request_rate_limiter/
keyed.rs

1//! Keyed rate limiting functionality.
2//!
3//! This module provides rate limiting with per-key isolation, allowing independent
4//! rate limiting across different clients, users, or request types.
5
6use std::{fmt::Debug, hash::Hash, time::Duration};
7
8use async_trait::async_trait;
9use dashmap::{mapref::one::Ref, DashMap};
10
11use crate::{
12    algorithms::RateLimitAlgorithm,
13    limiter::{DefaultRateLimiter, RateLimiter, RequestOutcome, Token},
14};
15
16/// Controls the rate of requests over time with per-key rate limiting.
17///
18/// Each key maintains its own rate limit state, allowing for independent
19/// rate limiting across different clients, users, or request types.
20#[async_trait]
21pub trait RateLimiterKeyed<K>: Sync
22where
23    K: Hash + Eq + Send + Sync,
24{
25    /// Acquire permission to make a request for a specific key. Waits until a token is available.
26    async fn acquire(&self, key: &K) -> Token;
27
28    /// Acquire permission to make a request for a specific key with a timeout.
29    /// Returns a token if successful.
30    async fn acquire_timeout(&self, key: &K, duration: Duration) -> Option<Token>;
31
32    /// Release the token and record the outcome of the request for the specific key.
33    /// The response time is calculated from when the token was acquired.
34    async fn release(&self, key: &K, token: Token, outcome: Option<RequestOutcome>);
35}
36
37/// A keyed rate limiter that maintains separate rate limiters for each key.
38///
39/// Uses DashMap for efficient concurrent access to per-key rate limiters.
40/// Each key gets its own independent rate limiter instance.
41pub struct DefaultRateLimiterKeyed<T, K>
42where
43    T: RateLimitAlgorithm + Debug + Clone,
44    K: Hash + Eq + Send + Sync,
45{
46    limiters: DashMap<K, DefaultRateLimiter<T>>,
47    algorithm: T,
48}
49
50impl<T, K> DefaultRateLimiterKeyed<T, K>
51where
52    T: RateLimitAlgorithm + Debug + Clone,
53    K: Hash + Eq + Clone + Send + Sync,
54{
55    /// Create a new keyed rate limiter with the given algorithm factory function.
56    /// Each key will get a fresh instance of the algorithm created by calling the factory.
57    pub fn new(algorithm: T) -> Self {
58        Self {
59            limiters: DashMap::new(),
60            algorithm,
61        }
62    }
63
64    /// Get or create a rate limiter for the given key.
65    fn get_or_create_limiter(&self, key: &K) -> Ref<'_, K, DefaultRateLimiter<T>> {
66        if !self.limiters.contains_key(key) {
67            self.limiters
68                .insert(key.clone(), DefaultRateLimiter::new(self.algorithm.clone()));
69        }
70
71        self.limiters.get(key).unwrap()
72    }
73
74    /// Get the number of active keys being tracked.
75    pub fn active_keys(&self) -> usize {
76        self.limiters.len()
77    }
78
79    /// Remove a key and its associated rate limiter.
80    /// Returns true if the key existed and was removed.
81    pub fn remove_key(&self, key: &K) -> bool {
82        self.limiters.remove(key).is_some()
83    }
84
85    /// Clear all keys and their associated rate limiters.
86    pub fn clear(&self) {
87        self.limiters.clear();
88    }
89}
90
91#[async_trait]
92impl<T, K> RateLimiterKeyed<K> for DefaultRateLimiterKeyed<T, K>
93where
94    T: RateLimitAlgorithm + Send + Clone + Sync + Debug,
95    K: Hash + Eq + Clone + Send + Sync,
96{
97    async fn acquire(&self, key: &K) -> Token {
98        let limiter = self.get_or_create_limiter(key);
99        limiter.acquire().await
100    }
101
102    async fn acquire_timeout(&self, key: &K, duration: Duration) -> Option<Token> {
103        let limiter = self.get_or_create_limiter(key);
104        limiter.acquire_timeout(duration).await
105    }
106
107    async fn release(&self, key: &K, token: Token, outcome: Option<RequestOutcome>) {
108        let limiter = self.get_or_create_limiter(key);
109        limiter.release(token, outcome).await
110    }
111}
112
113#[cfg(test)]
114mod tests {
115    use crate::{
116        algorithms::Fixed,
117        keyed::{DefaultRateLimiterKeyed, RateLimiterKeyed},
118        limiter::RequestOutcome,
119    };
120
121    #[tokio::test]
122    async fn keyed_rate_limiter_works_independently_per_key() {
123        let limiter = DefaultRateLimiterKeyed::<_, String>::new(Fixed::new(1));
124
125        let key1 = "key1".to_string();
126        let key2 = "key2".to_string();
127        // Acquire tokens for different keys - should work independently
128        let token1 = limiter.acquire(&key1).await;
129        let token2 = limiter.acquire(&key2).await;
130
131        // Both should succeed because they're different keys
132        limiter
133            .release(&key1, token1, Some(RequestOutcome::Success))
134            .await;
135        limiter
136            .release(&key2, token2, Some(RequestOutcome::Success))
137            .await;
138
139        assert_eq!(limiter.active_keys(), 2);
140    }
141
142    #[tokio::test]
143    async fn keyed_rate_limiter_manages_keys() {
144        let limiter = DefaultRateLimiterKeyed::<_, String>::new(Fixed::new(10));
145
146        // Create limiters for multiple keys
147        let _token1 = limiter.acquire(&"user1".to_string()).await;
148        let _token2 = limiter.acquire(&"user2".to_string()).await;
149        let _token3 = limiter.acquire(&"user3".to_string()).await;
150
151        assert_eq!(limiter.active_keys(), 3);
152
153        // Remove one key
154        assert!(limiter.remove_key(&"user2".to_string()));
155        assert_eq!(limiter.active_keys(), 2);
156
157        // Try to remove non-existent key
158        assert!(!limiter.remove_key(&"nonexistent".to_string()));
159
160        // Clear all keys
161        limiter.clear();
162        assert_eq!(limiter.active_keys(), 0);
163    }
164}
request_rate_limiter/keyed.rs

request_rate_limiter/
keyed.rs
