package com.framework.util;

/*******************************************************************************
 * Copyright (c) 2005, 2014 springside.github.io
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 *******************************************************************************/

import java.util.concurrent.ExecutorService;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

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

/**
 * 线程相关工具类.
 * 
 * @author calvin
 */
public class Threads {

	/**
	 * sleep等待, 单位为毫秒.
	 */
	public static void sleep(long durationMillis) {
		try {
			Thread.sleep(durationMillis);
		} catch (InterruptedException e) {
			Thread.currentThread().interrupt();
		}
	}

	/**
	 * sleep等待.
	 */
	public static void sleep(long duration, TimeUnit unit) {
		try {
			Thread.sleep(unit.toMillis(duration));
		} catch (InterruptedException e) {
			Thread.currentThread().interrupt();
		}
	}

	/**
	 * 创建ThreadFactory，使得创建的线程有自己的名字而不是默认的"pool-x-thread-y"，
	 * 在用threaddump查看线程时特别有用。 格式如"mythread-%d"，使用了Guava的工具类
	 */
	public static ThreadFactory buildJobFactory(String nameFormat) {
		return new ThreadFactoryBuilder().setNameFormat(nameFormat).build();
	}

	/**
	 * 按照ExecutorService JavaDoc示例代码编写的Graceful Shutdown方法.
	 * 先使用shutdown, 停止接收新任务并尝试完成所有已存在任务.
	 * 如果超时, 则调用shutdownNow, 取消在workQueue中Pending的任务,并中断所有阻塞函数.
	 * 如果仍然超時，則強制退出.
	 * 另对在shutdown时线程本身被调用中断做了处理.
	 */
	public static void gracefulShutdown(ExecutorService pool, int shutdownTimeout, int shutdownNowTimeout,
			TimeUnit timeUnit) {
		pool.shutdown(); // Disable new tasks from being submitted
		try {
			// Wait a while for existing tasks to terminate
			if (!pool.awaitTermination(shutdownTimeout, timeUnit)) {
				pool.shutdownNow(); // Cancel currently executing tasks
				// Wait a while for tasks to respond to being cancelled
				if (!pool.awaitTermination(shutdownNowTimeout, timeUnit)) {
					System.err.println("Pool did not terminated");
				}
			}
		} catch (InterruptedException ie) {
			// (Re-)Cancel if current thread also interrupted
			pool.shutdownNow();
			// Preserve interrupt status
			Thread.currentThread().interrupt();
		}
	}

	/**
	 * 直接调用shutdownNow的方法, 有timeout控制.取消在workQueue中Pending的任务,并中断所有阻塞函数.
	 */
	public static void normalShutdown(ExecutorService pool, int timeout, TimeUnit timeUnit) {
		try {
			pool.shutdownNow();
			if (!pool.awaitTermination(timeout, timeUnit)) {
				System.err.println("Pool did not terminated");
			}
		} catch (InterruptedException ie) {
			Thread.currentThread().interrupt();
		}
	}

	/**
	 * 保证不会有Exception抛出到线程池的Runnable，防止用户没有捕捉异常导致中断了线程池中的线程。
	 */
	public static class WrapExceptionRunnable implements Runnable {

		private static Logger logger = LoggerFactory.getLogger(WrapExceptionRunnable.class);

		private Runnable runnable;

		public WrapExceptionRunnable(Runnable runnable) {
			this.runnable = runnable;
		}

		@Override
		public void run() {
			try {
				runnable.run();
			} catch (Throwable e) {
				// catch any exception, because the scheduled thread will break if the exception thrown outside.
				logger.error("Unexpected error occurred in task", e);
			}
		}
	}

}