|
|
|
package gzip
|
|
|
|
|
|
|
|
import (
|
|
|
|
"bytes"
|
|
|
|
"compress/gzip"
|
|
|
|
"io"
|
|
|
|
)
|
|
|
|
|
|
|
|
// DefaultBufferSize is the default buffer size used by the Compressor.
|
|
|
|
const DefaultBufferSize = 65536
|
|
|
|
|
|
|
|
// Compressor is a wrapper around a gzip.Writer that reads from an io.Reader
|
|
|
|
// and writes to an internal buffer. The internal buffer is used to store
|
|
|
|
// compressed data until it is read by the caller.
|
|
|
|
type Compressor struct {
|
|
|
|
r io.Reader
|
|
|
|
bufSz int
|
|
|
|
buf *bytes.Buffer
|
|
|
|
gzw *gzip.Writer
|
|
|
|
|
|
|
|
nRx int64
|
|
|
|
nTx int64
|
|
|
|
}
|
|
|
|
|
|
|
|
// NewCompressor returns an instantiated Compressor that reads from r and
|
|
|
|
// compresses the data using gzip.
|
|
|
|
func NewCompressor(r io.Reader, bufSz int) (*Compressor, error) {
|
|
|
|
buf := new(bytes.Buffer)
|
|
|
|
gzw, err := gzip.NewWriterLevel(buf, gzip.DefaultCompression)
|
|
|
|
if err != nil {
|
|
|
|
return nil, err
|
|
|
|
}
|
|
|
|
return &Compressor{
|
|
|
|
r: r,
|
|
|
|
bufSz: bufSz,
|
|
|
|
buf: buf,
|
|
|
|
gzw: gzw,
|
|
|
|
}, nil
|
|
|
|
}
|
|
|
|
|
|
|
|
// Read reads compressed data.
|
|
|
|
func (c *Compressor) Read(p []byte) (n int, err error) {
|
|
|
|
if c.buf.Len() == 0 && c.gzw != nil {
|
|
|
|
nn, err := io.CopyN(c.gzw, c.r, int64(c.bufSz))
|
|
|
|
c.nRx += nn
|
|
|
|
c.nTx += int64(len(p))
|
|
|
|
if err != nil {
|
|
|
|
// Time to write the footer.
|
|
|
|
if err := c.Close(); err != nil {
|
|
|
|
return 0, err
|
|
|
|
}
|
|
|
|
if err != io.EOF {
|
|
|
|
// Actual error, let caller handle
|
|
|
|
return 0, err
|
|
|
|
}
|
|
|
|
} else if nn > 0 {
|
|
|
|
// We read some data, but didn't hit any error.
|
|
|
|
// Just flush the data in the buffer, ready
|
|
|
|
// to be read.
|
|
|
|
if err := c.gzw.Flush(); err != nil {
|
|
|
|
return 0, err
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
return c.buf.Read(p)
|
|
|
|
}
|
|
|
|
|
|
|
|
// Close closes the Compressor.
|
|
|
|
func (c *Compressor) Close() error {
|
|
|
|
if c.gzw == nil {
|
|
|
|
return nil
|
|
|
|
}
|
|
|
|
if err := c.gzw.Close(); err != nil {
|
|
|
|
return err
|
|
|
|
}
|
|
|
|
c.gzw = nil
|
|
|
|
return nil
|
|
|
|
}
|