/*
* 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.drill.jdbc.proxy;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
/**
* Tracing proxy-invocation handler.
* Reports invocations of methods of given proxied object to given invocation
* reporter.
*/
class TracingInvocationHandler<INTF> implements InvocationHandler
{
private final ProxiesManager proxiesManager;
private final InvocationReporter callReporter;
private final INTF proxiedObject;
private final Class<?> proxiedInterface;
/**
* Constructs invocation handler for given object, treats ~as given (single)
* interface.
*
* @param proxiesManager
* the proxies manager to use for creating new proxy objects
* @param reporter
* the invocation report to use to report invocation events
* @param proxiedObject
* ...
* @param proxiedInterface
* ...
*/
TracingInvocationHandler( final ProxiesManager proxiesManager,
final InvocationReporter reporter,
final INTF proxiedObject,
final Class<?> proxiedInterface ) {
this.proxiesManager = proxiesManager;
this.callReporter = reporter;
this.proxiedObject = proxiedObject;
this.proxiedInterface = proxiedInterface;
}
@Override
public Object invoke( Object proxy, Method method, Object[] args )
throws Throwable {
// Report that method was called:
callReporter.methodCalled( proxiedObject, proxiedInterface, method, args );
final Object rawReturnedResult;
final Object netReturnedResult;
try {
// Invoke proxied original object's method:
rawReturnedResult = method.invoke( proxiedObject, args );
if ( null == rawReturnedResult ) {
netReturnedResult = null;
}
else {
Class<?> methodReturnType = method.getReturnType();
if ( ! methodReturnType.isInterface() ) {
// Declared type is not an interface type, so don't proxy the returned
// instance. (We could proxy and intercept some methods, but we can't
// intercept all, so intercepting only some would be misleading.)
netReturnedResult = rawReturnedResult;
}
else {
// Get the new or existing proxying instance for the returned instance.
netReturnedResult =
proxiesManager.getProxyInstanceForOriginal( rawReturnedResult,
methodReturnType );
}
}
}
catch ( IllegalAccessException | IllegalArgumentException e ) {
throw new RuntimeException(
"Unexpected/unhandled error calling proxied method: " + e, e );
}
catch ( InvocationTargetException e ) {
Throwable thrownResult = e.getCause();
// Report that method threw exception:
callReporter.methodThrew( proxiedObject, proxiedInterface, method, args,
thrownResult );
throw thrownResult;
}
// Report that method returned:
callReporter.methodReturned( proxiedObject, proxiedInterface, method, args,
rawReturnedResult );
return netReturnedResult;
} // invoke(...)
} // class ProxyInvocationHandler<INTF>