Fixed missing model import for codec with undefined Entry

internal/codec.go

@@ -0,0 +1,114 @@
+package internal
+
+import (
+	"bufio"
+	"encoding/binary"
+	"io"
+
+	"github.com/pkg/errors"
+
+	"github.com/prologic/bitcask/internal/model"
+)
+
+const (
+	KeySize      = 4
+	ValueSize    = 8
+	checksumSize = 4
+)
+
+// 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 model.Entry) (int64, error) {
+	var bufKeyValue = make([]byte, ValueSize)
+
+	bufKeySize := bufKeyValue[:KeySize]
+	binary.BigEndian.PutUint32(bufKeySize, uint32(len(msg.Key)))
+	if _, err := e.w.Write(bufKeySize); err != nil {
+		return 0, errors.Wrap(err, "failed writing key length prefix")
+	}
+
+	bufValueSize := bufKeyValue[:ValueSize]
+	binary.BigEndian.PutUint64(bufValueSize, uint64(len(msg.Value)))
+	if _, err := e.w.Write(bufValueSize); err != nil {
+		return 0, errors.Wrap(err, "failed writing value length prefix")
+	}
+
+	if _, err := e.w.Write([]byte(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 := make([]byte, checksumSize)
+	binary.BigEndian.PutUint32(bufChecksumSize, msg.Checksum)
+	if _, err := e.w.Write(bufChecksumSize); err != nil {
+		return 0, errors.Wrap(err, "failed writing checksum 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), nil
+}
+
+// NewDecoder creates a streaming Entry decoder.
+func NewDecoder(r io.Reader) *Decoder {
+	return &Decoder{r: r}
+}
+
+// Decoder wraps an underlying io.Reader and allows you to stream
+// Entry decodings on it.
+type Decoder struct {
+	r io.Reader
+}
+
+func (d *Decoder) Decode(v *model.Entry) (int64, error) {
+	prefixBuf := make([]byte, KeySize+ValueSize)
+
+	_, err := io.ReadFull(d.r, prefixBuf)
+	if err != nil {
+		return 0, err
+	}
+
+	actualKeySize, actualValueSize := GetKeyValueSizes(prefixBuf)
+	buf := make([]byte, actualKeySize+actualValueSize+checksumSize)
+	if _, err = io.ReadFull(d.r, buf); err != nil {
+		return 0, errors.Wrap(translateError(err), "failed reading saved data")
+	}
+
+	DecodeWithoutPrefix(buf, actualValueSize, v)
+	return int64(KeySize + ValueSize + actualKeySize + actualValueSize + checksumSize), nil
+}
+
+func GetKeyValueSizes(buf []byte) (uint64, uint64) {
+	actualKeySize := binary.BigEndian.Uint32(buf[:KeySize])
+	actualValueSize := binary.BigEndian.Uint64(buf[KeySize:])
+
+	return uint64(actualKeySize), actualValueSize
+}
+
+func DecodeWithoutPrefix(buf []byte, valueOffset uint64, v *model.Entry) {
+	v.Key = buf[:valueOffset]
+	v.Value = buf[valueOffset : len(buf)-checksumSize]
+	v.Checksum = binary.BigEndian.Uint32(buf[len(buf)-checksumSize:])
+}
+
+func translateError(err error) error {
+	if err == io.EOF {
+		return io.ErrUnexpectedEOF
+	}
+	return err
+}