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61 lines
1.3 KiB
Go

package gzip
import (
"compress/gzip"
"io"
"github.com/rqlite/rqlite/v8/progress"
)
// Decompressor is a wrapper around a gzip.Reader that reads from an io.Reader
// and decompresses the data.
type Decompressor struct {
cr *progress.CountingReader
gzr *gzip.Reader
nRx int64
nTx int64
}
// NewDecompressor returns an instantied Decompressor that reads from r and
// decompresses the data using gzip.
func NewDecompressor(r io.Reader) *Decompressor {
return &Decompressor{
cr: progress.NewCountingReader(r),
}
}
// Read reads decompressed data.
func (c *Decompressor) Read(p []byte) (nn int, err error) {
defer func() {
c.nTx += int64(nn)
}()
if c.cr == nil {
return 0, io.EOF
}
if c.gzr == nil {
var err error
c.gzr, err = gzip.NewReader(c.cr)
if err != nil {
return 0, err
}
// Setting Multistream to false means the gzip reader will
// return io.EOF when it reaches the end of the gzip stream.
// Otherwise the reader hangs. This seems to be needed only
// for the gzip over a stream.
c.gzr.Multistream(false)
}
n, err := c.gzr.Read(p)
c.nRx += int64(n)
if err == io.EOF {
if err := c.gzr.Close(); err != nil {
return 0, err
}
c.cr = nil // Signal no more re-use of the underlying reader.
c.gzr = nil
}
return n, err
}