| package org.apache.helix.store; |
| |
| /* |
| * 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. |
| */ |
| |
| /** |
| * Callback interface on property changes |
| * @param <T> |
| */ |
| public interface PropertyChangeListener<T> { |
| /** |
| * Callback function when there is a change in any property that starts with key |
| * It's upto the implementation to handle the following different cases 1) key |
| * is a simple key and does not have any children. PropertyStore.getProperty(key) must |
| * be used to retrieve the value; 2) key is a prefix and has children. |
| * PropertyStore.getPropertyNames(key) must be used to retrieve all the children keys. |
| * Its important to know that PropertyStore will not be able to provide the |
| * delta[old value,new value] or which child was added/deleted. The |
| * implementation must take care of the fact that there might be callback for |
| * every child thats added/deleted. General way applications handle this is |
| * keep a local cache of keys and compare against the latest keys. |
| * @param key |
| */ |
| void onPropertyChange(String key); |
| } |
