/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.core.util;

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

import ch.qos.logback.core.CoreConstants;

/**
 * Static utility methods for manipulating an {@link ExecutorService}.
 * 
 * @author Carl Harris
 * @author Mikhail Mazursky
 */
public class ExecutorServiceUtil {

  private static final ThreadFactory THREAD_FACTORY = new ThreadFactory() {

    private final ThreadFactory defaultFactory = Executors.defaultThreadFactory();
    private final AtomicInteger threadNumber = new AtomicInteger(1);

    public Thread newThread(Runnable r) {
      Thread thread = defaultFactory.newThread(r);
      if (!thread.isDaemon()) {
        thread.setDaemon(true);
      }
      thread.setName("logback-" + threadNumber.getAndIncrement());
      return thread;
    }
  };

  /**
   * Creates an executor service suitable for use by logback components.
   * @return executor service
   */
  static public ExecutorService newExecutorService() {
    return new ThreadPoolExecutor(CoreConstants.CORE_POOL_SIZE, 
        CoreConstants.MAX_POOL_SIZE,
        0L, TimeUnit.MILLISECONDS,
        new SynchronousQueue<Runnable>(),
        THREAD_FACTORY);
  }
  
  /**
   * Shuts down an executor service.
   * <p>
   * @param executorService the executor service to shut down
   */
  static public void shutdown(ExecutorService executorService) {
    executorService.shutdownNow();
  }

}
