Fix room membership race with PREPARED event

[jotto]

See the call site of the original triggering event of this function:

matrix-js-sdk/src/sliding-sync.ts

Lines 789 to 806 in b265d79

	Object.keys(resp.rooms).forEach((roomId) => {
	this.invokeRoomDataListeners(
	roomId,
	resp.rooms[roomId],
	);
	});
	const listIndexesWithUpdates: Set<number> = new Set();
	if (!doNotUpdateList) {
	resp.lists.forEach((list, listIndex) => {
	list.ops = list.ops || [];
	if (list.ops.length > 0) {
	listIndexesWithUpdates.add(listIndex);
	}
	this.processListOps(list, listIndex);
	});
	}
	this.invokeLifecycleListeners(SlidingSyncState.Complete, resp);

I think the bug is current code assumes downstream event listeners of SlidingSyncEvent.RoomData have synchronous execution so that by the time it emits SlidingSyncState.Complete, and eventually SyncState.Prepared the room state is correct. But since SlidingSyncSdk's processRoomData is async, and the membership field was being set after the async, it looks like SlidingSyncState.Complete was being fired before the membership field was set.

Signed-off-by: Jonathan Otto jonathan.otto@gmail.com

---

Here's what your changelog entry will look like:

🐛 Bug Fixes

• Fix room membership race with PREPARED event (#2613). Contributed by @jotto.

[kegsay]

Thanks for this. I thought I did basically what sync.ts did here, but this makes sense to set it prior to invoking listeners. Needs linting fixes and a regression test though ideally.

[t3chguy]

Thanks for this