feat: round-9 abstractions — RetryExt ergonomic retry, ResilientHttpClient

crates/mytheclipse/src/lib.rs

@@ -34,6 +34,10 @@ pub mod bg;
 #[cfg(feature = "resiliency")]
 pub mod retry;
 #[cfg(feature = "resiliency")]
+pub mod retry_ext;
+#[cfg(feature = "resiliency")]
+pub use retry_ext::RetryExt;
+#[cfg(feature = "resiliency")]
 pub mod circuit_breaker;
 #[cfg(feature = "resiliency")]
 pub mod timeout;

crates/mytheclipse/src/retry_ext.rs

@@ -0,0 +1,72 @@
+//! Ergonomic retry extension trait (feature `resiliency`).
+//!
+//! [`RetryExt`] extends any [`std::future::Future<Output = Result<T, E>>`]
+//! with a `.retry()` method that delegates to [`crate::retry::retry`].
+
+use std::future::Future;
+use std::pin::Pin;
+
+use crate::retry::{retry, RetryConfig, RetryError};
+
+/// Extension trait adding ergonomic `.retry()` to any fallible future.
+pub trait RetryExt<T, E>: Future<Output = Result<T, E>> + Sized + 'static
+where
+    E: std::fmt::Debug + Send + 'static,
+    T: Send + 'static,
+{
+    /// Retries the future's result via a reconstructive `self_fn` closure,
+    /// delegating to [`crate::retry::retry`]. The original future is consumed
+    /// on the first attempt; subsequent attempts use `self_fn()`.
+    fn retry<F, Fut, P>(
+        self,
+        config: RetryConfig,
+        predicate: P,
+        self_fn: F,
+    ) -> Pin<Box<dyn Future<Output = Result<T, RetryError<E>>>>>
+    where
+        F: FnMut() -> Fut + 'static,
+        Fut: Future<Output = Result<T, E>> + 'static,
+        P: Fn(&E) -> bool + 'static,
+    {
+        Box::pin(async move {
+            let _ = self.await;
+            retry(config, predicate, self_fn).await
+        })
+    }
+}
+
+impl<Fut, T, E> RetryExt<T, E> for Fut
+where
+    Fut: Future<Output = Result<T, E>> + Send + 'static,
+    E: std::fmt::Debug + Send + 'static,
+    T: Send + 'static,
+{
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::time::Duration;
+    use std::sync::Arc;
+    use std::sync::atomic::{AtomicU32, Ordering};
+
+    #[tokio::test]
+    async fn retry_ext_retries_then_succeeds() {
+        let attempts = Arc::new(AtomicU32::new(0));
+        let a = Arc::clone(&attempts);
+        let cfg = RetryConfig { max_attempts: 3, base_delay: Duration::from_millis(1), ..RetryConfig::default() };
+
+        let op = move || {
+            let a = Arc::clone(&a);
+            async move {
+                let n = a.fetch_add(1, Ordering::SeqCst);
+                if n < 2 { Err::<(), String>("transient".into()) } else { Ok(()) }
+            }
+        };
+
+        let fut = async { Err::<(), String>("first".into()) };
+        let result = fut.retry(cfg, |_: &String| true, op).await;
+        assert!(result.is_ok());
+        assert_eq!(attempts.load(Ordering::SeqCst), 3);
+    }
+}