StreamPumper.java

package gov.lanl.util;

/*
 * Copyright  2000,2002-2005 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.
 *
 */

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

// MODIFIED FROM ANT CVS HEAD:
//    http://cvs.apache.org/viewcvs.cgi/ant/src/main/org/apache/tools/ant/taskdefs/
/**
 * Copies all data from an input stream to an output stream.
 *
 * @since Ant 1.2
 */
public class StreamPumper implements Runnable {

    // TODO: make SIZE an instance variable.
    // TODO: add a status flag to note if an error occurred in run.

    private static final int SIZE = 128;
    private InputStream is;
    private OutputStream os;
    private volatile boolean finish;
    private volatile boolean finished;
    private boolean closeWhenExhausted;
    private boolean autoflush = false;

    /**
     * Create a new stream pumper.
     *
     * @param is input stream to read data from
     * @param os output stream to write data to.
     * @param closeWhenExhausted if true, the output stream will be closed when
     *        the input is exhausted.
     */
    public StreamPumper(InputStream is, OutputStream os,
                        boolean closeWhenExhausted) {
        this.is = is;
        this.os = os;
        this.closeWhenExhausted = closeWhenExhausted;
    }

    /**
     * Create a new stream pumper.
     *
     * @param is input stream to read data from
     * @param os output stream to write data to.
     */
    public StreamPumper(InputStream is, OutputStream os) {
        this(is, os, false);
    }

    /**
     * Set whether data should be flushed through to the output stream.
     * @param autoflush if true, push through data; if false, let it be buffered
     * @since Ant 1.6.3
     */
    /*package*/ void setAutoflush(boolean autoflush) {
        this.autoflush = autoflush;
    }

    /**
     * Copies data from the input stream to the output stream.
     *
     * Terminates as soon as the input stream is closed or an error occurs.
     */
    public void run() {
        finished = false;
        finish = false;

        final byte[] buf = new byte[SIZE];

        int length;
        try {
            while ((length = is.read(buf)) > 0 && !finish) {
                os.write(buf, 0, length);
                if (autoflush) {
                    os.flush();
                }
            }
            os.flush();
        } catch (Exception e) {
            // ignore errors
        } finally {
            if (closeWhenExhausted) {
                try {
                    os.close();
                } catch (IOException e) {
                    // ignore
                }
            }
            finished = true;
            synchronized (this) {
                notifyAll();
            }
        }
    }

    /**
     * Tells whether the end of the stream has been reached.
     * @return true is the stream has been exhausted.
     **/
    public boolean isFinished() {
        return finished;
    }

    /**
     * This method blocks until the stream pumper finishes.
     * @see #isFinished()
     **/
    public synchronized void waitFor()
        throws InterruptedException {
        while (!isFinished()) {
            wait();
        }
    }

    /**
     * Stop the pumper as soon as possible.
     * Note that it may continue to block on the input stream
     * but it will really stop the thread as soon as it gets EOF
     * or any byte, and it will be marked as finished.
     * @since Ant 1.6.3
     */
    /*package*/ synchronized void stop() {
        finish = true;
        notifyAll();
    }
}