feat: compute and cache `RoomInfo::active_service_members` by jmartinesp · Pull Request #6537 · matrix-org/matrix-rust-sdk

jmartinesp · 2026-05-05T10:17:21Z

Changes

Add a new RoomSummary::active_room_members field that will be used as a cache.
Rename Room::active_service_members to Room::update_active_service_members, which will compute new values for the cache.
Also reset this cached value when the member counts change in sync responses.
Rename async fn Room::is_dm to Room::compute_is_dm and also trigger Room::update_active_service_members to re-calculate the cache.
Add a new synchronous Room::is_dm function that will use the cached active_service_members value or calculate an approximate value as a fallback.
Then expose this Room::compute_is_dm and Room::is_dm in RoomInfo, NotificationRoomInfo and SpaceRoom.

Motivation

For both the room list filtering and the SpaceRoom instances we can't rely on an accurate value computed in place, since those APIs are synchronous. The approximate value previously calculated could be wrong in several cases, so if we can compute a better one instead that should make the checks more accurate.

I've documented the public API Changes in the appropriate CHANGELOG.md files.
This PR was made with the help of AI.

Signed-off-by:

codecov · 2026-05-05T10:28:33Z

Codecov Report

❌ Patch coverage is 88.94737% with 21 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.92%. Comparing base (99cfce8) to head (26c8b59).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
crates/matrix-sdk-base/src/room/mod.rs	66.66%	5 Missing and 3 partials ⚠️
crates/matrix-sdk-base/src/room/room_info.rs	96.62%	3 Missing ⚠️
crates/matrix-sdk/src/room/mod.rs	84.21%	0 Missing and 3 partials ⚠️
crates/matrix-sdk-ui/src/notification_client.rs	0.00%	0 Missing and 2 partials ⚠️
crates/matrix-sdk-ui/src/spaces/room.rs	33.33%	0 Missing and 2 partials ⚠️
crates/matrix-sdk/src/message_search.rs	0.00%	0 Missing and 2 partials ⚠️
...x-sdk-ui/src/room_list_service/filters/category.rs	98.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6537      +/-   ##
==========================================
- Coverage   89.93%   89.92%   -0.01%     
==========================================
  Files         381      381              
  Lines      106780   106867      +87     
  Branches   106780   106867      +87     
==========================================
+ Hits        96036    96105      +69     
- Misses       7096     7105       +9     
- Partials     3648     3657       +9

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codspeed-hq · 2026-05-05T10:41:46Z

Merging this PR will not alter performance

✅ 50 untouched benchmarks

_{Comparing feat/cache-active-service-member-count-in-room-info (26c8b59) with main (99cfce8)}

This will be used as a cache for the computed value.

jmartinesp · 2026-05-06T17:17:31Z

I rebased the PR to solve the conflicts, since I think you still hadn't started reviewing it. The changes should be minimal anyway, just using the new Room::update_and_save_room_info methods instead of manually cloning and setting the new room info.

poljar

Some commits seem like they won't compile, please fix this.

I left some other minor nits, but generally this looks fine.

Don't forget some changelog entries.

poljar · 2026-05-07T08:44:58Z

+    pub async fn update_active_service_members(&self) -> StoreResult<Option<Vec<RoomMember>>> {
        if let Some(service_members) = self.service_members() {


We need to document this new behavior in the docs of this method.

poljar · 2026-05-07T09:19:22Z

            }

+            trace!(
+                "Updating active service members ({}) in room {:?}",


Using Debug for the room ID instead of Display might not yield the result you'd want, i.e.:

println!("{room_id}, {room_id:?}");

Will yield:

!a:b.c, "!a:b.c"

poljar · 2026-05-07T09:27:24Z

+        // Re-calculate active service members
+        self.update_active_service_members().await?;
+


Why is this done here as well? We didn't receive a remote echo from the /sync nor did we sync the members yet.

This will contain the incorrect value and it will be recomputed when we sync the members.

poljar · 2026-05-07T09:29:10Z

+            if new_active_service_member_count != current_active_service_member_count {
+                self.update_and_save_room_info(|mut info| {
+                    info.update_active_service_member_count(Some(new_active_service_member_count));
+                    (info, RoomInfoNotableUpdateReasons::ACTIVE_SERVICE_MEMBERS)


This new notable update reason isn't available yet in commit 05e8811, as such the commit won't compile.

It's available in the next, the 61f1e57, commit.

Agh, wrong rebase of a fixup. Thanks.

poljar · 2026-05-07T09:37:03Z

+/// Checks if the room belongs in the expected category based on whether it's a
+/// DM or not.
+fn matches(room: &RoomListItem, expected_kind: RoomCategory) -> bool {
+    let kind = if room.is_dm() { RoomCategory::People } else { RoomCategory::Group };


Neat refactor.

…active_service_members` The function will now store the computed value if it changed into the `RoomSummary` cache

…ing the room members of the room or when inviting someone

…the joined/invited user count or the heroes in a room change

This function will now also compute and store the active service members under the hood

This function will check the cached value and use it if available, falling back to using an approximate value that will be calculated synchronously if not.

…ring to have more accurate results

…::is_dm` Based on `Room::compute_is_dm`

Based on the cached and synchronous `Room::is_dm`

…when you receive a member hints event that doesn't match what you previously had

…ange

jmartinesp force-pushed the feat/cache-active-service-member-count-in-room-info branch from 45f313e to 88a8cc5 Compare May 5, 2026 10:17

jmartinesp force-pushed the feat/cache-active-service-member-count-in-room-info branch 2 times, most recently from 51c245a to 1a6b534 Compare May 5, 2026 11:53

jmartinesp changed the title ~~WIP: compute and cache RoomInfo::active_service_members~~ feat: compute and cache RoomInfo::active_service_members May 5, 2026

jmartinesp marked this pull request as ready for review May 5, 2026 12:01

jmartinesp requested a review from a team as a code owner May 5, 2026 12:01

jmartinesp requested review from poljar and removed request for a team May 5, 2026 12:01

feat(sdk-base): Add RoomInfo::summary::active_service_members

e6ba744

This will be used as a cache for the computed value.

jmartinesp force-pushed the feat/cache-active-service-member-count-in-room-info branch from 20a48b4 to 53e84fa Compare May 6, 2026 17:16

poljar approved these changes May 7, 2026

View reviewed changes

jmartinesp added 16 commits May 7, 2026 11:56

refactor(sdk-base): Rename Room::active_service_members to `update_…

22b7c6e

…active_service_members` The function will now store the computed value if it changed into the `RoomSummary` cache

refactor(sdk): Update RoomSummary::active_service_members when sync…

1dce1d4

…ing the room members of the room or when inviting someone

refactor(sdk-base): Reset RoomSummary::active_service_members when …

67387b2

…the joined/invited user count or the heroes in a room change

refactor: Rename the async fn Room::is_dm to Room::compute_is_dm

3f3b74f

This function will now also compute and store the active service members under the hood

refactor: Add a new synchronous Room::is_dm fn

7f06915

This function will check the cached value and use it if available, falling back to using an approximate value that will be calculated synchronously if not.

refactor(sdk-ui): Use the new Room::is_dm fn in the room list filte…

8aa752b

…ring to have more accurate results

feat(sdk-ui): Add NotificationItem::is_dm and `NotificationRoomInfo…

8da6cb0

…::is_dm` Based on `Room::compute_is_dm`

feat(sdk-ui): Add SpaceRoom::is_dm

a6aa676

Based on the cached and synchronous `Room::is_dm`

feat(ffi): Expose the new fields and functions in the FFI layer

a9d36e1

test(sdk): Add new tests for Room::active_service_members_count

1a9dd95

feat(sdk-base): Also reset the RoomSummary::active_service_members …

113737f

…when you receive a member hints event that doesn't match what you previously had

tests: Add test for resetting the computed value when member hints ch…

c5fcfc5

…ange

doc: Fix docs of Room::update_active_service_members

9f06dcf

refactor: Remove debug formatting in log

f7a85bf

fix: No need to recompute service members in Room::invite_user_by_id

a905408

doc: Add changelog entries

26c8b59

jmartinesp force-pushed the feat/cache-active-service-member-count-in-room-info branch from 53e84fa to 26c8b59 Compare May 7, 2026 10:08

jmartinesp enabled auto-merge (rebase) May 7, 2026 10:08

jmartinesp merged commit 777ce05 into main May 7, 2026
53 checks passed

jmartinesp deleted the feat/cache-active-service-member-count-in-room-info branch May 7, 2026 10:23

jmartinesp mentioned this pull request May 7, 2026

[Story] A DM has exactly 2 human users element-hq/element-meta#3160

Open

1 task

		pub async fn update_active_service_members(&self) -> StoreResult<Option<Vec<RoomMember>>> {
		if let Some(service_members) = self.service_members() {

		// Re-calculate active service members
		self.update_active_service_members().await?;

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jmartinesp commented May 5, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Changes

Motivation

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Merging this PR will not alter performance

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jmartinesp commented May 6, 2026

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jmartinesp commented May 5, 2026 •

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