如何获取经过时间在.net核心中使用httpclient异步获取REST GET请求/等待答案

【问题标题】：How To Get Elapsed Time Getting REST GET request in async / await with httpclient in .net core如何获取经过时间在.net核心中使用httpclient异步获取REST GET请求/等待
【发布时间】：2019-05-03 04:02:18
【问题描述】：

当我用 Task.Wait 调用下面的方法 DoRestCall 时，经过的时间基本上显示为 0（好吧，它显示 3ms）。我知道这是因为异步/等待模式。我想获得完成其余通话所需的实际时间。我想不出办法进入 HttpClient 来解决这个问题。

public static async Task DoRestCall()
{
    HttpClient client = new HttpClient();
    HttpResponseMessage response = await client.GetAsync("https://http://myrest.com");
    if (response.IsSuccessStatusCode)
    {
        var sw = new Stopwatch();
        sw.Start();
        var x = await response.Content.ReadAsStringAsync();
        sw.Stop();
        Console.WriteLine($"{x.Length} {sw.ElapsedMilliseconds}");
    }
}

【问题讨论】：

为什么只在请求后才启动秒表？您正在计时 ReadAsString 部分。异步不是这里的问题，只是秒表的位置。

标签： c# asp.net-core .net-core async-await

【解决方案1】：

您应该移动秒表以将您的 .GetAsync 呼叫也包括在内。

public static async Task DoRestCall()
{
    HttpClient client = new HttpClient();
    string responseBody = String.Empty;
    var sw = new Stopwatch();
    sw.Start();
    HttpResponseMessage response = await client.GetAsync("https://http://myrest.com");
    if (response.IsSuccessStatusCode)
    {        
        responseBody = await response.Content.ReadAsStringAsync();
    }
    sw.Stop();    
    Console.WriteLine($"{responseBody.Length} {sw.ElapsedMilliseconds}");
}

【讨论】：

【解决方案2】：

其他方式查看Elapsed Time的HttpClient

1.将Log Level 改为Information或Trace

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      //"System.Net.Http.HttpClient": "Information"
    }
  }
}

样本输出

info: System.Net.Http.HttpClient.MyClient.LogicalHandler[100]
  Start processing HTTP request GET https://api.github.com/repos/aspnet/docs/branches

info: System.Net.Http.HttpClient.MyClient.ClientHandler[100]
  Sending HTTP request GET https://api.github.com/repos/aspnet/docs/branches

info: System.Net.Http.HttpClient.MyClient.ClientHandler[101]
  Received HTTP response after 682.9818ms - OK

info: System.Net.Http.HttpClient.MyClient.LogicalHandler[101]
  End processing HTTP request after 693.1094ms - OK

2.创建一个新的Handler

public class TimingHandler : DelegatingHandler
{
    private readonly ILogger<TimingHandler> _logger;

    public TimingHandler(ILogger<TimingHandler> logger)
    {
        _logger = logger;
    }

    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, 
        CancellationToken cancellationToken)
    {
        var sw = Stopwatch.StartNew();

        _logger.LogInformation("Starting request");

        var response = await base.SendAsync(request, cancellationToken);

        _logger.LogInformation($"Finished request in {sw.ElapsedMilliseconds}ms");

        return response;
    }
}

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【讨论】：