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zstd.go
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zstd.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"
"reflect"
"github.com/klauspost/compress/zstd"
"github.com/vdaas/vald/internal/errors"
)
type zstdCompressor struct {
gobc Compressor
eoptions []zstd.EOption
}
func NewZstd(opts ...ZstdOption) (Compressor, error) {
c := new(zstdCompressor)
for _, opt := range append(defaultZstdOpts, opts...) {
if err := opt(c); err != nil {
return nil, errors.ErrOptionFailed(err, reflect.ValueOf(opt))
}
}
return c, nil
}
func (z *zstdCompressor) CompressVector(vector []float32) ([]byte, error) {
gob, err := z.gobc.CompressVector(vector)
if err != nil {
return nil, err
}
buf := new(bytes.Buffer)
zw, err := zstd.NewWriter(buf, z.eoptions...)
if err != nil {
return nil, err
}
_, err = zw.ReadFrom(bytes.NewReader(gob))
if err != nil {
return nil, err
}
err = zw.Close()
if err != nil {
return nil, err
}
return buf.Bytes(), nil
}
func (z *zstdCompressor) DecompressVector(bs []byte) ([]float32, error) {
buf := new(bytes.Buffer)
zr, err := zstd.NewReader(bytes.NewReader(bs))
if err != nil {
return nil, err
}
defer zr.Close()
_, err = zr.WriteTo(buf)
if err != nil {
return nil, err
}
vec, err := z.gobc.DecompressVector(buf.Bytes())
if err != nil {
return nil, err
}
return vec, nil
}