Make Stream.Flush no-op on read-only streams (#57079)

* Make Stream.Flush no-op

Make implementations of `Stream.Flush()` a no-op instead of throw an exception.
Relates to #57064.

* Make Stream.FlushAsync no-op

- Override `Stream.FlushAsync()` methods as a no-op.
- Make implementations of `Stream.FlushAsync()` a no-op instead of throw an exception.

Author: martincostello

src/Components/Server/src/Circuits/RemoteJSDataStream.cs

@@ -161,7 +161,11 @@ public override long Position
     }
 
     public override void Flush()
-        => throw new NotSupportedException();
+    {
+        // No-op
+    }
+
+    public override Task FlushAsync(CancellationToken cancellationToken) => Task.CompletedTask;
 
     public override int Read(byte[] buffer, int offset, int count)
         => throw new NotSupportedException("Synchronous reads are not supported.");

src/Components/Shared/src/PullFromJSDataStream.cs

@@ -55,7 +55,11 @@ public override long Position
     }
 
     public override void Flush()
-        => throw new NotSupportedException();
+    {
+        // No-op
+    }
+
+    public override Task FlushAsync(CancellationToken cancellationToken) => Task.CompletedTask;
 
     public override int Read(byte[] buffer, int offset, int count)
         => throw new NotSupportedException("Synchronous reads are not supported.");

src/Hosting/TestHost/src/ResponseBodyReaderStream.cs

@@ -48,9 +48,12 @@ public override long Position
 
     public override void SetLength(long value) => throw new NotSupportedException();
 
-    public override void Flush() => throw new NotSupportedException();
+    public override void Flush()
+    {
+        // No-op
+    }
 
-    public override Task FlushAsync(CancellationToken cancellationToken) => throw new NotSupportedException();
+    public override Task FlushAsync(CancellationToken cancellationToken) => Task.CompletedTask;
 
     // Write with count 0 will still trigger OnFirstWrite
     public override void Write(byte[] buffer, int offset, int count) => throw new NotSupportedException();

src/Mvc/shared/Mvc.Core.TestCommon/NonSeekableReadableStream.cs

@@ -38,9 +38,11 @@ public override long Position
 
     public override void Flush()
     {
-        throw new NotImplementedException();
+        // No-op
     }
 
+    public override Task FlushAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+
     public override long Seek(long offset, SeekOrigin origin)
     {
         throw new NotSupportedException();

src/Servers/HttpSys/src/RequestProcessing/RequestStream.cs

@@ -77,10 +77,12 @@ public override long Seek(long offset, SeekOrigin origin)
 
     public override void SetLength(long value) => throw new NotSupportedException(Resources.Exception_NoSeek);
 
-    public override void Flush() => throw new InvalidOperationException(Resources.Exception_ReadOnlyStream);
+    public override void Flush()
+    {
+        // No-op
+    }
 
-    public override Task FlushAsync(CancellationToken cancellationToken)
-        => throw new InvalidOperationException(Resources.Exception_ReadOnlyStream);
+    public override Task FlushAsync(CancellationToken cancellationToken) => Task.CompletedTask;
 
     internal void SwitchToOpaqueMode()
     {

src/Shared/SegmentWriteStream.cs

@@ -99,12 +99,11 @@ protected override void Dispose(bool disposing)
 
     public override void Flush()
     {
-        if (!CanWrite)
-        {
-            throw new ObjectDisposedException(nameof(SegmentWriteStream), "The stream has been closed for writing.");
-        }
+        // No-op
     }
 
+    public override Task FlushAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+
     public override int Read(byte[] buffer, int offset, int count)
     {
         throw new NotSupportedException("The stream does not support reading.");