lemmy/crates/api_common/src/send_activity.rs

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use crate::context::LemmyContext;
use activitypub_federation::config::Data;
use futures::future::BoxFuture;
use lemmy_db_schema::source::post::Post;
use lemmy_utils::{error::LemmyResult, SYNCHRONOUS_FEDERATION};
use once_cell::sync::{Lazy, OnceCell};
use tokio::{
sync::{
mpsc,
mpsc::{UnboundedReceiver, UnboundedSender, WeakUnboundedSender},
Mutex,
},
task::JoinHandle,
};
type MatchOutgoingActivitiesBoxed =
Box<for<'a> fn(SendActivityData, &'a Data<LemmyContext>) -> BoxFuture<'a, LemmyResult<()>>>;
/// This static is necessary so that activities can be sent out synchronously for tests.
pub static MATCH_OUTGOING_ACTIVITIES: OnceCell<MatchOutgoingActivitiesBoxed> = OnceCell::new();
#[derive(Debug)]
pub enum SendActivityData {
CreatePost(Post),
}
// TODO: instead of static, move this into LemmyContext. make sure that stopping the process with
// ctrl+c still works.
static ACTIVITY_CHANNEL: Lazy<ActivityChannel> = Lazy::new(|| {
let (sender, receiver) = mpsc::unbounded_channel();
let weak_sender = sender.downgrade();
ActivityChannel {
weak_sender,
receiver: Mutex::new(receiver),
keepalive_sender: Mutex::new(Some(sender)),
}
});
pub struct ActivityChannel {
weak_sender: WeakUnboundedSender<SendActivityData>,
receiver: Mutex<UnboundedReceiver<SendActivityData>>,
keepalive_sender: Mutex<Option<UnboundedSender<SendActivityData>>>,
}
impl ActivityChannel {
pub async fn retrieve_activity() -> Option<SendActivityData> {
let mut lock = ACTIVITY_CHANNEL.receiver.lock().await;
lock.recv().await
}
pub async fn submit_activity(
data: SendActivityData,
context: &Data<LemmyContext>,
) -> LemmyResult<()> {
if *SYNCHRONOUS_FEDERATION {
MATCH_OUTGOING_ACTIVITIES
.get()
.expect("retrieve function pointer")(data, context)
.await?;
}
// could do `ACTIVITY_CHANNEL.keepalive_sender.lock()` instead and get rid of weak_sender,
// not sure which way is more efficient
else if let Some(sender) = ACTIVITY_CHANNEL.weak_sender.upgrade() {
sender.send(data)?;
}
Ok(())
}
pub async fn close(outgoing_activities_task: JoinHandle<LemmyResult<()>>) -> LemmyResult<()> {
ACTIVITY_CHANNEL.keepalive_sender.lock().await.take();
outgoing_activities_task.await??;
Ok(())
}
}