update async stream writing

MediaBrowser.Server.Implementations/HttpServer/AsyncStreamWriterFunc.cs

@@ -0,0 +1,56 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading.Tasks;
+using ServiceStack;
+using ServiceStack.Web;
+
+namespace MediaBrowser.Server.Implementations.HttpServer
+{
+    public class AsyncStreamWriterFunc : IStreamWriter, IAsyncStreamWriter, IHasOptions
+    {
+        /// <summary>
+        /// Gets or sets the source stream.
+        /// </summary>
+        /// <value>The source stream.</value>
+        private Func<Stream, Task> Writer { get; set; }
+
+        /// <summary>
+        /// Gets the options.
+        /// </summary>
+        /// <value>The options.</value>
+        public IDictionary<string, string> Options { get; }
+
+        public Action OnComplete { get; set; }
+        public Action OnError { get; set; }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="StreamWriter" /> class.
+        /// </summary>
+        public AsyncStreamWriterFunc(Func<Stream, Task> writer, IDictionary<string, string> headers)
+        {
+            Writer = writer;
+
+            if (headers == null)
+            {
+                headers = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+            }
+            Options = headers;
+        }
+
+        /// <summary>
+        /// Writes to.
+        /// </summary>
+        /// <param name="responseStream">The response stream.</param>
+        public void WriteTo(Stream responseStream)
+        {
+            var task = Writer(responseStream);
+            Task.WaitAll(task);
+        }
+
+        public async Task WriteToAsync(Stream responseStream)
+        {
+            await Writer(responseStream).ConfigureAwait(false);
+        }
+    }
+}