go thread-safe rand

mtrnd.go

package mtrnd

import (
        "math/rand"
        "sync"
        "time"

        "github.com/vizee/asm/hack"
)

var (
        rndmu sync.Mutex
        rnds  []*rand.Rand
)

func currnd() *rand.Rand {
        pid := hack.ProcPin()
        if pid >= len(rnds) {
                hack.ProcUnpin()
                rndmu.Lock()
                pid = hack.ProcPin()
                if pid >= len(rnds) {
                        t := make([]*rand.Rand, pid+1)
                        n := copy(t, rnds)
                        for i := n; i < len(t); i++ {
                                t[i] = rand.New(rand.NewSource(time.Now().UnixNano() ^ int64(i)))
                        }
                        rnds = t
                }
                rndmu.Unlock()
        }
        r := rnds[pid]
        hack.ProcUnpin()
        return r
}

func Int() int {
        return currnd().Int()
}

func Intn(n int) int {
        return currnd().Intn(n)
}

func Uint64() uint64 {
        return currnd().Uint64()
}