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use std::convert::Infallible;
use futures::Future;
use rocket::{
fairing::{self, Fairing, Info, Kind},
http::Status,
request::{FromRequest, Outcome},
tokio::{
self,
sync::broadcast::{channel, Sender},
task::JoinHandle,
},
Request, Response, Sentinel,
};
// does the same as try_outcome!(...).map_forward(|_| data),
// but without moving data in non-failure cases.
macro_rules! try_outcome_data {
($data:expr, $e:expr) => {
match $e {
::rocket::outcome::Outcome::Success(val) => val,
::rocket::outcome::Outcome::Failure(e) => {
return ::rocket::outcome::Outcome::Failure(::std::convert::From::from(e))
},
::rocket::outcome::Outcome::Forward(()) => {
return ::rocket::outcome::Outcome::Forward($data)
},
}
};
}
pub fn spawn_logged<F>(context: &'static str, future: F) -> JoinHandle<()>
where
F: Future<Output = anyhow::Result<()>> + Send + 'static,
{
tokio::spawn(async move {
if let Err(e) = future.await {
warn!("{context}: {e:?}");
}
})
}
pub struct DeferredActions;
struct HasDeferredActions;
pub struct DeferAction(Sender<()>);
#[async_trait]
impl Fairing for DeferredActions {
fn info(&self) -> Info {
Info { name: "deferred actions", kind: Kind::Ignite | Kind::Response }
}
async fn on_ignite(&self, rocket: rocket::Rocket<rocket::Build>) -> fairing::Result {
Ok(rocket.manage(HasDeferredActions))
}
async fn on_response<'r>(&self, req: &'r Request<'_>, res: &mut Response<'r>) {
if res.status() == Status::Ok {
if let Some(DeferAction(tx)) = req.local_cache(|| None) {
// could have no receivers, that's not an error here
tx.send(()).ok();
}
}
}
}
impl<'r> Sentinel for &'r DeferAction {
fn abort(rocket: &rocket::Rocket<rocket::Ignite>) -> bool {
rocket.state::<HasDeferredActions>().is_none()
}
}
#[async_trait]
impl<'r> FromRequest<'r> for &'r DeferAction {
type Error = Infallible;
async fn from_request(req: &'r Request<'_>) -> Outcome<Self, Self::Error> {
Outcome::Success(
req.local_cache(|| {
let (tx, _) = channel(1);
Some(DeferAction(tx))
})
.as_ref()
.unwrap(),
)
}
}
impl DeferAction {
pub fn spawn_after_success<F>(&self, context: &'static str, future: F)
where
F: Future<Output = anyhow::Result<()>> + Send + 'static,
{
let mut r = self.0.subscribe();
spawn_logged(context, async move {
match r.recv().await {
Ok(_) => {
// the request finished with success, now wait for it to be dropped
// to ensure that all other fairings have run to completion.
r.recv().await.ok();
future.await
},
Err(_) => Ok(()),
}
});
}
}
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