From 6bbbfefb75c89afa1ed0d4100ffa8522359f45af Mon Sep 17 00:00:00 2001
From: aler9 <46489434+aler9@users.noreply.github.com>
Date: Sat, 27 Jun 2020 16:06:16 +0200
Subject: [PATCH] reuse interleaved frame buffer to minimize ram and cpu

---
 conn-client.go       | 12 ++++++++----
 conn-server.go       |  4 ++--
 interleaved-frame.go | 26 +++++++++++---------------
 3 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/conn-client.go b/conn-client.go
index fbfff0a0..6d44d332 100644
--- a/conn-client.go
+++ b/conn-client.go
@@ -144,7 +144,7 @@ func (c *ConnClient) WriteRequestNoResponse(req *Request) error {
 }
 
 // ReadInterleavedFrameOrResponse reads an InterleavedFrame or a Response.
-func (c *ConnClient) ReadInterleavedFrameOrResponse() (interface{}, error) {
+func (c *ConnClient) ReadInterleavedFrameOrResponse(frame *InterleavedFrame) (interface{}, error) {
 	c.conf.NConn.SetReadDeadline(time.Now().Add(c.conf.ReadTimeout))
 	b, err := c.br.ReadByte()
 	if err != nil {
@@ -153,16 +153,20 @@ func (c *ConnClient) ReadInterleavedFrameOrResponse() (interface{}, error) {
 	c.br.UnreadByte()
 
 	if b == _INTERLEAVED_FRAME_MAGIC {
-		return interleavedFrameRead(c.br)
+		err := frame.read(c.br)
+		if err != nil {
+			return nil, err
+		}
+		return frame, err
 	}
 
 	return readResponse(c.br)
 }
 
 // ReadInterleavedFrame reads an InterleavedFrame.
-func (c *ConnClient) ReadInterleavedFrame() (*InterleavedFrame, error) {
+func (c *ConnClient) ReadInterleavedFrame(frame *InterleavedFrame) error {
 	c.conf.NConn.SetReadDeadline(time.Now().Add(c.conf.ReadTimeout))
-	return interleavedFrameRead(c.br)
+	return frame.read(c.br)
 }
 
 // WriteInterleavedFrame writes an InterleavedFrame.
diff --git a/conn-server.go b/conn-server.go
index 7a095561..2c6afe4e 100644
--- a/conn-server.go
+++ b/conn-server.go
@@ -75,9 +75,9 @@ func (s *ConnServer) WriteResponse(res *Response) error {
 }
 
 // ReadInterleavedFrame reads an InterleavedFrame.
-func (s *ConnServer) ReadInterleavedFrame() (*InterleavedFrame, error) {
+func (s *ConnServer) ReadInterleavedFrame(frame *InterleavedFrame) error {
 	s.conf.NConn.SetReadDeadline(time.Now().Add(s.conf.ReadTimeout))
-	return interleavedFrameRead(s.br)
+	return frame.read(s.br)
 }
 
 // WriteInterleavedFrame writes an InterleavedFrame.
diff --git a/interleaved-frame.go b/interleaved-frame.go
index b18dfe7e..539d816e 100644
--- a/interleaved-frame.go
+++ b/interleaved-frame.go
@@ -8,9 +8,7 @@ import (
 )
 
 const (
-	_INTERLEAVED_FRAME_MAGIC            = 0x24
-	_INTERLEAVED_FRAME_MAX_SIZE         = 512 * 1024
-	_INTERLEAVED_FRAME_MAX_CONTENT_SIZE = (_INTERLEAVED_FRAME_MAX_SIZE - 4)
+	_INTERLEAVED_FRAME_MAGIC = 0x24
 )
 
 // InterleavedFrame is a structure that allows to send and receive binary data
@@ -21,34 +19,32 @@ type InterleavedFrame struct {
 	Content []byte
 }
 
-func interleavedFrameRead(r io.Reader) (*InterleavedFrame, error) {
+func (f *InterleavedFrame) read(r io.Reader) error {
 	var header [4]byte
 	_, err := io.ReadFull(r, header[:])
 	if err != nil {
-		return nil, err
+		return err
 	}
 
 	if header[0] != _INTERLEAVED_FRAME_MAGIC {
-		return nil, fmt.Errorf("wrong magic byte (0x%.2x)", header[0])
+		return fmt.Errorf("wrong magic byte (0x%.2x)", header[0])
 	}
 
 	framelen := int(binary.BigEndian.Uint16(header[2:]))
-	if framelen > _INTERLEAVED_FRAME_MAX_SIZE {
-		return nil, fmt.Errorf("frame length greater than maximum allowed (%d vs %d)",
-			framelen, _INTERLEAVED_FRAME_MAX_SIZE)
+	if framelen > len(f.Content) {
+		return fmt.Errorf("frame length greater than maximum allowed (%d vs %d)",
+			framelen, len(f.Content))
 	}
 
-	f := &InterleavedFrame{
-		Channel: header[1],
-		Content: make([]byte, framelen),
-	}
+	f.Channel = header[1]
+	f.Content = f.Content[:framelen]
 
 	_, err = io.ReadFull(r, f.Content)
 	if err != nil {
-		return nil, err
+		return err
 	}
 
-	return f, nil
+	return nil
 }
 
 func (f *InterleavedFrame) write(bw *bufio.Writer) error {