com.hazelcast.util.IConcurrentMap Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2018, Hazelcast, Inc. All Rights Reserved.
*
* Licensed 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 com.hazelcast.util;
import com.hazelcast.core.IBiFunction;
import com.hazelcast.core.IFunction;
/**
* A {@link java.util.concurrent.ConcurrentMap} with applyIfAbsent function.
*
* 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
* happen-before
* actions subsequent to the access or removal of that object from
* the {@code ConcurrentMap} in another thread.
*
*
* @param the type of keys maintained by this map
* @param the type of mapped values
*/
public interface IConcurrentMap extends java.util.concurrent.ConcurrentMap {
/**
* {@inheritDoc}
*
* @implSpec
* The default implementation is equivalent to the following steps for this
* {@code map}, then returning the current value or {@code null} if now
* absent:
*
* {@code
* if (map.get(key) == null) {
* V newValue = mappingFunction.apply(key);
* if (newValue != null)
* return map.putIfAbsent(key, newValue);
* }
* }
*
* The default implementation may retry these steps when multiple
* threads attempt updates including potentially calling the mapping
* function multiple times.
*
* This implementation assumes that the ConcurrentMap cannot contain null
* values and {@code get()} returning null unambiguously means the key is
* absent. Implementations which support null values must
* override this default implementation.
*
* @throws UnsupportedOperationException {@inheritDoc}
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException {@inheritDoc}
*/
V applyIfAbsent(K key, IFunction mappingFunction);
/**
* {@inheritDoc}
*
* @implSpec
* The default implementation is equivalent to performing the following
* steps for this {@code map}, then returning the current value or
* {@code null} if now absent. :
*
*
{@code
* if (map.get(key) != null) {
* V oldValue = map.get(key);
* V newValue = remappingFunction.apply(key, oldValue);
* if (newValue != null)
* map.replace(key, oldValue, newValue);
* else
* map.remove(key, oldValue);
* }
* }
*
* The default implementation may retry these steps when multiple threads
* attempt updates including potentially calling the remapping function
* multiple times.
*
* This implementation assumes that the ConcurrentMap cannot contain null
* values and {@code get()} returning null unambiguously means the key is
* absent. Implementations which support null values must
* override this default implementation.
*
* @throws UnsupportedOperationException {@inheritDoc}
* @throws ClassCastException {@inheritDoc}
* @throws NullPointerException {@inheritDoc}
*/
V applyIfPresent(K key, IBiFunction mappingFunction);
}