package org.apache.helix.zookeeper.zkclient;

/*
 * 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.
 */

/**
 * Updates the data of a znode. This is used together with {@link ZkClient#updateDataSerialized(String, DataUpdater)}.
 *
 * @param <T>
 */
public interface DataUpdater<T extends Object> {

    /**
     * Updates the current data of a znode.
     *
     * @param currentData
     *            The current contents.
     * @return the new data that should be written back to ZooKeeper.
     */
    public T update(T currentData);

}
