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     */
017    package org.apache.camel.processor;
018    
019    import org.apache.camel.AsyncCallback;
020    import org.apache.camel.Exchange;
021    import org.apache.camel.Processor;
022    import org.slf4j.Logger;
023    import org.slf4j.LoggerFactory;
024    
025    /**
026     * An {@link org.apache.camel.processor.ErrorHandler} used as a safe fallback when
027     * processing by other error handlers such as the {@link org.apache.camel.model.OnExceptionDefinition}.
028     *
029     * @version
030     */
031    public class FatalFallbackErrorHandler extends DelegateAsyncProcessor implements ErrorHandler {
032    
033        private static final Logger LOG = LoggerFactory.getLogger(FatalFallbackErrorHandler.class);
034    
035        public FatalFallbackErrorHandler(Processor processor) {
036            super(processor);
037        }
038    
039        @Override
040        protected boolean processNext(final Exchange exchange, final AsyncCallback callback) {
041            // support the asynchronous routing engine
042            boolean sync = super.processNext(exchange, new AsyncCallback() {
043                public void done(boolean doneSync) {
044                    if (exchange.getException() != null) {
045                        // an exception occurred during processing onException
046    
047                        // log detailed error message with as much detail as possible
048                        Throwable previous = exchange.getProperty(Exchange.EXCEPTION_CAUGHT, Throwable.class);
049                        String msg = "Exception occurred while trying to handle previously thrown exception on exchangeId: "
050                                + exchange.getExchangeId() + " using: [" + processor + "].";
051                        if (previous != null) {
052                            msg += " The previous and the new exception will be logged in the following.";
053                            LOG.error(msg);
054                            LOG.error("\\--> Previous exception on exchangeId: " + exchange.getExchangeId() , previous);
055                            LOG.error("\\--> New exception on exchangeId: " + exchange.getExchangeId(), exchange.getException());
056                        } else {
057                            LOG.error(msg);
058                            LOG.error("\\--> New exception on exchangeId: " + exchange.getExchangeId(), exchange.getException());
059                        }
060    
061                        // we can propagated that exception to the caught property on the exchange
062                        // which will shadow any previously caught exception and cause this new exception
063                        // to be visible in the error handler
064                        exchange.setProperty(Exchange.EXCEPTION_CAUGHT, exchange.getException());
065    
066                        // mark this exchange as already been error handler handled (just by having this property)
067                        // the false value mean the caught exception will be kept on the exchange, causing the
068                        // exception to be propagated back to the caller, and to break out routing
069                        exchange.setProperty(Exchange.ERRORHANDLER_HANDLED, false);
070                    }
071                    callback.done(doneSync);
072                }
073            });
074    
075            return sync;
076        }
077    
078        @Override
079        public String toString() {
080            return "FatalFallbackErrorHandler[" + processor + "]";
081        }
082    }