touch_ratelimit 0.1.0

A composable, extensible rate limiting crate for Rust
Documentation 
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use std::{future::Future, pin::Pin};

use tower::Service;

use crate::{
    middleware::{error::RateLimitError, KeyExtractor},
    storage::RateLimitStore,
};

/// Tower service that enforces rate limiting before forwarding requests
/// to the inner service.
#[derive(Clone)]
pub struct RateLimitService<S, Store, Extractor> {
    pub(crate) inner: S,
    pub(crate) store: Store,
    pub(crate) extractor: Extractor,
}

impl<S, Store, Extractor, Req> Service<Req> for RateLimitService<S, Store, Extractor>
where
    S: Service<Req> + Send,
    S::Future: Send + 'static,
    Store: RateLimitStore,
    Extractor: KeyExtractor<Req>,
{
    type Response = S::Response;
    type Error = RateLimitError<S::Error>;

    type Future = Pin<Box<dyn Future<Output = Result<Self::Response, Self::Error>> + Send>>;

    fn poll_ready(
        &mut self,
        cx: &mut std::task::Context<'_>,
    ) -> std::task::Poll<Result<(), Self::Error>> {
        self.inner.poll_ready(cx).map_err(RateLimitError::Inner)
    }

    fn call(&mut self, req: Req) -> Self::Future {
        if let Some(key) = self.extractor.extract(&req) {
            if !self.store.allow(&key) {
                return Box::pin(async {
                    Err(RateLimitError::Rejected(crate::errors::RateLimitExceeded))
                });
            }
        }

        let fut = self.inner.call(req);
        Box::pin(async move { fut.await.map_err(RateLimitError::Inner) })
    }
}