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lz4.go
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lz4.go
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//
// Copyright (C) 2019-2020 Vdaas.org Vald team ( kpango, rinx, kmrmt )
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Package compress provides compress functions
package compress
import (
"bytes"
"io"
"reflect"
lz4 "github.com/pierrec/lz4/v3"
"github.com/vdaas/vald/internal/errors"
)
type lz4Compressor struct {
gobc Compressor
compressionLevel int
}
func NewLZ4(opts ...LZ4Option) (Compressor, error) {
c := new(lz4Compressor)
for _, opt := range append(defaultLZ4Opts, opts...) {
if err := opt(c); err != nil {
return nil, errors.ErrOptionFailed(err, reflect.ValueOf(opt))
}
}
return c, nil
}
func (l *lz4Compressor) CompressVector(vector []float32) ([]byte, error) {
gob, err := l.gobc.CompressVector(vector)
if err != nil {
return nil, err
}
buf := new(bytes.Buffer)
zw := lz4.NewWriter(buf)
zw.Header.CompressionLevel = l.compressionLevel
defer func() {
cerr := zw.Close()
if cerr != nil {
err = errors.Wrap(err, cerr.Error())
}
}()
_, err = zw.Write(gob)
if err != nil {
return nil, err
}
err = zw.Flush()
if err != nil {
return nil, err
}
return buf.Bytes(), nil
}
func (l *lz4Compressor) DecompressVector(bs []byte) ([]float32, error) {
buf := new(bytes.Buffer)
zr := lz4.NewReader(bytes.NewReader(bs))
_, err := io.Copy(buf, zr)
if err != nil {
return nil, err
}
vec, err := l.gobc.DecompressVector(buf.Bytes())
if err != nil {
return nil, err
}
return vec, nil
}