fixup

Author: Hywan

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

@@ -221,24 +221,50 @@ impl BaseClient {
         cross_process_store_locks_holder_name: &str,
         handle_verification_events: bool,
     ) -> Result<Self> {
-        let in_memory_store_config =
+        let StoreConfig { state_store, event_cache_store, media_store, .. } =
             StoreConfig::new(cross_process_store_locks_holder_name.to_owned())
-                .state_store(MemoryStore::new())
-                .crypto_store(self.crypto_store.clone());
+                .event_cache_store({
+                    if cross_process_store_locks_holder_name == self.event_cache_store.lock_holder()
+                    {
+                        return Err(Error::DuplicatedCrossProcessLockHolder(
+                            cross_process_store_locks_holder_name.to_owned(),
+                        ));
+                    }
+
+                    // SAFETY: the store will be used behind another lock holder, so it's safe to
+                    // use a clone of it.
+                    unsafe { self.event_cache_store.clone_store() }
+                })
+                .media_store({
+                    if cross_process_store_locks_holder_name == self.media_store.lock_holder() {
+                        return Err(Error::DuplicatedCrossProcessLockHolder(
+                            cross_process_store_locks_holder_name.to_owned(),
+                        ));
+                    }
+
+                    // SAFETY: the store will be used behind another lock holder, so it's safe to
+                    // use a clone of it.
+                    unsafe { self.media_store.clone_store() }
+                });
+
+        // Clone the Crypto store.
+        // We copy the crypto store as well as the `OlmMachine` for two reasons:
+        // 1. The `self.crypto_store` is the same as the one used inside the
+        //    `OlmMachine`.
+        // 2. We need to ensure that the parent and child use the same data and caches
+        //    inside the `OlmMachine` so the various ratchets and places where new
+        //    randomness gets introduced don't diverge, i.e. one-time keys that get
+        //    generated by the Olm Account or Olm sessions when they encrypt or decrypt
+        //    messages.
+        let crypto_store = self.crypto_store.clone();
+        let olm_machine = self.olm_machine.clone();
 
         let copy = Self {
-            state_store: BaseStateStore::new(in_memory_store_config.state_store),
-            // The event and media stores both have cross process locking support.
-            event_cache_store: self.event_cache_store.clone(),
-            media_store: self.media_store.clone(),
-            // We copy the crypto store as well as the `OlmMachine` for two reasons:
-            // 1. The `self.crypto_store` is the same as the one used inside the `OlmMachine`.
-            // 2. We need to ensure that the parent and child use the same data and caches inside
-            //    the `OlmMachine` so the various ratchets and places where new randomness gets
-            //    introduced don't diverge, i.e. one-time keys that get generated by the Olm Account
-            //    or Olm sessions when they encrypt or decrypt messages.
-            crypto_store: self.crypto_store.clone(),
-            olm_machine: self.olm_machine.clone(),
+            state_store: BaseStateStore::new(state_store),
+            event_cache_store,
+            media_store,
+            crypto_store,
+            olm_machine,
             ignore_user_list_changes: Default::default(),
             room_info_notable_update_sender: self.room_info_notable_update_sender.clone(),
             room_key_recipient_strategy: self.room_key_recipient_strategy.clone(),

crates/matrix-sdk-base/src/error.rs

@@ -58,6 +58,10 @@ pub enum Error {
     #[error(transparent)]
     CryptoStore(#[from] CryptoStoreError),
 
+    /// The given cross-process lock holder name is already used by a store.
+    #[error("The given cross-process lock holder name is already used by a store: `{0}`")]
+    DuplicatedCrossProcessLockHolder(String),
+
     /// An error occurred during a E2EE operation.
     #[cfg(feature = "e2e-encryption")]
     #[error(transparent)]

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

@@ -91,6 +91,22 @@ impl EventCacheStoreLock {
 
         Ok(lock_state)
     }
+
+    /// Clone the inner store, by-passing the lock.
+    ///
+    /// # Safety
+    ///
+    /// This method is useful when you want to build a new client with another
+    /// lock holder name for example. But the lock is fully by-passed in this
+    /// method. Be extremely careful!
+    pub(crate) unsafe fn clone_store(&self) -> Arc<DynEventCacheStore> {
+        self.store.clone()
+    }
+
+    /// Get the lock holder name.
+    pub(crate) fn lock_holder(&self) -> &str {
+        self.cross_process_lock.lock_holder()
+    }
 }
 
 /// The equivalent of [`CrossProcessLockState`] but for the [`EventCacheStore`].

crates/matrix-sdk-base/src/media/store/mod.rs

@@ -150,6 +150,22 @@ impl MediaStoreLock {
 
         Ok(MediaStoreLockGuard { cross_process_lock_guard, store: self.store.deref() })
     }
+
+    /// Clone the inner store, by-passing the lock.
+    ///
+    /// # Safety
+    ///
+    /// This method is useful when you want to build a new client with another
+    /// lock holder name for example. But the lock is fully by-passed in this
+    /// method. Be extremely careful!
+    pub(crate) unsafe fn clone_store(&self) -> Arc<DynMediaStore> {
+        self.store.clone()
+    }
+
+    /// Get the lock holder name.
+    pub(crate) fn lock_holder(&self) -> &str {
+        self.cross_process_lock.lock_holder()
+    }
 }
 
 /// An RAII implementation of a “scoped lock” of an [`MediaStoreLock`].