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package blockcodecs
import (
"encoding/binary"
"fmt"
"sync"
"go.uber.org/atomic"
)
type CodecID uint16
type Codec interface {
ID() CodecID
Name() string
DecodedLen(in []byte) (int, error)
Encode(dst, src []byte) ([]byte, error)
Decode(dst, src []byte) ([]byte, error)
}
var (
codecsByID sync.Map
codecsByName sync.Map
)
// Register new codec.
//
// NOTE: update FindCodecByName description, after adding new codecs.
func Register(c Codec) {
if _, duplicate := codecsByID.LoadOrStore(c.ID(), c); duplicate {
panic(fmt.Sprintf("codec with id %d is already registered", c.ID()))
}
RegisterAlias(c.Name(), c)
}
func RegisterAlias(name string, c Codec) {
if _, duplicate := codecsByName.LoadOrStore(name, c); duplicate {
panic(fmt.Sprintf("codec with name %s is already registered", c.Name()))
}
}
func ListCodecs() []Codec {
var c []Codec
codecsByID.Range(func(key, value interface{}) bool {
c = append(c, value.(Codec))
return true
})
return c
}
func FindCodec(id CodecID) Codec {
c, ok := codecsByID.Load(id)
if ok {
return c.(Codec)
} else {
return nil
}
}
// FindCodecByName returns codec by name.
//
// Possible names:
//
// null
// snappy
// zstd08_{level} - level is integer 1, 3 or 7.
// zstd_{level} - level is integer 1, 3 or 7.
func FindCodecByName(name string) Codec {
c, ok := codecsByName.Load(name)
if ok {
return c.(Codec)
} else {
return nil
}
}
var (
maxDecompressedBlockSize = atomic.NewInt32(16 << 20) // 16 MB
)
func DecodedLen(in []byte) (int, error) {
if len(in) < 8 {
return 0, fmt.Errorf("short block: %d < 8", len(in))
}
return int(binary.LittleEndian.Uint64(in[:8])), nil
}
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