tidb vitess_hash 代码
文件路径：/util/vitess/vitess_hash.go
/ Copyright 2021 PingCAP, Inc.
/
/ Licensed under the Apache License, Version 2.0 (the "License");
/ you may not use this file except in compliance with the License.
/ You may obtain a copy of the License at
/
/ http://www.apache.org/licenses/LICENSE-2.0
/
/ Unless required by applicable law or agreed to in writing, software
/ distributed under the License is distributed on an "AS IS" BASIS,
/ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/ See the License for the specific language governing permissions and
/ limitations under the License.
package vitess
import (
"crypto/cipher"
"crypto/des" / #nosec G502
"encoding/binary"
"github.com/pingcap/errors"
)
var nullKeyBlock cipher.Block
func init() {
var err error
nullKeyBlock, err = des.NewCipher(make([]byte, 8)) / #nosec G401 G502
if err != nil {
panic(errors.Trace(err))
}
}
/ HashUint64 implements vitess' method of calculating a hash used for determining a shard key range.
/ Uses a DES encryption with 64 bit key, 64 bit block, null-key
func HashUint64(shardKey uint64) (uint64, error) {
var keybytes [8]byte
binary.BigEndian.PutUint64(keybytes[:], shardKey)
var hashed [8]byte
nullKeyBlock.Encrypt(hashed[:], keybytes[:])
return binary.BigEndian.Uint64(hashed[:]), nil
}