feat(base): Create EventCacheStoreLock.

Author: Hywan

crates/matrix-sdk-base/src/event_cache_store/mod.rs

@@ -19,15 +19,15 @@
 //! into the event cache for the actual storage. By default this brings an
 //! in-memory store.
 
-use std::{str::Utf8Error, sync::Arc};
+use std::{fmt, str::Utf8Error, sync::Arc};
 
 #[cfg(any(test, feature = "testing"))]
 #[macro_use]
 pub mod integration_tests;
 mod memory_store;
 mod traits;
 
-use matrix_sdk_common::store_locks::BackingStore;
+use matrix_sdk_common::store_locks::{BackingStore, CrossProcessStoreLock};
 pub use matrix_sdk_store_encryption::Error as StoreEncryptionError;
 
 #[cfg(any(test, feature = "testing"))]
@@ -85,10 +85,8 @@ impl EventCacheStoreError {
 /// An `EventCacheStore` specific result type.
 pub type Result<T, E = EventCacheStoreError> = std::result::Result<T, E>;
 
-/// The public API to read the event cache store: it is behind a cross-process
-/// lock.
 #[derive(Clone, Debug)]
-pub struct LockableEventCacheStore(Arc<dyn EventCacheStore<Error = EventCacheStoreError>>);
+struct LockableEventCacheStore(Arc<DynEventCacheStore>);
 
 #[cfg_attr(target_arch = "wasm32", async_trait::async_trait(?Send))]
 #[cfg_attr(not(target_arch = "wasm32"), async_trait::async_trait)]
@@ -104,3 +102,32 @@ impl BackingStore for LockableEventCacheStore {
         self.0.try_take_leased_lock(lease_duration_ms, key, holder).await
     }
 }
+
+/// The high-level public type to represent an `EventCacheStore` lock.
+pub struct EventCacheStoreLock {
+    cross_process_lock: CrossProcessStoreLock<LockableEventCacheStore>,
+    store: Arc<DynEventCacheStore>,
+}
+
+impl fmt::Debug for EventCacheStoreLock {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        formatter.debug_struct("EventCacheStoreLock").finish_non_exhaustive()
+    }
+}
+
+impl EventCacheStoreLock {
+    pub fn new(store: Arc<DynEventCacheStore>, key: String, holder: String) -> Self {
+        Self {
+            cross_process_lock: CrossProcessStoreLock::new(
+                LockableEventCacheStore(store.clone()),
+                key,
+                holder,
+            ),
+            store,
+        }
+    }
+
+    pub async fn lock(&self) -> &Arc<DynEventCacheStore> {
+        todo!()
+    }
+}