Line data Source code
1 : use std::{
2 : borrow::Cow,
3 : collections::hash_map::RandomState,
4 : hash::{BuildHasher, Hash},
5 : sync::{
6 : atomic::{AtomicUsize, Ordering},
7 : Mutex,
8 : },
9 : };
10 :
11 : use anyhow::bail;
12 : use dashmap::DashMap;
13 : use itertools::Itertools;
14 : use rand::{rngs::StdRng, Rng, SeedableRng};
15 : use tokio::time::{Duration, Instant};
16 : use tracing::info;
17 :
18 : use crate::intern::EndpointIdInt;
19 :
20 : pub(crate) struct GlobalRateLimiter {
21 : data: Vec<RateBucket>,
22 : info: Vec<RateBucketInfo>,
23 : }
24 :
25 : impl GlobalRateLimiter {
26 0 : pub(crate) fn new(info: Vec<RateBucketInfo>) -> Self {
27 0 : Self {
28 0 : data: vec![
29 0 : RateBucket {
30 0 : start: Instant::now(),
31 0 : count: 0,
32 0 : };
33 0 : info.len()
34 0 : ],
35 0 : info,
36 0 : }
37 0 : }
38 :
39 : /// Check that number of connections is below `max_rps` rps.
40 0 : pub(crate) fn check(&mut self) -> bool {
41 0 : let now = Instant::now();
42 0 :
43 0 : let should_allow_request = self
44 0 : .data
45 0 : .iter_mut()
46 0 : .zip(&self.info)
47 0 : .all(|(bucket, info)| bucket.should_allow_request(info, now, 1));
48 0 :
49 0 : if should_allow_request {
50 0 : // only increment the bucket counts if the request will actually be accepted
51 0 : self.data.iter_mut().for_each(|b| b.inc(1));
52 0 : }
53 :
54 0 : should_allow_request
55 0 : }
56 : }
57 :
58 : // Simple per-endpoint rate limiter.
59 : //
60 : // Check that number of connections to the endpoint is below `max_rps` rps.
61 : // Purposefully ignore user name and database name as clients can reconnect
62 : // with different names, so we'll end up sending some http requests to
63 : // the control plane.
64 : pub type WakeComputeRateLimiter = BucketRateLimiter<EndpointIdInt, StdRng, RandomState>;
65 :
66 : pub struct BucketRateLimiter<Key, Rand = StdRng, Hasher = RandomState> {
67 : map: DashMap<Key, Vec<RateBucket>, Hasher>,
68 : info: Cow<'static, [RateBucketInfo]>,
69 : access_count: AtomicUsize,
70 : rand: Mutex<Rand>,
71 : }
72 :
73 : #[derive(Clone, Copy)]
74 : struct RateBucket {
75 : start: Instant,
76 : count: u32,
77 : }
78 :
79 : impl RateBucket {
80 3000915 : fn should_allow_request(&mut self, info: &RateBucketInfo, now: Instant, n: u32) -> bool {
81 3000915 : if now - self.start < info.interval {
82 3000907 : self.count + n <= info.max_rpi
83 : } else {
84 : // bucket expired, reset
85 8 : self.count = 0;
86 8 : self.start = now;
87 8 :
88 8 : true
89 : }
90 3000915 : }
91 :
92 3000909 : fn inc(&mut self, n: u32) {
93 3000909 : self.count += n;
94 3000909 : }
95 : }
96 :
97 : #[derive(Clone, Copy, PartialEq)]
98 : pub struct RateBucketInfo {
99 : pub(crate) interval: Duration,
100 : // requests per interval
101 : pub(crate) max_rpi: u32,
102 : }
103 :
104 : impl std::fmt::Display for RateBucketInfo {
105 19 : fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
106 19 : let rps = self.rps().floor() as u64;
107 19 : write!(f, "{rps}@{}", humantime::format_duration(self.interval))
108 19 : }
109 : }
110 :
111 : impl std::fmt::Debug for RateBucketInfo {
112 0 : fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
113 0 : write!(f, "{self}")
114 0 : }
115 : }
116 :
117 : impl std::str::FromStr for RateBucketInfo {
118 : type Err = anyhow::Error;
119 :
120 32 : fn from_str(s: &str) -> Result<Self, Self::Err> {
121 32 : let Some((max_rps, interval)) = s.split_once('@') else {
122 0 : bail!("invalid rate info")
123 : };
124 32 : let max_rps = max_rps.parse()?;
125 32 : let interval = humantime::parse_duration(interval)?;
126 32 : Ok(Self::new(max_rps, interval))
127 32 : }
128 : }
129 :
130 : impl RateBucketInfo {
131 : pub const DEFAULT_SET: [Self; 3] = [
132 : Self::new(300, Duration::from_secs(1)),
133 : Self::new(200, Duration::from_secs(60)),
134 : Self::new(100, Duration::from_secs(600)),
135 : ];
136 :
137 : pub const DEFAULT_ENDPOINT_SET: [Self; 3] = [
138 : Self::new(500, Duration::from_secs(1)),
139 : Self::new(300, Duration::from_secs(60)),
140 : Self::new(200, Duration::from_secs(600)),
141 : ];
142 :
143 19 : pub fn rps(&self) -> f64 {
144 19 : (self.max_rpi as f64) / self.interval.as_secs_f64()
145 19 : }
146 :
147 3 : pub fn validate(info: &mut [Self]) -> anyhow::Result<()> {
148 8 : info.sort_unstable_by_key(|info| info.interval);
149 3 : let invalid = info
150 3 : .iter()
151 3 : .tuple_windows()
152 4 : .find(|(a, b)| a.max_rpi > b.max_rpi);
153 3 : if let Some((a, b)) = invalid {
154 1 : bail!(
155 1 : "invalid bucket RPS limits. {b} allows fewer requests per bucket than {a} ({} vs {})",
156 1 : b.max_rpi,
157 1 : a.max_rpi,
158 1 : );
159 2 : }
160 2 :
161 2 : Ok(())
162 3 : }
163 :
164 36 : pub const fn new(max_rps: u32, interval: Duration) -> Self {
165 36 : Self {
166 36 : interval,
167 36 : max_rpi: ((max_rps as u64) * (interval.as_millis() as u64) / 1000) as u32,
168 36 : }
169 36 : }
170 : }
171 :
172 : impl<K: Hash + Eq> BucketRateLimiter<K> {
173 4 : pub fn new(info: impl Into<Cow<'static, [RateBucketInfo]>>) -> Self {
174 4 : Self::new_with_rand_and_hasher(info, StdRng::from_entropy(), RandomState::new())
175 4 : }
176 : }
177 :
178 : impl<K: Hash + Eq, R: Rng, S: BuildHasher + Clone> BucketRateLimiter<K, R, S> {
179 5 : fn new_with_rand_and_hasher(
180 5 : info: impl Into<Cow<'static, [RateBucketInfo]>>,
181 5 : rand: R,
182 5 : hasher: S,
183 5 : ) -> Self {
184 5 : let info = info.into();
185 5 : info!(buckets = ?info, "endpoint rate limiter");
186 5 : Self {
187 5 : info,
188 5 : map: DashMap::with_hasher_and_shard_amount(hasher, 64),
189 5 : access_count: AtomicUsize::new(1), // start from 1 to avoid GC on the first request
190 5 : rand: Mutex::new(rand),
191 5 : }
192 5 : }
193 :
194 : /// Check that number of connections to the endpoint is below `max_rps` rps.
195 1000457 : pub(crate) fn check(&self, key: K, n: u32) -> bool {
196 1000457 : // do a partial GC every 2k requests. This cleans up ~ 1/64th of the map.
197 1000457 : // worst case memory usage is about:
198 1000457 : // = 2 * 2048 * 64 * (48B + 72B)
199 1000457 : // = 30MB
200 1000457 : if self.access_count.fetch_add(1, Ordering::AcqRel) % 2048 == 0 {
201 488 : self.do_gc();
202 999969 : }
203 :
204 1000457 : let now = Instant::now();
205 1000457 : let mut entry = self.map.entry(key).or_insert_with(|| {
206 1000004 : vec![
207 1000004 : RateBucket {
208 1000004 : start: now,
209 1000004 : count: 0,
210 1000004 : };
211 1000004 : self.info.len()
212 1000004 : ]
213 1000457 : });
214 1000457 :
215 1000457 : let should_allow_request = entry
216 1000457 : .iter_mut()
217 1000457 : .zip(&*self.info)
218 3000915 : .all(|(bucket, info)| bucket.should_allow_request(info, now, n));
219 1000457 :
220 1000457 : if should_allow_request {
221 1000453 : // only increment the bucket counts if the request will actually be accepted
222 3000909 : entry.iter_mut().for_each(|b| b.inc(n));
223 1000453 : }
224 :
225 1000457 : should_allow_request
226 1000457 : }
227 :
228 : /// Clean the map. Simple strategy: remove all entries in a random shard.
229 : /// At worst, we'll double the effective max_rps during the cleanup.
230 : /// But that way deletion does not aquire mutex on each entry access.
231 488 : pub(crate) fn do_gc(&self) {
232 488 : info!(
233 0 : "cleaning up bucket rate limiter, current size = {}",
234 0 : self.map.len()
235 : );
236 488 : let n = self.map.shards().len();
237 488 : // this lock is ok as the periodic cycle of do_gc makes this very unlikely to collide
238 488 : // (impossible, infact, unless we have 2048 threads)
239 488 : let shard = self.rand.lock().unwrap().gen_range(0..n);
240 488 : self.map.shards()[shard].write().clear();
241 488 : }
242 : }
243 :
244 : #[cfg(test)]
245 : mod tests {
246 : use std::{hash::BuildHasherDefault, time::Duration};
247 :
248 : use rand::SeedableRng;
249 : use rustc_hash::FxHasher;
250 : use tokio::time;
251 :
252 : use super::{BucketRateLimiter, WakeComputeRateLimiter};
253 : use crate::{intern::EndpointIdInt, rate_limiter::RateBucketInfo, EndpointId};
254 :
255 : #[test]
256 1 : fn rate_bucket_rpi() {
257 1 : let rate_bucket = RateBucketInfo::new(50, Duration::from_secs(5));
258 1 : assert_eq!(rate_bucket.max_rpi, 50 * 5);
259 :
260 1 : let rate_bucket = RateBucketInfo::new(50, Duration::from_millis(500));
261 1 : assert_eq!(rate_bucket.max_rpi, 50 / 2);
262 1 : }
263 :
264 : #[test]
265 1 : fn rate_bucket_parse() {
266 1 : let rate_bucket: RateBucketInfo = "100@10s".parse().unwrap();
267 1 : assert_eq!(rate_bucket.interval, Duration::from_secs(10));
268 1 : assert_eq!(rate_bucket.max_rpi, 100 * 10);
269 1 : assert_eq!(rate_bucket.to_string(), "100@10s");
270 :
271 1 : let rate_bucket: RateBucketInfo = "100@1m".parse().unwrap();
272 1 : assert_eq!(rate_bucket.interval, Duration::from_secs(60));
273 1 : assert_eq!(rate_bucket.max_rpi, 100 * 60);
274 1 : assert_eq!(rate_bucket.to_string(), "100@1m");
275 1 : }
276 :
277 : #[test]
278 1 : fn default_rate_buckets() {
279 1 : let mut defaults = RateBucketInfo::DEFAULT_SET;
280 1 : RateBucketInfo::validate(&mut defaults[..]).unwrap();
281 1 : }
282 :
283 : #[test]
284 : #[should_panic = "invalid bucket RPS limits. 10@10s allows fewer requests per bucket than 300@1s (100 vs 300)"]
285 1 : fn rate_buckets_validate() {
286 1 : let mut rates: Vec<RateBucketInfo> = ["300@1s", "10@10s"]
287 1 : .into_iter()
288 2 : .map(|s| s.parse().unwrap())
289 1 : .collect();
290 1 : RateBucketInfo::validate(&mut rates).unwrap();
291 1 : }
292 :
293 : #[tokio::test]
294 1 : async fn test_rate_limits() {
295 1 : let mut rates: Vec<RateBucketInfo> = ["100@1s", "20@30s"]
296 1 : .into_iter()
297 2 : .map(|s| s.parse().unwrap())
298 1 : .collect();
299 1 : RateBucketInfo::validate(&mut rates).unwrap();
300 1 : let limiter = WakeComputeRateLimiter::new(rates);
301 1 :
302 1 : let endpoint = EndpointId::from("ep-my-endpoint-1234");
303 1 : let endpoint = EndpointIdInt::from(endpoint);
304 1 :
305 1 : time::pause();
306 1 :
307 101 : for _ in 0..100 {
308 100 : assert!(limiter.check(endpoint, 1));
309 1 : }
310 1 : // more connections fail
311 1 : assert!(!limiter.check(endpoint, 1));
312 1 :
313 1 : // fail even after 500ms as it's in the same bucket
314 1 : time::advance(time::Duration::from_millis(500)).await;
315 1 : assert!(!limiter.check(endpoint, 1));
316 1 :
317 1 : // after a full 1s, 100 requests are allowed again
318 1 : time::advance(time::Duration::from_millis(500)).await;
319 6 : for _ in 1..6 {
320 255 : for _ in 0..50 {
321 250 : assert!(limiter.check(endpoint, 2));
322 1 : }
323 5 : time::advance(time::Duration::from_millis(1000)).await;
324 1 : }
325 1 :
326 1 : // more connections after 600 will exceed the 20rps@30s limit
327 1 : assert!(!limiter.check(endpoint, 1));
328 1 :
329 1 : // will still fail before the 30 second limit
330 1 : time::advance(time::Duration::from_millis(30_000 - 6_000 - 1)).await;
331 1 : assert!(!limiter.check(endpoint, 1));
332 1 :
333 1 : // after the full 30 seconds, 100 requests are allowed again
334 1 : time::advance(time::Duration::from_millis(1)).await;
335 101 : for _ in 0..100 {
336 100 : assert!(limiter.check(endpoint, 1));
337 1 : }
338 1 : }
339 :
340 : #[tokio::test]
341 1 : async fn test_rate_limits_gc() {
342 1 : // fixed seeded random/hasher to ensure that the test is not flaky
343 1 : let rand = rand::rngs::StdRng::from_seed([1; 32]);
344 1 : let hasher = BuildHasherDefault::<FxHasher>::default();
345 1 :
346 1 : let limiter =
347 1 : BucketRateLimiter::new_with_rand_and_hasher(&RateBucketInfo::DEFAULT_SET, rand, hasher);
348 1000001 : for i in 0..1_000_000 {
349 1000000 : limiter.check(i, 1);
350 1000000 : }
351 1 : assert!(limiter.map.len() < 150_000);
352 1 : }
353 : }
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