feat(ui): RoomListService re-enables share_pos

[Hywan]

WIP

The idea is the following: if we keep the sliding sync pos, first off, the homeservers will be happier because they don't have to re-compute a session every time, and second, the overall user experience may be better as we receive much less limited responses from the homeservers.

I don't know why it was creating slowness at some moment. My hope it that the problem has resolved by itself because many refactorings happened since then 🤞.

---

• Follow up of fix(ui): Disable share_pos() inside RoomListService #4256
• Address SSS: Persist the pos token so that it gets reused across app restarts #3936

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.15%. Comparing base (95b53d7) to head (8570354).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4741   +/-   ##
=======================================
  Coverage   86.14%   86.15%           
=======================================
  Files         292      292           
  Lines       34295    34295           
=======================================
+ Hits        29544    29547    +3     
+ Misses       4751     4748    -3     

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[bnjbvr]

Might be a bit premature to review without manual testing or some code tests 😇

[ganfra]

Might be a bit premature to review without manual testing or some code tests 😇

Do you want me to test on android first?

[bnjbvr]

Might be a bit premature to review without manual testing or some code tests 😇

Do you want me to test on android first?

Yes please, that would be amazing 🙏

[Hywan]

@ganfra @pixlwave any news ❤️?

[jmartinesp]

I've linked a rageshake with some issues where the initial loading sometimes takes several seconds and what's more troublesome, some rooms never get a display name: on a first attempt it seemed like the issue was solved after a few seconds, then I restarted the app, saw those rooms with no display name again but this time the name never loaded.

[bnjbvr]

thanks for testing! the display name issue might be #4051 which becomes more visible, now that we're not getting multiple syncs at start.

[bnjbvr]

Spotted a very slow response from the server, taking around 8 seconds:

2025-03-24T10:25:11.508204Z DEBUG matrix_sdk::sliding_sync: Sending request | crates/matrix-sdk/src/sliding_sync/mod.rs:547 | spans: sync_once{conn_id="room-list" pos="800706/s24077829_1_2604_32014512_8404560_11162949_18873789_46996665_0_2700"}
2025-03-24T10:25:11.508319Z TRACE matrix_sdk::http_client: Serializing request request_type="ruma_client_api::sync::sync_events::v5::Request" | crates/matrix-sdk/src/http_client/mod.rs:109 | spans: sync_once{conn_id="room-list" pos="800706/s24077829_1_2604_32014512_8404560_11162949_18873789_46996665_0_2700"} > send{server_versions=[V1_1, V1_2, V1_3, V1_4, V1_5, V1_6, V1_7, V1_8, V1_9, V1_10, V1_11] config=RequestConfig { timeout: 60s, retry_limit: 3 } request_id="REQ-2"}
2025-03-24T10:25:11.508431Z DEBUG matrix_sdk::http_client::native: Sending request num_attempt=1 | crates/matrix-sdk/src/http_client/native.rs:55 | spans: sync_once{conn_id="room-list" pos="800706/s24077829_1_2604_32014512_8404560_11162949_18873789_46996665_0_2700"} > send{server_versions=[V1_1, V1_2, V1_3, V1_4, V1_5, V1_6, V1_7, V1_8, V1_9, V1_10, V1_11] config=RequestConfig { timeout: 60s, retry_limit: 3 } request_id="REQ-2" method=POST uri="https://element.ems.host/_matrix/client/unstable/org.matrix.simplified_msc3575/sync" request_size="651 B"}

And much later:

2025-03-24T10:25:19.549911Z DEBUG matrix_sdk::http_client: Got response | crates/matrix-sdk/src/http_client/mod.rs:220 | spans: sync_once{conn_id="room-list" pos="800706/s24077829_1_2604_32014512_8404560_11162949_18873789_46996665_0_2700"} > send{server_versions=[V1_1, V1_2, V1_3, V1_4, V1_5, V1_6, V1_7, V1_8, V1_9, V1_10, V1_11] config=RequestConfig { timeout: 60s, retry_limit: 3 } request_id="REQ-2" method=POST uri="https://element.ems.host/_matrix/client/unstable/org.matrix.simplified_msc3575/sync" request_size="651 B" status=200 response_size="1.1 kiB"}

It takes 28ms to fully process the response (including i/o access for storing the next pos), so the Rust 🦀 SDK is Blazingly 😎 Fast 🚀 .

[pixlwave]

I'm afraid I can reproduce all 3 reasons why we disabled this in the first place:
#4244 (comment)

Logs for the delayed pagination:

2025-03-24T11:21:45.628899Z  INFO elementx: Paginating backwards | TimelineProxy.swift:115 | spans: root
2025-03-24T11:21:48.631601Z DEBUG matrix_sdk::http_client::native: Sending request num_attempt=1 | crates/matrix-sdk/src/http_client/native.rs:55 | spans: root > paginate_backwards{room_id="!qmswaOZGwjTAUbcmtC:sync.boats"} > run_backwards_once{batch_size=20} > messages{room_id="!qmswaOZGwjTAUbcmtC:sync.boats" options=MessagesOptions { dir: Backward, limit: 20 }} > send{server_versions=[V1_1, V1_2, V1_3, V1_4, V1_5, V1_6, V1_7, V1_8, V1_9, V1_10, V1_11] config=RequestConfig { timeout: 30s, retry_limit: 0 } request_id="REQ-51" method=GET uri="https://matrix.sync.boats/_matrix/client/v3/rooms/!qmswaOZGwjTAUbcmtC:sync.boats/messages"}
2025-03-24T11:21:48.746445Z DEBUG matrix_sdk::http_client: Got response | crates/matrix-sdk/src/http_client/mod.rs:220 | spans: root > paginate_backwards{room_id="!qmswaOZGwjTAUbcmtC:sync.boats"} > run_backwards_once{batch_size=20} > messages{room_id="!qmswaOZGwjTAUbcmtC:sync.boats" options=MessagesOptions { dir: Backward, limit: 20 }} > send{server_versions=[V1_1, V1_2, V1_3, V1_4, V1_5, V1_6, V1_7, V1_8, V1_9, V1_10, V1_11] config=RequestConfig { timeout: 30s, retry_limit: 0 } request_id="REQ-51" method=GET uri="https://matrix.sync.boats/_matrix/client/v3/rooms/!qmswaOZGwjTAUbcmtC:sync.boats/messages" status=200 response_size="11.9 kiB"}

[bnjbvr]

Thanks for testing, Doug!