forked from funny/link
/
codec_packet.go
224 lines (200 loc) · 5.29 KB
/
codec_packet.go
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package link
import (
"bufio"
"bytes"
"encoding/binary"
"io"
"sync"
)
var (
BigEndian = binary.BigEndian
LittleEndian = binary.LittleEndian
)
func Packet(n, maxPacketSize, readBufferSize int, byteOrder binary.ByteOrder, base CodecType) CodecType {
return &packetCodecType{
n: n,
base: base,
maxPacketSize: maxPacketSize,
readBufferSize: readBufferSize,
byteOrder: byteOrder,
}
}
type packetCodecType struct {
n int
maxPacketSize int
readBufferSize int
base CodecType
encoderPool sync.Pool
decoderPool sync.Pool
byteOrder binary.ByteOrder
}
func (codecType *packetCodecType) NewEncoder(w io.Writer) Encoder {
encoder, ok := codecType.encoderPool.Get().(*packetEncoder)
if ok {
encoder.writer = w
} else {
encoder = &packetEncoder{
n: codecType.n,
writer: w,
parent: codecType,
}
switch codecType.n {
case 1:
encoder.encodeHead = codecType.encodeHead1
codecType.prepareBuffer1(&encoder.buffer)
case 2:
encoder.encodeHead = codecType.encodeHead2
codecType.prepareBuffer2(&encoder.buffer)
case 4:
encoder.encodeHead = codecType.encodeHead4
codecType.prepareBuffer4(&encoder.buffer)
case 8:
encoder.encodeHead = codecType.encodeHead8
codecType.prepareBuffer8(&encoder.buffer)
}
}
encoder.base = codecType.base.NewEncoder(&encoder.buffer)
return encoder
}
func (codecType *packetCodecType) prepareBuffer1(buf *bytes.Buffer) {
buf.WriteByte(0)
}
func (codecType *packetCodecType) prepareBuffer2(buf *bytes.Buffer) {
var b [2]byte
buf.Write(b[:])
}
func (codecType *packetCodecType) prepareBuffer4(buf *bytes.Buffer) {
var b [4]byte
buf.Write(b[:])
}
func (codecType *packetCodecType) prepareBuffer8(buf *bytes.Buffer) {
var b [8]byte
buf.Write(b[:])
}
func (codecType *packetCodecType) encodeHead1(b []byte) {
if n := len(b) - 1; n <= 254 && n <= codecType.maxPacketSize {
b[0] = byte(n)
} else {
panic("too large packet size")
}
}
func (codecType *packetCodecType) encodeHead2(b []byte) {
if n := len(b) - 2; n <= 65534 && n <= codecType.maxPacketSize {
codecType.byteOrder.PutUint16(b, uint16(n))
} else {
panic("too large packet size")
}
}
func (codecType *packetCodecType) encodeHead4(b []byte) {
if n := len(b) - 4; n <= codecType.maxPacketSize {
codecType.byteOrder.PutUint32(b, uint32(n))
} else {
panic("too large packet size")
}
}
func (codecType *packetCodecType) encodeHead8(b []byte) {
if n := len(b) - 8; n <= codecType.maxPacketSize {
codecType.byteOrder.PutUint64(b, uint64(n))
} else {
panic("too large packet size")
}
}
func (codecType *packetCodecType) NewDecoder(r io.Reader) Decoder {
decoder, ok := codecType.decoderPool.Get().(*packetDecoder)
if ok {
decoder.reader.Reset(r)
} else {
decoder = &packetDecoder{
n: codecType.n,
parent: codecType,
reader: bufio.NewReaderSize(r, codecType.readBufferSize),
}
switch codecType.n {
case 1:
decoder.decodeHead = codecType.decodeHead1
case 2:
decoder.decodeHead = codecType.decodeHead2
case 4:
decoder.decodeHead = codecType.decodeHead4
case 8:
decoder.decodeHead = codecType.decodeHead8
}
}
decoder.base = codecType.base.NewDecoder(&decoder.buffer)
return decoder
}
func (codecType *packetCodecType) decodeHead1(b []byte) int {
if n := int(b[0]); n <= 254 && n <= codecType.maxPacketSize {
return n
}
panic("too large packet size")
}
func (codecType *packetCodecType) decodeHead2(b []byte) int {
if n := int(codecType.byteOrder.Uint16(b)); n > 0 && n <= 65534 && n <= codecType.maxPacketSize {
return n
}
panic("too large packet size")
}
func (codecType *packetCodecType) decodeHead4(b []byte) int {
if n := int(codecType.byteOrder.Uint32(b)); n > 0 && n <= codecType.maxPacketSize {
return n
}
panic("too large packet size")
}
func (codecType *packetCodecType) decodeHead8(b []byte) int {
if n := int(codecType.byteOrder.Uint64(b)); n > 0 && n <= codecType.maxPacketSize {
return n
}
panic("too large packet size")
}
type packetEncoder struct {
n int
base Encoder
buffer bytes.Buffer
writer io.Writer
parent *packetCodecType
encodeHead func([]byte)
}
type packetDecoder struct {
n int
base Decoder
buffer bytes.Buffer
reader *bufio.Reader
parent *packetCodecType
decodeHead func([]byte) int
}
func (encoder *packetEncoder) Encode(msg interface{}) (err error) {
encoder.buffer.Truncate(encoder.n)
if err = encoder.base.Encode(msg); err != nil {
return err
}
b := encoder.buffer.Bytes()
encoder.encodeHead(b)
_, err = encoder.writer.Write(b)
return err
}
func (decoder *packetDecoder) Decode(msg interface{}) (err error) {
decoder.buffer.Reset()
if _, err = decoder.buffer.ReadFrom(io.LimitReader(decoder.reader, int64(decoder.n))); err != nil {
return err
}
n := decoder.decodeHead(decoder.buffer.Next(decoder.n))
if _, err = decoder.buffer.ReadFrom(io.LimitReader(decoder.reader, int64(n))); err != nil {
return err
}
return decoder.base.Decode(msg)
}
func (encoder *packetEncoder) Dispose() {
if d, ok := encoder.base.(Disposeable); ok {
d.Dispose()
}
encoder.base = nil
encoder.parent.encoderPool.Put(encoder)
}
func (decoder *packetDecoder) Dispose() {
if d, ok := decoder.base.(Disposeable); ok {
d.Dispose()
}
decoder.base = nil
decoder.parent.decoderPool.Put(decoder)
}