/*
* JBoss, Home of Professional Open Source
* Copyright 2005, JBoss Inc., and individual contributors as indicated
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* 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.jboss.aop.advice;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;
import org.jboss.aop.joinpoint.Invocation;
import org.jboss.aop.pointcut.CFlowMatcher;
import org.jboss.aop.pointcut.ast.ASTCFlowExpression;
/**
* This interceptor represents an interceptor chain bound with one or more cflow
* expressions. Such interceptor chain is kept in a precedence-sorted order. When
* this interceptor is invoked, it wraps the internal chain in the invocation.
*
* Notice that, given that each interceptor can have a cflow expression associated
* with it, an interceptor will be invoked only if it has no cflow, or if it has a
* cflow expression that matches the current invocation.
*
* The SortedCFlowInterceptor should belong always to unitary chains; otherwise, we
* cannot ensure the interceptor invocations will take place in the expected order.
*
* @author <a href="flavia.rainone@jboss.com">Flavia Rainone</a>
* @version $Revision: 88405 $
* @see CFlowInterceptor
* @see PrecedenceSorter
*/
class SortedCFlowInterceptor implements Interceptor
{
private Interceptor[] sortedInterceptors;
private CachedCFlow[] sortedCFlows;
private CachedCFlow[] cflows;
private Map<Integer, Interceptor[]> chains;
/**
* Constructor.
*
* @param sortedInterceptors a list of all interceptors in a precedence-sorted
* order.
* @param sortedCFlows a list of the cflow expressions associated with each
* interceptor of the {@code sortedInterceptors} array
* @see PrecedenceSorter
*/
public SortedCFlowInterceptor(Interceptor[] sortedInterceptors,
ASTCFlowExpression[] sortedCFlows)
{
this.sortedInterceptors = sortedInterceptors;
this.sortedCFlows = new CachedCFlow[sortedCFlows.length];
Collection<CachedCFlow> cflowSet = new HashSet<CachedCFlow>();
for (int i = 0; i < sortedCFlows.length; i++)
{
if (sortedCFlows[i] != null)
{
this.sortedCFlows[i] = new CachedCFlow(sortedCFlows[i]);
cflowSet.add(this.sortedCFlows[i]);
}
}
this.chains = new LinkedHashMap<Integer, Interceptor[]>(2, 1, true){
@Override
protected boolean removeEldestEntry(Entry<Integer,Interceptor[]> eldest)
{
return size() > 5;
}
};
this.cflows = cflowSet.toArray(new CachedCFlow[cflowSet.size()]);
}
public String getName()
{
return "SortedCFlowInterceptor";
}
public Object invoke(Invocation invocation) throws Throwable
{
// create a key identifying the overall cflow match status
int key = 0;
for (int i = 0; i < cflows.length; i++)
{
key = key + cflows[i].evaluate(invocation) << i;
}
Interceptor[] chain;
// if we have seen the same match status before, just reuse the chain
if (this.chains.containsKey(key))
{
chain = this.chains.get(key);
}
else
{
Collection<Interceptor> chainCollection = new ArrayList<Interceptor>();
for (int i = 0; i < this.sortedInterceptors.length; i++)
{
if (this.sortedCFlows[i] == null || this.sortedCFlows[i].matches())
{
chainCollection.add(this.sortedInterceptors[i]);
}
}
chain = chainCollection.toArray(new Interceptor[chainCollection.size()]);
// store the chain in the cache for reuse on subsequent invocations
this.chains.put(key, chain);
}
return invocation.getWrapper(chain).invokeNext();
}
/**
* Wraps a cflow expression and caches its matching result during an joinpoint
* invocation.
*/
private static class CachedCFlow
{
private ASTCFlowExpression cflow;
private boolean matches;
public CachedCFlow(ASTCFlowExpression cflow)
{
this.cflow = cflow;
this.matches = false;
}
public byte evaluate(Invocation invocation)
{
this.matches = new CFlowMatcher().matches(cflow, invocation);
return this.matches? (byte) 1: 0;
}
public boolean matches()
{
return this.matches;
}
}
}