/**
* 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.hadoop.gateway.audit.log4j.correlation;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.concurrent.Callable;
import org.apache.hadoop.gateway.audit.api.CorrelationContext;
import org.apache.hadoop.gateway.audit.api.CorrelationService;
import org.apache.log4j.MDC;
public class Log4jCorrelationService implements CorrelationService {
public static final String MDC_CORRELATION_CONTEXT_KEY = "correlation_context";
@Override
public CorrelationContext createContext() {
CorrelationContext context = getContext();
if ( context == null ) {
context = new Log4jCorrelationContext();
attachContext( context );
}
return context;
}
@Override
public CorrelationContext getContext() {
return (CorrelationContext) MDC.get( MDC_CORRELATION_CONTEXT_KEY );
}
@Override
public void attachContext( CorrelationContext context ) {
if ( context != null ) {
MDC.put( MDC_CORRELATION_CONTEXT_KEY, context );
}
}
@Override
public CorrelationContext detachContext() {
CorrelationContext context = (CorrelationContext) MDC.get( MDC_CORRELATION_CONTEXT_KEY );
MDC.remove( MDC_CORRELATION_CONTEXT_KEY );
return context;
}
@Override
public <T> T execute( CorrelationContext context, Callable<T> callable ) throws Exception {
try {
attachContext( context );
return callable.call();
} finally {
detachContext();
}
}
@Override
public CorrelationContext attachExternalizedContext(byte[] externalizedContext) {
CorrelationContext context = readExternalizedContext( externalizedContext );
attachContext( context );
return context;
}
@Override
public byte[] detachExternalizedContext() {
byte[] result = getExternalizedContext();
detachContext();
return result;
}
@Override
public CorrelationContext readExternalizedContext(byte[] externalizedContext) {
ByteArrayInputStream bais = new ByteArrayInputStream( externalizedContext );
ObjectInput oi = null;
CorrelationContext context = null;
try {
oi = new ObjectInputStream( bais );
context = (CorrelationContext) oi.readObject();
} catch ( IOException e ) {
throw new IllegalArgumentException( e );
} catch ( ClassNotFoundException e ) {
throw new IllegalArgumentException( e );
} finally {
try {
bais.close();
if ( oi != null) {
oi.close();
}
} catch ( IOException e ) {
throw new IllegalArgumentException( e );
}
}
return context;
}
@Override
public byte[] getExternalizedContext() {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
try {
ObjectOutputStream oos = new ObjectOutputStream( baos );
oos.writeObject( getContext() );
oos.close();
} catch ( IOException e ) {
throw new RuntimeException( e );
}
return baos.toByteArray();
}
}