org.opentripplanner.framework.application.ApplicationShutdownSupport Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of otp Show documentation

The OpenTripPlanner multimodal journey planning system

The newest version!

package org.opentripplanner.framework.application;

import java.util.Optional;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Utility class for managing application shutdown.
 */
public final class ApplicationShutdownSupport {

  private static final Logger LOG = LoggerFactory.getLogger(ApplicationShutdownSupport.class);

  private ApplicationShutdownSupport() {}

  /**
   * Attempt to add a shutdown hook. If the application is already shutting down, the shutdown hook
   * will be executed immediately.
   *
   * @param hookName the name of the thread
   * @param shutdownHook the payload to be executed in the thread
   * @return an Optional possibly containing the created thread, needed to un-schedule the shutdown hook
   */
  public static Optional addShutdownHook(String hookName, Runnable shutdownHook) {
    final Thread shutdownThread = new Thread(shutdownHook, hookName);
    try {
      LOG.info("Adding shutdown hook '{}'.", hookName);
      Runtime.getRuntime().addShutdownHook(shutdownThread);
      return Optional.of(shutdownThread);
    } catch (IllegalStateException ignore) {
      LOG.info("OTP is already shutting down, running shutdown hook '{}' immediately.", hookName);
      shutdownThread.start();
    }
    return Optional.empty();
  }

  /**
   * Remove a previously scheduled shutdown hook.
   *
   * @param shutdownThread an Optional possibly containing a thread
   */
  public static void removeShutdownHook(Thread shutdownThread) {
    LOG.info("Removing shutdown hook '{}'.", shutdownThread.getName());
    Runtime.getRuntime().removeShutdownHook(shutdownThread);
  }
}