[开发工具]Task线程管理：重启线程及CancellationToken用法

需求分析：假定有3个线程，有一个PLC下位机，当连接成功时，开启3个线程干活，如果连接不成功，则重新开启3个线程。当3个线程开启成功并工作一段时间后 ，利用CancellationToken退出线程 。
设计如下 ：首先设计一个类TaskModel，用来封装线程名字，任务，实际执行的委托及取消令牌，然后实例化三个TaskModel，并放入一个队列，最后开一个轮询线程，看看队列中的线程状态，如果没有running 就重新开启新的线程，主要利用Task的IsCanceled 、IsFaulted 和IsCompleted属性进行判断。

public class TaskModel
    {
        //线程名称
        public string Name;
        //当前任务
        public Task Task;
        //实际方法
        public Action<CancellationToken> Action;
        //取消令牌
        public CancellationTokenSource TokenSource;
        public TaskModel(string name,Action<CancellationToken> action, CancellationTokenSource tokenSource)
        {
            this.Name = name;
            this.Action = action;
            this.TokenSource = tokenSource;
            this.Task = Task.Run(() => action.Invoke(tokenSource.Token));
        }
    }
    class Program
    {
        //线程取消令牌
        private static CancellationTokenSource cancel = new CancellationTokenSource();
        //任务队列
        private static ConcurrentQueue<TaskModel> tasks = new ConcurrentQueue<TaskModel>();
        //下位机连接状态
        private static bool isConnect = false;
        static void Main(string[] args)
        {
            //初始化三个线程
            TaskModel SleepTask = new TaskModel("Sleep线程", Sleep, cancel);
            TaskModel WorkTask = new TaskModel("Work线程", Work, cancel);
            TaskModel EatTask = new TaskModel("Eat线程", Eat, cancel);

            //入队
            tasks.Enqueue(SleepTask);
            tasks.Enqueue(WorkTask);
            tasks.Enqueue(EatTask);

            //轮询
            Task.Run(() =>
            {
                Console.WriteLine($"Start...");

                int i = 0;//只轮询10次
                while (i < 10)
                {
                    foreach (var item in tasks)
                    {
                        if (item.Task.IsCanceled || item.Task.IsFaulted || item.Task.IsCompleted)
                        {
                            Console.WriteLine($"{DateTime.Now}: {item.Name} 重新启动!");
                            item.Task = Task.Run(() => item.Action.Invoke(item.TokenSource.Token));
                        }
                        Thread.Sleep(1000);
                    }

                    if (i++ == 0)
                    {
                        isConnect = true;
                        foreach (var item in tasks)
                        {
                            if (item.Task.Status == TaskStatus.RanToCompletion) continue;
                            item.Task.Start();
                        }
                    }

                    if (i == 5)
                    {
                        cancel.Cancel();
                    }
                }

                Console.WriteLine($"End...");

            });

            Console.ReadKey();
        }

        //睡觉线程 
        public static void Sleep(CancellationToken token)
        {
            while (isConnect && cancel.IsCancellationRequested == false)
            {
                Console.WriteLine($"{DateTime.Now}: Sleeping...");
                Thread.Sleep(1000);
            }
        }

        //工作线程
        public static void Work(CancellationToken token)
        {
            while (isConnect && cancel.IsCancellationRequested == false)
            {
                Console.WriteLine($"{DateTime.Now}: Working...");
                Thread.Sleep(1000);
            }
        }

        //吃饭线程
        public static void Eat(CancellationToken token)
        {
            while (isConnect && cancel.IsCancellationRequested == false)
            {
                Console.WriteLine($"{DateTime.Now}: Eatting...");
                Thread.Sleep(1000);
            }
        }       
    }