Polly服务熔断

 //自定义异常
 public class MyException : Exception
 {
     public MyException(string? message) : base(message)
     {
     }
 }


 public class CircuitBreakerExample
 {
     //熔断规则
     private static readonly IAsyncPolicy<HttpResponseMessage> _circuitBreakerPolicy = Policy<HttpResponseMessage>
  .Handle<MyException>() // 可以指定更具体>的异常类型  
  .OrResult(resopnse=>resopnse.StatusCode==HttpStatusCode.InternalServerError)
  .CircuitBreakerAsync(
      handledEventsAllowedBeforeBreaking: 5, // 在断路器跳闸前允许通过的失败事件数（连续失败的次数）
      durationOfBreak: TimeSpan.FromSeconds(3), // 断路器跳闸后保持打开的时间  
      onBreak: (ex, breakTimeout) => // 当断路器跳闸时执行的回调  
      {
          Console.WriteLine("熔断开关状态为open, 服务" +
                            breakTimeout.TotalSeconds + " 秒后才能再次访问");
      },
      onReset: () => // 当断路器从跳闸状态恢复时执行的回调  
      {
          Console.WriteLine("熔断开关状态为closed,现在能再次访问服务");
      },
      onHalfOpen: () => // 当断路器从关闭状态变为半开状态时执行的回调  
      {
          Console.WriteLine("熔断开关现在状态为 half-open。允许单次呼叫查看服务是否可用.");
      }
  );




     //通过熔断规则调用服务
     public static async Task CallServiceWithCircuitBreakerAsync()
     {
         try
         {
             // 使用断路器策略来调用服务  
             await _circuitBreakerPolicy.ExecuteAsync(RemoteService);
         }
         //捕获断路异常
         catch (BrokenCircuitException ex)
         {
             Console.WriteLine("熔断开关状态为open");
         }
     }

     //模拟远程服务
     private static int FailCount = 6;
     public static async Task<HttpResponseMessage> RemoteService()
     {
         try
         {
             await Task.Delay(100);
             if (FailCount == 0)
             {
                 Console.WriteLine("请求服务成功!");
                 return new HttpResponseMessage(System.Net.HttpStatusCode.OK);
             }
             // 模拟成功的服务响应  
             FailCount = FailCount - 1;
             throw new MyException("请求服务失败!");
         }
         catch
         {
             Console.WriteLine("请求服务失败!");
             return new HttpResponseMessage(System.Net.HttpStatusCode.InternalServerError);
         }
     }
 }

#region Polly熔断服务
#if true
await Task.Run(async () =>
{
    while (true)
    {
        await Task.Delay(1000);
        CircuitBreakerExample.CallServiceWithCircuitBreakerAsync().Wait();
    }
});
#endif 
#endregion