refactor(event cache): get rid of the RoomPaginationData data structure

It only contained two fields, and it avoids one extra level of cognitive
overhead and makes the type hierarchy flatter.

crates/matrix-sdk/src/event_cache/mod.rs

@@ -39,7 +39,7 @@ use matrix_sdk_base::{
     sync::{JoinedRoomUpdate, LeftRoomUpdate, RoomUpdates, Timeline},
 };
 use matrix_sdk_common::executor::{spawn, JoinHandle};
-use paginator::PaginatorState;
+use paginator::{Paginator, PaginatorState};
 use ruma::{
     events::{
         relation::RelationType,
@@ -52,12 +52,11 @@ use ruma::{
 };
 use tokio::sync::{
     broadcast::{error::RecvError, Receiver, Sender},
-    Mutex, RwLock, RwLockReadGuard, RwLockWriteGuard,
+    Mutex, Notify, RwLock, RwLockReadGuard, RwLockWriteGuard,
 };
 use tracing::{error, info_span, instrument, trace, warn, Instrument as _, Span};
 
 use self::{
-    pagination::RoomPaginationData,
     paginator::PaginatorError,
     store::{Gap, RoomEvents},
 };
@@ -634,6 +633,9 @@ struct RoomEventCacheInner {
     /// [`RoomEventCacheInner`] instances.
     all_events: Arc<RwLock<AllEventsCache>>,
 
+    /// A notifier that we received a new pagination token.
+    pub pagination_batch_token_notifier: Notify,
+
     /// A paginator instance, that's configured to run back-pagination on our
     /// behalf.
     ///
@@ -642,7 +644,7 @@ struct RoomEventCacheInner {
     /// events received from those kinds of pagination with the cache. This
     /// paginator is only used for queries that interact with the actual event
     /// cache.
-    pagination: RoomPaginationData<WeakRoom>,
+    pub paginator: Paginator<WeakRoom>,
 }
 
 impl RoomEventCacheInner {
@@ -665,7 +667,8 @@ impl RoomEventCacheInner {
             }),
             all_events: all_events_cache,
             sender,
-            pagination: RoomPaginationData::new(weak_room),
+            pagination_batch_token_notifier: Default::default(),
+            paginator: Paginator::new(weak_room),
         }
     }
 
@@ -788,7 +791,7 @@ impl RoomEventCacheInner {
         .await?;
 
         // Reset the paginator status to initial.
-        self.pagination.paginator.set_idle_state(PaginatorState::Initial, prev_batch, None)?;
+        self.paginator.set_idle_state(PaginatorState::Initial, prev_batch, None)?;
 
         Ok(())
     }
@@ -923,7 +926,7 @@ impl RoomEventCacheInner {
         // Now that all events have been added, we can trigger the
         // `pagination_token_notifier`.
         if prev_batch.is_some() {
-            self.pagination.token_notifier.notify_one();
+            self.pagination_batch_token_notifier.notify_one();
         }
 
         // The order of `RoomEventCacheUpdate`s is **really** important here.

crates/matrix-sdk/src/event_cache/pagination.rs

@@ -18,31 +18,16 @@ use std::{future::Future, ops::ControlFlow, sync::Arc, time::Duration};
 
 use eyeball::Subscriber;
 use matrix_sdk_base::deserialized_responses::SyncTimelineEvent;
-use tokio::{sync::Notify, time::timeout};
+use tokio::time::timeout;
 use tracing::{debug, instrument, trace};
 
 use super::{
-    paginator::{PaginableRoom, PaginationResult, Paginator, PaginatorState},
+    paginator::{PaginationResult, PaginatorState},
     store::Gap,
     BackPaginationOutcome, Result, RoomEventCacheInner,
 };
 use crate::event_cache::{linked_chunk::ChunkContent, store::RoomEvents};
 
-#[derive(Debug)]
-pub(super) struct RoomPaginationData<PR: PaginableRoom> {
-    /// A notifier that we received a new pagination token.
-    pub token_notifier: Notify,
-
-    /// The stateful paginator instance used for the integrated pagination.
-    pub paginator: Paginator<PR>,
-}
-
-impl<PR: PaginableRoom> RoomPaginationData<PR> {
-    pub(super) fn new(room: PR) -> Self {
-        Self { token_notifier: Default::default(), paginator: Paginator::new(room) }
-    }
-}
-
 /// An API object to run pagination queries on a [`super::RoomEventCache`].
 ///
 /// Can be created with [`super::RoomEventCache::pagination()`].
@@ -135,7 +120,7 @@ impl RoomPagination {
 
         let prev_token = self.get_or_wait_for_token(Some(DEFAULT_WAIT_FOR_TOKEN_DURATION)).await;
 
-        let paginator = &self.inner.pagination.paginator;
+        let paginator = &self.inner.paginator;
 
         paginator.set_idle_state(PaginatorState::Idle, prev_token.clone(), None)?;
 
@@ -282,7 +267,7 @@ impl RoomPagination {
         // Otherwise, wait for a notification that we received a previous-batch token.
         // Note the state lock is released while doing so, allowing other tasks to write
         // into the linked chunk.
-        let _ = timeout(wait_time, self.inner.pagination.token_notifier.notified()).await;
+        let _ = timeout(wait_time, self.inner.pagination_batch_token_notifier.notified()).await;
 
         let mut state = self.inner.state.write().await;
         let token = get_oldest(&state.events);
@@ -293,7 +278,7 @@ impl RoomPagination {
     /// Returns a subscriber to the pagination status used for the
     /// back-pagination integrated to the event cache.
     pub fn status(&self) -> Subscriber<PaginatorState> {
-        self.inner.pagination.paginator.state()
+        self.inner.paginator.state()
     }
 
     /// Returns whether we've hit the start of the timeline.
@@ -301,7 +286,7 @@ impl RoomPagination {
     /// This is true if, and only if, we didn't have a previous-batch token and
     /// running backwards pagination would be useless.
     pub fn hit_timeline_start(&self) -> bool {
-        self.inner.pagination.paginator.hit_timeline_start()
+        self.inner.paginator.hit_timeline_start()
     }
 
     /// Returns whether we've hit the end of the timeline.
@@ -309,7 +294,7 @@ impl RoomPagination {
     /// This is true if, and only if, we didn't have a next-batch token and
     /// running forwards pagination would be useless.
     pub fn hit_timeline_end(&self) -> bool {
-        self.inner.pagination.paginator.hit_timeline_end()
+        self.inner.paginator.hit_timeline_end()
     }
 }