【小做業】爲NLog自定義LayoutRenderer

長話短說

　　前文《解剖HttpClientFactory，自由擴展HttpMessageHandler》主要講如何爲HttpClientFactory自定義HttpMessageHandler組件,  

如今來完成課後的小做業： 將重點日誌字段顯示到Nlog的LayoutRenderer上。

本文實現一個簡單流暢的LoggingHttpMessageHandler，記錄該HttpClient請求耗時，並顯示到 NLog LayoutRenderer。

 什麼是Layout Renderer？

 nlog日誌上輸出的特定字段，便於檢索和分類。

配置nlog顯示elapse Renderer

# 截取自 nlog.config配置文件
<target name="bce-request"
           xsi:type="File"
           layout="${date:format=yy/MM/dd HH\:mm\:ss} [${level}].[${logger}].[${threadid}}].[${elapse}]${newline}${message} ${exception:format=tostring}" 
           fileName="${logDir}/bce-request.log" encoding="utf-8"/> 

19/12/08 22:46:29 [Info].[System.Net.Http.HttpClient.bce-request.LogicalHandler].[6}].[415.2504] HTTP request http://localhost:5000/v1/eqid/e741e8d600151edc000000035decf3bf after 415.2504ms end -OK 
19/12/08 22:47:15 [Info].[System.Net.Http.HttpClient.bce-request.LogicalHandler].[40}].[80.2951] HTTP request http://localhost:5000/v1/eqid/2a41e8d600151edc000000028decf3bf after 80.2951ms end -OK 
19/12/08 22:48:06 [Info].[System.Net.Http.HttpClient.bce-request.LogicalHandler].[43}].[36.8624] HTTP request http://localhost:5000/v1/eqid/1a41e8d600151edc000000028decf3bf after 36.8624ms end -OK 

頭腦風暴

nlog全部的日誌Render 都來自日誌寫入的信息， 所以咱們在寫入日誌時附帶該Renderer值， 而後配置nlog顯示日誌時提取該Renderer。

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寫入日誌時，爲Message傳入參數{Url}, {Elapse}, {StatusCode}：

public class CustomHttpMessageHandler : DelegatingHandler { private readonly ILogger _logger; public AttachTraceIdScopeHttpMessageHandler(ILogger logger) { _logger = logger ?? throw new ArgumentNullException(nameof(logger)); } protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { if (request == null) { throw new ArgumentNullException(nameof(request)); } var stopwatch = Stopwatch.StartNew(); var response = await base.SendAsync(request, cancellationToken); stopwatch.Stop(); _logger.Log(LogLevel.Information, new EventId(101, "Request End"), "HTTP request {Url} after {Elapse}ms end -{StatusCode}", request.RequestUri, stopwatch.Elapsed.TotalMilliseconds, response.StatusCode); return response; } }

 

 

--------------------------------2--------------------------------

添加自定義LayOutRenderer

　　有簡單的lambda方式，這裏咱們採用稍微靈活的自定義類方式， 關鍵點是實現LayoutRenderer的抽象方法Append,  從LogEventInfo中提出Renderer值

[LayoutRenderer("elapse")] public class ElapseLayoutRenderer : LayoutRenderer { protected override void Append(StringBuilder builder, LogEventInfo logEvent) { builder.Append(logEvent.Properties["Elapse"].ToString()); } }
# 以上三個參數Url，Elapse，StatusCode都在LogEventInfo.Prpperties鍵值對中

--------------------------------3------------------------

按照文檔的要求，儘可能早點註冊自定義Nlog LayoutRenderer

public static void Main(string[] args) { LayoutRenderer.Register<ElapseLayoutRenderer>("elapse"); 　　　　...... }

關於將該HttpMessgaeHandler 應用到HttpClientFactory，請參閱 《解剖HttpClientFactory，自由擴展HttpMessageHandler》思路，

本文主要目的爲nlog 實現並添加自定義LayoutRenderer.

原文出處：https://www.cnblogs.com/JulianHuang/p/12000310.html