Dépôt officiel du code source de l'ERP OpenConcerto

/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

 *

 * Copyright 2011 OpenConcerto, by ILM Informatique. All rights reserved.

 *

 * The contents of this file are subject to the terms of the GNU General Public License Version 3

 * only ("GPL"). You may not use this file except in compliance with the License. You can obtain a

 * copy of the License at http://www.gnu.org/licenses/gpl-3.0.html See the License for the specific

 * language governing permissions and limitations under the License.

 *

 * When distributing the software, include this License Header Notice in each file.

 */

 package org.openconcerto.utils;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.OutputStream;

import java.io.PrintStream;

import java.lang.ProcessBuilder.Redirect;

import java.util.concurrent.Callable;

import java.util.concurrent.CountDownLatch;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.Future;

import java.util.function.Supplier;

/**

 * Redirect streams of a process to System.out and System.err.

 *

 * @author Sylvain

 */

public class ProcessStreams {

    static public enum Action {

        /**

         * Redirect process streams to ours.

         *

         * @deprecated use {@link ProcessStreams#redirect(ProcessBuilder)} (or

         *             {@link Redirect#INHERIT} directly) as it makes sure that

         *             {@link Process#waitFor()} only returns once all streams are flushed.

         */

        REDIRECT,

        /**

         * Consume streams.

         */

        CONSUME,

        /**

         * Close process streams. NOTE : some programs might fail (e.g. route on FreeBSD), in those

         * cases use {@link #CONSUME}.

         */

        CLOSE,

        /**

         * Do nothing, which is dangerous as the process will hang until its output is read.

         */

        DO_NOTHING

    }

    // Added to Java 9

    public static final Redirect DISCARD = Redirect.to(StreamUtils.NULL_FILE);

    static public final ProcessBuilder redirect(final ProcessBuilder pb) {

        return pb.redirectErrorStream(true).redirectOutput(Redirect.INHERIT);

    }

    static public final Process handle(final Process p, final Action action) throws IOException {

        if (action == Action.CLOSE) {

            p.getInputStream().close();

            p.getErrorStream().close();

        } else if (action == Action.REDIRECT) {

            new ProcessStreams(p, System.out, System.err);

        } else if (action == Action.CONSUME) {

            new ProcessStreams(p, StreamUtils.NULL_OS, StreamUtils.NULL_OS);

        }

        return p;

    }

    private final ExecutorService exec = Executors.newFixedThreadPool(2);

    private final CountDownLatch latch;

    private final Future<?> out;

    private final Future<?> err;

    /**

     * Create a new instance and start reading from the passed process. If a passed

     * {@link OutputStream} is <code>null</code>, then the corresponding {@link InputStream} is not

     * used at all, so the caller should handle it. If the output must be discarded, use

     * {@link StreamUtils#NULL_OS}.

     *

     * @param p the process to read from.

     * @param out where to write the {@link Process#getInputStream() standard output}.

     * @param err where to write the {@link Process#getErrorStream() standard error}.

     */

    public ProcessStreams(final Process p, final OutputStream out, final OutputStream err) {

        this.latch = new CountDownLatch(2);

        this.out = writeToAsync(p::getInputStream, out);

        this.err = writeToAsync(p::getErrorStream, err);

        this.exec.submit(new Runnable() {

            @Override

            public void run() {

                try {

                    ProcessStreams.this.latch.await();

                } catch (final InterruptedException e) {

                    // ne rien faire

                    e.printStackTrace();

                } finally {

                    ProcessStreams.this.exec.shutdown();

                }

            }

        });

    }

    protected final void stopOut() {

        this.stop(this.out);

    }

    protected final void stopErr() {

        this.stop(this.err);

    }

    private final void stop(final Future<?> f) {

        if (f == null)

            return;

        // TODO

        // ATTN don't interrupt, hangs in readLine()

        f.cancel(false);

    }

    private final Future<?> writeToAsync(final Supplier<InputStream> insSupplier, final Object outs) {

        if (outs == null) {

            this.latch.countDown();

            return null;

        }

        return this.exec.submit(new Callable<Object>() {

            @Override

            public Void call() throws InterruptedException, IOException {

                try (final InputStream ins = insSupplier.get()) {

                    // PrintStream is also an OutputStream

                    if (outs instanceof PrintStream)

                        writeTo(ins, (PrintStream) outs);

                    else

                        StreamUtils.copy(ins, (OutputStream) outs);

                    return null;

                } finally {

                    ProcessStreams.this.latch.countDown();

                }

            }

        });

    }

    /**

     * Copy ins to outs, line by line.

     *

     * @param ins the source.

     * @param outs the destination.

     * @throws InterruptedException if current thread is interrupted.

     * @throws IOException if I/O error.

     */

    public static final void writeTo(final InputStream ins, final PrintStream outs) throws InterruptedException, IOException {

        final BufferedReader r = new BufferedReader(new InputStreamReader(ins));

        String encodedName;

        while ((encodedName = r.readLine()) != null) {

            if (Thread.currentThread().isInterrupted()) {

                throw new InterruptedException();

            }

            outs.println(encodedName);

        }

    }

}