randutil

Documentation

Index

• func NewPseudoRand() (*rand.Rand, int64)
• func NewPseudoSeed() int64
• func RandBytes(r *rand.Rand, size int) []byte
• func RandIntInRange(r *rand.Rand, min, max int) int
• func ReadTestdataBytes(r *rand.Rand, arr []byte)
• func SeedForTests()

Functions

func NewPseudoRand

func NewPseudoRand() (*rand.Rand, int64)

NewPseudoRand returns an instance of math/rand.Rand seeded from the environment variable COCKROACH_RANDOM_SEED. If that variable is not set, crypto/rand is used to generate a seed. The seed is also returned so we can easily and cheaply generate unique streams of numbers. The created object is not safe for concurrent access.

func NewPseudoSeed

func NewPseudoSeed() int64

NewPseudoSeed generates a seed from crypto/rand.

func RandBytes

func RandBytes(r *rand.Rand, size int) []byte

RandBytes returns a byte slice of the given length with random data.

func RandIntInRange

func RandIntInRange(r *rand.Rand, min, max int) int

RandIntInRange returns a value in [min, max)

func ReadTestdataBytes

func ReadTestdataBytes(r *rand.Rand, arr []byte)

ReadTestdataBytes reads random bytes, but then nudges them into printable ASCII, *reducing their randomness* to make them a little friendlier for humans using them as testdata.

func SeedForTests

func SeedForTests()

SeedForTests seeds the random number generator and prints the seed value used. This value can be specified via an environment variable COCKROACH_RANDOM_SEED=x to reuse the same value later. This function should be called from TestMain; individual tests should not touch the seed of the global random number generator.