/*
 *                 Sun Public License Notice
 *
 * The contents of this file are subject to the Sun Public License
 * Version 1.0 (the "License"). You may not use this file except in
 * compliance with the License. A copy of the License is available at
 * http://www.sun.com/
 *
 * The Original Code is NetBeans. The Initial Developer of the Original
 * Code is Sun Microsystems, Inc. Portions Copyright 1997-2000 Sun
 * Microsystems, Inc. All Rights Reserved.
 */

package org.netbeans.modules.javacvs.caching;

/**
 * A watchdog class that lets to be only a specified number of commands to run at once..
 * 
 * @author  Milos Kleint
 */

import java.util.*;
import org.netbeans.modules.javacvs.commands.FileSystemCommand;


public class CommandLocker extends org.netbeans.modules.javacvs.events.CommandDisplayerAdapter {

    private LinkedList commandList;
    
    public static final int COMMAND_NUMBER = 7;
    /** Creates new RefreshLocker */
    public CommandLocker() {
        commandList = new LinkedList();
    }

    public void showFinishedCommand() {
        super.showFinishedCommand();
        removeFromQueue();
    }
    
    public void showExecutionFailed(Exception exception) {
        super.showExecutionFailed(exception);
        removeFromQueue();
    }
    
    public synchronized void removeFromQueue() {
        if (commandList.size() > COMMAND_NUMBER) {
            FileSystemCommand comm  = (FileSystemCommand)commandList.get(COMMAND_NUMBER);
            comm.startCommand();
        }
        // it actually doesn't matter which one is removed.. what counts is the size of the list
        commandList.removeFirst();
    }
    
    public synchronized void addToQueueAndRun(FileSystemCommand command) {
        commandList.addLast(command);
        command.addDisplayerListener(this);
        if (commandList.size() <= COMMAND_NUMBER) {
            command.startCommand();
        }
    }
}