126 lines
3.9 KiB
Rust
126 lines
3.9 KiB
Rust
//#![warn(missing_docs)]
|
|
use anyhow::Context;
|
|
use std::ops::Add;
|
|
use tokio::time::{Duration, Instant};
|
|
|
|
pub use deadpool_redis::redis;
|
|
pub use deadpool_redis::{
|
|
Config as RedisConfig, Connection as RedisConnection, Manager as RedisManager,
|
|
Pool as RedisPool, PoolError as RedisPoolError, Runtime as DeadpoolRuntime,
|
|
};
|
|
|
|
#[derive(Clone)]
|
|
pub struct RedisRateLimiter {
|
|
key_prefix: String,
|
|
/// The default maximum requests allowed in a period.
|
|
pub max_requests_per_period: u64,
|
|
/// seconds
|
|
pub period: f32,
|
|
pool: RedisPool,
|
|
}
|
|
|
|
pub enum RedisRateLimitResult {
|
|
/// TODO: what is the inner value?
|
|
Allowed(u64),
|
|
/// TODO: what is the inner value?
|
|
RetryAt(Instant, u64),
|
|
RetryNever,
|
|
}
|
|
|
|
impl RedisRateLimiter {
|
|
pub fn new(
|
|
app: &str,
|
|
label: &str,
|
|
max_requests_per_period: u64,
|
|
period: f32,
|
|
pool: RedisPool,
|
|
) -> Self {
|
|
let key_prefix = format!("{}:rrl:{}", app, label);
|
|
|
|
Self {
|
|
pool,
|
|
key_prefix,
|
|
max_requests_per_period,
|
|
period,
|
|
}
|
|
}
|
|
|
|
pub fn now_as_secs(&self) -> f32 {
|
|
// TODO: if system time doesn't match redis, this won't work great
|
|
(chrono::Utc::now().timestamp_millis() as f32) / 1_000.0
|
|
}
|
|
|
|
pub fn period_id(&self, now_as_secs: f32) -> f32 {
|
|
(now_as_secs / self.period) % self.period
|
|
}
|
|
|
|
pub fn next_period(&self, now_as_secs: f32) -> Instant {
|
|
let seconds_left_in_period = self.period - (now_as_secs % self.period);
|
|
|
|
Instant::now().add(Duration::from_secs_f32(seconds_left_in_period))
|
|
}
|
|
|
|
/// label might be an ip address or a rpc_key id.
|
|
/// if setting max_per_period, be sure to keep the period the same for all requests to this label
|
|
pub async fn throttle_label(
|
|
&self,
|
|
label: &str,
|
|
max_per_period: Option<u64>,
|
|
count: u64,
|
|
) -> anyhow::Result<RedisRateLimitResult> {
|
|
let max_per_period = max_per_period.unwrap_or(self.max_requests_per_period);
|
|
|
|
if max_per_period == 0 {
|
|
return Ok(RedisRateLimitResult::RetryNever);
|
|
}
|
|
|
|
let now = self.now_as_secs();
|
|
|
|
// if self.period is 60, period_id will be the minute of the current time
|
|
let period_id = self.period_id(now);
|
|
|
|
// TODO: include max per period in the throttle key?
|
|
let throttle_key = format!("{}:{}:{}", self.key_prefix, label, period_id);
|
|
|
|
let mut conn = self
|
|
.pool
|
|
.get()
|
|
.await
|
|
.context("get redis connection for rate limits")?;
|
|
|
|
// TODO: at high concurency, this gives "connection reset by peer" errors. at least they are off the hot path
|
|
// TODO: only set expire if this is a new key
|
|
|
|
// TODO: automatic retry
|
|
let x: Vec<_> = redis::pipe()
|
|
.atomic()
|
|
// we could get the key first, but that means an extra redis call for every check. this seems better
|
|
.incr(&throttle_key, count)
|
|
// set expiration each time we set the key. ignore the result
|
|
.expire(&throttle_key, 1 + self.period as usize)
|
|
// TODO: NX will make it only set the expiration the first time. works in redis, but not elasticache
|
|
// .arg("NX")
|
|
.ignore()
|
|
// do the query
|
|
.query_async(&mut *conn)
|
|
.await
|
|
.context("cannot increment rate limit or set expiration")?;
|
|
|
|
let new_count: u64 = *x.first().expect("check redis");
|
|
|
|
if new_count > max_per_period {
|
|
// TODO: this might actually be early if we are way over the count
|
|
let retry_at = self.next_period(now);
|
|
|
|
Ok(RedisRateLimitResult::RetryAt(retry_at, new_count))
|
|
} else {
|
|
Ok(RedisRateLimitResult::Allowed(new_count))
|
|
}
|
|
}
|
|
|
|
#[inline]
|
|
pub async fn throttle(&self) -> anyhow::Result<RedisRateLimitResult> {
|
|
self.throttle_label("", None, 1).await
|
|
}
|
|
}
|