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package snappy
import (
"bytes"
"encoding/binary"
"github.com/golang/snappy"
"github.com/segmentio/kafka-go"
)
func init() {
kafka.RegisterCompressionCodec(func() kafka.CompressionCodec {
return NewCompressionCodec()
})
}
type CompressionCodec struct{}
const Code = 2
func NewCompressionCodec() CompressionCodec {
return CompressionCodec{}
}
// Code implements the kafka.CompressionCodec interface.
func (c CompressionCodec) Code() int8 {
return Code
}
// Encode implements the kafka.CompressionCodec interface.
func (c CompressionCodec) Encode(src []byte) ([]byte, error) {
// NOTE : passing a nil dst means snappy will allocate it.
return snappy.Encode(nil, src), nil
}
// Decode implements the kafka.CompressionCodec interface.
func (c CompressionCodec) Decode(src []byte) ([]byte, error) {
return decode(src)
}
var xerialHeader = []byte{130, 83, 78, 65, 80, 80, 89, 0}
// From github.com/eapache/go-xerial-snappy
func decode(src []byte) ([]byte, error) {
if !bytes.Equal(src[:8], xerialHeader) {
return snappy.Decode(nil, src)
}
var (
pos = uint32(16)
max = uint32(len(src))
dst = make([]byte, 0, len(src))
chunk []byte
err error
)
for pos < max {
size := binary.BigEndian.Uint32(src[pos : pos+4])
pos += 4
chunk, err = snappy.Decode(chunk, src[pos:pos+size])
if err != nil {
return nil, err
}
pos += size
dst = append(dst, chunk...)
}
return dst, nil
}
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