sdk: add PinnedEventCache to Client.

This ensures the cache keeps the events even when the associated `Room` is dropped, which is what we want when using it to cache the pinned events for rooms in the client.

Add `fn Client::pinned_event_cached()` to get a reference to it.

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

@@ -88,6 +88,7 @@ use crate::{
     http_client::HttpClient,
     matrix_auth::MatrixAuth,
     notification_settings::NotificationSettings,
+    pinned_events_cache::PinnedEventCache,
     room_preview::RoomPreview,
     send_queue::SendQueueData,
     sync::{RoomUpdate, SyncResponse},
@@ -286,6 +287,9 @@ pub(crate) struct ClientInner {
     /// It becomes active when [`EventCache::subscribe`] is called.
     pub(crate) event_cache: OnceCell<EventCache>,
 
+    /// A central cache for pinned events.
+    pub(crate) pinned_event_cache: PinnedEventCache,
+
     /// End-to-end encryption related state.
     #[cfg(feature = "e2e-encryption")]
     pub(crate) e2ee: EncryptionData,
@@ -341,6 +345,7 @@ impl ClientInner {
             respect_login_well_known,
             sync_beat: event_listener::Event::new(),
             event_cache,
+            pinned_event_cache: PinnedEventCache::new(),
             send_queue_data: send_queue,
             #[cfg(feature = "e2e-encryption")]
             e2ee: EncryptionData::new(encryption_settings),
@@ -2229,6 +2234,11 @@ impl Client {
         // SAFETY: always initialized in the `Client` ctor.
         self.inner.event_cache.get().unwrap()
     }
+
+    /// The [`PinnedEventCache`] instance for this [`Client`].
+    pub fn pinned_event_cache(&self) -> &PinnedEventCache {
+        &self.inner.pinned_event_cache
+    }
 }
 
 /// A weak reference to the inner client, useful when trying to get a handle

crates/matrix-sdk/src/lib.rs

@@ -96,5 +96,8 @@ uniffi::setup_scaffolding!();
 #[cfg(any(test, feature = "testing"))]
 pub mod test_utils;
 
+/// Contains the pinned events cache implementation.
+pub mod pinned_events_cache;
+
 #[cfg(test)]
 matrix_sdk_test::init_tracing_for_tests!();