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package com.xiaoleilu.hutool.util;

import java.util.concurrent.Callable;
import java.util.concurrent.CompletionService;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorCompletionService;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;

import com.xiaoleilu.hutool.exceptions.UtilException;

/**
 * 线程池工具
 * 
 * @author luxiaolei
 */
public final class ThreadUtil {
	private static ExecutorService executor = Executors.newCachedThreadPool();
	
	private ThreadUtil() {}

	/**
	 * 直接在公共线程池中执行线程
	 * 
	 * @param runnable 可运行对象
	 */
	public static void execute(Runnable runnable) {
		try {
			executor.execute(runnable);
		} catch (Exception e) {
			throw new UtilException("Exception when running task!", e);
		}
	}

	/**
	 * 重启公共线程池
	 */
	public static void restart() {
		executor.shutdownNow();
		executor = Executors.newCachedThreadPool();
	}

	/**
	 * 新建一个线程池
	 * 
	 * @param threadSize 同时执行的线程数大小
	 * @return ExecutorService
	 */
	public static ExecutorService newExecutor(int threadSize) {
		return Executors.newFixedThreadPool(threadSize);
	}

	/**
	 * 获得一个新的线程池
	 * 
	 * @return ExecutorService
	 */
	public static ExecutorService newExecutor() {
		return Executors.newCachedThreadPool();
	}

	/**
	 * 获得一个新的线程池，只有单个线程
	 * 
	 * @return ExecutorService
	 */
	public static ExecutorService newSingleExecutor() {
		return Executors.newSingleThreadExecutor();
	}

	/**
	 * 执行异步方法
	 * 
	 * @param runnable 需要执行的方法体
	 * @return 执行的方法体
	 */
	public static Runnable excAsync(final Runnable runnable, boolean isDeamon) {
		Thread thread = new Thread(){
			@Override
			public void run() {
				runnable.run();
			}
		};
		thread.setDaemon(isDeamon);
		thread.start();

		return runnable;
	}

	/**
	 * 执行有返回值的异步方法

	 * Future代表一个异步执行的操作，通过get()方法可以获得操作的结果，如果异步操作还没有完成，则，get()会使当前线程阻塞
	 * 
	 * @return Future
	 */
	public static  Future execAsync(Callable task) {
		return executor.submit(task);
	}

	/**
	 * 新建一个CompletionService，调用其submit方法可以异步执行多个任务，最后调用take方法按照完成的顺序获得其结果。，若未完成，则会阻塞
	 * 
	 * @return CompletionService
	 */
	public static  CompletionService newCompletionService() {
		return new ExecutorCompletionService(executor);
	}

	/**
	 * 新建一个CompletionService，调用其submit方法可以异步执行多个任务，最后调用take方法按照完成的顺序获得其结果。，若未完成，则会阻塞
	 * 
	 * @return CompletionService
	 */
	public static  CompletionService newCompletionService(ExecutorService executor) {
		return new ExecutorCompletionService(executor);
	}

	/**
	 * 新建一个CountDownLatch
	 * 
	 * @param threadCount 线程数量
	 * @return CountDownLatch
	 */
	public static CountDownLatch newCountDownLatch(int threadCount) {
		return new CountDownLatch(threadCount);
	}
	
	/**
	 * 挂起当前线程
	 * 
	 * @param timeout 挂起的时长
	 * @param timeUnit 时长单位
	 * @return 被中断返回false，否则true
	 */
	public static boolean sleep(Number timeout, TimeUnit timeUnit) {
		try {
			timeUnit.sleep(timeout.longValue());
		} catch (InterruptedException e) {
			return false;
		}
		return true;
	}

	/**
	 * 挂起当前线程
	 * 
	 * @param millis 挂起的毫秒数
	 * @return 被中断返回false，否则true
	 */
	public static boolean sleep(Number millis) {
		if (millis == null) {
			return true;
		}

		try {
			Thread.sleep(millis.longValue());
		} catch (InterruptedException e) {
			return false;
		}
		return true;
	}
	
	/**
	 * 考虑{@link Thread#sleep(long)}方法有可能时间不足给定毫秒数，此方法保证sleep时间不小于给定的毫秒数
	 * @see ThreadUtil#sleep(Number)
	 * @param millis 给定的sleep时间
	 * @return 被中断返回false，否则true
	 */
	public static boolean safeSleep(Number millis){
		long millisLong = millis.longValue();
		long done = 0;
		while(done < millisLong){
			long before = System.currentTimeMillis();
			if(false == sleep(millisLong - done)){
				return false;
			}
			long after = System.currentTimeMillis();
			done += (after - before);
		}
		return true;
	}
	
	/**
	 * @return 获得堆栈列表
	 */
	public static StackTraceElement[] getStackTrace() {
		return Thread.currentThread().getStackTrace();
	}

	/**
	 * 获得堆栈项
	 * 
	 * @param i 第几个堆栈项
	 * @return 堆栈项
	 */
	public static StackTraceElement getStackTraceElement(int i) {
		StackTraceElement[] stackTrace = getStackTrace();
		if (i < 0) {
			i += stackTrace.length;
		}
		return stackTrace[i];
	}
	
	/**
	 * 创建本地线程对象
	 * @return 本地线程
	 */
	public static  ThreadLocal createThreadLocal(boolean isInheritable){
		if(isInheritable){
			return new InheritableThreadLocal<>();
		}else{
			return new ThreadLocal<>();
		}
	}
	
	/**
	 * 结束线程，调用此方法后，线程将抛出 {@link InterruptedException}异常
	 * @param thread 线程
	 * @param isJoin 是否等待结束
	 */
	public static void interupt(Thread thread, boolean isJoin){
		if(null != thread && false == thread.isInterrupted()){
			thread.interrupt();
			if(isJoin){
				waitForDie(thread);
			}
		}
	}
	
	/**
	 * 等待线程结束. 调用 {@link Thread#join()} 并忽略 {@link InterruptedException}
	 * 
	 * @param thread 线程
	 */
	public static void waitForDie(Thread thread) {
		boolean dead = false;
		do {
			try {
				thread.join();
				dead = true;
			} catch (InterruptedException e) {
				//ignore
			}
		} while (!dead);
	}
	
	/**
	 * 获取JVM中与当前线程同组的所有线程

	 * @return 线程对象数组
	 */
	public static Thread[] getThreads(){
		return getThreads(Thread.currentThread().getThreadGroup().getParent());
	}
	
	/**
	 * 获取JVM中与当前线程同组的所有线程

	 * 使用数组二次拷贝方式，防止在线程列表获取过程中线程终止

	 * from Voovan
	 * 
	 * @param group 线程组
	 * @return 线程对象数组
	 */
	public static Thread[] getThreads(ThreadGroup group){
		final Thread[] slackList = new Thread[group.activeCount() * 2];
		final int actualSize = group.enumerate(slackList);
		final Thread[] result = new Thread[actualSize];
		System.arraycopy(slackList, 0, result, 0, actualSize);
		return result;
	}
	
	/**
	 * 获取进程的主线程

	 * from Voovan
	 * @return 进程的主线程
	 */
	public static Thread getMainThread(){
		for(Thread thread: getThreads()){
			if(thread.getId()==1){
				return thread;
			}
		}
		return null;
	}
}