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

appnav/src/main/kotlin/io/element/android/appnav/RootFlowNode.kt

@@ -54,7 +54,9 @@ import io.element.android.libraries.di.AppScope
 import io.element.android.libraries.matrix.api.auth.MatrixAuthenticationService
 import io.element.android.libraries.matrix.api.core.SessionId
 import io.element.android.libraries.matrix.api.core.UserId
+import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.onEach
 import kotlinx.parcelize.Parcelize
@@ -88,11 +90,17 @@ class RootFlowNode @AssistedInject constructor(
     private fun observeLoggedInState() {
         authenticationService.isLoggedIn()
             .distinctUntilChanged()
+            .combine(
+                authenticationService.cacheIdx().onEach {
+                    Timber.v("cacheIdx=$it")
+                    matrixClientsHolder.removeAll()
+                }
+            ) { isLoggedIn, cacheIdx -> isLoggedIn to cacheIdx }
             .onEach { isLoggedIn ->
                 Timber.v("isLoggedIn=$isLoggedIn")
-                if (isLoggedIn) {
+                if (isLoggedIn.first) {
                     tryToRestoreLatestSession(
-                        onSuccess = { switchToLoggedInFlow(it) },
+                        onSuccess = { switchToLoggedInFlow(it, isLoggedIn.second) },
                         onFailure = { switchToNotLoggedInFlow() }
                     )
                 } else {
@@ -102,8 +110,8 @@ class RootFlowNode @AssistedInject constructor(
             .launchIn(lifecycleScope)
     }
 
-    private fun switchToLoggedInFlow(sessionId: SessionId) {
+    private fun switchToLoggedInFlow(sessionId: SessionId, cacheIndex: Int) {
-        backstack.safeRoot(NavTarget.LoggedInFlow(sessionId))
+        backstack.safeRoot(NavTarget.LoggedInFlow(sessionId, cacheIndex))
     }
 
     private fun switchToNotLoggedInFlow() {
@@ -163,7 +171,7 @@ class RootFlowNode @AssistedInject constructor(
         object NotLoggedInFlow : NavTarget
 
         @Parcelize
-        data class LoggedInFlow(val sessionId: SessionId) : NavTarget
+        data class LoggedInFlow(val sessionId: SessionId, val cacheIndex: Int) : NavTarget
 
         @Parcelize
         object BugReport : NavTarget
@@ -235,8 +243,9 @@ class RootFlowNode @AssistedInject constructor(
     }
 
     private suspend fun attachSession(sessionId: SessionId): LoggedInFlowNode {
+        val cacheIdx = authenticationService.cacheIdx().first()
         return attachChild {
-            backstack.newRoot(NavTarget.LoggedInFlow(sessionId))
+            backstack.newRoot(NavTarget.LoggedInFlow(sessionId, cacheIdx))
         }
     }
 }

features/preferences/impl/src/main/kotlin/io/element/android/features/preferences/impl/tasks/ClearCacheUseCase.kt

@@ -22,6 +22,7 @@ import io.element.android.libraries.core.coroutine.CoroutineDispatchers
 import io.element.android.libraries.di.ApplicationContext
 import io.element.android.libraries.di.SessionScope
 import io.element.android.libraries.matrix.api.MatrixClient
+import io.element.android.libraries.matrix.api.auth.MatrixAuthenticationService
 import kotlinx.coroutines.withContext
 import javax.inject.Inject
 
@@ -34,11 +35,11 @@ class DefaultClearCacheUseCase @Inject constructor(
     @ApplicationContext private val context: Context,
     private val matrixClient: MatrixClient,
     private val coroutineDispatchers: CoroutineDispatchers,
+    private val authenticationService: MatrixAuthenticationService,
 ) : ClearCacheUseCase {
     override suspend fun execute() = withContext(coroutineDispatchers.io) {
-        matrixClient.stopSync()
         matrixClient.clearCache()
         context.cacheDir.deleteRecursively()
-        matrixClient.startSync()
+        authenticationService.incrementCacheIdx()
     }
 }

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/MatrixClient.kt

@@ -51,6 +51,10 @@ interface MatrixClient : Closeable {
     fun pushersService(): PushersService
     fun notificationService(): NotificationService
     suspend fun getCacheSize(): Long
+
+    /**
+     * Will close the client and delete the cache data.
+     */
     suspend fun clearCache()
     suspend fun logout()
     suspend fun loadUserDisplayName(): Result<String>

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/auth/MatrixAuthenticationService.kt

@@ -29,6 +29,13 @@ interface MatrixAuthenticationService {
     suspend fun setHomeserver(homeserver: String): Result<Unit>
     suspend fun login(username: String, password: String): Result<SessionId>
 
+    /*
+     * Cache index
+     */
+
+    fun cacheIdx(): Flow<Int>
+    fun incrementCacheIdx()
+
     /*
      * OIDC part.
      */

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) }
     }