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package sarama
import (
"sync"
"github.com/klauspost/compress/zstd"
)
// zstdMaxBufferedEncoders maximum number of not-in-use zstd encoders
// If the pool of encoders is exhausted then new encoders will be created on the fly
const zstdMaxBufferedEncoders = 1
type ZstdEncoderParams struct {
Level int
}
type ZstdDecoderParams struct {
}
var zstdDecMap sync.Map
var zstdAvailableEncoders sync.Map
func getZstdEncoderChannel(params ZstdEncoderParams) chan *zstd.Encoder {
if c, ok := zstdAvailableEncoders.Load(params); ok {
return c.(chan *zstd.Encoder)
}
c, _ := zstdAvailableEncoders.LoadOrStore(params, make(chan *zstd.Encoder, zstdMaxBufferedEncoders))
return c.(chan *zstd.Encoder)
}
func getZstdEncoder(params ZstdEncoderParams) *zstd.Encoder {
select {
case enc := <-getZstdEncoderChannel(params):
return enc
default:
encoderLevel := zstd.SpeedDefault
if params.Level != CompressionLevelDefault {
encoderLevel = zstd.EncoderLevelFromZstd(params.Level)
}
zstdEnc, _ := zstd.NewWriter(nil, zstd.WithZeroFrames(true),
zstd.WithEncoderLevel(encoderLevel),
zstd.WithEncoderConcurrency(1))
return zstdEnc
}
}
func releaseEncoder(params ZstdEncoderParams, enc *zstd.Encoder) {
select {
case getZstdEncoderChannel(params) <- enc:
default:
}
}
func getDecoder(params ZstdDecoderParams) *zstd.Decoder {
if ret, ok := zstdDecMap.Load(params); ok {
return ret.(*zstd.Decoder)
}
// It's possible to race and create multiple new readers.
// Only one will survive GC after use.
zstdDec, _ := zstd.NewReader(nil, zstd.WithDecoderConcurrency(0))
zstdDecMap.Store(params, zstdDec)
return zstdDec
}
func zstdDecompress(params ZstdDecoderParams, dst, src []byte) ([]byte, error) {
return getDecoder(params).DecodeAll(src, dst)
}
func zstdCompress(params ZstdEncoderParams, dst, src []byte) ([]byte, error) {
enc := getZstdEncoder(params)
out := enc.EncodeAll(src, dst)
releaseEncoder(params, enc)
return out, nil
}
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