Add no_std flag, hide blocking retrys behind std flag

.gitignore

@@ -1,2 +1,3 @@
 /target
 /Cargo.lock
+/.idea

backon/Cargo.toml

@@ -12,15 +12,17 @@ repository.workspace = true
 [package.metadata.docs.rs]
 all-features = true
 targets = [
-  "x86_64-unknown-linux-gnu",
-  "x86_64-apple-darwin",
-  "x86_64-pc-windows-msvc",
-  "wasm32-unknown-unknown",
+    "x86_64-unknown-linux-gnu",
+    "x86_64-apple-darwin",
+    "x86_64-pc-windows-msvc",
+    "wasm32-unknown-unknown",
 ]
 
 [features]
 gloo-timers-sleep = ["dep:gloo-timers", "gloo-timers?/futures"]
 tokio-sleep = ["dep:tokio", "tokio?/time"]
+default = ["std"]
+std = []
 
 [dependencies]
 fastrand = "2.0.0"
@@ -34,21 +36,22 @@ gloo-timers = { version = "0.3", optional = true }
 [dev-dependencies]
 anyhow = "1"
 reqwest = "0.12"
+spin = "0.9.8"
 
 [target.'cfg(target_arch = "wasm32")'.dev-dependencies]
 tokio = { version = "1", features = [
-  "macros",
-  "rt",
-  "sync",
+    "macros",
+    "rt",
+    "sync",
 ], default-features = false }
 wasm-bindgen-test = "0.3"
 
 [target.'cfg(not(target_arch = "wasm32"))'.dev-dependencies]
 sqlx = { version = "0.8.0", features = ["runtime-tokio", "sqlite"] }
 tokio = { version = "1", features = [
-  "time",
-  "rt",
-  "macros",
-  "sync",
-  "rt-multi-thread",
+    "time",
+    "rt",
+    "macros",
+    "sync",
+    "rt-multi-thread",
 ] }

backon/src/backoff/api.rs

@@ -1,5 +1,5 @@
-use std::fmt::Debug;
-use std::time::Duration;
+use core::fmt::Debug;
+use core::time::Duration;
 
 /// BackoffBuilder is utilized to construct a new backoff.
 pub trait BackoffBuilder: Debug + Send + Sync + Unpin {

backon/src/backoff/constant.rs

@@ -1,4 +1,4 @@
-use std::time::Duration;
+use core::time::Duration;
 
 use crate::backoff::BackoffBuilder;
 
@@ -121,7 +121,7 @@ impl Iterator for ConstantBackoff {
 
 #[cfg(test)]
 mod tests {
-    use std::time::Duration;
+    use core::time::Duration;
 
     #[cfg(target_arch = "wasm32")]
     use wasm_bindgen_test::wasm_bindgen_test as test;

backon/src/backoff/exponential.rs

@@ -1,4 +1,4 @@
-use std::time::Duration;
+use core::time::Duration;
 
 use crate::backoff::BackoffBuilder;
 
@@ -182,7 +182,7 @@ pub(crate) fn saturating_mul(d: Duration, rhs: f32) -> Duration {
 
 #[cfg(test)]
 mod tests {
-    use std::time::Duration;
+    use core::time::Duration;
 
     #[cfg(target_arch = "wasm32")]
     use wasm_bindgen_test::wasm_bindgen_test as test;

backon/src/backoff/fibonacci.rs

@@ -1,4 +1,4 @@
-use std::time::Duration;
+use core::time::Duration;
 
 use crate::backoff::BackoffBuilder;
 
@@ -164,7 +164,7 @@ impl Iterator for FibonacciBackoff {
 
 #[cfg(test)]
 mod tests {
-    use std::time::Duration;
+    use core::time::Duration;
 
     #[cfg(target_arch = "wasm32")]
     use wasm_bindgen_test::wasm_bindgen_test as test;

backon/src/blocking_retry.rs

@@ -1,5 +1,5 @@
+use core::time::Duration;
 use std::thread;
-use std::time::Duration;
 
 use crate::backoff::BackoffBuilder;
 use crate::Backoff;
@@ -138,7 +138,7 @@ where
     /// # Examples
     ///
     /// ```no_run
-    /// use std::time::Duration;
+    /// use core::time::Duration;
     ///
     /// use anyhow::Result;
     /// use backon::BlockingRetryable;
@@ -171,7 +171,7 @@ where
 
     /// Call the retried function.
     ///
-    /// TODO: implement [`std::ops::FnOnce`] after it stable.
+    /// TODO: implement [`FnOnce`] after it stable.
     pub fn call(mut self) -> Result<T, E> {
         loop {
             let result = (self.f)();
@@ -198,8 +198,11 @@ where
 
 #[cfg(test)]
 mod tests {
-    use std::sync::Mutex;
-    use std::time::Duration;
+    use alloc::string::ToString;
+    use alloc::vec;
+    use alloc::vec::Vec;
+    use core::time::Duration;
+    use spin::Mutex;
 
     use super::*;
     use crate::ExponentialBuilder;
@@ -224,7 +227,7 @@ mod tests {
         let error_times = Mutex::new(0);
 
         let f = || {
-            let mut x = error_times.lock().unwrap();
+            let mut x = error_times.lock();
             *x += 1;
             Err::<(), anyhow::Error>(anyhow::anyhow!("not retryable"))
         };
@@ -240,7 +243,7 @@ mod tests {
         assert_eq!("not retryable", result.unwrap_err().to_string());
         // `f` always returns error "not retryable", so it should be executed
         // only once.
-        assert_eq!(*error_times.lock().unwrap(), 1);
+        assert_eq!(*error_times.lock(), 1);
         Ok(())
     }
 
@@ -249,8 +252,8 @@ mod tests {
         let error_times = Mutex::new(0);
 
         let f = || {
-            println!("I have been called!");
-            let mut x = error_times.lock().unwrap();
+            // println!("I have been called!");
+            let mut x = error_times.lock();
             *x += 1;
             Err::<(), anyhow::Error>(anyhow::anyhow!("retryable"))
         };
@@ -266,7 +269,7 @@ mod tests {
         assert_eq!("retryable", result.unwrap_err().to_string());
         // `f` always returns error "retryable", so it should be executed
         // 4 times (retry 3 times).
-        assert_eq!(*error_times.lock().unwrap(), 4);
+        assert_eq!(*error_times.lock(), 4);
         Ok(())
     }
 

backon/src/blocking_retry_with_context.rs

@@ -1,5 +1,5 @@
+use core::time::Duration;
 use std::thread;
-use std::time::Duration;
 
 use crate::backoff::BackoffBuilder;
 use crate::Backoff;
@@ -117,7 +117,7 @@ where
 
     /// Call the retried function.
     ///
-    /// TODO: implement [`std::ops::FnOnce`] after it stable.
+    /// TODO: implement [`FnOnce`] after it stable.
     pub fn call(mut self) -> (Ctx, Result<T, E>) {
         let mut ctx = self.ctx.take().expect("context must be valid");
         loop {
@@ -147,14 +147,13 @@ where
 
 #[cfg(test)]
 mod tests {
-    use std::time::Duration;
-
-    use anyhow::anyhow;
-    use std::sync::Mutex;
-
     use super::*;
     use crate::ExponentialBuilder;
+    use alloc::string::ToString;
+    use anyhow::anyhow;
     use anyhow::Result;
+    use core::time::Duration;
+    use std::sync::Mutex;
 
     struct Test;
 

backon/src/lib.rs

@@ -39,7 +39,7 @@
 //! use anyhow::Result;
 //! use backon::ExponentialBuilder;
 //! use backon::Retryable;
-//! use std::time::Duration;
+//! use core::time::Duration;
 //!
 //! async fn fetch() -> Result<String> {
 //!     Ok("hello, world!".to_string())
@@ -69,7 +69,7 @@
 //! use anyhow::Result;
 //! use backon::BlockingRetryable;
 //! use backon::ExponentialBuilder;
-//! use std::time::Duration;
+//! use core::time::Duration;
 //!
 //! fn fetch() -> Result<String> {
 //!     Ok("hello, world!".to_string())
@@ -94,6 +94,10 @@
 
 #![deny(missing_docs)]
 #![deny(unused_qualifications)]
+#![no_std]
+#[cfg(feature = "std")]
+extern crate alloc;
+extern crate std;
 
 mod backoff;
 pub use backoff::*;
@@ -114,13 +118,15 @@ pub use sleep::Sleeper;
 #[cfg(all(not(target_arch = "wasm32"), feature = "tokio-sleep"))]
 pub use sleep::TokioSleeper;
 
+#[cfg(feature = "std")]
 mod blocking_retry;
-pub use blocking_retry::BlockingRetry;
-pub use blocking_retry::BlockingRetryable;
+#[cfg(feature = "std")]
+pub use blocking_retry::{BlockingRetry, BlockingRetryable};
 
+#[cfg(feature = "std")]
 mod blocking_retry_with_context;
-pub use blocking_retry_with_context::BlockingRetryWithContext;
-pub use blocking_retry_with_context::BlockingRetryableWithContext;
+#[cfg(feature = "std")]
+pub use blocking_retry_with_context::{BlockingRetryWithContext, BlockingRetryableWithContext};
 
 #[cfg(docsrs)]
 pub mod docs;

backon/src/retry.rs

@@ -1,9 +1,9 @@
-use std::future::Future;
-use std::pin::Pin;
-use std::task::ready;
-use std::task::Context;
-use std::task::Poll;
-use std::time::Duration;
+use core::future::Future;
+use core::pin::Pin;
+use core::task::ready;
+use core::task::Context;
+use core::task::Poll;
+use core::time::Duration;
 
 use crate::backoff::BackoffBuilder;
 use crate::Backoff;
@@ -201,7 +201,7 @@ where
     /// # Examples
     ///
     /// ```no_run
-    /// use std::time::Duration;
+    /// use core::time::Duration;
     ///
     /// use anyhow::Result;
     /// use backon::ExponentialBuilder;
@@ -320,7 +320,10 @@ where
 #[cfg(test)]
 #[cfg(any(feature = "tokio-sleep", feature = "gloo-timers-sleep"))]
 mod tests {
-    use std::{future::ready, time::Duration};
+    use alloc::string::ToString;
+    use alloc::vec;
+    use alloc::vec::Vec;
+    use core::{future::ready, time::Duration};
     use tokio::sync::Mutex;
 
     #[cfg(target_arch = "wasm32")]

backon/src/retry_with_context.rs

@@ -1,9 +1,9 @@
-use std::future::Future;
-use std::pin::Pin;
-use std::task::ready;
-use std::task::Context;
-use std::task::Poll;
-use std::time::Duration;
+use core::future::Future;
+use core::pin::Pin;
+use core::task::ready;
+use core::task::Context;
+use core::task::Poll;
+use core::time::Duration;
 
 use crate::backoff::BackoffBuilder;
 use crate::Backoff;
@@ -241,7 +241,7 @@ where
     /// # Examples
     ///
     /// ```no_run
-    /// use std::time::Duration;
+    /// use core::time::Duration;
     ///
     /// use anyhow::Result;
     /// use backon::ExponentialBuilder;
@@ -362,9 +362,9 @@ where
 
 #[cfg(test)]
 mod tests {
-    use std::time::Duration;
-
+    use alloc::string::ToString;
     use anyhow::{anyhow, Result};
+    use core::time::Duration;
     use tokio::sync::Mutex;
 
     #[cfg(target_arch = "wasm32")]

backon/src/sleep.rs

@@ -1,4 +1,4 @@
-use std::{
+use core::{
     future::{Future, Ready},
     time::Duration,
 };