/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
    *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.giraph.utils;
  
  import org.apache.log4j.Logger;
  
  import com.google.common.util.concurrent.ThreadFactoryBuilder;
  
  import java.util.concurrent.Callable;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Future;
  import java.util.concurrent.ThreadFactory;
  
  /**
   * Utility class for thread related functions.
   */
  public class ThreadUtils {
    /** Logger */
    private static final Logger LOG = Logger.getLogger(ThreadUtils.class);
  
    /**
     * Utility class. Do not inherit or create objects.
     */
    private ThreadUtils() { }
  
    /**
     * Creates new thread factory with specified thread name format.
     *
     * @param nameFormat defines naming format for threads created by
     *                   thread factory
     * @param exceptionHandler handles uncaught exceptions in all threads
     *                         produced created thread factory
     * @return new thread factory with specified thread name format and
     * exception handler.
     */
    public static ThreadFactory createThreadFactory(
        String nameFormat,
        Thread.UncaughtExceptionHandler exceptionHandler) {
      ThreadFactoryBuilder builder = new ThreadFactoryBuilder().
          setNameFormat(nameFormat).setDaemon(true);
      if (exceptionHandler != null) {
        builder.setUncaughtExceptionHandler(exceptionHandler);
      }
      return builder.build();
    }
  
    /**
     * Creates new thread factory with specified thread name format.
     *
     * @param nameFormat defines naming format for threads created by
     *                   thread factory
     * @return new thread factory with specified thread name format
     */
    public static ThreadFactory createThreadFactory(String nameFormat) {
      return createThreadFactory(nameFormat, null);
    }
  
    /**
     * Submit a callable to executor service, ensuring any exceptions are
     * caught with provided exception handler.
     *
     * When using submit(), UncaughtExceptionHandler which is set on ThreadFactory
     * isn't used, so we need this utility.
     *
     * @param executorService Executor service to submit callable to
     * @param callable Callable to submit
     * @param uncaughtExceptionHandler Handler for uncaught exceptions in callable
     * @param <T> Type of callable result
     * @return Future for callable
     */
    public static <T> Future<T> submitToExecutor(
        ExecutorService executorService,
        Callable<T> callable,
        Thread.UncaughtExceptionHandler uncaughtExceptionHandler) {
      return executorService.submit(
          new LogStacktraceCallable<>(callable, uncaughtExceptionHandler));
    }
  
    /**
     * Start thread with specified name and runnable, and make it daemon
     *
     * @param threadName Name of the thread
     * @param runnable Runnable to execute
     * @return Thread
    */
   public static Thread startThread(Runnable runnable, String threadName) {
     Thread thread = new Thread(runnable, threadName);
     thread.setDaemon(true);
     thread.start();
     return thread;
   }
 
   /**
    * Start thread with specified name, runnable and exception handler, and make
    * it daemon
    *
    * @param runnable Runnable to execute
    * @param threadName Name of the thread
    * @param handler Exception handler
    * @return Thread
    */
   public static Thread startThread(Runnable runnable, String threadName,
                                    Thread.UncaughtExceptionHandler handler) {
     Thread thread = new Thread(runnable, threadName);
     thread.setUncaughtExceptionHandler(handler);
     thread.setDaemon(true);
     thread.start();
     return thread;
   }
 
   /**
    * Sleep for specified milliseconds, logging and ignoring interrupted
    * exceptions
    *
    * @param millis How long to sleep for
    * @return Whether the sleep was successful or the thread was interrupted
    */
   public static boolean trySleep(long millis) {
     try {
       Thread.sleep(millis);
       return true;
     } catch (InterruptedException e) {
       if (LOG.isInfoEnabled()) {
         LOG.info("Thread interrupted");
       }
       return false;
     }
   }
 }