标签：core 自定义 Random public context ._ using net logger
网上关于net core实现服务熔断的都是客户端的例子，下面我来分享一个服务器端的例子，可以针对每一个用户请求做到服务器端熔断的操作。
通过middleware可以实现针对用户级别的流控。感谢张浩帮忙。
CircuitBreakerMiddleware.cs
1 using System;
2 using System.Collections.Concurrent;
3 using System.Net;
4 using System.Threading.Tasks;
5 using Microsoft.AspNetCore.Http;
6 using Microsoft.AspNetCore.Http.Extensions;
7 using Microsoft.Extensions.Configuration;
8 using Microsoft.Extensions.Logging;
9 using Polly;
10 using Polly.CircuitBreaker;
11
12 namespace CircuitBreakerDemo
13 {
14 /// <summary>
15 /// net core 实现自定义断路器中间件
16 /// </summary>
17 public class CircuitBreakerMiddleware : IDisposable
18 {
19 private readonly RequestDelegate _next;
20 private readonly ConcurrentDictionary<string, AsyncPolicy> _asyncPolicyDict = null;
21 private readonly ILogger<CircuitBreakerMiddleware> _logger;
22 private readonly IConfiguration _configuration;
23
24 public CircuitBreakerMiddleware(RequestDelegate next, ILogger<CircuitBreakerMiddleware> logger, IConfiguration configuration)
25 {
26 this._next = next;
27 this._logger = logger;
28 this._configuration = configuration; //未来url的断路规则可以从config文件里读取，增加灵活性
29 logger.LogInformation($"{nameof(CircuitBreakerMiddleware)}.Ctor()");
30 this._asyncPolicyDict = new ConcurrentDictionary<string, AsyncPolicy>(Environment.ProcessorCount, 31);
31 }
32
33 public async Task InvokeAsync(HttpContext context)
34 {
35 var request = context.Request;
36 try
37 {
38 await this._asyncPolicyDict.GetOrAdd(string.Concat(request.Method, request.GetEncodedPathAndQuery())
39 , key => Policy.Handle<Exception>()
40 .AdvancedCircuitBreakerAsync
41 (
42 //备注：20秒内，请求次数达到10次以上，失败率达到20%后开启断路器，断路器一旦被打开至少要保持5秒钟的打开状态。
43 failureThreshold: 0.2D, //失败率达到20%熔断开启
44 minimumThroughput: 10, //最多调用10次
45 samplingDuration: TimeSpan.FromSeconds(20), //评估故障持续时长20秒
46 durationOfBreak: TimeSpan.FromSeconds(5), //恢复正常使用前电路保持打开状态的最少时长5秒
47 onBreak: (exception, breakDelay, context) => //断路器打开时触发事件，程序不能使用
48 {
49 var ex = exception.InnerException ?? exception;
50 this._logger.LogError($"{key} => 进入打开状态，中断持续时长：{breakDelay}，错误类型：{ex.GetType().Name}，信息：{ex.Message}");
51 },
52 onReset: context => //断路器关闭状态触发事件，断路器关闭
53 {
54 this._logger.LogInformation($"{key} => 进入关闭状态，程序恢复正常使用");
55 },
56 onHalfOpen: () => //断路器进入半打开状态触发事件，断路器准备再次尝试操作执行
57 {
58 this._logger.LogInformation($"{key} => 进入半开状态，重新尝试接收请求");
59 }
60 )
61 )
62 .ExecuteAsync(async () => await this._next(context))
63 ;
64 }
65 catch (BrokenCircuitException exception)
66 {
67 this._logger.LogError($"{nameof(BrokenCircuitException)}.InnerException.Message：{exception.InnerException.Message}");
68 var response = context.Response;
69 response.StatusCode = (int)HttpStatusCode.BadRequest;
70 response.ContentType = "text/plain; charset=utf-8";
71 await response.WriteAsync("Circuit Broken o(╥﹏╥)o");
72 }
73
74 //var endpoint = context.GetEndpoint();
75 //if (endpoint != null)
76 //{
77 // var controllerActionDescriptor = endpoint.Metadata.GetMetadata<ControllerActionDescriptor>();
78 // var controllerName = controllerActionDescriptor.ControllerName;
79 // var actionName = controllerActionDescriptor.ActionName;
80 // if (string.Equals(controllerName, "WeatherForecast", StringComparison.OrdinalIgnoreCase)
81 // && string.Equals(actionName, "Test", StringComparison.OrdinalIgnoreCase))
82 // {//针对某一个控制器的某一个action，单独设置断路
83 // await Policy.Handle<Exception>().CircuitBreakerAsync(3, TimeSpan.FromSeconds(10)).ExecuteAsync(async () => await this._next(context));
84 // }
85 // else
86 // {
87 // await this._next(context);
88 // }
89 //}
90 }
91
92 public void Dispose()
93 {
94 this._asyncPolicyDict.Clear();
95 this._logger.LogInformation($"{nameof(CircuitBreakerMiddleware)}.Dispose()");
96 }
97 }
98 }
CircuitBreakerMiddleware.cs
Startup.cs
1 public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
2 {
3 if (env.IsDevelopment())
4 {
5 app.UseDeveloperExceptionPage();
6 }
7
8 app.UseRouting();
9
10 //注意位置在Routing下面，UseEndpoints上面
11 app.UseMiddleware<CircuitBreakerMiddleware>();
12
13 app.UseEndpoints(endpoints =>
14 {
15 endpoints.MapControllers();
16 });
17 }
Startup.cs
WeatherForecastController.cs
1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using Microsoft.AspNetCore.Mvc;
5 using Microsoft.Extensions.Logging;
6
7 namespace CircuitBreakerDemo.Controllers
8 {
9 [ApiController]
10 [Route("[controller]")]
11 public class WeatherForecastController : ControllerBase
12 {
13 private static readonly string[] Summaries = new[]
14 {
15 "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
16 };
17
18 private static Random _Random = new Random();
19
20 private readonly ILogger<WeatherForecastController> _logger;
21
22 public WeatherForecastController(ILogger<WeatherForecastController> logger)
23 {
24 this._logger = logger;
25 }
26
27 [HttpGet]
28 public IEnumerable<WeatherForecast> Get()
29 {
30 if (_Random.Next(Summaries.Length) % 3 == 0)
31 {
32 throw new Exception("程序运行错误");
33 }
34
35 return Enumerable.Range(1, 5).Select(index => new WeatherForecast
36 {
37 Date = DateTime.Now.AddDays(index),
38 TemperatureC = _Random.Next(-20, 55),
39 Summary = Summaries[_Random.Next(Summaries.Length)]
40 })
41 .ToArray();
42 }
43
44 [HttpGet("test")]
45 public string Test()
46 {
47 if (_Random.Next(Summaries.Length) % 3 == 0)
48 {
49 throw new Exception("程序运行错误");
50 }
51 return Summaries[_Random.Next(Summaries.Length)];
52 }
53 }
54 }
WeatherForecastController.cs
项目跑起来就是各种刷新，然后就可以看到结果了。
标签：core,自定义,Random,public,context,._,using,net,logger 来源： https://www.cnblogs.com/xitianqujing/p/13737729.html
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