camel-core/src/test/java/org/apache/camel/processor/MDCAsyncTest.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.processor;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import org.apache.camel.AsyncCallback;
import org.apache.camel.AsyncProcessor;
import org.apache.camel.ContextTestSupport;
import org.apache.camel.Exchange;
import org.apache.camel.Processor;
import org.apache.camel.RuntimeCamelException;
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.component.mock.MockEndpoint;

import org.slf4j.MDC;

import static org.junit.Assert.assertNotEquals;

/**
 * @version 
 */
public class MDCAsyncTest extends ContextTestSupport {

    public void testMdcPreservedAfterAsyncEndpoint() throws Exception {
        MockEndpoint mock = getMockEndpoint("mock:end");
        mock.expectedMessageCount(1);

        template.sendBody("direct:a", "Hello World");

        assertMockEndpointsSatisfied();
    }

    @Override
    protected RouteBuilder createRouteBuilder() throws Exception {
        return new RouteBuilder() {
            @Override
            public void configure() throws Exception {
                // enable MDC
                context.setUseMDCLogging(true);

                MdcCheckerProcessor checker = new MdcCheckerProcessor();
                
                from("direct:a").routeId("route-async")
                    .process(checker)
                    .to("log:foo")
                    .process(new MyAsyncProcessor())
                    .process(checker)
                    .to("mock:end");                    

            }
        };
    }
    
    private static class MyAsyncProcessor implements AsyncProcessor {
        
        private static final ExecutorService EXECUTOR = Executors.newFixedThreadPool(1);

        public MyAsyncProcessor() {
            // submit a Runnable that does nothing just to initialise the threads
            EXECUTOR.submit(new Runnable() {
                @Override
                public void run() {
                    // do nothing
                }
            });
        }
        
        @Override
        public void process(Exchange exchange) throws Exception {
            throw new RuntimeCamelException("This processor does not support the sync pattern.");
        }

        @Override
        public boolean process(Exchange exchange, final AsyncCallback callback) {
            EXECUTOR.submit(new Runnable() {
                @Override
                public void run() {
                    callback.done(false);
                }
            });
            
            return false;
        }
    }

    /**
     * Stores values from the first invocation to compare them with the second invocation later.
     */
    private static class MdcCheckerProcessor implements Processor {
        
        private String routeId = "route-async";
        private String exchangeId;
        private String messageId;
        private String breadcrumbId;
        private String contextId;
        private Long threadId;

        @Override
        public void process(Exchange exchange) throws Exception {
            if (threadId != null) {
                assertNotEquals(threadId, Long.valueOf(Thread.currentThread().getId()));
            } else {
                threadId = Long.valueOf(Thread.currentThread().getId());
            }
            
            if (routeId != null) {
                assertEquals(routeId, MDC.get("camel.routeId"));
            }
            
            if (exchangeId != null) {
                assertEquals(exchangeId, MDC.get("camel.exchangeId"));
            } else {
                exchangeId = MDC.get("camel.exchangeId");
                assertTrue(exchangeId != null && exchangeId.length() > 0);
            }
            
            if (messageId != null) {
                assertEquals(messageId, MDC.get("camel.messageId"));
            } else {
                messageId = MDC.get("camel.messageId");
                assertTrue(messageId != null && messageId.length() > 0);
            }
            
            if (breadcrumbId != null) {
                assertEquals(breadcrumbId, MDC.get("camel.breadcrumbId"));
            } else {
                breadcrumbId = MDC.get("camel.breadcrumbId");
                assertTrue(breadcrumbId != null && breadcrumbId.length() > 0);
            }
            
            if (contextId != null) {
                assertEquals(contextId, MDC.get("camel.contextId"));
            } else {
                contextId = MDC.get("camel.contextId");
                assertTrue(contextId != null && contextId.length() > 0);
            }
            
        }
    }

}