From 64a08262ca5c0be4fca8c68c05d75edcbbfbccd4 Mon Sep 17 00:00:00 2001
From: timedout <git@nexy7574.co.uk>
Date: Fri, 10 Jul 2026 22:59:12 +0100
Subject: [PATCH] perf: Change signature of `build_local_dag` to remove refmap
 hacks

---
 src/api/server/send.rs                              |  6 +-----
 .../event_handler/fetch_and_handle_outliers.rs      |  8 ++------
 src/service/rooms/event_handler/fetch_auth.rs       | 13 +++----------
 src/service/rooms/event_handler/fetch_prev.rs       |  6 ++----
 src/service/rooms/event_handler/mod.rs              |  2 +-
 5 files changed, 9 insertions(+), 26 deletions(-)

diff --git a/src/api/server/send.rs b/src/api/server/send.rs
index dde08a100..1615d513b 100644
--- a/src/api/server/send.rs
+++ b/src/api/server/send.rs
@@ -306,11 +306,7 @@ async fn handle_room(
 	// failure (e.g., cycles). This is best-effort; proper ordering is the sender's
 	// responsibility.
 	let sorted_event_ids = if pdu_map.len() >= 2 {
-		let refmap = pdu_map
-			.iter()
-			.map(|(event_id, obj)| (event_id.clone(), obj))
-			.collect();
-		build_local_dag(&refmap, DagBuilderTree::PrevEvents)
+		build_local_dag(&pdu_map, DagBuilderTree::PrevEvents)
 			.await
 			.unwrap_or_else(|e| {
 				debug_warn!("Failed to build local DAG for room {room_id}: {e}");
diff --git a/src/service/rooms/event_handler/fetch_and_handle_outliers.rs b/src/service/rooms/event_handler/fetch_and_handle_outliers.rs
index 655b24429..c5a7fe1e2 100644
--- a/src/service/rooms/event_handler/fetch_and_handle_outliers.rs
+++ b/src/service/rooms/event_handler/fetch_and_handle_outliers.rs
@@ -42,7 +42,7 @@ pub enum DagBuilderTree {
 /// not account for power levels or other tie breaks.
 #[allow(clippy::implicit_hasher)]
 pub async fn build_local_dag(
-	pdu_map: &HashMap<OwnedEventId, &CanonicalJsonObject>,
+	pdu_map: &HashMap<OwnedEventId, CanonicalJsonObject>,
 	tree: DagBuilderTree,
 ) -> Result<Vec<OwnedEventId>> {
 	debug_assert!(pdu_map.len() >= 2, "needless call to build_local_dag with less than 2 PDUs");
@@ -538,11 +538,7 @@ pub(super) async fn fetch_and_handle_auth_events<Pdu>(
 			}
 		}
 
-		let refmap: HashMap<OwnedEventId, &CanonicalJsonObject> = discovered_events
-			.iter()
-			.map(|(id, data)| (id.clone(), data))
-			.collect();
-		let seeded_ordered = build_local_dag(&refmap, DagBuilderTree::AuthEvents)
+		let seeded_ordered = build_local_dag(&discovered_events, DagBuilderTree::AuthEvents)
 			.await
 			.expect("failed to build local DAG");
 		let mut pdus = HashMap::with_capacity(seeded_ordered.len());
diff --git a/src/service/rooms/event_handler/fetch_auth.rs b/src/service/rooms/event_handler/fetch_auth.rs
index b36fef05d..ea99b4afb 100644
--- a/src/service/rooms/event_handler/fetch_auth.rs
+++ b/src/service/rooms/event_handler/fetch_auth.rs
@@ -2,8 +2,7 @@
 
 use conduwuit::{Err, Event, EventTypeExt, PduEvent, Result, err, warn};
 use ruma::{
-	CanonicalJsonObject, OwnedEventId, ServerName,
-	api::federation::authorization::get_event_authorization,
+	OwnedEventId, ServerName, api::federation::authorization::get_event_authorization,
 	room_version_rules::RoomVersionRules,
 };
 use tokio::join;
@@ -126,17 +125,11 @@ async fn authorise_remote_auth_chain<Pdu>(
 	where
 		Pdu: Event + Send + Sync,
 	{
-		// TODO(nex): build_local_dag's signature needs changing because all callsites
-		// seem to do this refmap hack.
 		let pdu_objects = auth_chain_map
 			.iter()
-			.map(|(event_id, pdu)| (event_id, pdu.to_canonical_object()))
+			.map(|(event_id, pdu)| (event_id.clone(), pdu.to_canonical_object()))
 			.collect::<HashMap<_, _>>();
-		let refmap: HashMap<OwnedEventId, &CanonicalJsonObject> = pdu_objects
-			.iter()
-			.map(|(id, data)| ((*id).to_owned(), data))
-			.collect();
-		let auth_chain_topo = build_local_dag(&refmap, DagBuilderTree::AuthEvents)
+		let auth_chain_topo = build_local_dag(&pdu_objects, DagBuilderTree::AuthEvents)
 			.await?
 			.into_iter()
 			.map(|event_id| (event_id.clone(), auth_chain_map.get(&event_id).unwrap().to_owned()))
diff --git a/src/service/rooms/event_handler/fetch_prev.rs b/src/service/rooms/event_handler/fetch_prev.rs
index 3f7e845f6..387d56031 100644
--- a/src/service/rooms/event_handler/fetch_prev.rs
+++ b/src/service/rooms/event_handler/fetch_prev.rs
@@ -5,7 +5,7 @@
 	utils::{BoolExt, IterStream, stream::BroadbandExt},
 };
 use futures::StreamExt;
-use ruma::{CanonicalJsonObject, MilliSecondsSinceUnixEpoch, OwnedEventId, RoomId, ServerName};
+use ruma::{MilliSecondsSinceUnixEpoch, RoomId, ServerName};
 
 use crate::rooms::event_handler::{build_local_dag, fetch_and_handle_outliers::DagBuilderTree};
 
@@ -87,9 +87,7 @@ pub(super) async fn fetch_prevs(
 		let to_persist = if mapped.len() <= 1 {
 			mapped.keys().map(ToOwned::to_owned).collect()
 		} else {
-			let refmap: HashMap<OwnedEventId, &CanonicalJsonObject> =
-				mapped.iter().map(|(id, data)| (id.clone(), data)).collect();
-			build_local_dag(&refmap, DagBuilderTree::PrevEvents).await?
+			build_local_dag(&mapped, DagBuilderTree::PrevEvents).await?
 		};
 
 		let job_start = Instant::now();
diff --git a/src/service/rooms/event_handler/mod.rs b/src/service/rooms/event_handler/mod.rs
index b21f2fe2e..3788a961b 100644
--- a/src/service/rooms/event_handler/mod.rs
+++ b/src/service/rooms/event_handler/mod.rs
@@ -20,7 +20,7 @@
 	DagBuilderTree, GET_MISSING_EVENTS_MAX_BATCH_SIZE, build_local_dag,
 };
 use ruma::{
-	OwnedEventId, OwnedRoomId, RoomId, events::room::create::RoomCreateEventContent,
+	OwnedEventId, OwnedRoomId, events::room::create::RoomCreateEventContent,
 	room_version_rules::RoomVersionRules,
 };
 use tokio::sync::{Notify, mpsc};