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|
use futures::{
Stream, future,
stream::{self, StreamExt as _},
};
use itertools::Itertools as _;
use sqlx::sqlite::SqlitePool;
use super::{Event, Sequence, Sequenced, broadcaster::Broadcaster};
use crate::{
conversation::{self, repo::Provider as _},
db::{self, NotFound as _},
error::failed::{Failed, ResultExt as _},
message::{self, repo::Provider as _},
user::{self, repo::Provider as _},
vapid,
vapid::repo::Provider as _,
};
pub struct Events {
db: SqlitePool,
events: Broadcaster,
}
impl Events {
pub const fn new(db: SqlitePool, events: Broadcaster) -> Self {
Self { db, events }
}
pub async fn subscribe(
&self,
resume_at: Sequence,
) -> Result<impl Stream<Item = Event> + std::fmt::Debug + use<>, Failed> {
// Subscribe before retrieving, to catch messages broadcast while we're
// querying the DB. We'll prune out duplicates later.
let live_messages = self.events.subscribe();
let mut tx = self.db.begin().await.fail(db::failed::BEGIN)?;
let users = tx
.users()
.replay(resume_at)
.await
.fail("Failed to load user events")?;
let user_events = users
.iter()
.map(user::History::events)
.kmerge_by(Sequence::merge)
.filter(Sequence::after(resume_at))
.map(Event::from);
let conversations = tx
.conversations()
.replay(resume_at)
.await
.fail("Failed to load conversation events")?;
let conversation_events = conversations
.iter()
.map(conversation::History::events)
.kmerge_by(Sequence::merge)
.filter(Sequence::after(resume_at))
.map(Event::from);
let messages = tx
.messages()
.replay(resume_at)
.await
.fail("Failed to load message events")?;
let message_events = messages
.iter()
.map(message::History::events)
.kmerge_by(Sequence::merge)
.filter(Sequence::after(resume_at))
.map(Event::from);
let vapid = tx
.vapid()
.current()
.await
.optional()
.fail("Failed to load VAPID key events")?;
let vapid_events = vapid
.iter()
.flat_map(vapid::History::events)
.filter(Sequence::after(resume_at))
.map(Event::from);
let replay_events = user_events
.merge_by(conversation_events, Sequence::merge)
.merge_by(message_events, Sequence::merge)
.merge_by(vapid_events, Sequence::merge)
.collect::<Vec<_>>();
let resume_live_at = replay_events.last().map_or(resume_at, Sequenced::sequence);
let replay = stream::iter(replay_events);
let live_messages = live_messages
// Filtering on the broadcast resume point filters out messages
// before resume_at, and filters out messages duplicated from
// `replay_events`.
.flat_map(stream::iter)
.filter(Self::resume(resume_live_at));
Ok(replay.chain(live_messages))
}
fn resume(resume_at: Sequence) -> impl for<'m> FnMut(&'m Event) -> future::Ready<bool> + use<> {
let filter = Sequence::after(resume_at);
move |event| future::ready(filter(event))
}
}
|
