Added PushStreamContent<T> to avoid delegate allocation.

Author: CodeBlanch

ClassLibraries/Macross.Json.Extensions/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## 2.1.0
 
+* Added `PushStreamContent<T>` to allow passing of state to the callback invoked
+  to write data to the request stream which can be used to avoid allocation of a
+  delegate.
+
 * If you are using the 5.0.0+ version of System.Text.Json you can now decorate
   enum values with `JsonPropertyName` instead of `EnumMember` for
   `JsonStringEnumMemberConverter`.

ClassLibraries/Macross.Json.Extensions/Code/Macross.Json.Extensions.csproj

@@ -19,13 +19,14 @@
       System.Text.Json.Serialization.JsonDelegatedStringConverter
       System.Text.Json.Serialization.JsonTypeConverterAdapter
       System.Net.Http.PushStreamContent
+      System.Net.Http.PushStreamContent<T>
     </Description>
     <Product>Macross.Json.Extensions</Product>
     <GenerateAssemblyInfo>true</GenerateAssemblyInfo>
     <GenerateAssemblyVersionAttribute>false</GenerateAssemblyVersionAttribute>
     <GeneratePackageOnBuild>false</GeneratePackageOnBuild>
     <VersionPrefix>2.1.0</VersionPrefix>
-    <VersionSuffix>beta2</VersionSuffix>
+    <VersionSuffix>beta3</VersionSuffix>
     <FileVersion>$(VersionPrefix)</FileVersion>
     <PackageProjectUrl>https://github.com/Macross-Software/core/tree/develop/ClassLibraries/Macross.Json.Extensions</PackageProjectUrl>
   </PropertyGroup>

ClassLibraries/Macross.Json.Extensions/Code/Properties/AssemblyInfo.cs

@@ -10,4 +10,4 @@
 
 [assembly: InternalsVisibleTo("Macross.Json.Extensions.Tests, PublicKey=002400000480000094000000060200000024000052534131000400000100010051b7a480b13cecfa44862449486c6884bd6168c325445a0848f48deca9643657c5ae85df3cf6ffdb24d5bd3e9b71dc074ca602544b83511fbce1f83f1d06bb8b7b564414c9d8c719e4e39b95643dfc8e9ce997b5e2a1542a8ff6379186f87b8b695fee82c506170c4fb8ffcbf2e68f4b5d270083f8909c67916500608ce747e9")]
 
-[assembly: AssemblyVersion("2.1.0.21080")]
+[assembly: AssemblyVersion("2.1.0.21178")]

ClassLibraries/Macross.Json.Extensions/Code/System.Net.Http/PushStreamContent{T}.cs

@@ -0,0 +1,40 @@
+using System.IO;
+using System.Threading.Tasks;
+
+namespace System.Net.Http
+{
+	/// <summary>
+	/// Provides an <see cref="HttpContent"/> implementation that exposes an output <see cref="Stream"/>
+	/// which can be written to directly. The ability to push data to the output stream differs from the
+	/// <see cref="StreamContent"/> where data is pulled and not pushed.
+	/// </summary>
+	/// <typeparam name="T">State type.</typeparam>
+	public class PushStreamContent<T> : HttpContent
+	{
+		private readonly Func<Stream, T, Task> _OnStreamAvailable;
+		private readonly T _State;
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="PushStreamContent{T}"/> class.
+		/// </summary>
+		/// <param name="onStreamAvailable">Callback function to write to the stream once it is available.</param>
+		/// <param name="state">State to be passed to the callback function.</param>
+		public PushStreamContent(Func<Stream, T, Task> onStreamAvailable, T state)
+		{
+			_OnStreamAvailable = onStreamAvailable ?? throw new ArgumentNullException(nameof(onStreamAvailable));
+			_State = state;
+		}
+
+		/// <inheritdoc/>
+		protected override async Task SerializeToStreamAsync(Stream stream, TransportContext? context)
+			=> await _OnStreamAvailable(stream, _State).ConfigureAwait(false);
+
+		/// <inheritdoc/>
+		protected override bool TryComputeLength(out long length)
+		{
+			// We can't know the length of the content being pushed to the output stream.
+			length = -1;
+			return false;
+		}
+	}
+}