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Commit `cd3986c6d5e2`

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atagen <boss@atagen.co>2026-10-28 02:46 UTC

3 files changed+47-24

indexeddb: save a batch of events in one transaction, and read chunk metadata read-only

`RoomEventCache::save_events` stored each event in its own readwrite transaction on the events store, so a page of 100 thread roots queued every other event cache transaction behind 100 commits, and a soak saw single sync writes take 100 to 700ms and some 5s while the room state lock was held. `EventCacheStore::save_events` now defaults to the per-event loop and IndexedDB overrides it with one transaction. `load_all_chunks` and `load_all_chunks_metadata` only read, so they no longer take readwrite transactions that serialise with every write.

Modified file: crates/matrix-sdk-base/src/event_cache/store/traits.rs+13 additions@@ -176,6 +176,15 @@ pub trait EventCacheStore: AsyncTraitDeps {
     /// without causing an error.
     async fn save_event(&self, room_id: &RoomId, event: Event) -> Result<(), Self::Error>;
 
+    /// Save several events as [`Self::save_event`] does, in as few store
+    /// transactions as the store allows.
+    async fn save_events(&self, room_id: &RoomId, events: Vec<Event>) -> Result<(), Self::Error> {
+        for event in events {
+            self.save_event(room_id, event).await?;
+        }
+        Ok(())
+    }
+
     /// Close the store, releasing all held resources (database connections,
     /// file descriptors, file locks).
     ///
@@ -305,6 +314,10 @@ impl<T: EventCacheStore> EventCacheStore for EraseEventCacheStoreError<T> {
         self.0.save_event(room_id, event).await.map_err(Into::into)
     }
 
+    async fn save_events(&self, room_id: &RoomId, events: Vec<Event>) -> Result<(), Self::Error> {
+        self.0.save_events(room_id, events).await.map_err(Into::into)
+    }
+
     async fn close(&self) -> Result<(), Self::Error> {
         self.0.close().await.map_err(Into::into)
     }

Modified file: crates/matrix-sdk-indexeddb/src/event_cache_store/mod.rs+33 additions−21 deletions@@ -313,7 +313,7 @@ impl EventCacheStore for IndexeddbEventCacheStore {
 
         let transaction = self.transaction(
             &[keys::LINKED_CHUNKS, keys::GAPS, keys::EVENTS],
-            IdbTransactionMode::Readwrite,
+            IdbTransactionMode::Readonly,
         )?;
 
         let mut raw_chunks = Vec::new();
@@ -348,7 +348,7 @@ impl EventCacheStore for IndexeddbEventCacheStore {
 
         let transaction = self.transaction(
             &[keys::LINKED_CHUNKS, keys::EVENTS, keys::GAPS],
-            IdbTransactionMode::Readwrite,
+            IdbTransactionMode::Readonly,
         )?;
 
         let mut raw_chunks = Vec::new();
@@ -611,29 +611,41 @@ impl EventCacheStore for IndexeddbEventCacheStore {
         room_id: &RoomId,
         event: Event,
     ) -> Result<(), IndexeddbEventCacheStoreError> {
+        self.save_events(room_id, vec![event]).await
+    }
+
+    #[instrument(skip(self, events), fields(count = events.len()))]
+    async fn save_events(
+        &self,
+        room_id: &RoomId,
+        events: Vec<Event>,
+    ) -> Result<(), IndexeddbEventCacheStoreError> {
         let _timer = timer!("method");
 
-        let Some(event_id) = event.event_id() else {
-            error!(%room_id, "Trying to save an event with no ID");
-            return Ok(());
-        };
+        // one readwrite transaction per event queued every other event cache transaction behind a
+        // page of them, a hundred commits long
         let transaction = self.transaction(&[keys::EVENTS], IdbTransactionMode::Readwrite)?;
-
-        let mut events = transaction
-            .get_events_by_room(room_id, &event_id)
-            .await?
-            .into_iter()
-            .map(|e| e.with_content(event.clone()))
-            .collect::<Vec<types::Event>>();
-        if events.is_empty() {
-            events.push(types::Event::OutOfBand(OutOfBandEvent {
-                linked_chunk_id: LinkedChunkId::Room(room_id).to_owned(),
-                content: event,
-                position: (),
-            }));
-        }
         for event in events {
-            transaction.put_event(&event).await?;
+            let Some(event_id) = event.event_id() else {
+                error!(%room_id, "Trying to save an event with no ID");
+                continue;
+            };
+            let mut stored = transaction
+                .get_events_by_room(room_id, &event_id)
+                .await?
+                .into_iter()
+                .map(|e| e.with_content(event.clone()))
+                .collect::<Vec<types::Event>>();
+            if stored.is_empty() {
+                stored.push(types::Event::OutOfBand(OutOfBandEvent {
+                    linked_chunk_id: LinkedChunkId::Room(room_id).to_owned(),
+                    content: event,
+                    position: (),
+                }));
+            }
+            for event in stored {
+                transaction.put_event(&event).await?;
+            }
         }
         transaction.commit().await?;
         Ok(())

Modified file: crates/matrix-sdk/src/event_cache/caches/mod.rs+1 additions−3 deletions@@ -65,9 +65,7 @@ pub(super) async fn save_events(
         let room_id = room_id.clone();
         async move {
             debug!(%room_id, count, "saving events to the store");
-            for event in events {
-                store.save_event(&room_id, event).await?;
-            }
+            store.save_events(&room_id, events).await?;
             Result::Ok(())
         }
     });

matrix-rust-sdk

Commit cd3986c6d5e2

Commit `cd3986c6d5e2`