core/src/main/java/org/apache/mina/handler/StreamIoHandler.java

/*
 *  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. 
 *  
 */
package org.apache.mina.handler;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.SocketTimeoutException;

import org.apache.mina.common.ByteBuffer;
import org.apache.mina.common.IdleStatus;
import org.apache.mina.common.IoHandler;
import org.apache.mina.common.IoHandlerAdapter;
import org.apache.mina.common.IoSession;
import org.apache.mina.handler.support.IoSessionInputStream;
import org.apache.mina.handler.support.IoSessionOutputStream;
import org.apache.mina.util.SessionLog;

/**
 * A {@link IoHandler} that adapts asynchronous MINA events to stream I/O.
 * <p>
 * Please extend this class and implement
 * {@link #processStreamIo(IoSession, InputStream, OutputStream)} to
 * execute your stream I/O logic; <b>please note that you must forward
 * the process request to other thread or thread pool.</b>
 * 
 * @author The Apache Directory Project (mina-dev@directory.apache.org)
 * @version $Rev$, $Date$
 */
public abstract class StreamIoHandler extends IoHandlerAdapter
{
    private static final String KEY_IN = StreamIoHandler.class.getName() + ".in";
    private static final String KEY_OUT = StreamIoHandler.class.getName() + ".out";
    
    private int readTimeout;
    private int writeTimeout;
    
    protected StreamIoHandler()
    {
    }
    
    /**
     * Implement this method to execute your stream I/O logic;
     * <b>please note that you must forward the process request to other
     * thread or thread pool.</b>
     */
    protected abstract void processStreamIo( IoSession session,
                                             InputStream in, OutputStream out );
    
    /**
     * Returns read timeout in seconds.
     * The default value is <tt>0</tt> (disabled).
     */
    public int getReadTimeout()
    {
        return readTimeout;
    }
    
    /**
     * Sets read timeout in seconds.
     * The default value is <tt>0</tt> (disabled).
     */
    public void setReadTimeout( int readTimeout )
    {
        this.readTimeout = readTimeout;
    }
    
    /**
     * Returns write timeout in seconds.
     * The default value is <tt>0</tt> (disabled).
     */
    public int getWriteTimeout()
    {
        return writeTimeout;
    }
    
    /**
     * Sets write timeout in seconds.
     * The default value is <tt>0</tt> (disabled).
     */
    public void setWriteTimeout( int writeTimeout )
    {
        this.writeTimeout = writeTimeout;
    }

    /**
     * Initializes streams and timeout settings.
     */
    public void sessionOpened( IoSession session )
    {
        // Set timeouts
        session.setWriteTimeout( writeTimeout );
        session.setIdleTime( IdleStatus.READER_IDLE, readTimeout );

        // Create streams
        InputStream in = new IoSessionInputStream();
        OutputStream out = new IoSessionOutputStream( session );
        session.setAttribute( KEY_IN, in );
        session.setAttribute( KEY_OUT, out );
        processStreamIo( session, in, out );
    }

    /**
     * Closes streams
     */
    public void sessionClosed( IoSession session ) throws Exception
    {
        final InputStream in = ( InputStream ) session.getAttribute( KEY_IN );
        final OutputStream out = ( OutputStream ) session.getAttribute( KEY_OUT );
        try
        {
            in.close();
        }
        finally
        {
            out.close();
        }
    }
    
    /**
     * Forwards read data to input stream.
     */
    public void messageReceived( IoSession session, Object buf )
    {
        final IoSessionInputStream in = ( IoSessionInputStream ) session.getAttribute( KEY_IN );
        in.write( ( ByteBuffer ) buf );
    }

    /**
     * Forwards caught exceptions to input stream.
     */
    public void exceptionCaught( IoSession session, Throwable cause )
    {
        final IoSessionInputStream in = ( IoSessionInputStream ) session.getAttribute( KEY_IN );
        
        IOException e = null;
        if( cause instanceof StreamIoException )
        {
            e = ( IOException ) cause.getCause();
        }
        else if( cause instanceof IOException )
        {
            e = ( IOException ) cause;
        }
        
        if( e != null && in != null )
        {
            in.throwException( e );
        }
        else
        {
            SessionLog.warn( session, "Unexpected exception.", cause );
            session.close();
        }
    }

    /**
     * Handles read timeout.
     */
    public void sessionIdle( IoSession session, IdleStatus status )
    {
        if( status == IdleStatus.READER_IDLE )
        {
            throw new StreamIoException(
                    new SocketTimeoutException( "Read timeout" ) );
        }
    }

    private static class StreamIoException extends RuntimeException
    {
        private static final long serialVersionUID = 3976736960742503222L;

        public StreamIoException( IOException cause )
        {
            super(cause);
        }
    }
}