org/objectweb/proactive/core/gc/GarbageCollector.java

/* 
 * ################################################################
 * 
 * ProActive: The Java(TM) library for Parallel, Distributed, 
 *            Concurrent computing with Security and Mobility
 * 
 * Copyright (C) 1997-2007 INRIA/University of Nice-Sophia Antipolis
 * Contact: proactive@objectweb.org
 * 
 * This library 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 any later version.
 *  
 * This library 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 library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
 * USA
 *  
 *  Initial developer(s):               The ProActive Team
 *                        http://www.inria.fr/oasis/ProActive/contacts.html
 *  Contributor(s): 
 * 
 * ################################################################
 */ 
package org.objectweb.proactive.core.gc;

import org.apache.log4j.Logger;

import org.objectweb.proactive.core.UniqueID;
import org.objectweb.proactive.core.body.AbstractBody;
import org.objectweb.proactive.core.body.LocalBodyStore;
import org.objectweb.proactive.core.body.UniversalBody;
import org.objectweb.proactive.core.body.proxy.UniversalBodyProxy;
import org.objectweb.proactive.core.util.log.Loggers;
import org.objectweb.proactive.core.util.log.ProActiveLogger;

import java.util.Collection;
import java.util.LinkedList;
import java.util.List;
import java.util.ListIterator;


public class GarbageCollector {
    private static final Logger logger = ProActiveLogger.getLogger(Loggers.GC);

    private final List<Proxy> proxies;

    public GarbageCollector(AbstractBody body) {
        this.proxies = new LinkedList<Proxy>();
    }

    private void strongReferenceProxies() {
        int nrRemoved = 0;

        for (ListIterator<Proxy> iter = this.proxies.listIterator();
                iter.hasNext();) {
            Proxy p = iter.next();

            if (!p.setStrong()) {
                iter.remove();
                nrRemoved++;
            }
        }

        if (nrRemoved != 0) {
            logger.debug("Removed " + nrRemoved + " proxies");
        }
    }

    private void weakReferenceProxies() {
        for (Proxy p : this.proxies) {
            p.setWeak();
        }
    }

    public synchronized void addProxy(UniversalBodyProxy proxy) {
        proxies.add(new Proxy(proxy));
        logger.debug("New proxy");
    }

    public static String getDgcState(UniqueID bodyID) {
        UniversalBody body = LocalBodyStore.getInstance().getLocalBody(bodyID);

        if (body == null) {
            logger.error("Body " + bodyID + " not found");

            return "Body not found";
        }

        return "DGC";
    }

    public Collection<UniversalBodyProxy> getReferences() {
        Collection<UniversalBodyProxy> refs = new LinkedList<UniversalBodyProxy>();
        strongReferenceProxies();

        for (Proxy p : this.proxies) {
            refs.add(p.getStrong());
        }

        weakReferenceProxies();

        return refs;
    }

    public static boolean isBuildingTopology() {
        return "true".equals(System.getProperty("proactive.build_topology"));
    }
}

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