Struct ProbabilisticStore 

pub struct ProbabilisticStore { /* private fields */ }

Random-sampling cleanup store implementation

This store uses probabilistic cleanup where each operation has a small chance to trigger a cleanup cycle. Best suited for high-throughput applications where periodic cleanup would cause latency spikes.

Features

• Cleanup probability configurable (e.g., 1 in 10,000 operations)
• Distributes cleanup cost across all operations
• No periodic latency spikes
• Excellent for very high request rates

Example

use throttlecrab::{RateLimiter, ProbabilisticStore};
use std::time::SystemTime;

// Clean up with 1 in 5000 probability (0.02% chance per operation)
let store = ProbabilisticStore::builder()
    .cleanup_probability(5000)
    .build();
let mut limiter = RateLimiter::new(store);

Cleanup Strategy

Uses a deterministic pseudo-random approach based on operation count, ensuring uniform distribution of cleanup operations over time.

Implementations

impl ProbabilisticStore

pub fn new() -> Self

Create a new ProbabilisticStore with default configuration

Uses a default capacity of 1000 entries and cleanup probability of 1/1000.

pub fn with_capacity(capacity: usize) -> Self

Create a new ProbabilisticStore with specified capacity

The store will allocate 30% more space to reduce hash collisions.

Parameters

• capacity: Expected number of unique keys to track

pub fn builder() -> ProbabilisticStoreBuilder

Create a new builder for configuring a ProbabilisticStore

Provides fine-grained control over store configuration.

Trait Implementations

impl Default for ProbabilisticStore

fn default() -> Self

Returns the “default value” for a type.

impl Store for ProbabilisticStore

fn compare_and_swap_with_ttl( &mut self, key: &str, old: i64, new: i64, ttl: Duration, now: SystemTime, ) -> Result<bool, String>

Atomically compare and swap a value with TTL

fn get(&self, key: &str, now: SystemTime) -> Result<Option<i64>, String>

Get the current value for a key

fn set_if_not_exists_with_ttl( &mut self, key: &str, value: i64, ttl: Duration, now: SystemTime, ) -> Result<bool, String>

Set a value with TTL if the key doesn’t exist