Close the client before deleting data, and ensure the app is restarted, using a cache Index.

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/RustMatrixClient.kt

@@ -339,11 +339,13 @@ class RustMatrixClient constructor(
     }
 
     override suspend fun getCacheSize(): Long {
-        return baseDirectory.getCacheSize(userID = client.userId())
+        // Do not use client.userId since it can throw if client has been closed (during clear cache)
+        return baseDirectory.getCacheSize(userID = sessionId.value)
     }
 
     override suspend fun clearCache() {
-        baseDirectory.deleteSessionDirectory(userID = client.userId())
+        close()
+        baseDirectory.deleteSessionDirectory(userID = sessionId.value, deleteCryptoDb = false)
     }
 
     override suspend fun logout() = withContext(dispatchers.io) {

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/auth/RustMatrixAuthenticationService.kt

@@ -58,6 +58,8 @@ class RustMatrixAuthenticationService @Inject constructor(
     private val clock: SystemClock,
 ) : MatrixAuthenticationService {
 
+    private val cacheIdxState = MutableStateFlow(0)
+
     private val authService: RustAuthenticationService = RustAuthenticationService(
         basePath = baseDirectory.absolutePath,
         passphrase = null,
@@ -71,6 +73,14 @@ class RustMatrixAuthenticationService @Inject constructor(
         return sessionStore.isLoggedIn()
     }
 
+    override fun incrementCacheIdx() {
+        cacheIdxState.value++
+    }
+
+    override fun cacheIdx(): Flow<Int> {
+        return cacheIdxState
+    }
+
     override suspend fun getLatestSessionId(): SessionId? = withContext(coroutineDispatchers.io) {
         sessionStore.getLatestSession()?.userId?.let { SessionId(it) }
     }