Split up code files

src/Components/Endpoints/src/Rendering/Buffering/BufferedTextWriter.cs

@@ -0,0 +1,80 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Buffers;
+using System.Text;
+
+namespace Microsoft.AspNetCore.Components.Endpoints.Rendering;
+
+internal class BufferedTextWriter : TextWriter
+{
+    private const int PageSize = 64;
+    private readonly TextWriter _underlying;
+    private TextChunkListBuilder _currentOutput;
+    private TextChunkListBuilder? _previousOutput;
+    private Task _currentFlushAsyncTask = Task.CompletedTask;
+
+    public BufferedTextWriter(TextWriter underlying)
+    {
+        _underlying = underlying;
+        _currentOutput = new(ArrayPool<TextChunk>.Shared, PageSize);
+    }
+
+    public override Encoding Encoding => Encoding.UTF8;
+
+    public override void Write(char value)
+        => _currentOutput.Add(new TextChunk(value));
+
+    public override void Write(char[] buffer, int index, int count)
+        => _currentOutput.Add(new TextChunk(new ArraySegment<char>(buffer, index, count)));
+
+    public override void Write(string? value)
+    {
+        if (value is not null)
+        {
+            _currentOutput.Add(new TextChunk(value));
+        }
+    }
+
+    public override void Write(int value)
+        => _currentOutput.Add(new TextChunk(value));
+
+    public override void Flush()
+        => throw new NotSupportedException();
+
+    public override Task FlushAsync()
+    {
+        _currentFlushAsyncTask = FlushAsyncCore(_currentFlushAsyncTask);
+        return _currentFlushAsyncTask;
+    }
+
+    private async Task FlushAsyncCore(Task priorTask)
+    {
+        // Must always wait for prior flushes to complete first, since they are
+        // using _previousOutput and nothing else is allowed to do so
+        if (!priorTask.IsCompletedSuccessfully)
+        {
+            await priorTask;
+        }
+
+        // Swap buffers
+        var outputToFlush = _currentOutput;
+        _currentOutput = _previousOutput ?? new(ArrayPool<TextChunk>.Shared, PageSize);
+        _previousOutput = outputToFlush;
+
+        await outputToFlush.WriteToAsync(_underlying);
+        outputToFlush.Clear();
+        await _underlying.FlushAsync();
+    }
+
+    protected override void Dispose(bool disposing)
+    {
+        if (disposing)
+        {
+            _currentOutput.Dispose();
+            _previousOutput?.Dispose();
+        }
+
+        base.Dispose(disposing);
+    }
+}