Use PipeWriter instead of ArrayWriter when writing to outputStream (#8476)

Author: michaelstaib

src/HotChocolate/Core/src/Execution/Serialization/JsonResultFormatter.cs

@@ -1,5 +1,6 @@
 using System.Buffers;
 using System.Collections;
+using System.IO.Pipelines;
 using System.Runtime.CompilerServices;
 using System.Text;
 using System.Text.Json;
@@ -226,29 +227,24 @@ private async ValueTask FormatInternalAsync(
         Stream outputStream,
         CancellationToken cancellationToken = default)
     {
-        using var buffer = new ArrayWriter();
-        FormatInternal(result, buffer);
-
-        await outputStream
-            .WriteAsync(buffer.GetWrittenMemory(), cancellationToken)
-            .ConfigureAwait(false);
-
-        await outputStream.FlushAsync(cancellationToken).ConfigureAwait(false);
+        var writer = PipeWriter.Create(outputStream, new StreamPipeWriterOptions(leaveOpen: true));
+        FormatInternal(result, writer);
+        await writer.CompleteAsync().ConfigureAwait(false);
     }
 
     private async ValueTask FormatInternalAsync(
         OperationResultBatch resultBatch,
         Stream outputStream,
         CancellationToken cancellationToken = default)
     {
-        using var buffer = new ArrayWriter();
+        var writer = PipeWriter.Create(outputStream, new StreamPipeWriterOptions(leaveOpen: true));
 
         foreach (var result in resultBatch.Results)
         {
             switch (result)
             {
                 case IOperationResult singleResult:
-                    FormatInternal(singleResult, buffer);
+                    FormatInternal(singleResult, writer);
                     break;
 
                 case IResponseStream batchResult:
@@ -259,7 +255,7 @@ private async ValueTask FormatInternalAsync(
                     {
                         try
                         {
-                            FormatInternal(partialResult, buffer);
+                            FormatInternal(partialResult, writer);
                         }
                         finally
                         {
@@ -271,39 +267,31 @@ private async ValueTask FormatInternalAsync(
             }
         }
 
-        await outputStream
-            .WriteAsync(buffer.GetWrittenMemory(), cancellationToken)
-            .ConfigureAwait(false);
-
-        await outputStream.FlushAsync(cancellationToken).ConfigureAwait(false);
+        await writer.CompleteAsync().ConfigureAwait(false);
     }
 
     private async ValueTask FormatInternalAsync(
         IResponseStream batchResult,
         Stream outputStream,
         CancellationToken cancellationToken = default)
     {
-        using var buffer = new ArrayWriter();
+        var writer = PipeWriter.Create(outputStream, new StreamPipeWriterOptions(leaveOpen: true));
 
         await foreach (var partialResult in batchResult.ReadResultsAsync()
             .WithCancellation(cancellationToken)
             .ConfigureAwait(false))
         {
             try
             {
-                FormatInternal(partialResult, buffer);
+                FormatInternal(partialResult, writer);
             }
             finally
             {
                 await partialResult.DisposeAsync().ConfigureAwait(false);
             }
         }
 
-        await outputStream
-            .WriteAsync(buffer.GetWrittenMemory(), cancellationToken)
-            .ConfigureAwait(false);
-
-        await outputStream.FlushAsync(cancellationToken).ConfigureAwait(false);
+        await writer.CompleteAsync().ConfigureAwait(false);
     }
 
     private void WriteResult(Utf8JsonWriter writer, IOperationResult result)