K> the type of keys maintained by this map |
| * @param <V> the type of mapped values |
| */ |
| 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. |
| * This is equivalent to |
| * <pre> |
| * if (!map.containsKey(key)) |
| * return map.put(key, value); |
| * else |
| * return map.get(key);</pre> |
| * except that the action is performed atomically. |
| * |
| * @param key key with which the specified value is to be associated |
| * @param value value to be associated with the specified key |
| * @return the previous value associated with the specified key, or |
| * <tt>null</tt> if there was no mapping for the key. |
| * (A <tt>null</tt> return can also indicate that the map |
| * previously associated <tt>null</tt> with the key, |
| * if the implementation supports null values.) |
| * @throws UnsupportedOperationException if the <tt>put</tt> operation |
| * is not supported by this map |
| * @throws ClassCastException if the class of the specified key or value |
| * prevents it from being stored in this map |
| * @throws NullPointerException if the specified key or value is null, |
| * and this map does not permit null keys or values |
| * @throws IllegalArgumentException if some property of the specified key |
| * or value prevents it from being stored in this map |
| * |
| */ |
| V putIfAbsent(K key, V value); |
| |
| /** |
| * Removes the entry for a key only if currently mapped to a given value. |
| * This is equivalent to |
| * <pre> |
| * if (map.containsKey(key) && map.get(key).equals(value)) { |
| * map.remove(key); |
| * return true; |
| * } else return false;</pre> |
| * except that the action is performed atomically. |
| * |
| * @param key key with which the specified value is associated |
| * @param value value expected to be associated with the specified key |
| * @return <tt>true</tt> if the value was removed |
| * @throws UnsupportedOperationException if the <tt>remove</tt> operation |
| * is not supported by this map |
| * @throws ClassCastException if the key or value is of an inappropriate |
| * type for this map (optional) |
| * @throws NullPointerException if the specified key or value is null, |
| * and this map does not permit null keys or values (optional) |
| */ |
| boolean remove(Object key, Object value); |
| |
| /** |
| * Replaces the entry for a key only if currently mapped to a given value. |
| * This is equivalent to |
| * <pre> |
| * if (map.containsKey(key) && map.get(key).equals(oldValue)) { |
| * map.put(key, newValue); |
| * return true; |
| * } else return false;</pre> |
| * except that the action is performed atomically. |
| * |
| * @param key key with which the specified value is associated |
| * @param oldValue value expected to be associated with the specified key |
| * @param newValue value to be associated with the specified key |
| * @return <tt>true</tt> if the value was replaced |
| * @throws UnsupportedOperationException if the <tt>put</tt> operation |
| * is not supported by this map |
| * @throws ClassCastException if the class of a specified key or value |
| * prevents it from being stored in this map |
| * @throws NullPointerException if a specified key or value is null, |
| * and this map does not permit null keys or values |
| * @throws IllegalArgumentException if some property of a specified key |
| * or value prevents it from being stored in this map |
| */ |
| boolean replace(K key, V oldValue, V newValue); |
| |
| /** |
| * Replaces the entry for a key only if currently mapped to some value. |
| * This is equivalent to |
| * <pre> |
| * if (map.containsKey(key)) { |
| * return map.put(key, value); |
| * } else return null;</pre> |
| * except that the action is performed atomically. |
| * |
| * @param key key with which the specified value is associated |
| * @param value value to be associated with the specified key |
| * @return the previous value associated with the specified key, or |
| * <tt>null</tt> if there was no mapping for the key. |
| * (A <tt>null</tt> return can also indicate that the map |
| * previously associated <tt>null</tt> with the key, |
| * if the implementation supports null values.) |
| * @throws UnsupportedOperationException if the <tt>put</tt> operation |
| * is not supported by this map |
| * @throws ClassCastException if the class of the specified key or value |
| * prevents it from being stored in this map |
| * @throws NullPointerException if the specified key or value is null, |
| * and this map does not permit null keys or values |
| * @throws IllegalArgumentException if some property of the specified key |
| * or value prevents it from being stored in this map |
| */ |
| V replace(K key, V value); |
| } |
