github.com/matrixorigin/matrixone@v1.2.0/pkg/util/rand.go (about)

     1  // Copyright 2022 Matrix Origin
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package util
    16  
    17  import (
    18  	_ "unsafe"
    19  )
    20  
    21  // fastrand32 returns a lock free uint32 value. Compared to rand.Uint32, this
    22  // implementation scales. We're using the go runtime's implementation through a
    23  // linker trick.
    24  //
    25  //go:linkname fastrand32 runtime.fastrand
    26  func fastrand32() uint32
    27  
    28  // Fastrand64 returns a lock free uint64 value.
    29  // Compared to rand.Int63(), this implementation scales.
    30  func Fastrand64() uint64 {
    31  	x, y := fastrand32(), fastrand32() // 32-bit halves
    32  	return uint64(x)<<32 ^ uint64(y)
    33  }