From fa64db56e744a8d67ad46bc1727cb67213851388 Mon Sep 17 00:00:00 2001
From: Jorge Martin Espinosa <jorgem@element.io>
Date: Fri, 19 Sep 2025 16:24:06 +0200
Subject: [PATCH] Add logs to detect duplicates in the room list (#5364)

* Add logs to detect duplicates in the room list

* Add comments and helper class about the caching results logging
---
 .../impl/datasource/RoomListDataSource.kt     | 34 ++++++++++++++++++-
 .../impl/roomlist/RoomSummaryListProcessor.kt |  6 ++++
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/features/home/impl/src/main/kotlin/io/element/android/features/home/impl/datasource/RoomListDataSource.kt b/features/home/impl/src/main/kotlin/io/element/android/features/home/impl/datasource/RoomListDataSource.kt
index 28f7f95908..b9e8d27bf7 100644
--- a/features/home/impl/src/main/kotlin/io/element/android/features/home/impl/datasource/RoomListDataSource.kt
+++ b/features/home/impl/src/main/kotlin/io/element/android/features/home/impl/datasource/RoomListDataSource.kt
@@ -30,6 +30,7 @@ import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
 import kotlinx.coroutines.withContext
+import timber.log.Timber
 import kotlin.time.Duration.Companion.seconds
 
 @Inject
@@ -102,13 +103,44 @@ class RoomListDataSource(
     }
 
     private suspend fun buildAndEmitAllRooms(roomSummaries: List<RoomSummary>, useCache: Boolean = true) {
+        // Used to detect duplicates in the room list summaries - see comment below
+        data class CacheResult(val index: Int, val fromCache: Boolean)
+        val cachingResults = mutableMapOf<RoomId, MutableList<CacheResult>>()
+
         val roomListRoomSummaries = diffCache.indices().mapNotNull { index ->
             if (useCache) {
-                diffCache.get(index) ?: buildAndCacheItem(roomSummaries, index)
+                diffCache.get(index)?.let { cachedItem ->
+                    // Add the cached item to the caching results
+                    val pairs = cachingResults.getOrDefault(cachedItem.roomId, mutableListOf())
+                    pairs.add(CacheResult(index, fromCache = true))
+                    cachingResults[cachedItem.roomId] = pairs
+                    cachedItem
+                } ?: run {
+                    roomSummaries.getOrNull(index)?.roomId?.let {
+                        // Add the non-cached item to the caching results
+                        val pairs = cachingResults.getOrDefault(it, mutableListOf())
+                        pairs.add(CacheResult(index, fromCache = false))
+                        cachingResults[it] = pairs
+                    }
+                    buildAndCacheItem(roomSummaries, index)
+                }
             } else {
+                roomSummaries.getOrNull(index)?.roomId?.let {
+                    // Add the non-cached item to the caching results
+                    val pairs = cachingResults.getOrDefault(it, mutableListOf())
+                    pairs.add(CacheResult(index, fromCache = false))
+                    cachingResults[it] = pairs
+                }
                 buildAndCacheItem(roomSummaries, index)
             }
         }
+
+        // TODO remove once https://github.com/element-hq/element-x-android/issues/5031 has been confirmed as fixed
+        val duplicates = cachingResults.filter { (_, operations) -> operations.size > 1 }
+        if (duplicates.isNotEmpty()) {
+            Timber.e("Found duplicates in room summaries after an UI update: $duplicates. This could be a race condition/caching issue of some kind")
+        }
+
         _allRooms.emit(roomListRoomSummaries.toImmutableList())
     }
 
diff --git a/libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/roomlist/RoomSummaryListProcessor.kt b/libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/roomlist/RoomSummaryListProcessor.kt
index 66931a1f13..e26cea1c94 100644
--- a/libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/roomlist/RoomSummaryListProcessor.kt
+++ b/libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/roomlist/RoomSummaryListProcessor.kt
@@ -33,6 +33,12 @@ class RoomSummaryListProcessor(
             updates.forEach { update ->
                 applyUpdate(update)
             }
+
+            // TODO remove once https://github.com/element-hq/element-x-android/issues/5031 has been confirmed as fixed
+            val duplicates = groupingBy { it.roomId }.eachCount().filter { it.value > 1 }
+            if (duplicates.isNotEmpty()) {
+                Timber.e("Found duplicates in room summaries after a list update from the SDK: $duplicates. Updates: $updates")
+            }
         }
     }