PipeStream.java

/**
 * Copyright 2005-2014 Restlet
 * 
 * The contents of this file are subject to the terms of one of the following
 * open source licenses: Apache 2.0 or or EPL 1.0 (the "Licenses"). You can
 * select the license that you prefer but you may not use this file except in
 * compliance with one of these Licenses.
 * 
 * You can obtain a copy of the Apache 2.0 license at
 * http://www.opensource.org/licenses/apache-2.0
 * 
 * You can obtain a copy of the EPL 1.0 license at
 * http://www.opensource.org/licenses/eclipse-1.0
 * 
 * See the Licenses for the specific language governing permissions and
 * limitations under the Licenses.
 * 
 * Alternatively, you can obtain a royalty free commercial license with less
 * limitations, transferable or non-transferable, directly at
 * http://restlet.com/products/restlet-framework
 * 
 * Restlet is a registered trademark of Restlet S.A.S.
 */

package org.restlet.engine.io;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.TimeUnit;

// [excludes gwt]
/**
 * Pipe stream that pipes output streams into input streams. Implementation
 * based on a shared synchronized queue.
 * 
 * @author Jerome Louvel
 */
public class PipeStream {

    /** The queue timeout. */
    private static final long QUEUE_TIMEOUT = 5;

    /** The supporting synchronized queue. */
    private final BlockingQueue<Integer> queue;

    /** Constructor. */
    public PipeStream() {
        this.queue = new ArrayBlockingQueue<Integer>(1024);
    }

    /**
     * Returns a new input stream that can read from the pipe.
     * 
     * @return A new input stream that can read from the pipe.
     */
    public InputStream getInputStream() {
        return new InputStream() {
            private boolean endReached = false;

            @Override
            public int read() throws IOException {
                try {
                    if (this.endReached) {
                        return -1;
                    }

                    final Integer value = queue.poll(QUEUE_TIMEOUT,
                            TimeUnit.SECONDS);

                    if (value == null) {
                        throw new IOException(
                                "Timeout while reading from the queue-based input stream");
                    } else {
                        this.endReached = (value == -1);
                        return value.intValue();
                    }
                } catch (InterruptedException ie) {
                    throw new IOException(
                            "Interruption occurred while writing in the queue");
                }
            }
        };
    }

    /**
     * Returns a new output stream that can write into the pipe.
     * 
     * @return A new output stream that can write into the pipe.
     */
    public OutputStream getOutputStream() {
        return new OutputStream() {
            @Override
            public void write(int b) throws IOException {
                try {
                    if (!queue.offer(b & 0xff, QUEUE_TIMEOUT, TimeUnit.SECONDS)) {
                        throw new IOException(
                                "Timeout while writing to the queue-based output stream");
                    }
                } catch (InterruptedException ie) {
                    throw new IOException(
                            "Interruption occurred while writing in the queue");
                }
            }

            @Override
            public void close() throws IOException {
                try {
                    if (!queue.offer(-1, QUEUE_TIMEOUT, TimeUnit.SECONDS)) {
                        throw new IOException(
                                "Timeout while writing to the queue-based output stream");
                    }
                } catch (InterruptedException ie) {
                    throw new IOException(
                            "Interruption occurred while writing in the queue");
                }
            }
        };
    }

}