public TwillContainerController start()

in twill-core/src/main/java/org/apache/twill/internal/TwillContainerLauncher.java [83:154]
56 lines of code
7 McCabe index (conditional complexity)

  public TwillContainerController start(RunId runId, int instanceId, Class<?> mainClass, String classPath) {
    // Clean up zookeeper path in case this is a retry and there are old messages and state there.
    Futures.getUnchecked(ZKOperations.ignoreError(
      ZKOperations.recursiveDelete(zkClient, "/" + runId), KeeperException.NoNodeException.class, null));

    // Adds all file to be localized to container
    launchContext.addResources(runtimeSpec.getLocalFiles());

    // Optionally localize secure store.
    try {
      if (secureStoreLocation != null && secureStoreLocation.exists()) {
        launchContext.addResources(new DefaultLocalFile(Constants.Files.CREDENTIALS,
                                                        secureStoreLocation.toURI(),
                                                        secureStoreLocation.lastModified(),
                                                        secureStoreLocation.length(), false, null));
      }
    } catch (IOException e) {
      LOG.warn("Failed to launch container with secure store {}.", secureStoreLocation);
    }

    // Currently no reporting is supported for runnable containers
    launchContext
      .addEnvironment(EnvKeys.TWILL_RUN_ID, runId.getId())
      .addEnvironment(EnvKeys.TWILL_RUNNABLE_NAME, runtimeSpec.getName())
      .addEnvironment(EnvKeys.TWILL_INSTANCE_ID, Integer.toString(instanceId))
      .addEnvironment(EnvKeys.TWILL_INSTANCE_COUNT, Integer.toString(instanceCount));

    // assemble the command based on jvm options
    ImmutableList.Builder<String> commandBuilder = ImmutableList.builder();
    String firstCommand;
    if (jvmOpts.getDebugOptions().doDebug(runtimeSpec.getName())) {
      // for debugging we run a quick Java program to find a free port, then pass that port as the debug port and also
      // as a System property to the runnable (Java has no general way to determine the port from within the JVM).
      // PORT=$(java FindFreePort) && java -agentlib:jdwp=...,address=\$PORT -Dtwill.debug.port=\$PORT... TwillLauncher
      // The $ must be escaped, otherwise it gets expanded (to "") before the command is submitted.
      String suspend = jvmOpts.getDebugOptions().doSuspend() ? "y" : "n";
      firstCommand = "TWILL_DEBUG_PORT=$($JAVA_HOME/bin/java";
      commandBuilder.add("-cp", Constants.Files.LAUNCHER_JAR,
                         FindFreePort.class.getName() + ")",
                         "&&", // this will stop if FindFreePort fails
                         "$JAVA_HOME/bin/java",
                         "-agentlib:jdwp=transport=dt_socket,server=y,suspend=" + suspend + "," +
                           "address=\\$TWILL_DEBUG_PORT",
                         "-Dtwill.debug.port=\\$TWILL_DEBUG_PORT"
                         );
    } else {
      firstCommand = "$JAVA_HOME/bin/java";
    }

    int memory = Resources.computeMaxHeapSize(containerInfo.getMemoryMB(), reservedMemory, Constants.HEAP_MIN_RATIO);
    commandBuilder.add("-Djava.io.tmpdir=tmp",
                       "-Dyarn.container=$" + EnvKeys.YARN_CONTAINER_ID,
                       "-Dtwill.runnable=$" + EnvKeys.TWILL_APP_NAME + ".$" + EnvKeys.TWILL_RUNNABLE_NAME,
                       "-cp", Constants.Files.LAUNCHER_JAR + ":" + classPath,
                       "-Xmx" + memory + "m");
    if (jvmOpts.getExtraOptions() != null) {
      commandBuilder.add(jvmOpts.getExtraOptions());
    }
    commandBuilder.add(TwillLauncher.class.getName(),
                       Constants.Files.CONTAINER_JAR,
                       mainClass.getName(),
                       Boolean.TRUE.toString());
    List<String> command = commandBuilder.build();

    ProcessController<Void> processController = launchContext
      .addCommand(firstCommand, command.toArray(new String[command.size()]))
      .launch();

    TwillContainerControllerImpl controller = new TwillContainerControllerImpl(zkClient, runId, processController);
    controller.start();
    return controller;
  }