Load timeline without initial eventId if not found

changelog.d/5659.bugfix

@@ -0,0 +1 @@
+Fix endless loading if the event from a permalink is not found

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/timeline/DefaultTimeline.kt

@@ -223,7 +223,15 @@ internal class DefaultTimeline(private val roomId: String,
         updateState(direction) {
             it.copy(loading = true)
         }
-        val loadMoreResult = strategy.loadMore(count, direction, fetchOnServerIfNeeded)
+        val loadMoreResult = try {
+            strategy.loadMore(count, direction, fetchOnServerIfNeeded)
+        } catch (throwable: Throwable) {
+            // Timeline could not be loaded with a (likely) permanent issue, such as the
+            // server now knowing the initialEventId, so we want to show an error message
+            // and possibly restart without initialEventId.
+            onTimelineFailure(throwable)
+            return false
+        }
         Timber.v("$baseLogMessage: result $loadMoreResult")
         val hasMoreToLoad = loadMoreResult != LoadMoreResult.REACHED_END
         updateState(direction) {
@@ -342,6 +350,14 @@ internal class DefaultTimeline(private val roomId: String,
         }
     }
 
+    private fun onTimelineFailure(throwable: Throwable) {
+        timelineScope.launch(coroutineDispatchers.main) {
+            listeners.forEach {
+                tryOrNull { it.onTimelineFailure(throwable) }
+            }
+        }
+    }
+
     private fun buildStrategy(mode: LoadTimelineStrategy.Mode): LoadTimelineStrategy {
         return LoadTimelineStrategy(
                 roomId = roomId,

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/timeline/LoadTimelineStrategy.kt

@@ -24,6 +24,8 @@ import io.realm.RealmResults
 import io.realm.kotlin.createObject
 import kotlinx.coroutines.CompletableDeferred
 import org.matrix.android.sdk.api.extensions.orFalse
+import org.matrix.android.sdk.api.failure.Failure
+import org.matrix.android.sdk.api.failure.MatrixError
 import org.matrix.android.sdk.api.session.room.send.SendState
 import org.matrix.android.sdk.api.session.room.timeline.Timeline
 import org.matrix.android.sdk.api.session.room.timeline.TimelineEvent
@@ -194,6 +196,10 @@ internal class LoadTimelineStrategy(
                 getContextLatch?.await()
                 getContextLatch = null
             } catch (failure: Throwable) {
+                if (failure is Failure.ServerError && failure.error.code == MatrixError.M_NOT_FOUND) {
+                    // This failure is likely permanent, so handle in DefaultTimeline to restart without eventId
+                    throw failure
+                }
                 return LoadMoreResult.FAILURE
             }
         }