private void saveLauncher()

in twill-yarn/src/main/java/org/apache/twill/yarn/YarnTwillPreparer.java [548:589]
35 lines of code
4 McCabe index (conditional complexity)

  private void saveLauncher(Map<String, LocalFile> localFiles) throws URISyntaxException, IOException {

    LOG.debug("Create and copy {}", Constants.Files.LAUNCHER_JAR);
    Location location = createTempLocation(Constants.Files.LAUNCHER_JAR);

    final String launcherName = TwillLauncher.class.getName();
    final String portFinderName = FindFreePort.class.getName();

    // Create a jar file with the TwillLauncher optionally a json serialized classpath.json in it.
    // Also a little utility to find a free port, used for debugging.
    final JarOutputStream jarOut = new JarOutputStream(location.getOutputStream());
    ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
    if (classLoader == null) {
      classLoader = getClass().getClassLoader();
    }
    Dependencies.findClassDependencies(classLoader, new ClassAcceptor() {
      @Override
      public boolean accept(String className, URL classUrl, URL classPathUrl) {
        Preconditions.checkArgument(className.startsWith(launcherName) || className.equals(portFinderName),
                                    "Launcher jar should not have dependencies: %s", className);
        try {
          jarOut.putNextEntry(new JarEntry(className.replace('.', '/') + ".class"));
          try (InputStream is = classUrl.openStream()) {
            ByteStreams.copy(is, jarOut);
          }
        } catch (IOException e) {
          throw Throwables.propagate(e);
        }
        return true;
      }
    }, launcherName, portFinderName);

    try {
      addClassPaths(Constants.CLASSPATH, classPaths, jarOut);
      addClassPaths(Constants.APPLICATION_CLASSPATH, applicationClassPaths, jarOut);
    } finally {
      jarOut.close();
    }
    LOG.debug("Done {}", Constants.Files.LAUNCHER_JAR);

    localFiles.put(Constants.Files.LAUNCHER_JAR, createLocalFile(Constants.Files.LAUNCHER_JAR, location));
  }