Override CopyTo to improve performance (#278)

* Override CopyTo to improve performance

If CopyTo is not overriden, it is used the default implementation in Stream class which is inefficient as it uses ArrayPool and writes in loop.

* Update src/RecyclableMemoryStream.cs

good idea!

Co-authored-by: Gregory Bell <65985703+grbell-ms@users.noreply.github.com>

---------

Co-authored-by: lechu445 <xxx@example.com>
Co-authored-by: Gregory Bell <65985703+grbell-ms@users.noreply.github.com>

Author: 3 people

src/RecyclableMemoryStream.cs

@@ -551,6 +551,14 @@ public override byte[] GetBuffer()
             return this.largeBuffer;
         }
 
+#if NETCOREAPP2_1_OR_GREATER || NETSTANDARD2_1
+        /// <inheritdoc/>
+        public override void CopyTo(Stream destination, int bufferSize)
+        {
+            WriteTo(destination, this.position, this.length - this.position);
+        }
+#endif
+
         /// <summary>Asynchronously reads all the bytes from the current position in this stream and writes them to another stream.</summary>
         /// <param name="destination">The stream to which the contents of the current stream will be copied.</param>
         /// <param name="bufferSize">This parameter is ignored.</param>