event cache: add support for running back-pagination #3195
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bnjbvr
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Codecov ReportAttention: Patch coverage is
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## main #3195 +/- ##
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+ Coverage 83.72% 83.75% +0.03%
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Files 234 234
Lines 24085 24174 +89
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+ Hits 20165 20248 +83
- Misses 3920 3926 +6 ☔ View full report in Codecov by Sentry. |
| /// | ||
| /// Optionally, wait at most for the given duration for a back-pagination | ||
| /// token to be returned by a sync. | ||
| pub async fn earliest_backpagination_token( |
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Naming proposal: most_recent_backpagination_token?
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It's not the most recent, it's actually the "oldest" 🥲 aka the closest to the start of the timeline. Should I rename it to oldest_backpagination_token, or even furthest_backpagination_token?
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Oh, then oldest_backpagination_token makes more sense to me!
| @@ -388,16 +450,29 @@ struct RoomEventCacheInner { | |||
| /// See comment there. | |||
| store: Arc<Mutex<Arc<dyn EventCacheStore>>>, | |||
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| /// A notifier that we received a new pagination token. | |||
| pagination_token_notifier: Notify, | |||
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I wonder if we should not have a type to hold pagination data instead of 2 fields in this type.
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I think it's a bit premature at this point, but I'll keep this in mind 👍
| pub struct PaginationToken(pub String); | ||
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| #[derive(Clone)] | ||
| pub enum TimelineEntry { |
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This type is going to be removed once #3166 is merged: we will need to reconciliate those.
(We can sleep when we're dead.) Also, we can tweak the assertion so it's always valid, depending on the racy behavior. Bleh, but it's better than using sleep.
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This adds support for back-pagination into the event cache, supporting enough features for integrating with the timeline (which is going to happen in a separate PR).
The idea is to provide two new primitives:
The timeline code can then use those two primitives in a loop to replicate the current behavior it has (next PR to be open Soon™).
The representation of events in the store is changed, so that a timeline can have entries, which are one of two things:
This allows us to avoid a lot of complexity from the back-pagination code in the timeline, where we'd attach the backpagination token to an event that only had an event_id. We don't have to do this here, and I suppose we could even attach the backpagination token to the next event itself.
This doesn't do reconciliation yet; the plan is to add it as a next step.