| /* |
| * 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. |
| */ |
| |
| package org.apache.ignite.configuration; |
| |
| import java.io.Serializable; |
| import java.util.Collection; |
| import javax.cache.CacheException; |
| import org.apache.ignite.IgniteException; |
| import org.apache.ignite.cluster.ClusterNode; |
| |
| /** |
| * Topology validator is used to verify that cluster topology is valid for further cache operations. |
| * The topology validator is invoked every time the cluster topology changes (either a new node joined |
| * or an existing node failed or left). |
| * <p> |
| * If topology validator is not configured, then the cluster topology is always considered to be valid. |
| * <p> |
| * Whenever the {@link #validate(Collection)} method returns {@code true}, then the topology is considered valid |
| * for a certain cache and all operations on this cache will be allowed to proceed. Otherwise, all update operations |
| * on the cache are restricted with the following exceptions: |
| * <ul> |
| * <li>{@link CacheException} will be thrown for all update operations (put, remove, etc) attempt.</li> |
| * <li>{@link IgniteException} will be thrown for the transaction commit attempt.</li> |
| * </ul> |
| * After returning {@code false} and declaring the topology not valid, the topology validator can return |
| * to normal state whenever the next topology change happens. |
| * <h1 class="header">Example</h1> |
| * The example below shows how a validator can be used to allow cache updates only in case if the cluster |
| * topology contains exactly 2 nodes: |
| * <pre name="code" class="java"> |
| * new TopologyValidator() { |
| * public boolean validate(Collection<ClusterNode> nodes) { |
| * return nodes.size() == 2; |
| * } |
| * } |
| * </pre> |
| * <h1 class="header">Configuration</h1> |
| * The topology validator can be configured either from code or XML via |
| * {@link CacheConfiguration#setTopologyValidator(TopologyValidator)} method. |
| */ |
| public interface TopologyValidator extends Serializable { |
| /** |
| * Validates topology. |
| * |
| * @param nodes Collection of nodes. |
| * @return {@code true} in case topology is valid for specific cache, otherwise {@code false} |
| */ |
| public boolean validate(Collection<ClusterNode> nodes); |
| } |