Merge pull request #913 from vector-im/feature/fga/avoid_spamming_sync_flow

Avoid spamming sync flow by checking item origin

Author: ganfra

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/item/event/EventContent.kt

@@ -35,7 +35,13 @@ data class MessageContent(
 
 
 sealed interface InReplyTo {
+    /** The event details are not loaded yet. We can fetch them. */
     data class NotLoaded(val eventId: EventId) : InReplyTo
+
+    /** The event details are pending to be fetched. We should **not** fetch them again. */
+    object Pending : InReplyTo
+
+    /** The event details are available. */
     data class Ready(
         val eventId: EventId,
         val content: MessageContent,
@@ -44,6 +50,14 @@ sealed interface InReplyTo {
         val senderAvatarUrl: String?,
     ) : InReplyTo
 
+    /**
+     * Fetching the event details failed.
+     *
+     * We can try to fetch them again **with a proper retry strategy**, but not blindly:
+     *
+     * If the reason for the failure is consistent on the server, we'd enter a loop
+     * where we keep trying to fetch the same event.
+     * */
     object Error : InReplyTo
 }
 

libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/item/event/EventTimelineItem.kt

@@ -42,6 +42,6 @@ data class EventTimelineItem(
     }
     fun hasNotLoadedInReplyTo(): Boolean {
         val details = inReplyTo()
-        return details is InReplyTo.NotLoaded || details is InReplyTo.Error
+        return details is InReplyTo.NotLoaded
     }
 }

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

@@ -41,6 +41,7 @@ import io.element.android.libraries.matrix.impl.media.map
 import io.element.android.libraries.matrix.impl.room.location.toInner
 import io.element.android.libraries.matrix.impl.timeline.RustMatrixTimeline
 import io.element.android.libraries.matrix.impl.timeline.backPaginationStatusFlow
+import io.element.android.libraries.matrix.impl.timeline.eventOrigin
 import io.element.android.libraries.matrix.impl.timeline.timelineDiffFlow
 import io.element.android.libraries.sessionstorage.api.SessionData
 import io.element.android.services.toolbox.api.systemclock.SystemClock
@@ -54,6 +55,7 @@ import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
+import org.matrix.rustcomponents.sdk.EventItemOrigin
 import org.matrix.rustcomponents.sdk.RequiredState
 import org.matrix.rustcomponents.sdk.Room
 import org.matrix.rustcomponents.sdk.RoomListItem
@@ -119,9 +121,11 @@ class RustMatrixRoom(
         roomCoroutineScope.launch(roomDispatcher) {
             innerRoom.timelineDiffFlow { initialList ->
                 _timeline.postItems(initialList)
-            }.onEach {
-                _syncUpdateFlow.value = systemClock.epochMillis()
-                _timeline.postDiff(it)
+            }.onEach { diff ->
+                if (diff.eventOrigin() == EventItemOrigin.SYNC) {
+                    _syncUpdateFlow.value = systemClock.epochMillis()
+                }
+                _timeline.postDiff(diff)
             }.launchIn(this)
 
             innerRoom.backPaginationStatusFlow()

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

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2023 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.matrix.impl.timeline
+
+import org.matrix.rustcomponents.sdk.EventItemOrigin
+import org.matrix.rustcomponents.sdk.TimelineChange
+import org.matrix.rustcomponents.sdk.TimelineDiff
+import org.matrix.rustcomponents.sdk.TimelineItem
+
+/**
+ * Tries to get an event origin from the TimelineDiff.
+ * If there is multiple events in the diff, uses the first one as it should be a good indicator.
+ */
+internal fun TimelineDiff.eventOrigin(): EventItemOrigin? {
+    return when (change()) {
+        TimelineChange.APPEND -> {
+            append()?.firstOrNull()?.eventOrigin()
+        }
+        TimelineChange.PUSH_BACK -> {
+            pushBack()?.eventOrigin()
+        }
+        TimelineChange.PUSH_FRONT -> {
+            pushFront()?.eventOrigin()
+        }
+        TimelineChange.SET -> {
+            set()?.item?.eventOrigin()
+        }
+        TimelineChange.INSERT -> {
+            insert()?.item?.eventOrigin()
+        }
+        TimelineChange.RESET -> {
+            reset()?.firstOrNull()?.eventOrigin()
+        }
+        else -> null
+    }
+}
+
+private fun TimelineItem.eventOrigin(): EventItemOrigin? {
+    return asEvent()?.origin()
+}

libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/timeline/item/event/EventMessageMapper.kt

@@ -58,7 +58,8 @@ class EventMessageMapper {
                     )
                 }
                 is RepliedToEventDetails.Error -> InReplyTo.Error
-                is RepliedToEventDetails.Pending, is RepliedToEventDetails.Unavailable -> InReplyTo.NotLoaded(inReplyToId!!)
+                is RepliedToEventDetails.Pending -> InReplyTo.Pending
+                is RepliedToEventDetails.Unavailable -> InReplyTo.NotLoaded(inReplyToId!!)
             }
         }
         MessageContent(