RoomList: avoid to many recompositions

features/roomlist/src/main/java/io/element/android/x/features/roomlist/RoomListScreen.kt

@@ -16,53 +16,57 @@ import androidx.compose.ui.unit.sp
 import com.airbnb.mvrx.Success
 import com.airbnb.mvrx.compose.collectAsState
 import com.airbnb.mvrx.compose.mavericksViewModel
+import io.element.android.x.core.data.LogCompositions
 import io.element.android.x.designsystem.components.Avatar
+import io.element.android.x.features.roomlist.model.MatrixUser
 import io.element.android.x.matrix.core.RoomId
 import io.element.android.x.matrix.room.RoomSummary
 
 @Composable
 fun RoomListScreen(
-    viewModel: RoomListViewModel = mavericksViewModel(),
     onSuccessLogout: () -> Unit = { },
     onRoomClicked: (RoomId) -> Unit = { }
 ) {
-    val state by viewModel.collectAsState()
-    if (state.logoutAction is Success) {
+    val viewModel: RoomListViewModel = mavericksViewModel()
+    val logoutAction by viewModel.collectAsState(RoomListViewState::logoutAction)
+    if (logoutAction is Success) {
         onSuccessLogout()
         return
     }
+    LogCompositions(tag = "RoomListScreen", msg = "Root")
+    val roomSummaries by viewModel.collectAsState(RoomListViewState::rooms)
+    val matrixUser by viewModel.collectAsState(RoomListViewState::user)
     RoomListContent(
-        state = state,
+        roomSummaries = roomSummaries().orEmpty(),
+        matrixUser = matrixUser,
         onRoomClicked = onRoomClicked,
-        onLogoutClicked = {
-            viewModel.handle(RoomListActions.Logout)
-        }
+        onLogoutClicked = viewModel::logout
     )
 }
 
 @Composable
 fun RoomListContent(
-    state: RoomListViewState,
+    roomSummaries: List<RoomSummary>,
+    matrixUser: MatrixUser,
     onRoomClicked: (RoomId) -> Unit,
     onLogoutClicked: () -> Unit,
 ) {
+    LogCompositions(tag = "RoomListScreen", msg = "Content")
     Surface(color = MaterialTheme.colorScheme.background) {
         Column(
             modifier = Modifier.fillMaxSize()
         ) {
             RoomListTopBar(
-                state = state,
+                matrixUser = matrixUser,
                 onLogoutClicked = onLogoutClicked
             )
-            val rooms = state.rooms
-            if (rooms is Success) {
-                LazyColumn {
-                    items(rooms()) { room ->
-                        RoomItem(room = room) {
-                            onRoomClicked(it)
-                        }
+            LazyColumn {
+                items(roomSummaries, key = { it.identifier() }) { room ->
+                    RoomItem(room = room) {
+                        onRoomClicked(it)
                     }
                 }
+
             }
         }
     }
@@ -70,14 +74,14 @@ fun RoomListContent(
 
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
-fun RoomListTopBar(state: RoomListViewState, onLogoutClicked: () -> Unit) {
+fun RoomListTopBar(matrixUser: MatrixUser, onLogoutClicked: () -> Unit) {
+    LogCompositions(tag = "RoomListScreen", msg = "TopBar")
     TopAppBar(
         title = {
             Row(
                 modifier = Modifier.fillMaxWidth(),
                 verticalAlignment = Alignment.CenterVertically
             ) {
-                val matrixUser = state.user
                 Avatar(data = matrixUser.avatarData)
                 Spacer(modifier = Modifier.width(8.dp))
                 Text("${matrixUser.username}")

features/roomlist/src/main/java/io/element/android/x/features/roomlist/RoomListViewModel.kt

@@ -4,6 +4,7 @@ import com.airbnb.mvrx.Fail
 import com.airbnb.mvrx.Loading
 import com.airbnb.mvrx.MavericksViewModel
 import com.airbnb.mvrx.Success
+import io.element.android.x.features.roomlist.model.MatrixUser
 import io.element.android.x.matrix.MatrixClient
 import io.element.android.x.matrix.MatrixInstance
 import kotlinx.coroutines.launch
@@ -25,6 +26,10 @@ class RoomListViewModel(initialState: RoomListViewState) :
         }
     }
 
+    fun logout(){
+        handleLogout()
+    }
+
     private fun handleInit() {
         viewModelScope.launch {
             val client = getClient()

features/roomlist/src/main/java/io/element/android/x/features/roomlist/RoomListViewState.kt

@@ -3,9 +3,8 @@ package io.element.android.x.features.roomlist
 import com.airbnb.mvrx.Async
 import com.airbnb.mvrx.MavericksState
 import com.airbnb.mvrx.Uninitialized
+import io.element.android.x.features.roomlist.model.MatrixUser
 import io.element.android.x.matrix.room.RoomSummary
-import org.matrix.rustcomponents.sdk.Room
-import org.matrix.rustcomponents.sdk.UpdateSummary
 
 data class RoomListViewState(
     val user: MatrixUser = MatrixUser(),

features/roomlist/src/main/java/io/element/android/x/features/roomlist/model/MatrixUser.kt

@@ -1,5 +1,8 @@
-package io.element.android.x.features.roomlist
+package io.element.android.x.features.roomlist.model
 
+import androidx.compose.runtime.Stable
+
+@Stable
 data class MatrixUser(
     val username: String? = null,
     val avatarUrl: String? = null,

libraries/core/src/main/java/io/element/android/x/core/data/LogCompositions.kt

@@ -0,0 +1,22 @@
+package io.element.android.x.core.data
+
+import android.util.Log
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.SideEffect
+import androidx.compose.runtime.remember
+import io.element.android.x.core.BuildConfig
+
+
+// Note the inline function below which ensures that this function is essentially
+// copied at the call site to ensure that its logging only recompositions from the
+// original call site.
+@Composable
+inline fun LogCompositions(tag: String, msg: String) {
+    if (BuildConfig.DEBUG) {
+        val ref = remember { Ref(0) }
+        SideEffect { ref.value++ }
+        Log.d(tag, "Compositions: $msg ${ref.value}")
+    }
+}
+
+class Ref(var value: Int)

libraries/matrix/src/main/java/io/element/android/x/matrix/MatrixClient.kt

@@ -1,6 +1,5 @@
 package io.element.android.x.matrix
 
-import android.util.Log
 import io.element.android.x.core.data.CoroutineDispatchers
 import io.element.android.x.matrix.core.UserId
 import io.element.android.x.matrix.room.RoomSummaryDataSource
@@ -33,13 +32,13 @@ class MatrixClient internal constructor(
 
     private val slidingSyncObserver = object : SlidingSyncObserver {
         override fun didReceiveSyncUpdate(summary: UpdateSummary) {
-            Timber.v("didReceiveSyncUpdate=$summary")
+            Timber.v("didReceiveSyncUpdate=$summary on Thread: ${Thread.currentThread()}")
             roomSummaryDataSource.updateRoomsWithIdentifiers(summary.rooms)
         }
     }
 
     private val slidingSyncView = SlidingSyncViewBuilder()
-        .timelineLimit(limit = 10u)
+        .timelineLimit(limit = 1u)
         .requiredState(requiredState = listOf(RequiredState(key = "m.room.avatar", value = "")))
         .name(name = "HomeScreenView")
         .syncMode(mode = SlidingSyncMode.FULL_SYNC)
@@ -65,6 +64,7 @@ class MatrixClient internal constructor(
     }
 
     fun stopSync() {
+        roomSummaryDataSource.stopSync()
         slidingSync.setObserver(null)
         slidingSyncObserverToken?.cancel()
     }
@@ -73,6 +73,7 @@ class MatrixClient internal constructor(
 
     override fun close() {
         stopSync()
+        roomSummaryDataSource.close()
         client.setDelegate(null)
     }
 

libraries/matrix/src/main/java/io/element/android/x/matrix/room/RoomSummary.kt

@@ -2,6 +2,7 @@ package io.element.android.x.matrix.room
 
 import io.element.android.x.matrix.core.RoomId
 
+
 sealed interface RoomSummary {
     data class Empty(val identifier: String) : RoomSummary
     data class Filled(val details: RoomSummaryDetails) : RoomSummary

libraries/matrix/src/main/java/io/element/android/x/matrix/room/RoomSummaryDataSource.kt

@@ -5,14 +5,14 @@ import io.element.android.x.matrix.core.RoomId
 import io.element.android.x.matrix.room.message.RoomMessageFactory
 import io.element.android.x.matrix.sync.roomListDiff
 import io.element.android.x.matrix.sync.state
-import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.SupervisorJob
-import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.MutableStateFlow
-import kotlinx.coroutines.flow.launchIn
-import kotlinx.coroutines.flow.onEach
+import kotlinx.coroutines.cancel
+import kotlinx.coroutines.cancelChildren
+import kotlinx.coroutines.flow.*
 import org.matrix.rustcomponents.sdk.*
+import timber.log.Timber
+import java.io.Closeable
 import java.util.*
 
 interface RoomSummaryDataSource {
@@ -24,7 +24,7 @@ internal class RustRoomSummaryDataSource(
     private val slidingSyncView: SlidingSyncView,
     private val coroutineDispatchers: CoroutineDispatchers,
     private val roomMessageFactory: RoomMessageFactory = RoomMessageFactory(),
-) : RoomSummaryDataSource {
+) : RoomSummaryDataSource, Closeable {
 
     private val coroutineScope = CoroutineScope(SupervisorJob() + coroutineDispatchers.io)
 
@@ -33,6 +33,7 @@ internal class RustRoomSummaryDataSource(
 
     init {
         slidingSyncView.roomListDiff()
+            .buffer(50)
             .onEach { diff ->
                 updateRoomSummaries {
                     applyDiff(diff)
@@ -40,32 +41,43 @@ internal class RustRoomSummaryDataSource(
             }.launchIn(coroutineScope)
 
         slidingSyncView.state()
-            .onEach { newRoomState ->
-                state.value = newRoomState
+            .onEach { slidingSyncState ->
+                Timber.v("New sliding sync state: $slidingSyncState")
+                state.value = slidingSyncState
             }.launchIn(coroutineScope)
     }
 
+    fun stopSync() {
+        coroutineScope.coroutineContext.cancelChildren()
+    }
+
+    override fun close() {
+        coroutineScope.cancel()
+    }
+
     override fun roomSummaries(): Flow<List<RoomSummary>> {
-        return roomSummaries
+        return roomSummaries.sample(100)
     }
 
     internal fun updateRoomsWithIdentifiers(identifiers: List<String>) {
+        Timber.v("UpdateRooms with identifiers: $identifiers")
         if (state.value != SlidingSyncState.LIVE) {
             return
         }
-        val roomSummaryList = roomSummaries.value.toMutableList()
-        for (identifier in identifiers) {
-            val index = roomSummaryList.indexOfFirst { it.identifier() == identifier }
-            if (index == -1) {
-                continue
+        updateRoomSummaries {
+            for (identifier in identifiers) {
+                val index = indexOfFirst { it.identifier() == identifier }
+                if (index == -1) {
+                    continue
+                }
+                val updatedRoomSummary = buildRoomSummaryForIdentifier(identifier)
+                set(index, updatedRoomSummary)
             }
-            val updatedRoomSummary = buildRoomSummaryForIdentifier(identifier)
-            roomSummaryList[index] = updatedRoomSummary
         }
-        roomSummaries.value = roomSummaryList
     }
 
     private fun MutableList<RoomSummary>.applyDiff(diff: SlidingSyncViewRoomsListDiff) {
+        Timber.v("ApplyDiff: $diff")
         if (diff.isInvalidation()) {
             return
         }