/
compressor_s2.go
80 lines (61 loc) · 1.9 KB
/
compressor_s2.go
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package compression
import (
"bytes"
"sync"
"github.com/klauspost/compress/s2"
"github.com/pkg/errors"
"github.com/kopia/kopia/internal/iocopy"
)
const (
s2Parallel4Concurrency = 4
s2Parallel8Concurrency = 8
)
func init() {
RegisterCompressor("s2-default", newS2Compressor(headerS2Default))
RegisterCompressor("s2-better", newS2Compressor(headerS2Better, s2.WriterBetterCompression()))
RegisterCompressor("s2-parallel-4", newS2Compressor(headerS2Parallel4, s2.WriterConcurrency(s2Parallel4Concurrency)))
RegisterCompressor("s2-parallel-8", newS2Compressor(headerS2Parallel8, s2.WriterConcurrency(s2Parallel8Concurrency)))
}
func newS2Compressor(id HeaderID, opts ...s2.WriterOption) Compressor {
return &s2Compressor{id, compressionHeader(id), sync.Pool{
New: func() interface{} {
return s2.NewWriter(bytes.NewBuffer(nil), opts...)
},
}}
}
type s2Compressor struct {
id HeaderID
header []byte
pool sync.Pool
}
func (c *s2Compressor) HeaderID() HeaderID {
return c.id
}
func (c *s2Compressor) Compress(output *bytes.Buffer, input []byte) error {
if _, err := output.Write(c.header); err != nil {
return errors.Wrap(err, "unable to write header")
}
w := c.pool.Get().(*s2.Writer)
defer c.pool.Put(w)
w.Reset(output)
if _, err := w.Write(input); err != nil {
return errors.Wrap(err, "compression error")
}
if err := w.Close(); err != nil {
return errors.Wrap(err, "compression close error")
}
return nil
}
func (c *s2Compressor) Decompress(output *bytes.Buffer, input []byte) error {
if len(input) < compressionHeaderSize {
return errors.Errorf("invalid compression header")
}
if !bytes.Equal(input[0:compressionHeaderSize], c.header) {
return errors.Errorf("invalid compression header")
}
r := s2.NewReader(bytes.NewReader(input[compressionHeaderSize:]))
if _, err := iocopy.Copy(output, r); err != nil {
return errors.Wrap(err, "decompression error")
}
return nil
}