# BackON   [![Build Status]][actions] [![Latest Version]][crates.io] [](https://discord.gg/8ARnvtJePD)
[Build Status]: https://img.shields.io/github/actions/workflow/status/Xuanwo/backon/ci.yml?branch=main
[actions]: https://github.com/Xuanwo/backon/actions?query=branch%3Amain
[Latest Version]: https://img.shields.io/crates/v/backon.svg
[crates.io]: https://crates.io/crates/backon
<img src="./.github/assets/logo.jpeg" alt="BackON" width="38.2%"/>
Make **retry** like a built-in feature provided by Rust.
- **Simple**: Just like a built-in feature: `your_fn.retry(ExponentialBuilder::default()).await`.
- **Flexible**: Supports both blocking and async functions.
- **Powerful**: Allows control over retry behavior such as [`when`](https://docs.rs/backon/latest/backon/struct.Retry.html#method.when) and [`notify`](https://docs.rs/backon/latest/backon/struct.Retry.html#method.notify).
- **Customizable**: Supports custom retry strategies like [exponential](https://docs.rs/backon/latest/backon/struct.ExponentialBuilder.html), [constant](https://docs.rs/backon/latest/backon/struct.ConstantBuilder.html), etc.
- **Adaptable**: Works on all platforms supported by Rust, including both `wasm` and `no-std`.
---
## Quick Start
### Retry an async function.
```rust
use anyhow::Result;
use backon::ExponentialBuilder;
use backon::Retryable;
async fn fetch() -> Result<String> {
Ok("hello, world!".to_string())
}
#[tokio::main]
async fn main() -> Result<()> {
let content = fetch
// Retry with exponential backoff
.retry(ExponentialBuilder::default())
// Sleep implementation, required if no feature has been enabled
.sleep(tokio::time::sleep)
// When to retry
.when(|e| e.to_string() == "EOF")
// Notify when retrying
.notify(|err: &anyhow::Error, dur: Duration| {
println!("retrying {:?} after {:?}", err, dur);
})
.await?;
println!("fetch succeeded: {}", content);
Ok(())
}
```
### Retry a blocking function.
```rust
use anyhow::Result;
use backon::BlockingRetryable;
use backon::ExponentialBuilder;
fn fetch() -> Result<String> {
Ok("hello, world!".to_string())
}
fn main() -> Result<()> {
let content = fetch
// Retry with exponential backoff
.retry(ExponentialBuilder::default())
// Sleep implementation, required if no feature has been enabled
.sleep(std::thread::sleep)
// When to retry
.when(|e| e.to_string() == "EOF")
// Notify when retrying
.notify(|err: &anyhow::Error, dur: Duration| {
println!("retrying {:?} after {:?}", err, dur);
})
.call()?;
println!("fetch succeeded: {}", content);
Ok(())
}
```
## Contributing
Check out the [CONTRIBUTING.md](./CONTRIBUTING.md) guide for more details on getting started with contributing to this
project.
## Getting help
Submit [issues](https://github.com/Xuanwo/backon/issues/new/choose) for bug report or asking questions
in [discussion](https://github.com/Xuanwo/backon/discussions/new?category=q-a).
## License
Licensed under <a href="./LICENSE">Apache License, Version 2.0</a>.