VictoriaMetrics/lib/encoding/zstd/zstd_pure.go
2019-07-24 17:43:32 +03:00

70 lines
1.3 KiB
Go

// +build !cgo
package zstd
import (
"sync"
"sync/atomic"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
"github.com/klauspost/compress/zstd"
)
var (
decoder *zstd.Decoder
mu sync.Mutex
av atomic.Value
)
type registry map[int]*zstd.Encoder
func init() {
r := make(registry)
av.Store(r)
var err error
decoder, err = zstd.NewReader(nil)
if err != nil {
logger.Panicf("BUG: failed to create ZSTD reader: %s", err)
}
}
// Decompress appends decompressed src to dst and returns the result.
func Decompress(dst, src []byte) ([]byte, error) {
return decoder.DecodeAll(src, dst)
}
// CompressLevel appends compressed src to dst and returns the result.
//
// The given compressionLevel is used for the compression.
func CompressLevel(dst, src []byte, compressionLevel int) []byte {
e := getEncoder(compressionLevel)
return e.EncodeAll(src, dst)
}
func getEncoder(compressionLevel int) *zstd.Encoder {
r := av.Load().(registry)
if e, ok := r[compressionLevel]; ok {
return e
}
level := zstd.EncoderLevelFromZstd(compressionLevel)
e, err := zstd.NewWriter(nil, zstd.WithEncoderLevel(level))
if err != nil {
logger.Panicf("BUG: failed to create ZSTD writer: %s", err)
}
mu.Lock()
r1 := av.Load().(registry)
r2 := make(registry)
for k, v := range r1 {
r2[k] = v
}
r2[compressionLevel] = e
av.Store(r2)
mu.Unlock()
return e
}