PortLockedDataCollector.java

/* ==================================================================
 * PortLockedDataCollector.java - Jul 9, 2012 11:59:48 PM
 * 
 * Copyright 2007-2012 SolarNetwork.net Dev Team
 * 
 * This program is free software; you can redistribute it and/or 
 * modify it under the terms of the GNU General Public License as 
 * published by the Free Software Foundation; either version 2 of 
 * the License, or (at your option) any later version.
 * 
 * This program 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 
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License 
 * along with this program; if not, write to the Free Software 
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 
 * 02111-1307 USA
 * ==================================================================
 * $Id$
 * ==================================================================
 */

package net.solarnetwork.node;

import java.util.concurrent.locks.Lock;

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

/**
 * Implementation of {@link DataCollector} that provides locking
 * functionality so that only one conversation at a time occurs for a given
 * serial port.
 * 
 * <p>The {@link Lock} passed to the constructor is assumed to be locked,
 * and the code using this class <b>must</b> call {@link #stopCollecting()}
 * to release the lock.</p>
 * 
 * @author matt
 * @version $Revision$
 */
public class PortLockedDataCollector implements DataCollector {

	private final DataCollector delegate;
	private final String port;
	private Lock lock;
	
	private final Logger log = LoggerFactory.getLogger(getClass());
	
	/**
	 * Construct using the default timeout values.
	 * 
	 * @param delegate the delegate
	 * @param port the port
	 * @param lock the lock (assumed to be locked already)
	 */
	public PortLockedDataCollector(DataCollector delegate, String port, Lock lock) {
		super();
		this.delegate = delegate;
		this.port = port;
		this.lock = lock;
	}

	public void collectData() {
		delegate.collectData();
	}

	public int bytesRead() {
		return delegate.bytesRead();
	}

	public byte[] getCollectedData() {
		return delegate.getCollectedData();
	}

	public String getCollectedDataAsString() {
		return delegate.getCollectedDataAsString();
	}

	public void stopCollecting() {
		try {
			delegate.stopCollecting();
		} finally {
			if ( lock != null ) {
				log.debug("Releasing port {} lock", port);
				lock.unlock();
				lock = null;
			}
		}
	}

	@Override
	protected void finalize() throws Throwable {
		if ( lock != null ) {
			lock.unlock();
			lock = null;
		}
		super.finalize();
	}

}