TableSeed structv0.1.0

pub struct TableSeed {
    // private fields
}

Two words, which is what SipHash takes as a key. Drawing one per table costs a system call each; a program making many should draw one and hand it to all of them, which is what this being a value rather than a hidden global is for.

Associated functions

Random

pub func Random() -> TableSeed

A seed drawn from the operating system. Takes nothing. Falls back to a fixed pair of words when the system has no entropy to give, which keeps a table working on a system without a generator at the cost of the protection the seed exists for — a table keyed on adversarial input on such a system is as attackable as an unseeded one. Runs in constant time and allocates nothing.

Returns: a seed drawn from the system, so two tables in one process iterate differently

Source

Of

pub func Of(low: uint64, high: uint64) -> TableSeed

A seed with the words a caller chose. low and high are read by value. For a test that needs the same table twice, or a caller drawing one seed for many tables.

Returns: a seed made of those two words, which makes the iteration order reproducible

Source