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use axum::{Form, response::{IntoResponse, Response}, Extension};
use axum::http::StatusCode;
use self::queue::JobQueue;
pub mod queue;
#[derive(Clone, Debug, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
#[cfg_attr(feature = "sqlx", derive(sqlx::FromRow))]
pub struct Webmention {
source: String,
target: String,
}
impl queue::JobItem for Webmention {}
impl queue::PostgresJobItem for Webmention {
const DATABASE_NAME: &'static str = "kittybox.incoming_webmention_queue";
const NOTIFICATION_CHANNEL: &'static str = "incoming_webmention";
}
async fn accept_webmention<Q: JobQueue<Webmention>>(
Extension(queue): Extension<Q>,
Form(webmention): Form<Webmention>,
) -> Response {
if let Err(err) = webmention.source.parse::<url::Url>() {
return (StatusCode::BAD_REQUEST, err.to_string()).into_response()
}
if let Err(err) = webmention.target.parse::<url::Url>() {
return (StatusCode::BAD_REQUEST, err.to_string()).into_response()
}
match queue.put(&webmention).await {
Ok(id) => (StatusCode::ACCEPTED, [
("Location", format!("/.kittybox/webmention/{id}"))
]).into_response(),
Err(err) => (StatusCode::INTERNAL_SERVER_ERROR, [
("Content-Type", "text/plain")
], err.to_string()).into_response()
}
}
pub fn router<Q: JobQueue<Webmention>>(queue: Q, cancellation_token: tokio_util::sync::CancellationToken) -> (axum::Router, SupervisedTask) {
// Automatically spawn a background task to handle webmentions
let bgtask_handle = supervised_webmentions_task(queue.clone(), cancellation_token);
let router = axum::Router::new()
.route("/.kittybox/webmention",
axum::routing::post(accept_webmention::<Q>)
)
.layer(Extension(queue));
(router, bgtask_handle)
}
#[derive(thiserror::Error, Debug)]
pub enum SupervisorError {
#[error("the task was explicitly cancelled")]
Cancelled
}
pub type SupervisedTask = tokio::task::JoinHandle<Result<std::convert::Infallible, SupervisorError>>;
pub fn supervisor<E, A, F>(mut f: F, cancellation_token: tokio_util::sync::CancellationToken) -> SupervisedTask
where
E: std::error::Error + std::fmt::Debug + Send + 'static,
A: std::future::Future<Output = Result<std::convert::Infallible, E>> + Send + 'static,
F: FnMut() -> A + Send + 'static
{
let supervisor_future = async move {
loop {
// Don't spawn the task if we are already cancelled, but
// have somehow missed it (probably because the task
// crashed and we immediately received a cancellation
// request after noticing the crashed task)
if cancellation_token.is_cancelled() {
return Err(SupervisorError::Cancelled)
}
let task = tokio::task::spawn(f());
tokio::select! {
_ = cancellation_token.cancelled() => {
tracing::info!("Shutdown of background task {:?} requested.", std::any::type_name::<A>());
return Err(SupervisorError::Cancelled)
}
task_result = task => match task_result {
Err(e) => tracing::error!("background task {:?} exited unexpectedly: {}", std::any::type_name::<A>(), e),
Ok(Err(e)) => tracing::error!("background task {:?} returned error: {}", std::any::type_name::<A>(), e),
Ok(Ok(_)) => unreachable!("task's Ok is Infallible")
}
}
tracing::debug!("Sleeping for a little while to back-off...");
tokio::time::sleep(std::time::Duration::from_secs(5)).await;
}
};
#[cfg(not(tokio_unstable))]
return tokio::task::spawn(supervisor_future);
#[cfg(tokio_unstable)]
return tokio::task::Builder::new()
.name(format!("supervisor for background task {}", std::any::type_name::<A>()).as_str())
.spawn(supervisor_future)
.unwrap();
}
async fn process_webmentions_from_queue<Q: JobQueue<Webmention>>(queue: Q) -> Result<std::convert::Infallible, Q::Error> {
use futures_util::StreamExt;
use self::queue::Job;
let mut stream = queue.into_stream().await?;
while let Some(item) = stream.next().await.transpose()? {
let job = item.job();
let (source, target) = (
job.source.parse::<url::Url>().unwrap(),
job.target.parse::<url::Url>().unwrap()
);
todo!()
}
unreachable!()
}
fn supervised_webmentions_task<Q: JobQueue<Webmention>>(queue: Q, cancellation_token: tokio_util::sync::CancellationToken) -> SupervisedTask {
supervisor::<Q::Error, _, _>(move || process_webmentions_from_queue(queue.clone()), cancellation_token)
}
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