added pipe based benchmak

Tests/MQTTnet.Benchmarks/Tcp/SocketReceiver.cs

@@ -0,0 +1,39 @@
+using System;
+using System.IO.Pipelines;
+using System.Net.Sockets;
+using Playground.Client.Mqtt.Tcp;
+
+namespace MQTTnet.Benchmarks.Tcp
+{
+    public class SocketReceiver
+    {
+        private readonly Socket _socket;
+        private readonly SocketAsyncEventArgs _eventArgs = new SocketAsyncEventArgs();
+        private readonly SocketAwaitable _awaitable;
+
+        public SocketReceiver(Socket socket, PipeScheduler scheduler)
+        {
+            _socket = socket;
+            _awaitable = new SocketAwaitable(scheduler);
+            _eventArgs.UserToken = _awaitable;
+            _eventArgs.Completed += (_, e) => ((SocketAwaitable)e.UserToken).Complete(e.BytesTransferred, e.SocketError);
+        }
+
+        public SocketAwaitable ReceiveAsync(Memory<byte> buffer)
+        {
+#if NETCOREAPP2_1
+            _eventArgs.SetBuffer(buffer);
+#else
+            var segment = buffer.GetArray();
+
+            _eventArgs.SetBuffer(segment.Array, segment.Offset, segment.Count);
+#endif
+            if (!_socket.ReceiveAsync(_eventArgs))
+            {
+                _awaitable.Complete(_eventArgs.BytesTransferred, _eventArgs.SocketError);
+            }
+
+            return _awaitable;
+        }
+    }
+}