// Copyright 2009 The Apache Software Foundation
//
// Licensed 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.tapestry5.ioc.internal.services;
import org.apache.tapestry5.ioc.Invocation;
import org.apache.tapestry5.ioc.MethodAdvice;
import org.apache.tapestry5.ioc.MethodAdviceReceiver;
import org.apache.tapestry5.ioc.ObjectCreator;
import org.apache.tapestry5.ioc.annotations.NotLazy;
import org.apache.tapestry5.ioc.internal.util.InternalUtils;
import org.apache.tapestry5.ioc.services.LazyAdvisor;
import org.apache.tapestry5.ioc.services.ThunkCreator;
import java.lang.reflect.Method;
public class LazyAdvisorImpl implements LazyAdvisor
{
private final ThunkCreator thunkCreator;
public LazyAdvisorImpl(ThunkCreator thunkCreator)
{
this.thunkCreator = thunkCreator;
}
public void addLazyMethodInvocationAdvice(MethodAdviceReceiver methodAdviceReceiver)
{
for (Method m : methodAdviceReceiver.getInterface().getMethods())
{
if (filter(m))
addAdvice(m, methodAdviceReceiver);
}
}
private void addAdvice(Method method, MethodAdviceReceiver receiver)
{
final Class thunkType = method.getReturnType();
final String description = String.format("<%s Thunk for %s>",
thunkType.getName(),
InternalUtils.asString(method));
MethodAdvice advice = new MethodAdvice()
{
/**
* When the method is invoked, we don't immediately proceed. Intead, we return a thunk instance
* that defers its behavior to the lazily invoked invocation.
*/
public void advise(final Invocation invocation)
{
ObjectCreator deferred = new ObjectCreator()
{
public Object createObject()
{
invocation.proceed();
return invocation.getResult();
}
};
ObjectCreator cachingObjectCreator = new CachingObjectCreator(deferred);
Object thunk = thunkCreator.createThunk(thunkType, cachingObjectCreator, description);
invocation.overrideResult(thunk);
}
};
receiver.adviseMethod(method, advice);
}
private boolean filter(Method method)
{
if (method.getAnnotation(NotLazy.class) != null) return false;
if (!method.getReturnType().isInterface()) return false;
for (Class extype : method.getExceptionTypes())
{
if (!RuntimeException.class.isAssignableFrom(extype)) return false;
}
return true;
}
}