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decompressor.go
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/
decompressor.go
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package compress
import (
"bytes"
"compress/zlib"
"io"
"github.com/pkg/errors"
)
// Decompressor is a fast, single threaded compressor.
// This type allows us to reuse buffers etc for performance
type Decompressor interface {
// Decompress decompresses the byte array
Decompress(b []byte) ([]byte, error)
}
// NoOpDecompressor is a DeCompressor that does nothing. Useful for tests.
type NoOpDecompressor struct{}
func (c *NoOpDecompressor) Decompress(b []byte) ([]byte, error) {
return b, nil
}
// ZlibDecompressor decompresses Zlib
type ZlibDecompressor struct {
outputBuffer *bytes.Buffer
inputBuffer *bytes.Buffer
reader io.ReadCloser
}
func NewZlibDecompressor() *ZlibDecompressor {
var ib bytes.Buffer
var ob bytes.Buffer
return &ZlibDecompressor{
inputBuffer: &ib,
outputBuffer: &ob,
}
}
func (d *ZlibDecompressor) Decompress(b []byte) ([]byte, error) {
inputBuffer := bytes.NewBuffer(b)
if d.reader == nil {
reader, err := zlib.NewReader(inputBuffer)
if err != nil {
return nil, errors.WithStack(err)
}
d.reader = reader
} else {
err := d.reader.(zlib.Resetter).Reset(inputBuffer, nil)
if err != nil {
return nil, errors.WithStack(err)
}
d.outputBuffer.Reset()
}
// Decompress
_, err := io.Copy(d.outputBuffer, d.reader)
if err != nil {
return nil, errors.WithStack(err)
}
decompressed := d.outputBuffer.Bytes()
return decompressed, nil
}
// ThreadSafeZlibDecompressor provides a thread safe decompressor, at the cost of instantiating a new ZlibDecompressor
// for each Decompress call
type ThreadSafeZlibDecompressor struct{}
func NewThreadSafeZlibDecompressor() *ThreadSafeZlibDecompressor {
return &ThreadSafeZlibDecompressor{}
}
func (d *ThreadSafeZlibDecompressor) Decompress(b []byte) ([]byte, error) {
decompressor := NewZlibDecompressor()
decompressed, err := decompressor.Decompress(b)
if err != nil {
return nil, err
}
return decompressed, nil
}