From 8782c2727f80020eeed96841450bd849cc1e0539 Mon Sep 17 00:00:00 2001
From: Albie <albion@dragonfruit.network>
Date: Fri, 27 Aug 2021 09:09:51 +0100
Subject: [PATCH] add arraypool support to file downloads and json
 deserialization

---
 .../DragonFruit.Common.Data.Tests.csproj      |  2 +-
 DragonFruit.Common.Data/ApiClient.cs          | 10 +++++----
 .../DragonFruit.Common.Data.csproj            |  1 +
 .../Serializers/ApiJsonSerializer.cs          | 22 ++++++++++++++++++-
 4 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/DragonFruit.Common.Data.Tests/DragonFruit.Common.Data.Tests.csproj b/DragonFruit.Common.Data.Tests/DragonFruit.Common.Data.Tests.csproj
index 36621a5..e4f2a80 100644
--- a/DragonFruit.Common.Data.Tests/DragonFruit.Common.Data.Tests.csproj
+++ b/DragonFruit.Common.Data.Tests/DragonFruit.Common.Data.Tests.csproj
@@ -12,6 +12,6 @@
     <ItemGroup>
       <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.11.0" />
       <PackageReference Include="NUnit" Version="3.13.2" />
-      <PackageReference Include="NUnit3TestAdapter" Version="3.17.0" />
+      <PackageReference Include="NUnit3TestAdapter" Version="4.0.0" />
     </ItemGroup>
 </Project>
diff --git a/DragonFruit.Common.Data/ApiClient.cs b/DragonFruit.Common.Data/ApiClient.cs
index 67864d5..22630bb 100644
--- a/DragonFruit.Common.Data/ApiClient.cs
+++ b/DragonFruit.Common.Data/ApiClient.cs
@@ -2,6 +2,7 @@
 // Licensed under the MIT License. Please refer to the LICENSE file at the root of this project for details
 
 using System;
+using System.Buffers;
 using System.Globalization;
 using System.IO;
 using System.Linq;
@@ -267,8 +268,8 @@ HttpResponseMessage CopyProcess(HttpResponseMessage response)
                 using var networkStream = response.Content.ReadAsStreamAsync().Result;
 #endif
 
-                // create a buffer for progress reporting
-                var buffer = new byte[request.BufferSize];
+                // rent a buffer for progress reporting
+                var buffer = ArrayPool<byte>.Shared.Rent(request.BufferSize);
                 int count;
                 int iterations = 0;
 
@@ -282,10 +283,11 @@ HttpResponseMessage CopyProcess(HttpResponseMessage response)
                         progressUpdated?.Invoke(stream.Length, response.Content.Headers.ContentLength);
                 }
 
-                // flush, send a final update and return
+                // flush, return buffer and send a final update
                 stream.Flush();
-                progressUpdated?.Invoke(stream.Length, response.Content.Headers.ContentLength);
+                ArrayPool<byte>.Shared.Return(buffer);
 
+                progressUpdated?.Invoke(stream.Length, response.Content.Headers.ContentLength);
                 return response;
             }
 
diff --git a/DragonFruit.Common.Data/DragonFruit.Common.Data.csproj b/DragonFruit.Common.Data/DragonFruit.Common.Data.csproj
index 936727e..e6babf6 100644
--- a/DragonFruit.Common.Data/DragonFruit.Common.Data.csproj
+++ b/DragonFruit.Common.Data/DragonFruit.Common.Data.csproj
@@ -24,6 +24,7 @@
 
     <ItemGroup>
         <PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
+        <PackageReference Include="System.Buffers" Version="4.5.1" />
     </ItemGroup>
 
     <ItemGroup>
diff --git a/DragonFruit.Common.Data/Serializers/ApiJsonSerializer.cs b/DragonFruit.Common.Data/Serializers/ApiJsonSerializer.cs
index c6f9309..87125d5 100644
--- a/DragonFruit.Common.Data/Serializers/ApiJsonSerializer.cs
+++ b/DragonFruit.Common.Data/Serializers/ApiJsonSerializer.cs
@@ -1,6 +1,7 @@
 // DragonFruit.Common Copyright 2020 DragonFruit Network
 // Licensed under the MIT License. Please refer to the LICENSE file at the root of this project for details
 
+using System.Buffers;
 using System.Globalization;
 using System.IO;
 using System.Net.Http;
@@ -80,6 +81,7 @@ public HttpContent Serialize<T>(T input) where T : class
             using (var streamWriter = new StreamWriter(stream, Encoding, 4096, true))
             using (var jsonWriter = new JsonTextWriter(streamWriter))
             {
+                jsonWriter.ArrayPool = JsonArrayPool.Instance;
                 Serializer.Serialize(jsonWriter, input);
             }
 
@@ -95,9 +97,27 @@ public T Deserialize<T>(Stream input) where T : class
                 false when Encoding is null => new StreamReader(input),
                 false => new StreamReader(input, Encoding)
             };
-            using var reader = new JsonTextReader(sr);
+
+            using var reader = new JsonTextReader(sr)
+            {
+                ArrayPool = JsonArrayPool.Instance
+            };
 
             return Serializer.Deserialize<T>(reader);
         }
     }
+
+    /// <summary>
+    /// A wrapper for the <see cref="T:System.Buffers.ArrayPool`1" /> that implements <see cref="T:Newtonsoft.Json.IArrayPool`1" />
+    /// </summary>
+    /// <remarks>
+    /// Taken from https://github.com/JamesNK/Newtonsoft.Json/blob/52e257ee57899296d81a868b32300f0b3cfeacbe/Src/Newtonsoft.Json.Tests/DemoTests.cs#L709
+    /// </remarks>
+    internal class JsonArrayPool : IArrayPool<char>
+    {
+        public static readonly JsonArrayPool Instance = new JsonArrayPool();
+
+        public char[] Rent(int minimumLength) => ArrayPool<char>.Shared.Rent(minimumLength);
+        public void Return(char[] array) => ArrayPool<char>.Shared.Return(array);
+    }
 }