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package at.ac.tuwien.infosys.rnue.implementation.multicast;

import at.ac.tuwien.infosys.rnue.interfaces.IConstants;
import at.ac.tuwien.infosys.rnue.interfaces.IHostInfo;
import at.ac.tuwien.infosys.rnue.interfaces.IHostList;
import java.util.Enumeration;
import java.util.Hashtable;

/**
 *
 * @author Gengar
 */
public class HostListImpl implements IHostList
{

    private class GarbageCollector implements Runnable
    {

        private IHostList gcList = null;
        private boolean gcAllowed = true;

        public GarbageCollector(IHostList ihl)
        {
            gcList = ihl;
        }

        public void run()
        {
            synchronized (this)
            {
                while (gcAllowed)
                {
                    try
                    {
                        long currentTime = System.currentTimeMillis();
                        Enumeration elems = gcList.elements();

                        while (elems.hasMoreElements())
                        {
                            IHostInfo hostInfo = (IHostInfo) elems.nextElement();

                            if (currentTime - hostInfo.getTimestamp() > IConstants.LIFETIME_OF_HOSTINFOS)
                            {
                                gcList.remove(generateHostInfoKey(hostInfo));
                            }
                        }
                        ((java.lang.Object) this).wait(IConstants.GC_INTERVAL);


                    } catch (InterruptedException ie)
                    {
                        //nerob nic, len uplynul casovy interval
                    }
                }
            }
        }

        public void stop()
        {
            synchronized (this)
            {
                this.gcAllowed = false;
                this.notify();
            }
        }
    }
    private final Hashtable<String, IHostInfo> hostList = new Hashtable<String, IHostInfo>();

    private GarbageCollector gc;
    public HostListImpl()
    {
        gc = new GarbageCollector(this);

        new Thread(gc).start();
    }
    public IHostInfo get(String string)
    {
        synchronized (hostList)
        {
            return hostList.get(string);
        }
    }

    public IHostInfo put(IHostInfo ihi)
    {
        synchronized (hostList)
        {
            return hostList.put(generateHostInfoKey(ihi), ihi);
        }
    }

    public IHostInfo remove(String string)
    {
        synchronized (hostList)
        {
            return hostList.remove(string);
        }
    }

    public boolean contains(IHostInfo ihi)
    {
        return hostList.contains(ihi);
    }

    public Enumeration keys()
    {
        return hostList.keys();
    }

    public Enumeration elements()
    {
        return hostList.elements();
    }

    public void stopGarbageCollector()
    {
        gc.stop();
    }

    private String generateHostInfoKey(IHostInfo ihi)
    {
        return ihi.getHostInfoMessage().getRegistryHost() + ":" + ihi.getHostInfoMessage().getRegistryPort();
    }
}