From adc0adfb5039c39efa73c4d8864a586e238a7516 Mon Sep 17 00:00:00 2001
From: Corentin Altepe <corentin.altepe@gmail.com>
Date: Sat, 9 Mar 2024 10:38:54 +0100
Subject: [PATCH] Attempt at adding support for .NET Framework 4.8

This is only an idea of adding support for .NET Framework 4.8, following issue #114. This proof of concept is not ready to be merged.

* The added dependencies must be conditioned to only .NET Framework 4.8.
* The Json serliazing logic must be conditioned to .NET Framework 4.8 to avoid performance degradation for .NET 6+ users.
* Documentation and build, test, publish pipelines must be updated accordingly
---
 src/NLog.Loki/HttpLokiTransport.cs | 24 +++++++++++++++---------
 src/NLog.Loki/LokiTarget.cs        |  1 -
 src/NLog.Loki/NLog.Loki.csproj     |  5 ++++-
 3 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/src/NLog.Loki/HttpLokiTransport.cs b/src/NLog.Loki/HttpLokiTransport.cs
index c62bac1..d36d356 100644
--- a/src/NLog.Loki/HttpLokiTransport.cs
+++ b/src/NLog.Loki/HttpLokiTransport.cs
@@ -1,7 +1,7 @@
 using System.Collections.Generic;
+using System.IO;
 using System.IO.Compression;
 using System.Net.Http;
-using System.Net.Http.Json;
 using System.Text.Json;
 using System.Threading.Tasks;
 using NLog.Common;
@@ -25,7 +25,7 @@ public HttpLokiTransport(
     {
         _lokiHttpClient = lokiHttpClient;
         _gzipLevel = gzipLevel;
-        
+
         _jsonOptions = new JsonSerializerOptions();
         _jsonOptions.Converters.Add(new LokiEventsSerializer(orderWrites));
         _jsonOptions.Converters.Add(new LokiEventSerializer());
@@ -33,14 +33,14 @@ public HttpLokiTransport(
 
     public async Task WriteLogEventsAsync(IEnumerable<LokiEvent> lokiEvents)
     {
-        using var jsonStreamContent = CreateContent(lokiEvents);
+        using var jsonStreamContent = await CreateContent(lokiEvents);
         using var response = await _lokiHttpClient.PostAsync("loki/api/v1/push", jsonStreamContent).ConfigureAwait(false);
         await ValidateHttpResponse(response).ConfigureAwait(false);
     }
 
     public async Task WriteLogEventsAsync(LokiEvent lokiEvent)
     {
-        using var jsonStreamContent = CreateContent(lokiEvent);
+        using var jsonStreamContent = await CreateContent(lokiEvent);
         using var response = await _lokiHttpClient.PostAsync("loki/api/v1/push", jsonStreamContent).ConfigureAwait(false);
         await ValidateHttpResponse(response).ConfigureAwait(false);
     }
@@ -49,19 +49,25 @@ public async Task WriteLogEventsAsync(LokiEvent lokiEvent)
     /// Prepares the HttpContent for the loki event(s).
     /// If gzip compression is enabled, prepares a gzip stream with the appropriate headers.
     /// </summary>
-    private HttpContent CreateContent<T>(T lokiEvent)
+    private async Task<HttpContent> CreateContent<T>(T lokiEvent)
     {
-        var jsonContent = JsonContent.Create(lokiEvent, options: _jsonOptions);
+        //var jsonContent = JsonContent.Create(lokiEvent, options: _jsonOptions);
+
+        using var memStream = new MemoryStream();
+        await JsonSerializer.SerializeAsync(memStream, lokiEvent, options: _jsonOptions);
+        memStream.Position = 0;
+        using var con = new StreamContent(memStream);
+        con.Headers.ContentType.MediaType = "application/json";
 
         // Some old loki versions support only 'application/json',
         // not 'application/json; charset=utf-8' content-Type header
-        jsonContent.Headers.ContentType.CharSet = string.Empty;
+        con.Headers.ContentType.CharSet = string.Empty;
 
         // If no compression required
         if(_gzipLevel == CompressionLevel.NoCompression)
-            return jsonContent;
+            return con;
 
-        return new CompressedContent(jsonContent, _gzipLevel);
+        return new CompressedContent(con, _gzipLevel);
     }
 
     private static async ValueTask ValidateHttpResponse(HttpResponseMessage response)
diff --git a/src/NLog.Loki/LokiTarget.cs b/src/NLog.Loki/LokiTarget.cs
index 310747d..577ae5b 100644
--- a/src/NLog.Loki/LokiTarget.cs
+++ b/src/NLog.Loki/LokiTarget.cs
@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using System.IO.Compression;
-using System.Linq;
 using System.Net;
 using System.Net.Http;
 using System.Text;
diff --git a/src/NLog.Loki/NLog.Loki.csproj b/src/NLog.Loki/NLog.Loki.csproj
index 15cfb43..e414e93 100644
--- a/src/NLog.Loki/NLog.Loki.csproj
+++ b/src/NLog.Loki/NLog.Loki.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;net6.0;net7.0;net8.0</TargetFrameworks>
+    <TargetFrameworks>net48;netstandard2.0;net6.0;net7.0;net8.0</TargetFrameworks>
     <LangVersion>10.0</LangVersion>
     <PackageId>NLog.Targets.Loki</PackageId>
     <Authors>Anton Gogolev, Corentin Altepe</Authors>
@@ -27,7 +27,10 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="Microsoft.Net.Http" Version="2.2.29" />
     <PackageReference Include="NLog" Version="5.2.8" />
+    <PackageReference Include="System.Net.Http" Version="4.3.4" />
+    <PackageReference Include="System.Text.Json" Version="8.0.2" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">