From 677b75f3685854b94f494dabe5c8b370f7a43982 Mon Sep 17 00:00:00 2001
From: Stanislav Dmitrenko <7953703+avently@users.noreply.github.com>
Date: Wed, 26 Jul 2023 15:27:54 +0300
Subject: [PATCH] multiplatform: possible race in ChatList (#2757)

* multiplatform: possible race in ChatList

* more changes

---------

Co-authored-by: Evgeny Poberezkin <2769109+epoberezkin@users.noreply.github.com>
---
 .../chat/simplex/common/model/ChatModel.kt      |  9 +++++----
 .../common/views/chatlist/ChatListView.kt       | 17 ++++++++++-------
 2 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/apps/multiplatform/common/src/commonMain/kotlin/chat/simplex/common/model/ChatModel.kt b/apps/multiplatform/common/src/commonMain/kotlin/chat/simplex/common/model/ChatModel.kt
index 3189e1c705..e0f1e773c3 100644
--- a/apps/multiplatform/common/src/commonMain/kotlin/chat/simplex/common/model/ChatModel.kt
+++ b/apps/multiplatform/common/src/commonMain/kotlin/chat/simplex/common/model/ChatModel.kt
@@ -130,10 +130,11 @@ object ChatModel {
     }
   }
 
-  fun hasChat(id: String): Boolean = chats.firstOrNull { it.id == id } != null
-  fun getChat(id: String): Chat? = chats.firstOrNull { it.id == id }
-  fun getContactChat(contactId: Long): Chat? = chats.firstOrNull { it.chatInfo is ChatInfo.Direct && it.chatInfo.apiId == contactId }
-  private fun getChatIndex(id: String): Int = chats.indexOfFirst { it.id == id }
+  // toList() here is to prevent ConcurrentModificationException that is rarely happens but happens
+  fun hasChat(id: String): Boolean = chats.toList().firstOrNull { it.id == id } != null
+  fun getChat(id: String): Chat? = chats.toList().firstOrNull { it.id == id }
+  fun getContactChat(contactId: Long): Chat? = chats.toList().firstOrNull { it.chatInfo is ChatInfo.Direct && it.chatInfo.apiId == contactId }
+  private fun getChatIndex(id: String): Int = chats.toList().indexOfFirst { it.id == id }
   fun addChat(chat: Chat) = chats.add(index = 0, chat)
 
   fun updateChatInfo(cInfo: ChatInfo) {
diff --git a/apps/multiplatform/common/src/commonMain/kotlin/chat/simplex/common/views/chatlist/ChatListView.kt b/apps/multiplatform/common/src/commonMain/kotlin/chat/simplex/common/views/chatlist/ChatListView.kt
index ec5d0071c0..1e7d25346b 100644
--- a/apps/multiplatform/common/src/commonMain/kotlin/chat/simplex/common/views/chatlist/ChatListView.kt
+++ b/apps/multiplatform/common/src/commonMain/kotlin/chat/simplex/common/views/chatlist/ChatListView.kt
@@ -8,6 +8,7 @@ import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material.*
 import androidx.compose.runtime.*
 import androidx.compose.runtime.saveable.rememberSaveable
+import androidx.compose.runtime.snapshots.SnapshotStateList
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.*
@@ -27,9 +28,8 @@ import chat.simplex.common.views.usersettings.simplexTeamUri
 import chat.simplex.common.platform.*
 import chat.simplex.common.views.newchat.*
 import chat.simplex.res.MR
-import kotlinx.coroutines.delay
+import kotlinx.coroutines.*
 import kotlinx.coroutines.flow.MutableStateFlow
-import kotlinx.coroutines.launch
 import java.net.URI
 
 @Composable
@@ -344,7 +344,11 @@ private fun ChatList(chatModel: ChatModel, search: String) {
     onDispose { lazyListState = listState.firstVisibleItemIndex to listState.firstVisibleItemScrollOffset }
   }
   val showUnreadAndFavorites = remember { ChatController.appPrefs.showUnreadAndFavorites.state }.value
-  val chats by remember(search, showUnreadAndFavorites) { derivedStateOf { filteredChats(showUnreadAndFavorites, search) } }
+  val allChats = remember { chatModel.chats }
+  // In some not always reproducible situations this code produce IndexOutOfBoundsException on Compose's side
+  // which is related to [derivedStateOf]. Using safe alternative instead
+  // val chats by remember(search, showUnreadAndFavorites) { derivedStateOf { filteredChats(showUnreadAndFavorites, search, allChats.toList()) } }
+  val chats = filteredChats(showUnreadAndFavorites, search, allChats.toList())
   LazyColumn(
     modifier = Modifier.fillMaxWidth(),
     listState
@@ -360,13 +364,12 @@ private fun ChatList(chatModel: ChatModel, search: String) {
   }
 }
 
-private fun filteredChats(showUnreadAndFavorites: Boolean, searchText: String): List<Chat> {
-  val chatModel = ChatModel
+private fun filteredChats(showUnreadAndFavorites: Boolean, searchText: String, chats: List<Chat>): List<Chat> {
   val s = searchText.trim().lowercase()
   return if (s.isEmpty() && !showUnreadAndFavorites)
-    chatModel.chats
+    chats
   else {
-    chatModel.chats.filter { chat ->
+    chats.filter { chat ->
       when (val cInfo = chat.chatInfo) {
         is ChatInfo.Direct -> if (s.isEmpty()) {
           filtered(chat)