Ocelot（五）- 流量限制、服务质量 (2)

然后，在OcelotConsole项目中添加代码如下：

public static async Task Main(string[] args) { using (var client = new HttpClient()) { for (var i = 0; i < 100; i++) { Console.WriteLine(DateTime.Now); var result = await client.GetAsync("http://localhost:4727/ocelot/ratelimit/5"); Console.WriteLine($"{result.StatusCode}, {result.Content.ReadAsStringAsync().Result}"); System.Threading.Thread.Sleep(1000); } Console.Read(); } }

每隔1s就发出一次请求，运行，在命令窗口得到以下输出：

2019/6/3 13:33:31 OK, This is from localhost:8001, path: /api/ocelot/5 2019/6/3 13:33:32 OK, This is from localhost:8001, path: /api/ocelot/5 2019/6/3 13:33:33 OK, This is from localhost:8001, path: /api/ocelot/5 2019/6/3 13:33:34 OK, This is from localhost:8001, path: /api/ocelot/5 2019/6/3 13:33:35 OK, This is from localhost:8001, path: /api/ocelot/5 2019/6/3 13:33:36 TooManyRequests, API calls quota exceeded! maximum admitted 5 per 1m. 2019/6/3 13:33:37 TooManyRequests, API calls quota exceeded! maximum admitted 5 per 1m. 2019/6/3 13:33:38 TooManyRequests, API calls quota exceeded! maximum admitted 5 per 1m. 2019/6/3 13:33:39 TooManyRequests, API calls quota exceeded! maximum admitted 5 per 1m. 2019/6/3 13:33:40 TooManyRequests, API calls quota exceeded! maximum admitted 5 per 1m. 2019/6/3 13:33:41 OK, This is from localhost:8001, path: /api/ocelot/5 2019/6/3 13:33:43 OK, This is from localhost:8001, path: /api/ocelot/5 2019/6/3 13:33:44 OK, This is from localhost:8001, path: /api/ocelot/5 2019/6/3 13:33:45 OK, This is from localhost:8001, path: /api/ocelot/5 2019/6/3 13:33:46 OK, This is from localhost:8001, path: /api/ocelot/5 2019/6/3 13:33:47 TooManyRequests, API calls quota exceeded! maximum admitted 5 per 1m. 2019/6/3 13:33:48 TooManyRequests, API calls quota exceeded! maximum admitted 5 per 1m. 2019/6/3 13:33:49 TooManyRequests, API calls quota exceeded! maximum admitted 5 per 1m. 2019/6/3 13:33:50 TooManyRequests, API calls quota exceeded! maximum admitted 5 per 1m. 2019/6/3 13:33:51 TooManyRequests, API calls quota exceeded! maximum admitted 5 per 1m.

然后，我又通过修改参数，得出如下结果：

PeriodTimespan=10, Limit=5：5个成功，5个失败

PeriodTimespan=10, Limit=6：6个成功，4个失败

PeriodTimespan=20, Limit=5：5个成功，15个失败

PeriodTimespan=30, Limit=5：5个成功，25个失败

似乎都是与我前面得到的结论相同，与官方文档不一致。
我在GitHub上提了一个issue：https://github.com/ThreeMammals/Ocelot/issues/910，期待能得到答复。

流量限制的全局配置

"RateLimitOptions": { "DisableRateLimitHeaders": true, "QuotaExceededMessage": "Customize Tips!", "HttpStatusCode": 999, "ClientIdHeader": "Test" }

DisableRateLimitHeaders：当设为true时，请求头中就不会输出流量限制的相关信息，默认值："false"

QuotaExceededMessage：当请求数量超出流量限制时，输出的信息，默认值："API calls quota exceeded! maximum admitted {Limit} per {Period}."

HttpStatusCode：当请求数量超出流量限制时，输出的状态码，默认值："429"

ClientIdHeader：标识为白名单中的客户端的请求头key，默认值："ClientId"

案例七 服务质量

Ocelot支持服务质量与熔断，意味着当下游服务不可用时，Ocelot会进行自动熔断，不再将请求转发给该下游服务。来看看配置

"QoSOptions": { "ExceptionsAllowedBeforeBreaking":3, "DurationOfBreak":3000, "TimeoutValue":5000 }

ExceptionsAllowedBeforeBreaking：允许异常次数，当Ocelot转发给该下游服务连续出现异常次数达到该数字时，Ocelot会进行自动熔断，一段时间内不再向该下游服务转发请求

DurationOfBreak：熔断时间，单位为ms（毫秒），持续多长时间不向该下游服务转发请求

TimeoutValue：服务质量配置项，超时时间，单位为ms（毫秒），当Ocelot向下游服务转发请求多长时间后，自动认为该请求超时

ExceptionsAllowedBeforeBreaking 必须跟 DurationOfBreak一起使用，TimeoutValue可以单独使用。

首先需要安装Polly支持程序，通过Nuget搜索Ocelot.Provider.Polly或者通过以下命令安装

Install-Package Ocelot.Provider.Polly