src/java/org/apache/velocity/runtime/log/HoldingLogChute.java

package org.apache.velocity.runtime.log;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.    
 */

import java.util.Vector;
import java.util.Iterator;
import org.apache.velocity.runtime.RuntimeServices;

/**
 *  Pre-init logger.  I believe that this was suggested by
 *  Carsten Ziegeler <cziegeler@sundn.de> and
 *  Jeroen C. van Gelderen.  If this isn't correct, let me
 *  know as this was a good idea...
 *
 * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
 * @author <a href="mailto:nbubna@apache.org">Nathan Bubna</a>
 * @version $Id$
 * @since 1.5
 */
class HoldingLogChute implements LogChute
{
    private Vector pendingMessages = new Vector();
    private volatile boolean transferring = false;

    /**
     * @see org.apache.velocity.runtime.log.LogChute#init(org.apache.velocity.runtime.RuntimeServices)
     */
    public void init(RuntimeServices rs) throws Exception
    {
    }

    /**
     * Logs messages. All we do is store them until 'later'.
     *
     * @param level severity level
     * @param message complete error message
     */
    public synchronized void log(int level, String message)
    {
        if (!transferring)
        {
            Object[] data = new Object[2];
            data[0] = new Integer(level);
            data[1] = message;
            pendingMessages.addElement(data);
        }
    }

    /**
     * Logs messages and errors. All we do is store them until 'later'.
     *
     * @param level severity level
     * @param message complete error message
     * @param t the accompanying java.lang.Throwable
     */
    public synchronized void log(int level, String message, Throwable t)
    {
        if (!transferring)
        {
            Object[] data = new Object[3];
            data[0] = new Integer(level);
            data[1] = message;
            data[2] = t;
            pendingMessages.addElement(data);
        }
    }

    /**
     * @see org.apache.velocity.runtime.log.LogChute#isLevelEnabled(int)
     */
    public boolean isLevelEnabled(int level)
    {
        return true;
    }

    /**
     * Dumps the log messages this chute is holding into a new chute
     * @param newChute
     */
    public synchronized void transferTo(LogChute newChute)
    {
        if (!transferring && !pendingMessages.isEmpty())
        {
            // let the other methods know what's up
            transferring = true;

            // iterate and log each individual message...
            for(Iterator i = pendingMessages.iterator(); i.hasNext();)
            {
                Object[] data = (Object[])i.next();
                int level = ((Integer)data[0]).intValue();
                String message = (String)data[1];
                if (data.length == 2)
                {
                    newChute.log(level, message);
                }
                else
                {
                    newChute.log(level, message, (Throwable)data[2]);
                }
            }
        }
    }

}