/*
 * 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 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 {

  /**
   * 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));
  }
}