Struct rand::rngs::SmallRng[][src]

pub struct SmallRng(_);

An RNG recommended when small state, cheap initialization and good performance are required. The PRNG algorithm in SmallRng is chosen to be efficient on the current platform, without consideration for cryptography or security. The size of its state is much smaller than for StdRng.

Reproducibility of output from this generator is however not required, thus future library versions may use a different internal generator with different output. Further, this generator may not be portable and can produce different output depending on the architecture. If you require reproducible output, use a named RNG, for example XorShiftRng.

The current algorithm used on all platforms is Xorshift.

Examples

Initializing SmallRng with a random seed can be done using FromEntropy:

use rand::FromEntropy;
use rand::rngs::SmallRng;

// Create small, cheap to initialize and fast RNG with a random seed.
// The randomness is supplied by the operating system.
let mut small_rng = SmallRng::from_entropy();

When initializing a lot of SmallRng's, using thread_rng can be more efficient:

use std::iter;
use rand::{SeedableRng, thread_rng};
use rand::rngs::SmallRng;

// Create a big, expensive to initialize and slower, but unpredictable RNG.
// This is cached and done only once per thread.
let mut thread_rng = thread_rng();
// Create small, cheap to initialize and fast RNGs with random seeds.
// One can generally assume this won't fail.
let rngs: Vec<SmallRng> = iter::repeat(())
    .map(|()| SmallRng::from_rng(&mut thread_rng).unwrap())
    .take(10)
    .collect();

Trait Implementations

impl Clone for SmallRng
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Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

impl Debug for SmallRng
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Formats the value using the given formatter. Read more

impl RngCore for SmallRng
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Return the next random u32. Read more

Return the next random u64. Read more

Fill dest with random data. Read more

Fill dest entirely with random data. Read more

impl SeedableRng for SmallRng
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Seed type, which is restricted to types mutably-dereferencable as u8 arrays (we recommend [u8; N] for some N). Read more

Create a new PRNG using the given seed. Read more

Create a new PRNG seeded from another Rng. Read more

Create a new PRNG using a u64 seed. Read more

Auto Trait Implementations

impl Send for SmallRng

impl Sync for SmallRng