// Copyright 2010, 2011 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;
import org.apache.tapestry5.internal.plastic.ClassLoaderDelegate;
import org.apache.tapestry5.internal.plastic.PlasticClassLoader;
import org.apache.tapestry5.internal.plastic.PlasticInternalUtils;
import org.apache.tapestry5.internal.plastic.asm.ClassAdapter;
import org.apache.tapestry5.internal.plastic.asm.ClassReader;
import org.apache.tapestry5.internal.plastic.asm.ClassVisitor;
import org.apache.tapestry5.internal.plastic.asm.commons.EmptyVisitor;
import org.apache.tapestry5.ioc.Invokable;
import org.apache.tapestry5.ioc.ObjectCreator;
import org.apache.tapestry5.ioc.OperationTracker;
import org.apache.tapestry5.ioc.ReloadAware;
import org.apache.tapestry5.ioc.internal.util.CollectionFactory;
import org.apache.tapestry5.ioc.internal.util.InternalUtils;
import org.apache.tapestry5.ioc.internal.util.URLChangeTracker;
import org.apache.tapestry5.services.UpdateListener;
import org.slf4j.Logger;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.Set;
@SuppressWarnings("all")
public abstract class AbstractReloadableObjectCreator implements ObjectCreator, UpdateListener, ClassLoaderDelegate
{
private final ClassLoader baseClassLoader;
private final String implementationClassName;
private final Logger logger;
private final OperationTracker tracker;
private final URLChangeTracker changeTracker = new URLChangeTracker();
/**
* The set of class names that should be loaded by the class loader. This is necessary to support
* reloading the class when a base class changes, and to properly support access to protected methods.
*/
private final Set<String> classesToLoad = CollectionFactory.newSet();
private Object instance;
private boolean firstTime = true;
private PlasticClassLoader loader;
protected AbstractReloadableObjectCreator(ClassLoader baseClassLoader, String implementationClassName,
Logger logger, OperationTracker tracker)
{
this.baseClassLoader = baseClassLoader;
this.implementationClassName = implementationClassName;
this.logger = logger;
this.tracker = tracker;
}
public synchronized void checkForUpdates()
{
if (instance == null || !changeTracker.containsChanges())
{
return;
}
if (logger.isDebugEnabled())
{
logger.debug(String.format("Implementation class %s has changed and will be reloaded on next use.",
implementationClassName));
}
changeTracker.clear();
loader = null;
boolean reloadNow = informInstanceOfReload();
instance = reloadNow ? createInstance() : null;
}
private boolean informInstanceOfReload()
{
if (instance instanceof ReloadAware)
{
ReloadAware ra = (ReloadAware) instance;
return ra.shutdownImplementationForReload();
}
return false;
}
public synchronized Object createObject()
{
if (instance == null)
{
instance = createInstance();
}
return instance;
}
private Object createInstance()
{
return tracker.invoke(String.format("Reloading class %s.", implementationClassName), new Invokable<Object>()
{
public Object invoke()
{
Class reloadedClass = reloadImplementationClass();
return createInstance(reloadedClass);
}
});
}
/**
* Invoked when an instance of the class is needed. It is the responsibility of this method (as implemented in a
* subclass) to instantiate the class and inject dependencies into the class.
*
* @see InternalUtils#findAutobuildConstructor(Class)
*/
abstract protected Object createInstance(Class clazz);
private Class reloadImplementationClass()
{
if (logger.isDebugEnabled())
{
logger.debug(String.format("%s class %s.", firstTime ? "Loading" : "Reloading", implementationClassName));
}
loader = new PlasticClassLoader(baseClassLoader, this);
classesToLoad.clear();
add(implementationClassName);
try
{
Class result = loader.loadClass(implementationClassName);
firstTime = false;
return result;
} catch (Throwable ex)
{
throw new RuntimeException(String.format("Unable to %s class %s: %s", firstTime ? "load" : "reload",
implementationClassName, InternalUtils.toMessage(ex)), ex);
}
}
private void add(String className)
{
if (!classesToLoad.contains(className))
{
logger.debug(String.format("Marking class %s to be (re-)loaded", className));
classesToLoad.add(className);
}
}
public boolean shouldInterceptClassLoading(String className)
{
return classesToLoad.contains(className);
}
public Class<?> loadAndTransformClass(String className) throws ClassNotFoundException
{
logger.debug(String.format("BEGIN Analyzing %s", className));
Class<?> result;
try
{
result = doClassLoad(className);
} catch (IOException ex)
{
throw new ClassNotFoundException(String.format("Unable to analyze and load class %s: %s", className,
InternalUtils.toMessage(ex)), ex);
}
trackClassFileChanges(className);
logger.debug(String.format(" END Analyzing %s", className));
return result;
}
public Class<?> doClassLoad(String className) throws IOException
{
ClassVisitor analyzer = new ClassAdapter(new EmptyVisitor())
{
@Override
public void visit(int version, int access, String name, String signature, String superName, String[] interfaces)
{
String path = superName + ".class";
URL url = baseClassLoader.getResource(path);
if (isFileURL(url))
{
add(PlasticInternalUtils.toClassName(superName));
}
}
@Override
public void visitInnerClass(String name, String outerName, String innerName, int access)
{
// Anonymous inner classes show the outerName as null. Nested classes show the outer name as
// the internal name of the containing class.
if (outerName == null || classesToLoad.contains(PlasticInternalUtils.toClassName(outerName)))
{
add(PlasticInternalUtils.toClassName(name));
}
}
};
String path = PlasticInternalUtils.toClassPath(className);
InputStream stream = baseClassLoader.getResourceAsStream(path);
assert stream != null;
ByteArrayOutputStream classBuffer = new ByteArrayOutputStream(5000);
byte[] buffer = new byte[5000];
while (true)
{
int length = stream.read(buffer);
if (length < 0)
{
break;
}
classBuffer.write(buffer, 0, length);
}
stream.close();
byte[] bytecode = classBuffer.toByteArray();
new ClassReader(new ByteArrayInputStream(bytecode)).accept(analyzer,
ClassReader.SKIP_CODE | ClassReader.SKIP_DEBUG | ClassReader.SKIP_FRAMES);
return loader.defineClassWithBytecode(className, bytecode);
}
private void trackClassFileChanges(String className)
{
if (isInnerClassName(className))
{
return;
}
String path = PlasticInternalUtils.toClassPath(className);
URL url = baseClassLoader.getResource(path);
if (isFileURL(url))
{
changeTracker.add(url);
}
}
/**
* Returns true if the url is non-null, and is for the "file:" protocol.
*/
private boolean isFileURL(URL url)
{
return url != null && url.getProtocol().equals("file");
}
private boolean isInnerClassName(String className)
{
return className.indexOf('$') >= 0;
}
}