feat: Add more trait bound for backoff trait

src/backoff.rs

@@ -1,8 +1,9 @@
+use std::fmt::Debug;
 use std::time::Duration;
 
 /// Backoff is an [`Iterator`] that returns [`Duration`].
 ///
 /// - `Some(Duration)` means caller need to `sleep(Duration)` and retry the same request
 /// - `None` means we have reaching the limits, caller needs to return current error instead.
-pub trait Backoff: Iterator<Item = Duration> + Clone {}
-impl<T> Backoff for T where T: Iterator<Item = Duration> + Clone {}
+pub trait Backoff: Iterator<Item = Duration> + Default + Debug + Send + Sync + Unpin {}
+impl<T> Backoff for T where T: Iterator<Item = Duration> + Default + Debug + Send + Sync + Unpin {}

src/constant.rs

@@ -29,7 +29,7 @@ use std::time::Duration;
 ///     Ok(())
 /// }
 /// ```
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 pub struct ConstantBackoff {
     delay: Duration,
     max_times: Option<usize>,

src/exponential.rs

@@ -33,7 +33,7 @@ use std::time::Duration;
 ///     Ok(())
 /// }
 /// ```
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 pub struct ExponentialBackoff {
     jitter: bool,
     factor: f32,