| /* |
| * 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.geode.cache.util; |
| |
| |
| |
| /** |
| * GatewayConflictResolver is a Cache-level plugin that is called upon to decide what to do with |
| * events that originate in other systems and arrive through the WAN Gateway. A |
| * GatewayConflictResolver is invoked if the current value in a cache entry was established by a |
| * different distributed system (with a different distributed-system-id) than an event that is |
| * attempting to modify the entry. It is not invoked if the event has the same distributed system ID |
| * as the event that last changed the entry. |
| * |
| * @since GemFire 7.0 |
| */ |
| public interface GatewayConflictResolver { |
| /** |
| * This method is invoked when a change is received from another distributed system and the last |
| * modification to the affected cache entry did not also come from the same system. |
| * <p> |
| * The given GatewayConflictHelper can be used to allow the change to be made to the cache, |
| * disallow the modification or make a change to the value to be stored in the cache. |
| * <p> |
| * This method is invoked under synchronization on the cache entry in order to prevent it from |
| * concurrent modification |
| * <p> |
| * For any two events, all GatewayConflictResolvers must make the same decision on the resolution |
| * of the conflict in order to maintain consistency. They must do so regardless of the order of |
| * the events. |
| * <p> |
| * |
| * @param event the event that is in conflict with the current cache state |
| * @param helper an object to be used in modifying the course of action for this event |
| */ |
| void onEvent(TimestampedEntryEvent event, GatewayConflictHelper helper); |
| |
| } |