/*
 * $Header: /home/cvs/jakarta-commons/httpclient/src/test/org/apache/commons/httpclient/server/BidiStreamProxy.java,v 1.1.2.2 2004/02/22 18:21:18 olegk Exp $
 * $Revision: 1.1.2.2 $
 * $Date: 2004/02/22 18:21:18 $
 *
 * ====================================================================
 *
 *  Copyright 1999-2004 The Apache Software Foundation
 *
 *  Licensed 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * .
 *
 * [Additional notices, if required by prior licensing conditions]
 *
 */

package org.apache.commons.httpclient.server;

import java.io.InputStream;
import java.io.OutputStream;

/**
 * Pumps data between a pair of input / output streams. Used to
 * connect the two ends (left and right) of a bidirectional communication channel.
 * Instances of this class are thread safe.
 * 
 * @author Ortwin Glueck
 */
class BidiStreamProxy {
    private StreamProxy leftToRight, rightToLeft;
    private int state = 0;
    
    /**
     * Sets up a new connection between two peers (left and right)
     * @param leftIn input channel of the left peer
     * @param leftOut output channel of the left peer
     * @param rightIn input channel of the right peer
     * @param rightOut output channel of the right peer
     */
    public BidiStreamProxy(InputStream leftIn, OutputStream leftOut, InputStream rightIn, OutputStream rightOut) {
        leftToRight = new StreamProxy(leftIn, rightOut);
        rightToLeft = new StreamProxy(rightIn, leftOut);
    }
    
    /**
     * Starts pumping the information from left to right and vice versa.
     * This is performed asynchronously so this method returns immediately.
     */
    public synchronized void start() {
        if (state != 0) throw new IllegalStateException("Can not start twice");
        leftToRight.start();
        rightToLeft.start();
        state = 1;
    }
    
    /**
     * Aborts the communication between the peers and releases all resources.
     * Note: The method does not wait for the pump threads to terminate.
     */
    public synchronized void abort() {
        if (leftToRight != null) leftToRight.abort();
        if (rightToLeft != null)  rightToLeft.abort();
        leftToRight = null;
        rightToLeft = null;
    }
    
    /**
     * Blocks until all data has been copied. Basically calls the 
     * join method on the pump thread.
     * @throws InterruptedException
     */
    public void block() throws InterruptedException {
        if (state != 1) throw new IllegalStateException("Can not block before started");
        leftToRight.block();
        rightToLeft.block();
    }
}