fastrand

fastrand

This package provides the implementation of a pseudo-random number source which can be used with the standard rand.Rand type, and supports re-seeding with no overhead.

Note that the pseudo-random number source in this package is not safe to use for security-sensitive work.

Motivation

Deterministic random number generation is a powerful tool, we use it to build systems that have testable random behaviors. While the variety of outputs they produce can be seen as randomly distributed, a given set of inputs will always produce the same outputs.

The default pseudo-random number source in the math/rand package supports building such systems because the sequence of numbers it generates is determined by the value it was seeded with. However, seeding the source is an extremely expensive operation, taking many microseconds of compute time, which doesn't make it a good fit when the program needs to re-seed the PRNG based on inputs it receives thousands of times per second, very quickly most of the CPU time is spent re-seeding the PRNG.

This package provides an alternative pseudo-random number source which may not provide a distribution that is as uniform as the one in the standard library, but works well in practice, and supports re-seeding with zero overhead on CPU time.

Usage

package main

import (
    "fmt"
    "math/rand"

    "github.com/segmentio/fastrand"
)

func main() {
    s := fastrand.NewSource(0)
    r := rand.New(s)
    fmt.Println(r.Int())
}