Shutdown management for graceful shutdown of tokio applications. Guard creating and usage is lock-free and the crate only locks when:
One example to show it all:
```rust use std::time::Duration; use tokio_graceful::Shutdown;
async fn main() {
// most users can just use Shutdown::default() to initiate
// shutdown upon either Sigterm or CTRL+C (Sigint).
let signal = tokio::time::sleep(std::time::Duration::from_millis(100));
let shutdown = Shutdown::new(signal);
// you can use shutdown to spawn tasks that will
// include a guard to prevent the shutdown from completing
// aslong as these tasks are open
shutdown.spawn_task(async {
tokio::time::sleep(std::time::Duration::from_millis(10)).await;
});
// or spawn a function such that you have access to the guard coupled to the task
shutdown.spawn_task_fn(|guard| async move {
let guard2 = guard.clone();
guard.cancelled().await;
});
// this guard isn't dropped, but as it's a weak guard
// it has no impact on the ref count of the common tokens.
let guard_weak = shutdown.guard_weak();
// this guard needs to be dropped as otherwise the shutdown is prevented;
let guard = shutdown.guard();
drop(guard);
// guards can be downgraded to weak guards, to not have it be counted any longer in the ref count
let weak_guard_2 = shutdown.guard().downgrade();
// guards (weak or not) are cancel safe
tokio::select! {
_ = tokio::time::sleep(std::time::Duration::from_millis(10)) => {},
_ = weak_guard_2.into_cancelled() => {},
}
// you can also wait to shut down without any timeout limit
// `shutdown.shutdown().await;`
shutdown
.shutdown_with_limit(Duration::from_secs(60))
.await
.unwrap();
// once a shutdown is triggered the ::cancelled() fn will immediately return true,
// forever, not just once. Even after shutdown process is completely finished.
guard_weak.cancelled().await;
// weak guards can be upgraded to regular guards to take into account for ref count
let guard = guard_weak.upgrade();
// even this one however will know it was cancelled
guard.cancelled().await;
} ```
While the above example shows pretty much all parts of this crate at once, it might be useful to see examples on how this crate is to be used in an actual production-like setting. That's what these runnable examples are for.
The runnable examples are best run with RUST_LOG=trace environment variable set,
such that you see the verbose logs of tokio-graceful and really see it in action
and get a sense on how it works, or at least its flow.
bash RUST_LOG=trace cargo run --example tokio_tcp
The tokio_tcp example showcases the original use case of why tokio-graceful shutdown was developed,
as it makes managing graceful shutdown from start to finish a lot easier, without immediately grabbing
to big power tools or providing more than is needed.
The example runs a tcp 'echo' server which you can best play with using
telnet: telnet 127.0.0.1 8080. As you are in control of when to exit you can easily let it timeout if you wish.
bash RUST_LOG=trace cargo run --example hyper
In case you wish to use this library as a Hyper user you can do so using pretty much the same approach as the Tokio tcp example.
This example only has one router server function which returns 'hello' (200 OK) after 5s. The delay is there to allow you to see the graceful shutdown in action.
bash cargo run --example waitgroup
An example which showcases how you would use this crate to create a Waitgroup, which allows you to wait for multiple async jobs/tasks without first having to trigger a signal first.
In case you need a waitgroup which does first need to wait for a signal,
you would create a regular Shutdown instance using Shutdown::new to give
your 'trigger' signal (a future).
🎈 Thanks for your help improving the project! We are so happy to have
you! We have a contributing guide to help you get involved in the
tokio-graceful project.
Special shoutout for this library goes to the Tokio ecosystem. Those who developed it as well as the folks hanging on the Tokio discord server. The discussions and Q&A sessions with them were very crucial to the development of this project. Tokio's codebase is also a gem of examples on what is possible and what are good practices.
In this context also an extra shoutout to @tobz who gave me the idea of approaching it from an Atomic perspective instead of immediately going for channel solutions.
This project is dual-licensed under both the MIT license and Apache 2.0 License.
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in tokio-graceful by you, shall be licensed as both MIT and Apache 2.0,
without any additional terms or conditions.
tokio-graceful is completely free, open-source software which needs time to develop and maintain.
Support this project by becoming a sponsor. One time payments are accepted at GitHub as well as at "Buy me a Coffee"
Sponsors help us continue to maintain and improve tokio-graceful, as well as other
Free and Open Source (FOSS) technology. It also helps us to create
educational content such as https://github.com/plabayo/learn-rust-101,
and other open source libraries such as https://github.com/plabayo/tower-async.
Sponsors receive perks and depending on your regular contribution it also allows you to rely on us for support and consulting.
Part of the money we receive from sponsors is used to contribute to other projects
that we depend upon. Plabayo sponsors the following organisations and individuals
building and maintaining open source software that tokio-graceful depends upon:
| | name | projects | | - | - | - | | 💌 | Tokio | (Tokio, Async Runtime) | 💌 | Sean McArthur | (Tokio)
What is the difference with https://tokio.rs/tokio/topics/shutdown?
https://tokio.rs/tokio/topics/shutdown is an excellent tutorial by the Tokio developers. It is meant to teach and inspire you on how to be able to gracefully shutdown your Tokio-driven application and also to give you a rough idea on when to use it.
That said, nothing stops you from applying what you learn in that tutorial directly in your production application. It will work and very well so. However there is a lot of management of components you have to do yourself.
Ok, but what about the other crates on https://crates.io/ that provide graceful shutdown?
They work fine and they are just as easy to use as this crate. However we think that those crates offer more features then you need in a typical use case, are as a consequence more complex on the surface as well as the machinery inside.
How do I trigger the Shutdown from within a task?
You can achieve this by providing your own mechanism that you feed as the "signal"
to Shutdown::new. E.g. you could easily achieve this by using https://docs.rs/tokio/latest/tokio/sync/struct.Notify.html so you can notify from any task where you wish and have your signal be
https://docs.rs/tokio/latest/tokio/sync/struct.Notify.html#method.notified.
This is however not a usecase we have, as most web services (be it servers or proxies) typically wish to run all its connections independent without critical failures. In such environments there is no need for top-down cancellation mechanisms. Therefore we have nothing built in as this allows us to keep the API and source code simpler, and on top of that gives us the freedom to change some internal details in the future without having to continue to support this usecase.
Could you make a video explaining why you made this crate, how to use it and how it works?
Most certainly. You can find the VOD at https://www.youtube.com/watch?v=GAkOJgrE3CQ which is part of our Rust 101 video playlist: https://www.youtube.com/watch?v=EngAlbv2y98&list=PLQgXEsLXFxpVyLddG8FFXfNQEiodTzAjj
Do you want to learn Rust or improve your Rust knowledge?
Check out https://rust-lang.guide/ and see if it can help you in that journey.