From 86fba283131ab9b5315694ece8af42ba9f6bde78 Mon Sep 17 00:00:00 2001
From: Benoit Marty <benoitm@matrix.org>
Date: Tue, 5 May 2020 02:40:50 +0200
Subject: [PATCH] After jump to unread, newer messages are never loaded (#1008)

---
 CHANGES.md                                    |  2 +-
 .../internal/database/model/ChunkEntity.kt    |  3 +++
 .../session/room/timeline/DefaultTimeline.kt  | 27 ++++++++++++++++++-
 .../room/timeline/TokenChunkEventPersistor.kt |  9 ++++++-
 4 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/CHANGES.md b/CHANGES.md
index f0cf30af2d..bc04df2e39 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -8,7 +8,7 @@ Improvements 🙌:
  -
 
 Bugfix 🐛:
- -
+ - After jump to unread, newer messages are never loaded (#1008)
 
 Translations 🗣:
  -
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/database/model/ChunkEntity.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/database/model/ChunkEntity.kt
index 9c6bf5f757..19bf72970c 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/database/model/ChunkEntity.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/database/model/ChunkEntity.kt
@@ -34,6 +34,9 @@ internal open class ChunkEntity(@Index var prevToken: String? = null,
 
     fun identifier() = "${prevToken}_$nextToken"
 
+    // If true, then this chunk was previously a last forward chunk
+    fun hasBeenALastForwardChunk() = nextToken == null && !isLastForward
+
     @LinkingObjects("chunks")
     val room: RealmResults<RoomEntity>? = null
 
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/timeline/DefaultTimeline.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/timeline/DefaultTimeline.kt
index 82729f092d..8cfd498cc8 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/timeline/DefaultTimeline.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/timeline/DefaultTimeline.kt
@@ -559,6 +559,28 @@ internal class DefaultTimeline(
                 .executeBy(taskExecutor)
     }
 
+    // For debug purpose only
+    private fun dumpAndLogChunks() {
+        val liveChunk = getLiveChunk()
+        Timber.w("Live chunk: $liveChunk")
+
+        Realm.getInstance(realmConfiguration).use { realm ->
+            ChunkEntity.where(realm, roomId).findAll()
+                    .also { Timber.w("Found ${it.size} chunks") }
+                    .forEach {
+                        Timber.w("")
+                        Timber.w("ChunkEntity: $it")
+                        Timber.w("prevToken: ${it.prevToken}")
+                        Timber.w("nextToken: ${it.nextToken}")
+                        Timber.w("isLastBackward: ${it.isLastBackward}")
+                        Timber.w("isLastForward: ${it.isLastForward}")
+                        it.timelineEvents.forEach { tle ->
+                            Timber.w("   TLE: ${tle.root?.content}")
+                        }
+                    }
+        }
+    }
+
     /**
      * This has to be called on TimelineThread as it accesses realm live results
      */
@@ -569,6 +591,7 @@ internal class DefaultTimeline(
 
     /**
      * This has to be called on TimelineThread as it accesses realm live results
+     * Return the current Chunk
      */
     private fun getLiveChunk(): ChunkEntity? {
         return nonFilteredEvents.firstOrNull()?.chunk?.firstOrNull()
@@ -576,7 +599,7 @@ internal class DefaultTimeline(
 
     /**
      * This has to be called on TimelineThread as it accesses realm live results
-     * @return number of items who have been added
+     * @return the number of items who have been added
      */
     private fun buildTimelineEvents(startDisplayIndex: Int?,
                                     direction: Timeline.Direction,
@@ -617,6 +640,8 @@ internal class DefaultTimeline(
         }
         val time = System.currentTimeMillis() - start
         Timber.v("Built ${offsetResults.size} items from db in $time ms")
+        // For the case where wo reach the lastForward chunk
+        updateLoadingStates(filteredEvents)
         return offsetResults.size
     }
 
diff --git a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/timeline/TokenChunkEventPersistor.kt b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/timeline/TokenChunkEventPersistor.kt
index f6fd88f816..6161e8e5fb 100644
--- a/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/timeline/TokenChunkEventPersistor.kt
+++ b/matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/room/timeline/TokenChunkEventPersistor.kt
@@ -224,11 +224,18 @@ internal class TokenChunkEventPersistor @Inject constructor(private val monarchy
 
             currentChunk.addTimelineEvent(roomId, eventEntity, direction, roomMemberContentsByUser)
         }
+        // Find all the chunks which contain at least one event from the list of eventIds
         val chunks = ChunkEntity.findAllIncludingEvents(realm, eventIds)
+        Timber.d("Found ${chunks.size} chunks containing at least one of the eventIds")
         val chunksToDelete = ArrayList<ChunkEntity>()
         chunks.forEach {
             if (it != currentChunk) {
-                currentChunk.merge(roomId, it, direction)
+                if (direction == PaginationDirection.FORWARDS && it.hasBeenALastForwardChunk()) {
+                    Timber.d("Do not merge $it")
+                } else {
+                    Timber.d("Merge $it")
+                    currentChunk.merge(roomId, it, direction)
+                }
                 chunksToDelete.add(it)
             }
         }