import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;

import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class NMS6536 {

    private static Logger logger = LoggerFactory.getLogger(NMS6536.class);

    Map<String,Date> m_lastAccess = new HashMap<String,Date>();
    Map<String,Date> m_measurementSets = new HashMap<String,Date>();

    @Before
    public void setUp() throws Exception {
        Date oldDate = new Date(System.currentTimeMillis() - 500000);
        m_lastAccess.put("a", new Date());
        m_lastAccess.put("b", oldDate);
        m_lastAccess.put("c", new Date());

        m_measurementSets.put("a", new Date());
        m_measurementSets.put("b", oldDate);
        m_measurementSets.put("c", new Date());
    }

    @Test
    public void test() throws Exception {
        Assert.assertEquals(3, m_lastAccess.size());
        Assert.assertEquals(3, m_measurementSets.size());

        doHousekeeping();

        Assert.assertEquals(2, m_lastAccess.size());
        Assert.assertEquals(2, m_measurementSets.size());
        Assert.assertFalse(m_lastAccess.containsKey("b"));
        Assert.assertFalse(m_measurementSets.containsKey("b"));
    }

    private synchronized void doHousekeeping() {
        final Iterator<Entry<String,Date>> it = m_lastAccess.entrySet().iterator();
        while (it.hasNext()) {
            final Entry<String,Date> entry = it.next();
            final Date lastAccess = entry.getValue();
            final Date now = new Date();
            if (now.getTime() - lastAccess.getTime() > 120000) {
                it.remove(); // removes entry from m_lastAccess to avoid ConcurrentModificationException
                m_measurementSets.remove(entry.getKey());
                logger.warn("Timed out object removed '{}'", entry.getKey());
            }
        }
    }
}