tikhomirov@610: /*
tikhomirov@610:  * Copyright (c) 2013 TMate Software Ltd
tikhomirov@610:  *  
tikhomirov@610:  * This program is free software; you can redistribute it and/or modify
tikhomirov@610:  * it under the terms of the GNU General Public License as published by
tikhomirov@610:  * the Free Software Foundation; version 2 of the License.
tikhomirov@610:  *
tikhomirov@610:  * This program is distributed in the hope that it will be useful,
tikhomirov@610:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
tikhomirov@610:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
tikhomirov@610:  * GNU General Public License for more details.
tikhomirov@610:  *
tikhomirov@610:  * For information on how to redistribute this software under
tikhomirov@610:  * the terms of a license other than GNU General Public License
tikhomirov@610:  * contact TMate Software at support@hg4j.com
tikhomirov@610:  */
tikhomirov@610: package org.tmatesoft.hg.internal;
tikhomirov@610: 
tikhomirov@610: import java.io.File;
tikhomirov@610: 
tikhomirov@610: /**
tikhomirov@610:  * This shall become interface/abstract class accessible from SessionContext,
tikhomirov@610:  * with plugable implementations, e.g. Java7 (file monitoring facilities) based,
tikhomirov@610:  * or any other convenient means. It shall allow both "check at the moment asked" 
tikhomirov@610:  * and "collect changes and dispatch on demand" implementation approaches, so that
tikhomirov@610:  * implementors may use best available technology   
tikhomirov@610:  * 
tikhomirov@610:  * @author Artem Tikhomirov
tikhomirov@610:  * @author TMate Software Ltd.
tikhomirov@610:  */
tikhomirov@610: public class FileChangeMonitor {
tikhomirov@610: 	private final File file;
tikhomirov@610: 	private long lastModified;
tikhomirov@610: 	private long length;
tikhomirov@610: 	
tikhomirov@610: 	/**
tikhomirov@610: 	 * First round: support for 1-monitor-1-file only
tikhomirov@610: 	 * Next round: 1-monitor-N files
tikhomirov@610: 	 */
tikhomirov@610: 	public FileChangeMonitor(File f) {
tikhomirov@610: 		file = f;
tikhomirov@610: 	}
tikhomirov@610: 	
tikhomirov@610: 	// shall work for files that do not exist
tikhomirov@610: 	public void touch(Object source) {
tikhomirov@610: 		lastModified = file.lastModified();
tikhomirov@610: 		length = file.length();
tikhomirov@610: 	}
tikhomirov@610: 	
tikhomirov@610: 	public void check(Object source, Action onChange) {
tikhomirov@610: 		if (changed(source)) {
tikhomirov@610: 			onChange.changed();
tikhomirov@610: 		}
tikhomirov@610: 	}
tikhomirov@610: 
tikhomirov@610: 	public boolean changed(Object source) {
tikhomirov@610: 		if (file.lastModified() != lastModified) {
tikhomirov@610: 			return true;
tikhomirov@610: 		}
tikhomirov@610: 		return file.length() != length; 
tikhomirov@610: 	}
tikhomirov@610: 	
tikhomirov@610: 	public interface Action {
tikhomirov@610: 		public void changed();
tikhomirov@610: 	}
tikhomirov@610: }