Struct FixedWindowCounter 

pub struct FixedWindowCounter { /* private fields */ }

A Fixed Window Counter rate limiter.

This implementation uses fixed time windows to limit the number of requests within each window. It’s simple to understand and implement, but can allow twice the rate of requests around window boundaries.

Features

• Uses fixed time windows for rate limiting.
• Allows a specified number of requests within each time window.
• Automatically clears old windows to prevent memory growth.

Example

use std::time::Duration;
use limitr::window::FixedWindowCounter;

let mut counter = FixedWindowCounter::new(100, Duration::from_secs(60));
for _ in 0..100 {
    assert!(counter.try_consume().await);
}

assert!(!counter.try_consume().await);

Implementations

impl FixedWindowCounter

pub fn new(limit: u32, window_duration: Duration) -> Self

Creates a new FixedWindowCounter with the specified limit and window_duration.

• limit: The maximum number of requests allowed in each time window.
• window_duration: The duration of each time window.

Example

use std::time::Duration;
use limitr::window::FixedWindowCounter;

let counter = FixedWindowCounter::new(100, Duration::from_secs(60)); // 100 requests per minute

pub async fn try_consume(&self) -> bool

Attempts to consume a token from the current time window.

Returns true if the request is allowed, and false if the limit has been reached for the current window.

Example

use std::time::Duration;
use limitr::window::FixedWindowCounter;

let mut counter = FixedWindowCounter::new(5, Duration::from_secs(60));
for _ in 0..5 {
    assert!(counter.try_consume().await);
}

assert!(!counter.try_consume().await);

pub async fn clear_old_windows(&self)

Clears old time windows to prevent unbounded growth of the internal HashMap.

This method should be called periodically to remove data for expired time windows.

Example

use std::time::Duration;
use limitr::window::FixedWindowCounter;

let mut counter = FixedWindowCounter::new(100, Duration::from_secs(60));
// ... some time passes ...
counter.clear_old_windows().await;