NewPseudoRand returns an instance of math/rand.Rand seeded from crypto/rand and its seed so we can easily and cheaply generate unique streams of numbers. The created object is not safe for concurrent access.
NewPseudoSeed generates a seed from crypto/rand.
RandBytes returns a byte slice of the given length with random data.
RandIntInRange returns a value in [min, max)
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.