Struct rand::rngs::ThreadRng

pub struct ThreadRng { /* private fields */ }

A reference to the thread-local generator

This type is a reference to a lazily-initialized thread-local generator. An instance can be obtained via thread_rng or via ThreadRng::default(). The handle cannot be passed between threads (is not Send or Sync).

ThreadRng uses the same CSPRNG as StdRng, ChaCha12. As with StdRng, the algorithm may be changed, subject to reasonable expectations of security and performance.

ThreadRng is automatically seeded from OsRng with periodic reseeding (every 64 kiB — see ReseedingRng documentation for details).

ThreadRng is not automatically reseeded on fork. It is recommended to explicitly call ThreadRng::reseed immediately after a fork, for example:

fn do_fork() {
    let pid = unsafe { libc::fork() };
    if pid == 0 {
        // Reseed ThreadRng in child processes:
        rand::thread_rng().reseed();
    }
}

Methods on ThreadRng are not reentrant-safe and thus should not be called from an interrupt (e.g. a fork handler) unless it can be guaranteed that no other method on the same ThreadRng is currently executing.

Security must be considered relative to a threat model and validation requirements. ThreadRng attempts to meet basic security considerations for producing unpredictable random numbers: use a CSPRNG, use a recommended platform-specific seed (OsRng), and avoid leaking internal secrets e.g. via Debug implementation or serialization. Memory is not zeroized on drop.

Implementations

impl ThreadRng

pub fn reseed(&mut self) -> Result<(), Error>

Immediately reseed the generator

This discards any remaining random data in the cache.

Trait Implementations

impl Clone for ThreadRng

fn clone(&self) -> ThreadRng

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ThreadRng

Debug implementation does not leak internal state

fn fmt(&self, fmt: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ThreadRng

fn default() -> ThreadRng

Returns the “default value” for a type.

impl RngCore for ThreadRng

fn next_u32(&mut self) -> u32

Return the next random u32.

fn next_u64(&mut self) -> u64

Return the next random u64.

fn fill_bytes(&mut self, dest: &mut [u8])

Fill dest with random data.

impl TryRngCore for ThreadRng

type Error = Infallible

The type returned in the event of a RNG error.

fn try_next_u32(&mut self) -> Result<u32, Self::Error>

Return the next random u32.

fn try_next_u64(&mut self) -> Result<u64, Self::Error>

Return the next random u64.

fn try_fill_bytes(&mut self, dst: &mut [u8]) -> Result<(), Self::Error>

Fill dest entirely with random data.

fn unwrap_err(self) -> UnwrapErr<Self>

where Self: Sized,

Wrap RNG with the UnwrapErr wrapper.

fn read_adapter(&mut self) -> RngReadAdapter<'_, Self>

where Self: Sized,

Convert an RngCore to a RngReadAdapter.

impl CryptoRng for ThreadRng

impl TryCryptoRng for ThreadRng