注册托管服务+timer实现简单定时任务

1.创建服务类

  public class TimerService : IHostedService, IDisposable
  {
      /// <summary>
      /// 定义定时器
      /// </summary>
      private static System.Threading.Timer _timer;

      private static int _count = 0;
      /// <summary>
      /// 销毁
      /// </summary>
      public void Dispose()
      {
          _timer.Dispose();
      }

      /// <summary>
      /// 开始
      /// </summary>
      /// <param name="cancellationToken"></param>
      /// <returns></returns>
      public Task StartAsync(CancellationToken cancellationToken)
      {
          //5秒执行一次
          var newTimer = new System.Threading.Timer(OnTimedEvent, null, 0, 1000);

          return Task.CompletedTask;
          //两种定时器
          //_timer = new System.Timers.Timer(1000);
          //_timer.Elapsed += OnTimedEvent;
          //_timer.Enabled = true;
          //Console.WriteLine("定时器已启动。按任意键停止...");
          //Console.ReadKey();
          //_timer.Enabled = false;
          //_timer.Dispose();
      }


      /// <summary>
      /// 
      /// </summary>
      /// <param name="state"></param>

      private  void OnTimedEvent(object? state)
      {
          _count++;
          Console.WriteLine($"定时器触发第 {_count} 次，时间：{DateTime.Now}");
      }

      /// <summary>
      /// 停止
      /// </summary>
      /// <param name="cancellationToken"></param>
      /// <returns></returns>
      /// <exception cref="NotImplementedException"></exception>

      public Task StopAsync(CancellationToken cancellationToken)
      {
          // 停止定时器
          _timer?.Change(Timeout.Infinite, 0);
          return Task.CompletedTask;
      }
  }

2.注册服务

//注册定时服务，如果要获取Service层的对象，可以放到最底下
builder.Services.AddHostedService<TimerService>();

 

3.启动查看

 

4.问题点：k8s有四台节点的话， 会同时跑这个定时任务，考虑是否要限流，限流代码

//可按照自己的项目内redis代码加分布式锁的方式
 await _cache.GetDistributedLockAsync<int>("分布式redis锁", 60,
     async () =>
     {
         var key = "限流redis key";
         var time = await _cache.GetAsync<string>(key);

         if (!string.IsNullOrWhiteSpace(time))
         {
             var date = Convert.ToDateTime(time);
            //5s内只会执行一个逻辑
             if ((DateTime.Now - date).TotalSeconds < 5)
             {
                 return -1;
             }
         }
         await _cache.SetAsync(key, DateTime.Now, 2);
       //执行业务

         return 1;
     });