TimeoutOutputStream.java

package gov.usgs.earthquake.util;

import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;

/**
 * An output stream that self-closes if the specified timeout elapses between
 * writes.
 */
public class TimeoutOutputStream extends FilterOutputStream implements Runnable {

    /** write timeout in milliseconds. */
    private final long timeout;
    /** thread that enforces timeout. */
    private final Thread timeoutThread;
    /** flag for timeoutThread to terminate. */
    private boolean closed = false;

    /**
     * Create a TimeoutOutputStream.
     * 
     * @param out
     *            the wrapped output stream.
     * @param timeout
     *            the timeout in milliseconds between writes. If this timeout
     *            completes, the underlying stream will be closed.
     */
    public TimeoutOutputStream(final OutputStream out, final long timeout) {
        super(out);
        this.timeout = timeout;
        this.timeoutThread = new Thread(this);
        this.timeoutThread.start();
    }

    @Override
    public void write(int b) throws IOException {
        // pass directly to underlying stream
        this.out.write(b);
        timeoutThread.interrupt();
    }

    @Override
    public void write(byte[] buf) throws IOException {
        // pass directly to underlying stream
        this.out.write(buf);
        timeoutThread.interrupt();
    }

    @Override
    public void write(byte[] buf, int offset, int length) throws IOException {
        // pass directly to underlying stream
        this.out.write(buf, offset, length);
        timeoutThread.interrupt();
    }

    @Override
    public void close() throws IOException {
        closed = true;
        try {
            super.close();
        } finally {
            // interrupt in case close called from outside timeoutThread
            timeoutThread.interrupt();
        }
    }

    @Override
    public void run() {
        while (!closed) {
            try {
                // wait for timeout milliseconds
                Thread.sleep(timeout);
                // timeout elapsed, close stream
                try {
                    close();
                } catch (IOException e) {
                }
            } catch (InterruptedException ie) {
                // a write occured
            }
        }
    }

}