From 39c84fabb446fc701f62f7299cfbdccb979e08e0 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Thu, 6 Nov 2025 06:25:17 +0000
Subject: [PATCH] Optimize filter fetch in syncv3 prologue.

Signed-off-by: Jason Volk <jason@zemos.net>
---
 src/api/client/sync/v3.rs | 65 ++++++++++++++++++++++++---------------
 1 file changed, 40 insertions(+), 25 deletions(-)

diff --git a/src/api/client/sync/v3.rs b/src/api/client/sync/v3.rs
index a1b700c8..c09d9740 100644
--- a/src/api/client/sync/v3.rs
+++ b/src/api/client/sync/v3.rs
@@ -128,16 +128,33 @@ pub(crate) async fn sync_events_route(
 ) -> Result<sync_events::v3::Response> {
 	let (sender_user, sender_device) = body.sender();
 
+	let filter: OptionFuture<_> = body
+		.body
+		.filter
+		.as_ref()
+		.map(async |filter| match filter {
+			| Filter::FilterDefinition(filter) => filter.clone(),
+			| Filter::FilterId(filter_id) => services
+				.users
+				.get_filter(sender_user, filter_id)
+				.await
+				.unwrap_or_default(),
+		})
+		.into();
+
+	let filter = filter.map(Option::unwrap_or_default);
+	let full_state = body.body.full_state;
+	let set_presence = &body.body.set_presence;
 	let ping_presence = services
 		.presence
-		.maybe_ping_presence(sender_user, Some(sender_device), &body.body.set_presence)
+		.maybe_ping_presence(sender_user, body.sender_device.as_deref(), set_presence)
 		.inspect_err(inspect_log)
 		.ok();
 
 	// Record user as actively syncing for push suppression heuristic.
 	let note_sync = services.presence.note_sync(sender_user);
 
-	join(ping_presence, note_sync).await;
+	let (filter, ..) = join3(filter, ping_presence, note_sync).await;
 
 	let mut since = body
 		.body
@@ -175,22 +192,31 @@ pub(crate) async fn sync_events_route(
 		let next_batch = services.globals.wait_pending().await?;
 		debug_assert!(since <= next_batch, "next_batch is monotonic");
 
-		if since < next_batch || body.body.full_state {
-			let response = build_sync_events(&services, &body, since, next_batch).await?;
+		if since < next_batch || full_state {
+			let response = build_sync_events(
+				&services,
+				body.sender(),
+				since,
+				next_batch,
+				full_state,
+				&filter,
+			)
+			.await?;
+
 			let empty = response.rooms.is_empty()
 				&& response.presence.is_empty()
 				&& response.account_data.is_empty()
 				&& response.device_lists.is_empty()
 				&& response.to_device.is_empty();
 
-			if !empty || body.body.full_state {
+			if !empty || full_state {
 				return Ok(response);
 			}
 		}
 
 		// Wait for activity
 		if time::timeout_at(stop_at, watchers).await.is_err() || services.server.is_stopping() {
-			let response = build_empty_response(&services, &body, next_batch).await;
+			let response = build_empty_response(&services, body.sender(), next_batch).await;
 			trace!(since, next_batch, "empty response");
 			return Ok(response);
 		}
@@ -209,13 +235,13 @@ pub(crate) async fn sync_events_route(
 
 async fn build_empty_response(
 	services: &Services,
-	body: &Ruma<sync_events::v3::Request>,
+	(sender_user, sender_device): (&UserId, &DeviceId),
 	next_batch: u64,
 ) -> sync_events::v3::Response {
 	sync_events::v3::Response {
 		device_one_time_keys_count: services
 			.users
-			.count_one_time_keys(body.sender_user(), body.sender_device())
+			.count_one_time_keys(sender_user, sender_device)
 			.await,
 
 		..sync_events::v3::Response::new(to_small_string(next_batch))
@@ -235,23 +261,12 @@ async fn build_empty_response(
 )]
 async fn build_sync_events(
 	services: &Services,
-	body: &Ruma<sync_events::v3::Request>,
+	(sender_user, sender_device): (&UserId, &DeviceId),
 	since: u64,
 	next_batch: u64,
+	full_state: bool,
+	filter: &FilterDefinition,
 ) -> Result<sync_events::v3::Response> {
-	let (sender_user, sender_device) = body.sender();
-
-	let full_state = body.body.full_state;
-	let filter = match body.body.filter.as_ref() {
-		| None => FilterDefinition::default(),
-		| Some(Filter::FilterDefinition(filter)) => filter.clone(),
-		| Some(Filter::FilterId(filter_id)) => services
-			.users
-			.get_filter(sender_user, filter_id)
-			.await
-			.unwrap_or_default(),
-	};
-
 	let joined_rooms = services
 		.state_cache
 		.rooms_joined(sender_user)
@@ -266,7 +281,7 @@ async fn build_sync_events(
 				since,
 				next_batch,
 				full_state,
-				&filter,
+				filter,
 			)
 			.map_ok(move |(joined_room, dlu, jeu)| (room_id, joined_room, dlu, jeu))
 			.ok()
@@ -297,7 +312,7 @@ async fn build_sync_events(
 				sender_user,
 				next_batch,
 				full_state,
-				&filter,
+				filter,
 			)
 			.map_ok(move |left_room| (room_id, left_room))
 			.ok()
@@ -356,7 +371,7 @@ async fn build_sync_events(
 	let presence_updates: OptionFuture<_> = services
 		.config
 		.allow_local_presence
-		.then(|| process_presence_updates(services, since, next_batch, sender_user, &filter))
+		.then(|| process_presence_updates(services, since, next_batch, sender_user, filter))
 		.into();
 
 	let account_data = services