JAVA高级面试进阶训练营视频教程

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Polly 是一种 .NET 弹性和瞬态故障处理库，允许开发人员以流畅和线程安全的方式表达策略，如重试，断路器，超时，隔离隔离和备用，Polly 适用于 .NET 4.0，.NET 4.5 和 .NET Standard 1.1。

安装 Nuget 程序包：

Install-Package Polly

简单使用：

// Execute an action
var policy = Policy
              .Handle<Exception>()
              .RetryAsync(10, async (exception, retryCount) =>
              {
                  await LogAsync(exception, $"第{retryCount}次重试");
              });

await policy.ExecuteAsync(async () => await DoSomething());

//另外一种使用方式：
var tokenResponse = await Policy
        .Handle<Exception>()
        .OrResult<TokenResponse>(x => x.IsError)
        .RetryAsync(5) //如果使用Retry，会报错误：Please use asynchronous-defined policies when calling asynchronous ExecuteAsync (and similar) methods
        .ExecuteAsync(async () =>
        {
            var client = new DiscoveryClient(_appSettings.IssuerUri);
            client.Policy.RequireHttps = false;
            var disco = await client.GetAsync();
            var tokenClient = new TokenClient(disco.TokenEndpoint, clientId, clientSecret);
            return await tokenClient.RequestRefreshTokenAsync(refreshToken);
        });

参考资料：

• Polly Github
• Implementing the retry pattern in c sharp using Polly