Ant example source code file (OutputStreamFunneler.java)

This example Ant source code file (OutputStreamFunneler.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Ant tags/keywords

default_timeout_millis, funnel, funnel, illegalargumentexception, interruptedexception, io, ioexception, ioexception, outputstream, outputstream, outputstreamfunneler, outputstreamfunneler, the

The OutputStreamFunneler.java source code

/*
 *  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.tools.ant.util;

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

/**
 * Manages a set of <code>OutputStreams to
 * write to a single underlying stream, which is
 * closed only when the last "funnel"
 * has been closed.
 */
public class OutputStreamFunneler {

    /**
     * Default timeout.
     * @see #setTimeout(long)
     */
    public static final long DEFAULT_TIMEOUT_MILLIS = 1000;

    private final class Funnel extends OutputStream {
        private boolean closed = false;

        private Funnel() {
            synchronized (OutputStreamFunneler.this) {
                ++count;
            }
        }

        public void flush() throws IOException {
            synchronized (OutputStreamFunneler.this) {
                dieIfClosed();
                out.flush();
            }
        }

        public void write(int b) throws IOException {
            synchronized (OutputStreamFunneler.this) {
                dieIfClosed();
                out.write(b);
            }
        }

        public void write(byte[] b) throws IOException {
            synchronized (OutputStreamFunneler.this) {
                dieIfClosed();
                out.write(b);
            }
        }

        public void write(byte[] b, int off, int len) throws IOException {
            synchronized (OutputStreamFunneler.this) {
                dieIfClosed();
                out.write(b, off, len);
            }
        }

        public void close() throws IOException {
            release(this);
        }
    }

    private OutputStream out;
    private int count = 0;
    private boolean closed;
    private long timeoutMillis;

    /**
     * Create a new <code>OutputStreamFunneler for
     * the specified <code>OutputStream.
     * @param out   <code>OutputStream.
     */
    public OutputStreamFunneler(OutputStream out) {
        this(out, DEFAULT_TIMEOUT_MILLIS);
    }

    /**
     * Create a new <code>OutputStreamFunneler for
     * the specified <code>OutputStream, with the
     * specified timeout value.
     * @param out             <code>OutputStream.
     * @param timeoutMillis   <code>long.
     * @see #setTimeout(long)
     */
    public OutputStreamFunneler(OutputStream out, long timeoutMillis) {
        if (out == null) {
            throw new IllegalArgumentException(
                "OutputStreamFunneler.<init>:  out == null");
        }
        this.out = out;
        this.closed = false; //as far as we know
        setTimeout(timeoutMillis);
    }

    /**
     * Set the timeout for this <code>OutputStreamFunneler.
     * This is the maximum time that may elapse between the closure
     * of the last "funnel" and the next call to
     * <code>getOutputStream() without closing the
     * underlying stream.
     * @param timeoutMillis   <code>long timeout value.
     */
    public synchronized void setTimeout(long timeoutMillis) {
        this.timeoutMillis = timeoutMillis;
    }

    /**
     * Get a "funnel" <code>OutputStream instance to
     * write to this <code>OutputStreamFunneler's underlying
     * <code>OutputStream.
     * @return <code>OutputStream.
     * @throws IOException if unable to create the funnel.
     */
    public synchronized OutputStream getFunnelInstance()
        throws IOException {
        dieIfClosed();
        try {
            return new Funnel();
        } finally {
            notifyAll();
        }
    }

    private synchronized void release(Funnel funnel) throws IOException {
        //ignore release of an already-closed funnel
        if (!funnel.closed) {
            try {
                if (timeoutMillis > 0) {
                    try {
                        wait(timeoutMillis);
                    } catch (InterruptedException eyeEx) {
                        //ignore
                    }
                }
                if (--count == 0) {
                    close();
                }
            } finally {
                funnel.closed = true;
            }
        }
   }

    private synchronized void close() throws IOException {
        try {
            dieIfClosed();
            out.close();
        } finally {
            closed = true;
        }
    }

    private synchronized void dieIfClosed() throws IOException {
        if (closed) {
            throw new IOException("The funneled OutputStream has been closed.");
        }
    }

}