OpenConcerto

Dépôt officiel du code source de l'ERP OpenConcerto
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svn://code.openconcerto.org/openconcerto

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/*
 * 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;

/**
 * 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) throws IOException {
        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);
        } 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;

    public ProcessStreams(final Process p) {
        this(p, System.out, System.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() {
            public void run() {
                try {
                    ProcessStreams.this.latch.await();
                } catch (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(Future<?> f) {
        if (f == null)
            return;
        // TODO
        // ATTN don't interrupt, hangs in readLine()
        f.cancel(false);
    }

    private final Future<?> writeToAsync(final InputStream ins, final Object outs) {
        if (outs == null) {
            this.latch.countDown();
            return null;
        }
        return this.exec.submit(new Callable<Object>() {
            public Object call() throws InterruptedException, IOException {
                try {
                    // PrintStream is also an OutputStream
                    if (outs instanceof PrintStream)
                        writeTo(ins, (PrintStream) outs);
                    else
                        StreamUtils.copy(ins, (OutputStream) outs);
                    ins.close();
                    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(InputStream ins, 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);
        }
    }

}