70 行
2.0 KiB
Go
70 行
2.0 KiB
Go
package codec
|
|
|
|
import (
|
|
"bufio"
|
|
"encoding/binary"
|
|
"io"
|
|
|
|
"github.com/pkg/errors"
|
|
"git.tcp.direct/tcp.direct/bitcask-mirror/internal"
|
|
)
|
|
|
|
const (
|
|
keySize = 4
|
|
valueSize = 8
|
|
checksumSize = 4
|
|
ttlSize = 8
|
|
MetaInfoSize = keySize + valueSize + checksumSize + ttlSize
|
|
)
|
|
|
|
// NewEncoder creates a streaming Entry encoder.
|
|
func NewEncoder(w io.Writer) *Encoder {
|
|
return &Encoder{w: bufio.NewWriter(w)}
|
|
}
|
|
|
|
// Encoder wraps an underlying io.Writer and allows you to stream
|
|
// Entry encodings on it.
|
|
type Encoder struct {
|
|
w *bufio.Writer
|
|
}
|
|
|
|
// Encode takes any Entry and streams it to the underlying writer.
|
|
// Messages are framed with a key-length and value-length prefix.
|
|
func (e *Encoder) Encode(msg internal.Entry) (int64, error) {
|
|
var bufKeyValue = make([]byte, keySize+valueSize)
|
|
binary.BigEndian.PutUint32(bufKeyValue[:keySize], uint32(len(msg.Key)))
|
|
binary.BigEndian.PutUint64(bufKeyValue[keySize:keySize+valueSize], uint64(len(msg.Value)))
|
|
if _, err := e.w.Write(bufKeyValue); err != nil {
|
|
return 0, errors.Wrap(err, "failed writing key & value length prefix")
|
|
}
|
|
|
|
if _, err := e.w.Write(msg.Key); err != nil {
|
|
return 0, errors.Wrap(err, "failed writing key data")
|
|
}
|
|
if _, err := e.w.Write(msg.Value); err != nil {
|
|
return 0, errors.Wrap(err, "failed writing value data")
|
|
}
|
|
|
|
bufChecksumSize := bufKeyValue[:checksumSize]
|
|
binary.BigEndian.PutUint32(bufChecksumSize, msg.Checksum)
|
|
if _, err := e.w.Write(bufChecksumSize); err != nil {
|
|
return 0, errors.Wrap(err, "failed writing checksum data")
|
|
}
|
|
|
|
bufTTL := bufKeyValue[:ttlSize]
|
|
if msg.Expiry == nil {
|
|
binary.BigEndian.PutUint64(bufTTL, uint64(0))
|
|
} else {
|
|
binary.BigEndian.PutUint64(bufTTL, uint64(msg.Expiry.Unix()))
|
|
}
|
|
if _, err := e.w.Write(bufTTL); err != nil {
|
|
return 0, errors.Wrap(err, "failed writing ttl data")
|
|
}
|
|
|
|
if err := e.w.Flush(); err != nil {
|
|
return 0, errors.Wrap(err, "failed flushing data")
|
|
}
|
|
|
|
return int64(keySize + valueSize + len(msg.Key) + len(msg.Value) + checksumSize + ttlSize), nil
|
|
}
|