134 lines
2.9 KiB
Go
134 lines
2.9 KiB
Go
package badger
|
|
|
|
import (
|
|
"bytes"
|
|
"encoding/binary"
|
|
"fmt"
|
|
"hash/crc32"
|
|
|
|
"github.com/dgraph-io/badger/y"
|
|
)
|
|
|
|
type valuePointer struct {
|
|
Fid uint32
|
|
Len uint32
|
|
Offset uint32
|
|
}
|
|
|
|
func (p valuePointer) Less(o valuePointer) bool {
|
|
if p.Fid != o.Fid {
|
|
return p.Fid < o.Fid
|
|
}
|
|
if p.Offset != o.Offset {
|
|
return p.Offset < o.Offset
|
|
}
|
|
return p.Len < o.Len
|
|
}
|
|
|
|
func (p valuePointer) IsZero() bool {
|
|
return p.Fid == 0 && p.Offset == 0 && p.Len == 0
|
|
}
|
|
|
|
const vptrSize = 12
|
|
|
|
// Encode encodes Pointer into byte buffer.
|
|
func (p valuePointer) Encode(b []byte) []byte {
|
|
binary.BigEndian.PutUint32(b[:4], p.Fid)
|
|
binary.BigEndian.PutUint32(b[4:8], p.Len)
|
|
binary.BigEndian.PutUint32(b[8:12], p.Offset)
|
|
return b[:vptrSize]
|
|
}
|
|
|
|
func (p *valuePointer) Decode(b []byte) {
|
|
p.Fid = binary.BigEndian.Uint32(b[:4])
|
|
p.Len = binary.BigEndian.Uint32(b[4:8])
|
|
p.Offset = binary.BigEndian.Uint32(b[8:12])
|
|
}
|
|
|
|
// header is used in value log as a header before Entry.
|
|
type header struct {
|
|
klen uint32
|
|
vlen uint32
|
|
expiresAt uint64
|
|
meta byte
|
|
userMeta byte
|
|
}
|
|
|
|
const (
|
|
headerBufSize = 18
|
|
)
|
|
|
|
func (h header) Encode(out []byte) {
|
|
y.AssertTrue(len(out) >= headerBufSize)
|
|
binary.BigEndian.PutUint32(out[0:4], h.klen)
|
|
binary.BigEndian.PutUint32(out[4:8], h.vlen)
|
|
binary.BigEndian.PutUint64(out[8:16], h.expiresAt)
|
|
out[16] = h.meta
|
|
out[17] = h.userMeta
|
|
}
|
|
|
|
// Decodes h from buf.
|
|
func (h *header) Decode(buf []byte) {
|
|
h.klen = binary.BigEndian.Uint32(buf[0:4])
|
|
h.vlen = binary.BigEndian.Uint32(buf[4:8])
|
|
h.expiresAt = binary.BigEndian.Uint64(buf[8:16])
|
|
h.meta = buf[16]
|
|
h.userMeta = buf[17]
|
|
}
|
|
|
|
// Entry provides Key, Value, UserMeta and ExpiresAt. This struct can be used by the user to set data.
|
|
type Entry struct {
|
|
Key []byte
|
|
Value []byte
|
|
UserMeta byte
|
|
ExpiresAt uint64 // time.Unix
|
|
meta byte
|
|
|
|
// Fields maintained internally.
|
|
offset uint32
|
|
skipVlog bool
|
|
}
|
|
|
|
func (e *Entry) estimateSize(threshold int) int {
|
|
if len(e.Value) < threshold {
|
|
return len(e.Key) + len(e.Value) + 2 // Meta, UserMeta
|
|
}
|
|
return len(e.Key) + 12 + 2 // 12 for ValuePointer, 2 for metas.
|
|
}
|
|
|
|
// Encodes e to buf. Returns number of bytes written.
|
|
func encodeEntry(e *Entry, buf *bytes.Buffer) (int, error) {
|
|
h := header{
|
|
klen: uint32(len(e.Key)),
|
|
vlen: uint32(len(e.Value)),
|
|
expiresAt: e.ExpiresAt,
|
|
meta: e.meta,
|
|
userMeta: e.UserMeta,
|
|
}
|
|
|
|
var headerEnc [headerBufSize]byte
|
|
h.Encode(headerEnc[:])
|
|
|
|
hash := crc32.New(y.CastagnoliCrcTable)
|
|
|
|
buf.Write(headerEnc[:])
|
|
hash.Write(headerEnc[:])
|
|
|
|
buf.Write(e.Key)
|
|
hash.Write(e.Key)
|
|
|
|
buf.Write(e.Value)
|
|
hash.Write(e.Value)
|
|
|
|
var crcBuf [crc32.Size]byte
|
|
binary.BigEndian.PutUint32(crcBuf[:], hash.Sum32())
|
|
buf.Write(crcBuf[:])
|
|
|
|
return len(headerEnc) + len(e.Key) + len(e.Value) + len(crcBuf), nil
|
|
}
|
|
|
|
func (e Entry) print(prefix string) {
|
|
fmt.Printf("%s Key: %s Meta: %d UserMeta: %d Offset: %d len(val)=%d",
|
|
prefix, e.Key, e.meta, e.UserMeta, e.offset, len(e.Value))
|
|
}
|