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|
package blockzstd
import (
"encoding/binary"
"fmt"
"github.com/klauspost/compress/zstd"
"a.yandex-team.ru/library/go/blockcodecs"
)
type zstdCodec int
func (z zstdCodec) ID() blockcodecs.CodecID {
switch z {
case 1:
return 55019
case 3:
return 23308
case 7:
return 33533
default:
panic("unsupported level")
}
}
func (z zstdCodec) Name() string {
return fmt.Sprintf("zstd08_%d", z)
}
func (z zstdCodec) DecodedLen(in []byte) (int, error) {
return blockcodecs.DecodedLen(in)
}
func (z zstdCodec) Encode(dst, src []byte) ([]byte, error) {
if cap(dst) < 8 {
dst = make([]byte, 8)
}
dst = dst[:8]
binary.LittleEndian.PutUint64(dst, uint64(len(src)))
w, err := zstd.NewWriter(nil,
zstd.WithEncoderLevel(zstd.EncoderLevelFromZstd(int(z))),
zstd.WithEncoderConcurrency(1))
if err != nil {
return nil, err
}
defer w.Close()
return w.EncodeAll(src, dst), nil
}
func (z zstdCodec) Decode(dst, src []byte) ([]byte, error) {
if len(src) < 8 {
return nil, fmt.Errorf("short block: %d < 8", len(src))
}
r, err := zstd.NewReader(nil, zstd.WithDecoderConcurrency(1))
if err != nil {
return nil, err
}
defer r.Close()
return r.DecodeAll(src[8:], dst[:0])
}
func init() {
for _, i := range []int{1, 3, 7} {
blockcodecs.Register(zstdCodec(i))
blockcodecs.RegisterAlias(fmt.Sprintf("zstd_%d", i), zstdCodec(i))
}
}
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