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// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you 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
//
// http://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
import (
"io"
"sync"
"github.com/apache/arrow-go/v18/parquet/internal/debug"
"github.com/klauspost/compress/zstd"
)
type zstdCodec struct{}
type zstdcloser struct {
*zstd.Decoder
}
var (
enc *zstd.Encoder
dec *zstd.Decoder
initEncoder sync.Once
initDecoder sync.Once
)
func getencoder() *zstd.Encoder {
initEncoder.Do(func() {
enc, _ = zstd.NewWriter(nil, zstd.WithZeroFrames(true))
})
return enc
}
func getdecoder() *zstd.Decoder {
initDecoder.Do(func() {
dec, _ = zstd.NewReader(nil)
})
return dec
}
func (zstdCodec) Decode(dst, src []byte) []byte {
dst, err := getdecoder().DecodeAll(src, dst[:0])
if err != nil {
panic(err)
}
return dst
}
func (z *zstdcloser) Close() error {
z.Decoder.Close()
return nil
}
func (zstdCodec) NewReader(r io.Reader) io.ReadCloser {
ret, _ := zstd.NewReader(r)
return &zstdcloser{ret}
}
func (zstdCodec) NewWriter(w io.Writer) io.WriteCloser {
ret, _ := zstd.NewWriter(w)
return ret
}
func (zstdCodec) NewWriterLevel(w io.Writer, level int) (io.WriteCloser, error) {
var compressLevel zstd.EncoderLevel
if level == DefaultCompressionLevel {
compressLevel = zstd.SpeedDefault
} else {
compressLevel = zstd.EncoderLevelFromZstd(level)
}
return zstd.NewWriter(w, zstd.WithEncoderLevel(compressLevel))
}
func (z zstdCodec) Encode(dst, src []byte) []byte {
return getencoder().EncodeAll(src, dst[:0])
}
func (z zstdCodec) EncodeLevel(dst, src []byte, level int) []byte {
compressLevel := zstd.EncoderLevelFromZstd(level)
if level == DefaultCompressionLevel {
compressLevel = zstd.SpeedDefault
}
enc, _ := zstd.NewWriter(nil, zstd.WithZeroFrames(true), zstd.WithEncoderLevel(compressLevel))
return enc.EncodeAll(src, dst[:0])
}
// from zstd.h, ZSTD_COMPRESSBOUND
func (zstdCodec) CompressBound(len int64) int64 {
debug.Assert(len > 0, "len for zstd CompressBound should be > 0")
extra := ((128 << 10) - len) >> 11
if len >= (128 << 10) {
extra = 0
}
return len + (len >> 8) + extra
}
func init() {
RegisterCodec(Codecs.Zstd, zstdCodec{})
}
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