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common.go
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common.go
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package common
import (
"fmt"
"io"
)
const (
// pakcage version
MajorVersion = 1
MinorVersion = 1
FixVersion = 1
)
// make up version
func makeUpVersion(major, minor, fix uint8) uint32 {
return uint32(major)<<24 | uint32(minor)<<16 | uint32(fix)<<8
}
// break down version
func breadDownVersion(version uint32) (uint8, uint8, uint8) {
return uint8(version >> 24), uint8(version >> 16), uint8(version >> 8)
}
const (
// package type definition
Message PackageType = 0x01
Stream PackageType = 0x02
UserDefined PackageType = 0x04
// flags
FlagCompressed = 0x80
// the len of magic sequence
VersionSize = 4
PackageTypeSize = 1
PackageFlagsSize = 1
PayloadLenSize = 4
HeaderSize = VersionSize + PackageTypeSize + PackageFlagsSize + PayloadLenSize
// filed offsets
VersionOffset = 0
PackageTypeOffset = VersionSize
FlagsOffset = VersionSize + PackageTypeSize
PayloadLenOffset = VersionSize + PackageTypeSize + PackageFlagsSize
)
type PackageType uint8
type PackageHeader struct {
// major_version: Version << 24
// minor_version: Version << 16
// fix_version: Version << 8
// Version => {major_version} | {minor_version} | {fix_version}
Version uint32
// the package type
// message package: 0x01
// stream package: 0x02
// user-defined package: 0x04
PackageType PackageType
// flags
Flags uint8
// payload length
// the size of package payload
PayloadLen uint32
}
// new package
func NewPackageHeader(packageType PackageType) *PackageHeader {
return &PackageHeader{
PackageType: packageType,
Version: makeUpVersion(MajorVersion, MinorVersion, FixVersion),
}
}
// set version
func (h *PackageHeader) SetVersion(version uint32) *PackageHeader {
h.Version = version
return h
}
// get version
func (h *PackageHeader) GetVersion() uint32 {
return h.Version
}
// set payload len
func (h *PackageHeader) SetPayloadLen(payloadLen uint32) *PackageHeader {
h.PayloadLen = payloadLen
return h
}
// get payload len of package
func (h *PackageHeader) GetPayloadLen() uint32 {
return h.PayloadLen
}
// set package type
func (h *PackageHeader) SetPackageType(packageType PackageType) *PackageHeader {
h.PackageType = packageType
return h
}
// get package type
func (h *PackageHeader) GetPackageType() PackageType {
return h.PackageType
}
// set package flags
func (h *PackageHeader) SetFlags(flags uint8) *PackageHeader {
h.Flags = flags
return h
}
// get package flags
func (h *PackageHeader) GetFlags() uint8 {
return h.Flags
}
// do packing
func (h *PackageHeader) Pack(buffer *[]byte) {
*buffer = append(*buffer,
byte(h.Version>>24),
byte(h.Version>>16),
byte(h.Version>>8),
byte(h.Version),
byte(h.PackageType),
byte(h.Flags),
byte(h.PayloadLen>>24),
byte(h.PayloadLen>>16),
byte(h.PayloadLen>>8),
byte(h.PayloadLen))
}
// do unpacking
func (h *PackageHeader) Unpack(header []byte) {
h.Version = uint32(header[VersionOffset])<<24 |
uint32(header[VersionOffset+1])<<16 |
uint32(header[VersionOffset+2])<<8 |
uint32(header[VersionOffset+3])
h.PackageType = PackageType(header[PackageTypeOffset])
h.Flags = uint8(header[FlagsOffset])
h.PayloadLen = uint32(header[PayloadLenOffset])<<24 |
uint32(header[PayloadLenOffset+1])<<16 |
uint32(header[PayloadLenOffset+2])<<8 |
uint32(header[PayloadLenOffset+3])
}
type Writer struct {
Writer io.Writer
}
// new Writer instance
func NewWriter(w io.Writer) *Writer {
return &Writer{Writer: w}
}
// Write message raw data
// steps:
// 1) packer the package header
// 2) write header
// 3) write message raw data
func (w *Writer) Write(data []byte) (int, error) {
if w.Writer == nil {
fmt.Println("bad io writer")
return 0, fmt.Errorf("bad io writer")
}
// packing header
header := NewPackageHeader(Message)
header.SetPayloadLen(uint32(len(data)))
var headerBuffer []byte
header.Pack(&headerBuffer)
// write header
_, err := w.Writer.Write(headerBuffer)
if err != nil {
fmt.Println("failed to write header")
return 0, err
}
// write payload
_, err = w.Writer.Write(data)
if err != nil {
fmt.Println("failed to write payload")
return 0, err
}
return len(data), nil
}
type Reader struct {
Reader io.Reader
}
func NewReader(r io.Reader) *Reader {
return &Reader{Reader: r}
}
// Read message raw data from reader
// steps:
// 1)read the package header
// 2)unpack the package header and get the payload length
// 3)read the payload
func (r *Reader) Read() ([]byte, error) {
if r.Reader == nil {
fmt.Println("bad io reader")
return nil, fmt.Errorf("bad io reader")
}
headerBuffer := make([]byte, HeaderSize)
_, err := io.ReadFull(r.Reader, headerBuffer)
if err != nil {
if err != io.EOF {
fmt.Println("failed to read package header from buffer")
}
return nil, err
}
header := PackageHeader{}
header.Unpack(headerBuffer)
payloadBuffer := make([]byte, header.PayloadLen)
_, err = io.ReadFull(r.Reader, payloadBuffer)
if err != nil {
if err != io.EOF {
fmt.Println("failed to read payload from buffer")
}
return nil, err
}
return payloadBuffer, nil
}