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frame.go
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frame.go
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package frame
import (
"encoding/binary"
"github.com/bytedance/gopkg/lang/mcache"
"io"
)
/*
Frame: frameHeader + framePayload(packet)
frameHeader: uint16, 2 bytes => length of frame payload (Packet)
framePayload: Packet
*/
const (
FrameHeaderLen = 2
)
type FramePayload []byte
type StreamFrameCodec interface {
Encode(io.Writer, FramePayload) error
Decode(io.Reader) (FramePayload, error)
}
type frameCodec struct{}
func NewFrameCodec() StreamFrameCodec {
return &frameCodec{}
}
func (p *frameCodec) Encode(w io.Writer, framePayload FramePayload) error {
var f = framePayload
var totalLen = uint16(len(framePayload)) + FrameHeaderLen
err := binary.Write(w, binary.LittleEndian, &totalLen)
if err != nil {
return err
}
// make sure all data will be written to outbound stream
for {
n, err := w.Write(f) // write the frame payload to outbound stream
if err != nil {
return err
}
if n >= len(f) {
break
}
if n < len(f) {
f = f[n:]
}
}
return nil
}
func (p *frameCodec) Decode(r io.Reader) (FramePayload, error) {
var totalLen uint16
err := binary.Read(r, binary.LittleEndian, &totalLen)
if err != nil {
return nil, err
}
buf := mcache.Malloc(int(totalLen - FrameHeaderLen))
_, err = io.ReadFull(r, buf)
if err != nil {
return nil, err
}
return buf, nil
}