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/*
 * Druid - a distributed column store.
 * Copyright (C) 2012, 2013  Metamarkets Group Inc.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

package io.druid.concurrent;

import com.google.common.util.concurrent.ThreadFactoryBuilder;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

/**
 */
public class Execs
{
  public static ExecutorService singleThreaded(String nameFormat)
  {
    return Executors.newSingleThreadExecutor(makeThreadFactory(nameFormat));
  }

  public static ExecutorService multiThreaded(int threads, String nameFormat)
  {
    return Executors.newFixedThreadPool(threads, makeThreadFactory(nameFormat));
  }

  public static ScheduledExecutorService scheduledSingleThreaded(String nameFormat)
  {
    return Executors.newSingleThreadScheduledExecutor(makeThreadFactory(nameFormat));
  }

  public static ThreadFactory makeThreadFactory(String nameFormat)
  {
    return new ThreadFactoryBuilder().setDaemon(true).setNameFormat(nameFormat).build();
  }

  /**
   * @param nameFormat nameformat for threadFactory
   * @param capacity maximum capacity after which the executorService will block on accepting new tasks
   * @return ExecutorService which blocks accepting new tasks when the capacity reached
   */
  public static ExecutorService newBlockingSingleThreaded(final String nameFormat, final int capacity)
  {
    final BlockingQueue queue;
    if (capacity > 0) {
      queue = new ArrayBlockingQueue<>(capacity);
    } else {
      queue = new SynchronousQueue<>();
    }
    return new ThreadPoolExecutor(
        1, 1, 0L, TimeUnit.MILLISECONDS, queue, makeThreadFactory(nameFormat),
        new RejectedExecutionHandler()
        {
          @Override
          public void rejectedExecution(Runnable r, ThreadPoolExecutor executor)
          {
            try {
              executor.getQueue().put(r);
            }
            catch (InterruptedException e) {
              throw new RejectedExecutionException("Got Interrupted while adding to the Queue");
            }
          }
        }
    );
  }
}