/*
* Copyright (C) 2013 eXo Platform SAS.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.exoplatform.container;
import org.exoplatform.commons.utils.PropertyManager;
import org.exoplatform.container.management.ManageableContainer;
import org.exoplatform.container.spi.After;
import org.exoplatform.container.spi.Before;
import org.exoplatform.container.spi.Interceptor;
import org.exoplatform.container.spi.InterceptorChainFactory;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.ServiceLoader;
/**
* The default implementation of a {@link InterceptorChainFactory}. This implementation
* uses 3 static {@link Interceptor} which are {@link ConcurrentContainer},
* {@link CachingContainer} and {@link ManageableContainer} and uses a list of dynamic {@link Interceptor}
* that are retrieved thanks to the {@link ServiceLoader}. Then according to the annotations {@link Before}
* and {@link After} defined on the dynamic {@link Interceptor}, it will define an ordered list of {@link Interceptor}
* classes which will be used at each next calls of {@link #getInterceptorChain(ExoContainer, ExoContainer)} to
* re-create the exact same chain of {@link Interceptor}.
*
* @author <a href="mailto:nfilotto@exoplatform.com">Nicolas Filotto</a>
* @version $Id$
*
*/
public class DefaultInterceptorChainFactory implements InterceptorChainFactory
{
/**
* The list of class that will defined the {@link Interceptor} chain
*/
private volatile List<Class<? extends Interceptor>> chain;
/**
* {@inheritDoc}
*/
public Interceptor getInterceptorChain(ExoContainer holder, ExoContainer parent)
{
if (chain == null)
{
synchronized (this)
{
if (chain == null)
{
List<Interceptor> staticInts = getStaticInterceptors(holder, parent);
List<Interceptor> dynamicInts = getDynamicInterceptors(holder, parent);
List<Interceptor> interceptors = resolve(staticInts, dynamicInts);
Interceptor result = null;
List<Class<? extends Interceptor>> chain = new LinkedList<Class<? extends Interceptor>>();
StringBuilder sb = null;
boolean isDevelopping = PropertyManager.isDevelopping();
if (isDevelopping)
{
sb = new StringBuilder();
}
for (int i = 0, length = interceptors.size(); i < length; i++)
{
Interceptor it = interceptors.get(i);
it.setSuccessor(result);
chain.add(it.getClass());
if (isDevelopping)
{
sb.insert(0, "-> " + it.getClass().getName() + " ");
}
result = it;
}
if (isDevelopping)
{
System.out.println("The interceptor chain used is " + sb); //NOSONAR
}
this.chain = chain;
return result;
}
}
}
Interceptor result = null;
for (Iterator<Class<? extends Interceptor>> iter = chain.iterator(); iter.hasNext();)
{
Class<? extends Interceptor> iClass = iter.next();
try
{
Interceptor it = iClass.cast(iClass.newInstance());
it.setHolder(holder);
it.setParent(parent);
it.setSuccessor(result);
result = it;
}
catch (Exception e)
{
System.out.println("ERROR: Cannot instantiate inteceptor of class " + iClass + ": "
+ e.getLocalizedMessage()); //NOSONAR
}
}
return result;
}
/**
* Gives the static {@link Interceptor} from the last to the head
*/
protected List<Interceptor> getStaticInterceptors(ExoContainer holder, ExoContainer parent)
{
List<Interceptor> list = new ArrayList<Interceptor>(4);
list.add(new ConcurrentContainer(holder, parent));
list.add(new CachingContainer());
list.add(new ManageableContainer(holder, parent));
return list;
}
/**
* Gives the dynamic {@link Interceptor} from the last to the head
*/
protected List<Interceptor> getDynamicInterceptors(ExoContainer holder, ExoContainer parent)
{
List<Interceptor> list = new ArrayList<Interceptor>();
ServiceLoader<Interceptor> loader = ServiceLoader.load(Interceptor.class);
for (Iterator<Interceptor> it = loader.iterator(); it.hasNext();)
{
Interceptor interceptor = it.next();
interceptor.setHolder(holder);
interceptor.setParent(parent);
list.add(interceptor);
}
return list;
}
/**
* Resolves all the dynamic {@link Interceptor} and inject them into a list of {@link Interceptor}
* according to the annotation {@link Before} and {@link After}
* @return the ordered list of interceptors
*/
protected List<Interceptor> resolve(List<Interceptor> staticInts, List<Interceptor> dynamicInts)
{
List<Interceptor> alreadyResolved = new ArrayList<Interceptor>(staticInts);
List<Interceptor> toBeResolved = new LinkedList<Interceptor>(dynamicInts);
for (Iterator<Interceptor> iter = toBeResolved.iterator(); iter.hasNext();)
{
resolveNext(alreadyResolved, iter, false);
}
for (Iterator<Interceptor> iter = toBeResolved.iterator(); iter.hasNext();)
{
resolveNext(alreadyResolved, iter, true);
}
return alreadyResolved;
}
/**
* Resolves the next dynamic {@link Interceptor} using the annotation {@link Before} and {@link After}
* @param alreadyResolved the list of {@link Interceptor} already resolved
* @param iter the Iterator containing the remaining dynamic {@link Interceptor} to resolve
* @param resolveIfAbsent indicates if the interceptor must be resolved if the referred interceptor could not
* be found
*/
protected void resolveNext(List<Interceptor> alreadyResolved, Iterator<Interceptor> iter, boolean resolveIfAbsent)
{
Interceptor it = iter.next();
Before b = it.getClass().getAnnotation(Before.class);
if (b != null)
{
// An annotation Before has been defined
String id = b.value();
if (id == null || (id = id.trim()).isEmpty())
{
// No id set
if (PropertyManager.isDevelopping())
{
System.out.println("WARN: No value set for the annotation Before of the interceptor " + it.getClass()); //NOSONAR
}
alreadyResolved.add(it);
iter.remove();
return;
}
// The id has been set
for (int i = 0, length = alreadyResolved.size(); i < length; i++)
{
Interceptor interceptor = alreadyResolved.get(i);
if (id.equals(interceptor.getId()))
{
// The id has been found
if (i < length - 1)
{
alreadyResolved.add(i + 1, it);
}
else
{
alreadyResolved.add(it);
}
iter.remove();
return;
}
}
if (resolveIfAbsent)
{
if (PropertyManager.isDevelopping())
{
System.out.println("WARN: Could not find the interceptor of " + id + " required by the interceptor "
+ it.getClass()); //NOSONAR
}
alreadyResolved.add(it);
iter.remove();
}
return;
}
After a = it.getClass().getAnnotation(After.class);
if (a != null)
{
// An annotation After has been defined
String id = a.value();
if (id == null || (id = id.trim()).isEmpty())
{
// No id set
if (PropertyManager.isDevelopping())
{
System.out.println("WARN: No value set for the annotation After of the interceptor " + it.getClass()); //NOSONAR
}
alreadyResolved.add(it);
iter.remove();
return;
}
// The id has been set
for (int i = 0, length = alreadyResolved.size(); i < length; i++)
{
Interceptor interceptor = alreadyResolved.get(i);
if (id.equals(interceptor.getId()))
{
// The id has been found
alreadyResolved.add(i, it);
iter.remove();
return;
}
}
if (resolveIfAbsent)
{
if (PropertyManager.isDevelopping())
{
System.out.println("WARN: Could not find the interceptor of " + id + " required by the interceptor "
+ it.getClass()); //NOSONAR
}
alreadyResolved.add(it);
iter.remove();
}
return;
}
// No annotation has been defined
alreadyResolved.add(it);
iter.remove();
}
}