001/** 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.camel.processor.aggregate; 018 019import org.apache.camel.Exchange; 020 021/** 022 * A specialized {@link AggregationStrategy} which gets a callback when the aggregated {@link Exchange} fails to add 023 * in the {@link org.apache.camel.spi.OptimisticLockingAggregationRepository} because of 024 * an {@link org.apache.camel.spi.OptimisticLockingAggregationRepository.OptimisticLockingException}. 025 * <p/> 026 * Please note that when aggregating {@link Exchange}'s to be careful not to modify and return the {@code oldExchange} 027 * from the {@link AggregationStrategy#aggregate(org.apache.camel.Exchange, org.apache.camel.Exchange)} method. 028 * If you are using the default MemoryAggregationRepository this will mean you have modified the value of an object 029 * already referenced/stored by the MemoryAggregationRepository. This makes it impossible for optimistic locking 030 * to work correctly with the MemoryAggregationRepository. 031 * <p/> 032 * You should instead return either the new {@code newExchange} or a completely new instance of {@link Exchange}. This 033 * is due to the nature of how the underlying {@link java.util.concurrent.ConcurrentHashMap} performs CAS operations 034 * on the value identity. 035 * 036 * @see java.util.concurrent.ConcurrentHashMap 037 * 038 * @version 039 */ 040public interface OptimisticLockingAwareAggregationStrategy extends AggregationStrategy { 041 042 // TODO: In Camel 3.0 we should move this to org.apache.camel package 043 044 void onOptimisticLockFailure(Exchange oldExchange, Exchange newExchange); 045}