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