/*
* Copyright Terracotta, Inc.
*
* 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 org.ehcache.core.spi.store.events;
import org.ehcache.core.spi.store.Store;
import org.ehcache.event.EventType;
/**
* An event resulting from a mutative {@link Store} operation.
*
* @param <K> the type of the keys used to access data within the store
* @param <V> the type of the values held within the store
*/
public interface StoreEvent<K, V> {
/**
* The type of mutative event
*
* @return the @{link EventType}
*/
EventType getType();
/**
* The key of the mapping affected by the mutative event
*
* @return the mutated key
*/
K getKey();
/**
* The mapped value immediately after the mutative event occurred.
* <p>
* If the mutative event removes the mapping then {@code null} is returned.
*
* @return the mapped value after the mutation
*/
V getNewValue();
/**
* The mapped value immediately before the mutative event occurred.
* <p>
* If the mutative event created the mapping then {@code null} is returned.
*
* @return the mapped value before the mutation
*/
V getOldValue();
}