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.
41#[derive(Debug)]
42pub struct DefaultRateLimiterKeyed<T, K>
43where
44    T: RateLimitAlgorithm + Debug + Clone,
45    K: Hash + Eq + Send + Sync,
46{
47    limiters: DashMap<K, DefaultRateLimiter<T>>,
48    algorithm: T,
49}
50
51impl<T, K> DefaultRateLimiterKeyed<T, K>
52where
53    T: RateLimitAlgorithm + Debug + Clone,
54    K: Hash + Eq + Clone + Send + Sync,
55{
56    /// Create a new keyed rate limiter with the given algorithm factory function.
57    /// Each key will get a fresh instance of the algorithm created by calling the factory.
58    pub fn new(algorithm: T) -> Self {
59        Self {
60            limiters: DashMap::new(),
61            algorithm,
62        }
63    }
64
65    /// Get or create a rate limiter for the given key.
66    fn get_or_create_limiter(&self, key: &K) -> Ref<'_, K, DefaultRateLimiter<T>> {
67        if !self.limiters.contains_key(key) {
68            self.limiters
69                .insert(key.clone(), DefaultRateLimiter::new(self.algorithm.clone()));
70        }
71
72        self.limiters.get(key).unwrap()
73    }
74
75    /// Get the number of active keys being tracked.
76    pub fn active_keys(&self) -> usize {
77        self.limiters.len()
78    }
79
80    /// Remove a key and its associated rate limiter.
81    /// Returns true if the key existed and was removed.
82    pub fn remove_key(&self, key: &K) -> bool {
83        self.limiters.remove(key).is_some()
84    }
85
86    /// Clear all keys and their associated rate limiters.
87    pub fn clear(&self) {
88        self.limiters.clear();
89    }
90}
91
92#[async_trait]
93impl<T, K> RateLimiterKeyed<K> for DefaultRateLimiterKeyed<T, K>
94where
95    T: RateLimitAlgorithm + Send + Clone + Sync + Debug,
96    K: Hash + Eq + Clone + Send + Sync,
97{
98    async fn acquire(&self, key: &K) -> Token {
99        let limiter = self.get_or_create_limiter(key);
100        limiter.acquire().await
101    }
102
103    async fn acquire_timeout(&self, key: &K, duration: Duration) -> Option<Token> {
104        let limiter = self.get_or_create_limiter(key);
105        limiter.acquire_timeout(duration).await
106    }
107
108    async fn release(&self, key: &K, token: Token, outcome: Option<RequestOutcome>) {
109        let limiter = self.get_or_create_limiter(key);
110        limiter.release(token, outcome).await
111    }
112}
113
114#[cfg(test)]
115mod tests {
116    use crate::{
117        algorithms::Fixed,
118        keyed::{DefaultRateLimiterKeyed, RateLimiterKeyed},
119        limiter::RequestOutcome,
120    };
121
122    #[tokio::test]
123    async fn keyed_rate_limiter_works_independently_per_key() {
124        let limiter = DefaultRateLimiterKeyed::<_, String>::new(Fixed::new(1));
125
126        let key1 = "key1".to_string();
127        let key2 = "key2".to_string();
128        // Acquire tokens for different keys - should work independently
129        let token1 = limiter.acquire(&key1).await;
130        let token2 = limiter.acquire(&key2).await;
131
132        // Both should succeed because they're different keys
133        limiter
134            .release(&key1, token1, Some(RequestOutcome::Success))
135            .await;
136        limiter
137            .release(&key2, token2, Some(RequestOutcome::Success))
138            .await;
139
140        assert_eq!(limiter.active_keys(), 2);
141    }
142
143    #[tokio::test]
144    async fn keyed_rate_limiter_manages_keys() {
145        let limiter = DefaultRateLimiterKeyed::<_, String>::new(Fixed::new(10));
146
147        // Create limiters for multiple keys
148        let _token1 = limiter.acquire(&"user1".to_string()).await;
149        let _token2 = limiter.acquire(&"user2".to_string()).await;
150        let _token3 = limiter.acquire(&"user3".to_string()).await;
151
152        assert_eq!(limiter.active_keys(), 3);
153
154        // Remove one key
155        assert!(limiter.remove_key(&"user2".to_string()));
156        assert_eq!(limiter.active_keys(), 2);
157
158        // Try to remove non-existent key
159        assert!(!limiter.remove_key(&"nonexistent".to_string()));
160
161        // Clear all keys
162        limiter.clear();
163        assert_eq!(limiter.active_keys(), 0);
164    }
165}
request_rate_limiter/keyed.rs

request_rate_limiter/
keyed.rs
