Skip already-accepted events from inclusion in recursive evals.

Signed-off-by: Jason Volk <jason@zemos.net>

src/service/rooms/event_handler/fetch_prev.rs

@@ -8,6 +8,7 @@ use ruma::{
 use tuwunel_core::{
 	Result, debug_warn, err, implement,
 	matrix::{Event, PduEvent},
+	utils::stream::IterStream,
 };
 
 use super::check_room_id;
@@ -32,14 +33,27 @@ where
 	Events: Iterator<Item = &'a EventId> + Send,
 {
 	let mut todo_outlier_stack: FuturesOrdered<_> = initial_set
+		.stream()
 		.map(ToOwned::to_owned)
+		.filter_map(async |event_id| {
+			self.services
+				.timeline
+				.non_outlier_pdu_exists(&event_id)
+				.await
+				.is_err()
+				.then_some(event_id)
+		})
 		.map(async |event_id| {
-			let fetch = self.fetch_auth(origin, room_id, once(event_id.as_ref()), room_version);
+			let events = once(event_id.as_ref());
+			let auth = self
+				.fetch_auth(origin, room_id, events, room_version)
+				.await;
 
-			(event_id.clone(), fetch.await)
+			(event_id, auth)
 		})
 		.map(FutureExt::boxed)
-		.collect();
+		.collect()
+		.await;
 
 	let mut amount = 0;
 	let mut eventid_info = HashMap::new();
@@ -78,21 +92,20 @@ where
 		if pdu.origin_server_ts() > first_ts_in_room {
 			amount = amount.saturating_add(1);
 			for prev_prev in pdu.prev_events() {
-				if !graph.contains_key(prev_prev) {
-					let prev_prev = prev_prev.to_owned();
-					let fetch = async move {
-						let fetch = self.fetch_auth(
-							origin,
-							room_id,
-							once(prev_prev.as_ref()),
-							room_version,
-						);
-
-						(prev_prev.clone(), fetch.await)
-					};
-
-					todo_outlier_stack.push_back(fetch.boxed());
+				if graph.contains_key(prev_prev) {
+					continue;
 				}
+
+				let prev_prev = prev_prev.to_owned();
+				let fetch = async move {
+					let fetch = self
+						.fetch_auth(origin, room_id, once(prev_prev.as_ref()), room_version)
+						.await;
+
+					(prev_prev, fetch)
+				};
+
+				todo_outlier_stack.push_back(fetch.boxed());
 			}
 
 			graph.insert(