sergey-chugunov-1985 commented on code in PR #12459: URL: https://github.com/apache/ignite/pull/12459#discussion_r2472879199
########## modules/core/src/main/java/org/apache/ignite/cache/affinity/rendezvous/MdcAffinityBackupFilter.java: ########## @@ -0,0 +1,126 @@ +/* + * 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.cache.affinity.rendezvous; + +import java.util.HashMap; +import java.util.List; +import java.util.Map; +import org.apache.ignite.cluster.ClusterNode; +import org.apache.ignite.lang.IgniteBiPredicate; + +/** + * Multi-data center affinity backup filter that ensures each partition's data is distributed across multiple data centers, + * providing high availability and fault tolerance. This implementation guarantees at least one copy of the data in each + * data center and attempts to maintain the configured backup factor without discarding copies. + * <p> + * The filter works by grouping nodes based on their data center identification attribute (@see {@link ClusterNode#dataCenterId()}) + * and ensuring that for every partition, at least one node from each data center is included in the primary-backup set. + * <p> + * The filter will discard backup copies only if the number of available nodes in a given data center is less + * than the number of copies assigned to that data center. + * For example, if a partition has 4 copies (1 primary and 3 backups) and the cluster has 2 data centers, + * than 2 copies are assigned to each data center. The only scenario when just a single copy is assigned to a node in a data center is when + * the number of nodes in that data center is one. + * <p> + * This class is constructed with a number of data centers the cluster spans and a number of backups of the cache this filter is applied to. + * Implementation expects that all copies can be spread evenly across all data centers. In other words, (backups + 1) is divisible by + * number of data centers without remainder. Uneven distributions of copies are not supported. + * <p> + * Warning: Ensure that all nodes have a consistent and valid data center identifier attribute. Missing or inconsistent values + * may lead to unexpected placement of data. + * </pre> + * <h2 class="header">Spring Example</h2> + * Create a partitioned cache template where each data center has at least one copy of the data, and the backup count is maintained. + * <pre name="code" class="xml"> + * <property name="cacheConfiguration"> + * <list> + * <bean id="cache-template-bean" abstract="true" class="org.apache.ignite.configuration.CacheConfiguration"> + * <property name="name" value="JobcaseDefaultCacheConfig*"/> + * <property name="cacheMode" value="PARTITIONED" /> + * <property name="backups" value="3" /> + * <property name="affinity"> + * <bean class="org.apache.ignite.cache.affinity.rendezvous.RendezvousAffinityFunction"> + * <property name="affinityBackupFilter"> + * <bean class="org.apache.ignite.cache.affinity.rendezvous.MdcAffinityBackupFilter"> + * <constructor-arg value="2"/> <!-- dcsNumber --> + * <constructor-arg value="3"/> <!-- backups, the same as in the cache template --> + * </bean> + * </property> + * </bean> + * </property> + * </bean> + * </list> + * </property> + * </pre> + * <p> + * With more backups, additional replicas can be distributed across different data centers to further improve redundancy. + */ +public class MdcAffinityBackupFilter implements IgniteBiPredicate<ClusterNode, List<ClusterNode>> { Review Comment: Added -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
