// returns a reader for the right compression
func (s *scanner) compressionReader(r io.Reader, header *thrift.PageHeader) (io.Reader, error) {
switch s.codec {
case thrift.CompressionCodec_GZIP:
r, err := gzip.NewReader(r)
if err != nil {
return nil, fmt.Errorf("could not create gzip reader:%s", err)
}
b, err := ioutil.ReadAll(r)
if err != nil {
return nil, fmt.Errorf("could not read gzip reader:%s", err)
}
if err := r.Close(); err != nil {
log.Println("WARNING error closing gzip reader:%s", err)
}
return bytes.NewReader(b), nil
case thrift.CompressionCodec_LZO:
// https://github.com/rasky/go-lzo/blob/master/decompress.go#L149 s.r = r
return nil, fmt.Errorf("NYI")
case thrift.CompressionCodec_SNAPPY:
src, err := ioutil.ReadAll(r)
if err != nil {
return nil, fmt.Errorf("could not create gzip reader:%s", err)
}
out := make([]byte, int(header.GetUncompressedPageSize()))
out, err = snappy.Decode(out, src)
if err != nil {
return nil, fmt.Errorf("could not create gzip reader:%s", err)
}
return bytes.NewReader(out), nil
case thrift.CompressionCodec_UNCOMPRESSED:
// use the same reader
return r, nil
default:
return nil, fmt.Errorf("unknown compression format %s", s.codec)
}
}
