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package storage
import (
"compress/gzip"
"compress/zlib"
"io"
"git.iim.gay/grufwub/go-store/util"
"github.com/golang/snappy"
)
// Compressor defines a means of compressing/decompressing values going into a key-value store
type Compressor interface {
// Reader returns a new decompressing io.ReadCloser based on supplied (compressed) io.Reader
Reader(io.Reader) (io.ReadCloser, error)
// Writer returns a new compressing io.WriteCloser based on supplied (uncompressed) io.Writer
Writer(io.Writer) (io.WriteCloser, error)
}
type gzipCompressor struct {
level int
}
// GZipCompressor returns a new Compressor that implements GZip at default compression level
func GZipCompressor() Compressor {
return GZipCompressorLevel(gzip.DefaultCompression)
}
// GZipCompressorLevel returns a new Compressor that implements GZip at supplied compression level
func GZipCompressorLevel(level int) Compressor {
return &gzipCompressor{
level: level,
}
}
func (c *gzipCompressor) Reader(r io.Reader) (io.ReadCloser, error) {
return gzip.NewReader(r)
}
func (c *gzipCompressor) Writer(w io.Writer) (io.WriteCloser, error) {
return gzip.NewWriterLevel(w, c.level)
}
type zlibCompressor struct {
level int
dict []byte
}
// ZLibCompressor returns a new Compressor that implements ZLib at default compression level
func ZLibCompressor() Compressor {
return ZLibCompressorLevelDict(zlib.DefaultCompression, nil)
}
// ZLibCompressorLevel returns a new Compressor that implements ZLib at supplied compression level
func ZLibCompressorLevel(level int) Compressor {
return ZLibCompressorLevelDict(level, nil)
}
// ZLibCompressorLevelDict returns a new Compressor that implements ZLib at supplied compression level with supplied dict
func ZLibCompressorLevelDict(level int, dict []byte) Compressor {
return &zlibCompressor{
level: level,
dict: dict,
}
}
func (c *zlibCompressor) Reader(r io.Reader) (io.ReadCloser, error) {
return zlib.NewReaderDict(r, c.dict)
}
func (c *zlibCompressor) Writer(w io.Writer) (io.WriteCloser, error) {
return zlib.NewWriterLevelDict(w, c.level, c.dict)
}
type snappyCompressor struct{}
// SnappyCompressor returns a new Compressor that implements Snappy
func SnappyCompressor() Compressor {
return &snappyCompressor{}
}
func (c *snappyCompressor) Reader(r io.Reader) (io.ReadCloser, error) {
return util.NopReadCloser(snappy.NewReader(r)), nil
}
func (c *snappyCompressor) Writer(w io.Writer) (io.WriteCloser, error) {
return snappy.NewBufferedWriter(w), nil
}
type nopCompressor struct{}
// NoCompression is a Compressor that simply does nothing
func NoCompression() Compressor {
return &nopCompressor{}
}
func (c *nopCompressor) Reader(r io.Reader) (io.ReadCloser, error) {
return util.NopReadCloser(r), nil
}
func (c *nopCompressor) Writer(w io.Writer) (io.WriteCloser, error) {
return util.NopWriteCloser(w), nil
}
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