Struct SimulationRng 

pub struct SimulationRng { /* private fields */ }

A thread-safe, seeded random number generator for simulation.

All random decisions during simulation should go through this RNG to ensure deterministic replay when using the same seed.

Determinism

For deterministic replay:

1. All random decisions must use this RNG
2. Random calls must happen in the same order each run
3. Parallel access must be serialized (handled internally by Mutex)

Implementations

impl SimulationRng

pub fn new(seed: u64) -> Self

Creates a new simulation RNG with the given seed.

pub fn seed(&self) -> u64

Returns the seed used to create this RNG.

pub fn gen_bool(&self, probability: f64) -> bool

Generates a random boolean with the given probability of being true.

pub fn gen_u64(&self) -> u64

Generates a random u64.

pub fn gen_u32(&self) -> u32

Generates a random u32.

pub fn gen_range(&self, range: Range<usize>) -> usize

Generates a random usize in the given range.

pub fn gen_range_u64(&self, range: Range<u64>) -> u64

Generates a random u64 in the given range.

pub fn gen_f64(&self) -> f64

Generates a random f64 in [0, 1).

pub fn gen_duration(&self, range: Range<Duration>) -> Duration

Generates a random Duration within the given range.

pub fn choose<'a, T>(&self, slice: &'a [T]) -> Option<&'a T>

Chooses a random element from a slice, returning None if empty.

pub fn shuffle<T>(&self, slice: &mut [T])

Shuffles a slice in-place using Fisher-Yates algorithm.

pub fn child(&self) -> Self

Creates a child RNG with a derived seed.

This is useful for giving each peer its own RNG while maintaining overall determinism - the child’s seed is derived from the parent’s current state.

pub fn child_with_index(&self, index: u64) -> Self

Creates a child RNG with a specific derived seed based on an index.

This ensures that child RNGs are created deterministically regardless of the order in which they’re requested, as long as the indices are consistent.

pub fn lock(&self) -> MutexGuard<'_, SmallRng>

Access the inner RNG for operations that need direct Rng trait access.

Warning

The returned guard holds the lock. Be careful not to hold it across await points or other blocking operations.

Trait Implementations

impl Clone for SimulationRng

fn clone(&self) -> SimulationRng

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for SimulationRng

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

Formats the value using the given formatter.