From 63dfe8f7e37a7f70e8f8dbf23f5001701b7218eb Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Sat, 26 Jul 2025 04:59:00 +0000
Subject: [PATCH] Add upper-bound for presence_since().

Signed-off-by: Jason Volk <jason@zemos.net>
---
 src/admin/query/presence.rs   | 7 +++++--
 src/api/client/sync/v3.rs     | 5 +++--
 src/service/presence/data.rs  | 4 +++-
 src/service/presence/mod.rs   | 3 ++-
 src/service/sending/sender.rs | 9 +++++----
 5 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/src/admin/query/presence.rs b/src/admin/query/presence.rs
index d21795d7..b7bf1f79 100644
--- a/src/admin/query/presence.rs
+++ b/src/admin/query/presence.rs
@@ -19,6 +19,9 @@ pub(crate) enum PresenceCommand {
 	PresenceSince {
 		/// UNIX timestamp since (u64)
 		since: u64,
+
+		/// Upper-bound of since
+		to: Option<u64>,
 	},
 }
 
@@ -34,11 +37,11 @@ pub(super) async fn process(subcommand: PresenceCommand, context: &Context<'_>)
 
 			write!(context, "Query completed in {query_time:?}:\n\n```rs\n{results:#?}\n```")
 		},
-		| PresenceCommand::PresenceSince { since } => {
+		| PresenceCommand::PresenceSince { since, to } => {
 			let timer = tokio::time::Instant::now();
 			let results: Vec<(_, _, _)> = services
 				.presence
-				.presence_since(since)
+				.presence_since(since, to)
 				.map(|(user_id, count, bytes)| (user_id.to_owned(), count, bytes.to_vec()))
 				.collect()
 				.await;
diff --git a/src/api/client/sync/v3.rs b/src/api/client/sync/v3.rs
index 706dbb96..2b738f02 100644
--- a/src/api/client/sync/v3.rs
+++ b/src/api/client/sync/v3.rs
@@ -288,7 +288,7 @@ pub(crate) async fn build_sync_events(
 	let presence_updates: OptionFuture<_> = services
 		.config
 		.allow_local_presence
-		.then(|| process_presence_updates(services, since, sender_user))
+		.then(|| process_presence_updates(services, since, next_batch, sender_user))
 		.into();
 
 	let account_data = services
@@ -391,11 +391,12 @@ pub(crate) async fn build_sync_events(
 async fn process_presence_updates(
 	services: &Services,
 	since: u64,
+	next_batch: u64,
 	syncing_user: &UserId,
 ) -> PresenceUpdates {
 	services
 		.presence
-		.presence_since(since)
+		.presence_since(since, Some(next_batch))
 		.filter(|(user_id, ..)| {
 			services
 				.rooms
diff --git a/src/service/presence/data.rs b/src/service/presence/data.rs
index 53dee45c..de6b07cd 100644
--- a/src/service/presence/data.rs
+++ b/src/service/presence/data.rs
@@ -154,13 +154,15 @@ impl Data {
 	pub(super) fn presence_since(
 		&self,
 		since: u64,
+		to: Option<u64>,
 	) -> impl Stream<Item = (&UserId, u64, &[u8])> + Send + '_ {
 		self.presenceid_presence
 			.raw_stream()
 			.ignore_err()
 			.ready_filter_map(move |(key, presence)| {
 				let (count, user_id) = presenceid_parse(key).ok()?;
-				(count > since).then_some((user_id, count, presence))
+				(count > since && to.is_none_or(|to| count <= to))
+					.then_some((user_id, count, presence))
 			})
 	}
 }
diff --git a/src/service/presence/mod.rs b/src/service/presence/mod.rs
index 0b958206..79541b66 100644
--- a/src/service/presence/mod.rs
+++ b/src/service/presence/mod.rs
@@ -239,8 +239,9 @@ impl Service {
 	pub fn presence_since(
 		&self,
 		since: u64,
+		to: Option<u64>,
 	) -> impl Stream<Item = (&UserId, u64, &[u8])> + Send + '_ {
-		self.db.presence_since(since)
+		self.db.presence_since(since, to)
 	}
 
 	#[inline]
diff --git a/src/service/sending/sender.rs b/src/service/sending/sender.rs
index 6672d6e0..162b070e 100644
--- a/src/service/sending/sender.rs
+++ b/src/service/sending/sender.rs
@@ -605,14 +605,15 @@ impl Service {
 		since: (u64, u64),
 		max_edu_count: &AtomicU64,
 	) -> Option<EduBuf> {
-		let presence_since = self.services.presence.presence_since(since.0);
+		let presence_since = self
+			.services
+			.presence
+			.presence_since(since.0, Some(since.1));
 
 		pin_mut!(presence_since);
 		let mut presence_updates = HashMap::<OwnedUserId, PresenceUpdate>::new();
 		while let Some((user_id, count, presence_bytes)) = presence_since.next().await {
-			if count > since.1 {
-				break;
-			}
+			debug_assert!(count <= since.1, "exceeded upper-bound");
 
 			max_edu_count.fetch_max(count, Ordering::Relaxed);
 			if !self.services.globals.user_is_local(user_id) {