package com.xiangxue.ch6.mypool;

import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;

/**
 *类说明：自己线程池的实现
 */
public class MyThreadPool2 {
    // 线程池中默认线程的个数为5
    private static int WORK_NUM = 5;
    // 队列默认任务个数为100
    private static int TASK_COUNT = 100;  
    
    // 工作线程组
    private WorkThread[] workThreads;

    // 任务队列，作为一个缓冲
    private final BlockingQueue<Runnable> taskQueue;
    private final int worker_num;//用户在构造这个池，希望的启动的线程数

    // 创建具有默认线程个数的线程池
    public MyThreadPool2() {
        this(WORK_NUM,TASK_COUNT);
    }

    // 创建线程池,worker_num为线程池中工作线程的个数
    public MyThreadPool2(int worker_num,int taskCount) {
        if (worker_num<=0) worker_num = WORK_NUM;
        if(taskCount<=0) taskCount = TASK_COUNT;
        this.worker_num = worker_num;
        taskQueue = new ArrayBlockingQueue<>(taskCount);
        workThreads = new WorkThread[worker_num];
        for(int i=0;i<worker_num;i++) {
            workThreads[i] = new WorkThread();
            workThreads[i].start();
        }
        Runtime.getRuntime().availableProcessors();
    }


    // 执行任务,其实只是把任务加入任务队列，什么时候执行有线程池管理器决定
    public void execute(Runnable task) {
        try {
            taskQueue.put(task);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

    }


    // 销毁线程池,该方法保证在所有任务都完成的情况下才销毁所有线程，否则等待任务完成才销毁
    public void destroy() {
        // 工作线程停止工作，且置为null
        System.out.println("ready close pool.....");
        for(int i=0;i<worker_num;i++) {
            workThreads[i].stopWorker();
            workThreads[i] = null;//help gc
        }
        taskQueue.clear();// 清空任务队列
    }

    // 覆盖toString方法，返回线程池信息：工作线程个数和已完成任务个数
    @Override
    public String toString() {
        return "WorkThread number:" + worker_num
                + "  wait task number:" + taskQueue.size();
    }

    /**
     * 内部类，工作线程
     */
    private class WorkThread extends Thread{
        
        @Override
        public void run(){
            Runnable r = null;
            try {
                while (!isInterrupted()) {
                    r = taskQueue.take();
                    if(r!=null) {
                        System.out.println(getId()+" ready exec :"+r);
                        r.run();
                    }
                    r = null;//help gc;
                } 
            } catch (Exception e) {
                // TODO: handle exception
            }
        }
        
        public void stopWorker() {
            interrupt();
        }
        
    }
}

package com.xiangxue.ch6.mypool;

import java.util.Random;

/**
 *类说明：
 */
public class TestMyThreadPool {
    public static void main(String[] args) throws InterruptedException {
        // 创建3个线程的线程池
        MyThreadPool2 t = new MyThreadPool2(3,0);
        t.execute(new MyTask("testA"));
        t.execute(new MyTask("testB"));
        t.execute(new MyTask("testC"));
        t.execute(new MyTask("testD"));
        t.execute(new MyTask("testE"));
        System.out.println(t);
        Thread.sleep(10000);
        t.destroy();// 所有线程都执行完成才destory
        System.out.println(t);
    }

    // 任务类
    static class MyTask implements Runnable {

        private String name;
        private Random r = new Random();

        public MyTask(String name) {
            this.name = name;
        }

        public String getName() {
            return name;
        }

        @Override
        public void run() {// 执行任务
            try {
                Thread.sleep(r.nextInt(1000)+2000);
            } catch (InterruptedException e) {
                System.out.println(Thread.currentThread().getId()+" sleep InterruptedException:"
                        +Thread.currentThread().isInterrupted());
            }
            System.out.println("任务 " + name + " 完成");
        }
    }
}

public ThreadPoolExecutor(int corePoolSize,
                              int maximumPoolSize,
                              long keepAliveTime,
                              TimeUnit unit,
                              BlockingQueue<Runnable> workQueue,
                              ThreadFactory threadFactory,
                              RejectedExecutionHandler handler)

public void execute(Runnable command) {
  if (command == null)
     throw new NullPointerException();
  int c = ctl.get();
  if (workerCountOf(c) < corePoolSize) {
    if (addWorker(command, true))
        return;
    c = ctl.get();
  }
  if (isRunning(c) && workQueue.offer(command)) {
    int recheck = ctl.get();
    if (! isRunning(recheck) && remove(command))
        reject(command);
    else if (workerCountOf(recheck) == 0)
        addWorker(null, false);
  } else if (!addWorker(command, false))
      reject(command);
}

public Future<?> submit(Runnable task) {
  //提交的task为null，抛出空指针异常   
  if (task == null)
       throw new NullPointerException();
    RunnableFuture<Void> ftask = newTaskFor(task, null);
    //执行任务
    execute(ftask);
    return ftask;
}