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compression.go
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compression.go
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package stream
import (
"bytes"
"compress/gzip"
"fmt"
)
type CompressionType string
const (
CompressionNone CompressionType = "none"
CompressionGZip CompressionType = "application/gzip"
)
func (s CompressionType) String() string {
return string(s)
}
var _ fmt.Stringer = CompressionType("")
type MessageBodyCompressor interface {
Compress(body []byte) ([]byte, error)
Decompress(body []byte) ([]byte, error)
}
var messageBodyCompressors = map[CompressionType]MessageBodyCompressor{
CompressionNone: new(noopCompressor),
CompressionGZip: new(gZipCompressor),
}
func CompressMessage(compression CompressionType, body []byte) ([]byte, error) {
compressor, ok := messageBodyCompressors[compression]
if !ok {
return nil, fmt.Errorf("there is no compressor for compression '%s'", compression)
}
compressed, err := compressor.Compress(body)
if err != nil {
return nil, fmt.Errorf("failed to compress message body: %w", err)
}
return compressed, nil
}
func DecompressMessage(compression CompressionType, body []byte) ([]byte, error) {
compressor, ok := messageBodyCompressors[compression]
if !ok {
return nil, fmt.Errorf("there is no decompressor for compression '%s'", compression)
}
decompressed, err := compressor.Decompress(body)
if err != nil {
return nil, fmt.Errorf("failed to decompress message body: %w", err)
}
return decompressed, nil
}
type noopCompressor struct{}
func (n noopCompressor) Compress(body []byte) ([]byte, error) {
return body, nil
}
func (n noopCompressor) Decompress(body []byte) ([]byte, error) {
return body, nil
}
type gZipCompressor struct{}
func (g gZipCompressor) Compress(body []byte) ([]byte, error) {
if body == nil {
return body, nil
}
var out bytes.Buffer
zw := gzip.NewWriter(&out)
if _, err := zw.Write(body); err != nil {
return nil, fmt.Errorf("can not write body to gzip: %w", err)
}
if err := zw.Close(); err != nil {
return nil, fmt.Errorf("can not close gzip writer: %w", err)
}
compressed := out.Bytes()
return compressed, nil
}
func (g gZipCompressor) Decompress(body []byte) ([]byte, error) {
if body == nil {
return body, nil
}
bufBody := bytes.NewBuffer(body)
bufOut := &bytes.Buffer{}
reader, err := gzip.NewReader(bufBody)
if err != nil {
return nil, fmt.Errorf("can not create gzip reader from body: %w", err)
}
if _, err := bufOut.ReadFrom(reader); err != nil {
return nil, fmt.Errorf("can not read from gzip reader: %w", err)
}
uncompressed := bufOut.Bytes()
return uncompressed, nil
}