TUN-6035: Reduce buffer size when proxying data

cfio/copy.go

@@ -0,0 +1,27 @@
+package cfio
+
+import (
+	"io"
+	"sync"
+)
+
+const defaultBufferSize = 16 * 1024
+
+var bufferPool = sync.Pool{
+	New: func() interface{} {
+		return make([]byte, defaultBufferSize)
+	},
+}
+
+func Copy(dst io.Writer, src io.Reader) (written int64, err error) {
+	_, okWriteTo := src.(io.WriterTo)
+	_, okReadFrom := dst.(io.ReaderFrom)
+	var buffer []byte = nil
+
+	if !(okWriteTo || okReadFrom) {
+		buffer = bufferPool.Get().([]byte)
+		defer bufferPool.Put(buffer)
+	}
+
+	return io.CopyBuffer(dst, src, buffer)
+}