add WriteBulkFrom func write bulk from io.Reader, size n

Signed-off-by: weedge <[email protected]>

redcon.go

@@ -113,6 +113,8 @@ type Conn interface {
 	PeekPipeline() []Command
 	// NetConn returns the base net.Conn connection
 	NetConn() net.Conn
+	// WriteBulkFrom write bulk from io.Reader, size n
+	WriteBulkFrom(n int64, rb io.Reader)
 }
 
 // NewServer returns a new Redcon server configured on "tcp" network net.
@@ -494,6 +496,9 @@ func (c *conn) PeekPipeline() []Command {
 func (c *conn) NetConn() net.Conn {
 	return c.conn
 }
+func (c *conn) WriteBulkFrom(n int64, rb io.Reader) {
+	c.wr.WriteBulkFrom(n, rb)
+}
 
 // BaseWriter returns the underlying connection writer, if any
 func BaseWriter(c Conn) *Writer {
@@ -589,13 +594,30 @@ type Writer struct {
 	w   io.Writer
 	b   []byte
 	err error
+
+	// use golang buff io
+	buff *bufio.Writer
 }
 
 // NewWriter creates a new RESP writer.
 func NewWriter(wr io.Writer) *Writer {
 	return &Writer{
-		w: wr,
+		w:    wr,
+		buff: bufio.NewWriterSize(wr, maxBufferCap),
+	}
+}
+
+func (w *Writer) WriteBulkFrom(n int64, rb io.Reader) {
+	if w != nil && w.err != nil {
+		return
 	}
+	AppendBulkFrom(w, n, rb)
+}
+
+func AppendBulkFrom(writer *Writer, n int64, rb io.Reader) {
+	writer.buff.Write(appendPrefix([]byte{}, '$', n))
+	io.Copy(writer.w, rb)
+	writer.buff.Write([]byte{'\r', '\n'})
 }
 
 // WriteNull writes a null to the client