ConditionalExceptionProcessor.java

/**
 * 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.camel.component.jms.tx;

import org.apache.camel.Exchange;
import org.apache.camel.Processor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Conditionally throws exception causing a rollback
 */
public class ConditionalExceptionProcessor implements Processor {

    private static final Logger LOG = LoggerFactory.getLogger(ConditionalExceptionProcessor.class);
    private int count;
    private int maxCalls;
    private String errorMsg;

    public ConditionalExceptionProcessor() {
        this.maxCalls = 1;
    }

    public ConditionalExceptionProcessor(int maxCalls) {
        this.maxCalls = maxCalls;
    }

    public void process(Exchange exchange) throws Exception {
        setCount(getCount() + 1);

        if (getCount() > maxCalls * 2) {
            errorMsg = "Expected only " + maxCalls * 2 + " calls to process() but encountered "
                + getCount() + ". There should be 1 for intentionally triggered rollback, and 1 for redelivery for each call.";
        }

        // should be printed 2 times due to one re-delivery after one failure
        LOG.info("Exchange[" + getCount() + "][" + ((getCount() % 2 != 0) ? "Should rollback" : "Should succeed")
            + "] = " + exchange);

        // force rollback on every mod 2 attempt
        if (getCount() % 2 != 0) {
            throw new Exception("Rollback should be intentionally triggered: count[" + getCount() + "].");
        }
    }

    private void setCount(int count) {
        this.count = count;
    }

    public int getCount() {
        return count;
    }

    public String getErrorMessage() {
        return errorMsg;
    }
}