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log.go
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log.go
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package rpl
import (
"bytes"
"encoding/binary"
"io"
"sync"
)
const LogHeadSize = 17
type Log struct {
ID uint64
CreateTime uint32
Compression uint8
Data []byte
}
func (l *Log) HeadSize() int {
return LogHeadSize
}
func (l *Log) Size() int {
return l.HeadSize() + len(l.Data)
}
func (l *Log) Marshal() ([]byte, error) {
buf := bytes.NewBuffer(make([]byte, l.Size()))
buf.Reset()
if err := l.Encode(buf); err != nil {
return nil, err
}
return buf.Bytes(), nil
}
func (l *Log) Unmarshal(b []byte) error {
buf := bytes.NewBuffer(b)
return l.Decode(buf)
}
var headPool = sync.Pool{
New: func() interface{} { return make([]byte, LogHeadSize) },
}
func (l *Log) Encode(w io.Writer) error {
b := headPool.Get().([]byte)
pos := 0
binary.BigEndian.PutUint64(b[pos:], l.ID)
pos += 8
binary.BigEndian.PutUint32(b[pos:], uint32(l.CreateTime))
pos += 4
b[pos] = l.Compression
pos++
binary.BigEndian.PutUint32(b[pos:], uint32(len(l.Data)))
n, err := w.Write(b)
headPool.Put(b)
if err != nil {
return err
} else if n != LogHeadSize {
return io.ErrShortWrite
}
if n, err = w.Write(l.Data); err != nil {
return err
} else if n != len(l.Data) {
return io.ErrShortWrite
}
return nil
}
func (l *Log) Decode(r io.Reader) error {
length, err := l.DecodeHead(r)
if err != nil {
return err
}
l.growData(int(length))
if _, err := io.ReadFull(r, l.Data); err != nil {
return err
}
return nil
}
func (l *Log) DecodeHead(r io.Reader) (uint32, error) {
buf := headPool.Get().([]byte)
if _, err := io.ReadFull(r, buf); err != nil {
headPool.Put(buf)
return 0, err
}
length := l.decodeHeadBuf(buf)
headPool.Put(buf)
return length, nil
}
func (l *Log) DecodeAt(r io.ReaderAt, pos int64) error {
length, err := l.DecodeHeadAt(r, pos)
if err != nil {
return err
}
l.growData(int(length))
var n int
n, err = r.ReadAt(l.Data, pos+int64(LogHeadSize))
if err == io.EOF && n == len(l.Data) {
err = nil
}
return err
}
func (l *Log) growData(length int) {
l.Data = l.Data[0:0]
if cap(l.Data) >= length {
l.Data = l.Data[0:length]
} else {
l.Data = make([]byte, length)
}
}
func (l *Log) DecodeHeadAt(r io.ReaderAt, pos int64) (uint32, error) {
buf := headPool.Get().([]byte)
n, err := r.ReadAt(buf, pos)
if err != nil && err != io.EOF {
headPool.Put(buf)
return 0, err
}
length := l.decodeHeadBuf(buf)
headPool.Put(buf)
if err == io.EOF && (length != 0 || n != len(buf)) {
return 0, err
}
return length, nil
}
func (l *Log) decodeHeadBuf(buf []byte) uint32 {
pos := 0
l.ID = binary.BigEndian.Uint64(buf[pos:])
pos += 8
l.CreateTime = binary.BigEndian.Uint32(buf[pos:])
pos += 4
l.Compression = uint8(buf[pos])
pos++
length := binary.BigEndian.Uint32(buf[pos:])
return length
}