org.galicaster.dashboard.snapshot.GstreamerSnapshotTaker.java Source code

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Here is the source code for org.galicaster.dashboard.snapshot.GstreamerSnapshotTaker.java

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/**
 * Copyright (c) 2013, Teltek Video Research <galicaster@teltek.es>
 *
 * This work is licensed under the Creative Commons Attribution-
 * NonCommercial-ShareAlike 3.0 Unported License. To view a copy of 
 * this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/ 
 * or send a letter to Creative Commons, 171 Second Street, Suite 300, 
 * San Francisco, California, 94105, USA.
 *
 */

package org.galicaster.dashboard.snapshot;

import org.opencastproject.capture.admin.api.Agent;

import org.apache.commons.io.FileUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.IOException;
import java.util.LinkedList;
import java.util.List;
import java.util.Scanner;
import java.util.concurrent.Callable;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * This class implements a simple "snapshot taker" based on a Gstramer pipeline that connects via VNC to capture the screen
 *
 */
public class GstreamerSnapshotTaker implements Callable<File> {

    private static final Logger logger = LoggerFactory.getLogger(GstreamerSnapshotTaker.class);
    private static final String EXEC_NAME = "gst-launch";
    public static final String DEFAULT_RFB_VERSION = "3.0";

    /** Default extension for the snapshots extracted from the agents*/
    public static final String IMAGE_EXTENSION = ".png";

    private File destFile;
    private Agent agent;
    private String password, rfbVersion;

    Process p = null;

    public static final String pipeStr = "%s "
            + "rfbsrc host=\"%s\" view-only=true password=\"%s\" version=\"%s\" num-buffers=1 ! "
            + "ffmpegcolorspace ! " + "pngenc ! " + "filesink location=\"%s\"";

    public GstreamerSnapshotTaker(Agent agent, File destDir) throws IOException {
        this(agent, destDir, null, null);
    }

    public GstreamerSnapshotTaker(Agent agent, File destDir, String password) throws IOException {
        this(agent, destDir, password, null);
    }

    public GstreamerSnapshotTaker(Agent agent, File destDir, String password, String rfbVersion)
            throws IOException {

        if (agent == null)
            throw new NullPointerException("The agent must not be null");

        this.destFile = new File(destDir, agent.getName() + IMAGE_EXTENSION);
        this.agent = agent;
        this.password = password == null ? "" : password;
        this.rfbVersion = rfbVersion == null ? DEFAULT_RFB_VERSION : rfbVersion;
    };

    @Override
    public File call() {

        // Marks the file to be deleted on exist, if an error occurred
        boolean deleteOnExit = true;

        ProcessBuilder pb = new ProcessBuilder(splitCommandArguments(String.format(pipeStr, EXEC_NAME,
                agent.getUrl(), password, rfbVersion, destFile.getAbsolutePath())));

        Scanner s = null;
        try {
            p = pb.start();

            if (p.waitFor() != 0) {
                s = new Scanner(p.getErrorStream()).useDelimiter("\\A");
                String error = s.hasNext() ? s.next() : "";

                error = String.format("The subprocess returned error code %s: %s", p.exitValue(), error);
                logger.error(error);
                throw new RuntimeException(error);
            }

            if (!destFile.isFile())
                throw new RuntimeException("The subprocess did not create a file");

            deleteOnExit = false;

            return destFile;

        } catch (IOException e) {
            logger.error("Error when initiating the helper subprocess: {}", e.getMessage());
            throw new RuntimeException("Error when initiating the helper subprocess.", e);
        } catch (InterruptedException e) {
            logger.error("The subprocess was unexpectedly interrupted: {}", e.getMessage());
            throw new RuntimeException("The subprocess was unexpectedly interrupted.", e);
        } finally {
            if (s != null)
                s.close();
            if (deleteOnExit)
                FileUtils.deleteQuietly(destFile);
        }

    }

    /**
     * Interrupts the pipeline
     */
    public void interrupt() {
        p.destroy();
    }

    // This pattern matches:
    // - Any set of non-whitespaces that aren't surrounded by quotation marks (either single or double).
    // - Any set of characters, either whitespace or not, surrounded by single or double quotation marks.
    // - A combination of both (as in file('this is a file').
    // Please note:
    // - Escaped quotation marks are treated as normal characters (i.e. do not mark the beginning nor the end of a quoted area).
    // - Nesting quotation marks of different types has no effect (i.e. "this sentence 'matches fully'" and 'this sentence "also does" ').
    // - The quotation marks, if they are present, are not removed.
    // - The capture group 2, if not null, matches the last quoted part found, without the quotation marks..
    //   So, if the group 2's length equals the whole match length minus 2, then the group 2 equals the whole match without the quotation marks.
    private static final Pattern pattern = Pattern.compile("(?:(?:(?<!\\\\)([\'\"])(.*?)(?<!\\\\)\\1)|\\S)+");

    private List<String> splitCommandArguments(final String commandline) {
        final List<String> list = new LinkedList<String>();

        final Matcher m = pattern.matcher(commandline);

        while (m.find()) {
            // We want to remove the outer quotation marks only if the whole match is quoted.
            // For instance, in  param="This is the param", the last quotation mark shouldn't be removed.
            if ((m.group(2) != null) && (m.group(2).length() == m.group().length() - 2))
                list.add(m.group(2));
            else
                list.add(m.group());
        }
        return list;
    }
}