From 77e52817811c97a5e60c61360782fe8b30239eb7 Mon Sep 17 00:00:00 2001
From: Benjamin Bouvier <benjamin@bouvier.cc>
Date: Wed, 16 Oct 2024 14:18:40 +0200
Subject: [PATCH] chore(timeline): instrument timeline tasks with their focus
 and internal prefix

This would have avoided a few hours of debugging where we thought there
was an issue with multiple timelines spawned at the same time, and then
realized it was expected because of the existence of the pinned timeline
in EX apps.
---
 crates/matrix-sdk-ui/src/timeline/builder.rs  | 19 +++++++++++++++----
 crates/matrix-sdk-ui/src/timeline/mod.rs      | 10 ++++++++++
 .../tests/integration/timeline/echo.rs        |  8 +++++++-
 3 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/crates/matrix-sdk-ui/src/timeline/builder.rs b/crates/matrix-sdk-ui/src/timeline/builder.rs
index 3553c2ecd71..2314a1afd3a 100644
--- a/crates/matrix-sdk-ui/src/timeline/builder.rs
+++ b/crates/matrix-sdk-ui/src/timeline/builder.rs
@@ -163,7 +163,7 @@ impl TimelineBuilder {
         let controller = TimelineController::new(
             room,
             focus.clone(),
-            internal_id_prefix,
+            internal_id_prefix.clone(),
             unable_to_decrypt_hook,
             is_room_encrypted,
         )
@@ -206,8 +206,13 @@ impl TimelineBuilder {
             let room_event_cache = room_event_cache.clone();
             let inner = controller.clone();
 
-            let span =
-                info_span!(parent: Span::none(), "room_update_handler", room_id = ?room.room_id());
+            let span = info_span!(
+                parent: Span::none(),
+                "live_update_handler",
+                room_id = ?room.room_id(),
+                focus = focus.debug_string(),
+                prefix = internal_id_prefix
+            );
             span.follows_from(Span::current());
 
             async move {
@@ -307,7 +312,13 @@ impl TimelineBuilder {
                     timeline.handle_local_echo(echo).await;
                 }
 
-                let span = info_span!(parent: Span::none(), "local_echo_handler", room_id = ?room.room_id());
+                let span = info_span!(
+                    parent: Span::none(),
+                    "local_echo_handler",
+                    room_id = ?room.room_id(),
+                    focus = focus.debug_string(),
+                    prefix = internal_id_prefix
+                );
                 span.follows_from(Span::current());
 
                 // React to future local echoes too.
diff --git a/crates/matrix-sdk-ui/src/timeline/mod.rs b/crates/matrix-sdk-ui/src/timeline/mod.rs
index 0dc57b1e936..76c62e32f25 100644
--- a/crates/matrix-sdk-ui/src/timeline/mod.rs
+++ b/crates/matrix-sdk-ui/src/timeline/mod.rs
@@ -171,6 +171,16 @@ pub enum TimelineFocus {
     PinnedEvents { max_events_to_load: u16, max_concurrent_requests: u16 },
 }
 
+impl TimelineFocus {
+    pub(super) fn debug_string(&self) -> String {
+        match self {
+            TimelineFocus::Live => "live".to_owned(),
+            TimelineFocus::Event { target, .. } => format!("permalink:{target}"),
+            TimelineFocus::PinnedEvents { .. } => "pinned-events".to_owned(),
+        }
+    }
+}
+
 impl Timeline {
     /// Create a new [`TimelineBuilder`] for the given room.
     pub fn builder(room: &Room) -> TimelineBuilder {
diff --git a/crates/matrix-sdk-ui/tests/integration/timeline/echo.rs b/crates/matrix-sdk-ui/tests/integration/timeline/echo.rs
index 03047fa6a45..97366d6e9a6 100644
--- a/crates/matrix-sdk-ui/tests/integration/timeline/echo.rs
+++ b/crates/matrix-sdk-ui/tests/integration/timeline/echo.rs
@@ -60,7 +60,13 @@ async fn test_echo() {
     mock_encryption_state(&server, false).await;
 
     let room = client.get_room(room_id).unwrap();
-    let timeline = Arc::new(room.timeline().await.unwrap());
+    let timeline = Arc::new(
+        room.timeline_builder()
+            .with_internal_id_prefix("le_prefix".to_owned())
+            .build()
+            .await
+            .unwrap(),
+    );
     let (_, mut timeline_stream) = timeline.subscribe().await;
 
     Mock::given(method("PUT"))