From acfb98bd81a4943f46c68a15083e878e6df0115b Mon Sep 17 00:00:00 2001
From: Stanislav Dmitrenko <7953703+avently@users.noreply.github.com>
Date: Thu, 15 Dec 2022 22:57:57 +0300
Subject: [PATCH] android: Optimized chats snapshotFlow (#1578)

* android: Optimized chats snapshotFlow

* Concurrency test

* Revert "Concurrency test"

This reverts commit 911dd0c2ef8d341397e4dc0b1f8690cdb64cffaf.

* Comment

* Better catch
---
 .../chat/simplex/app/views/chat/ChatView.kt   | 25 ++++++++++++-------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/apps/android/app/src/main/java/chat/simplex/app/views/chat/ChatView.kt b/apps/android/app/src/main/java/chat/simplex/app/views/chat/ChatView.kt
index d2c178fe43..6edd148c30 100644
--- a/apps/android/app/src/main/java/chat/simplex/app/views/chat/ChatView.kt
+++ b/apps/android/app/src/main/java/chat/simplex/app/views/chat/ChatView.kt
@@ -77,16 +77,23 @@ fun ChatView(chatId: String, chatModel: ChatModel, onComposed: () -> Unit) {
         }
     }
     launch {
-      // .toList() is important for making observation working
-      snapshotFlow { chatModel.chats.toList() }
-        .distinctUntilChanged()
-        .collect { chats ->
-          chats.firstOrNull { chat -> chat.chatInfo.id == chatModel.chatId.value }.let {
-            // Only changed chatInfo is important thing. Other properties can be skipped for reducing recompositions
-            if (it?.chatInfo != activeChat.value?.chatInfo) {
-              activeChat.value = it
-          }}
+      snapshotFlow {
+        /**
+         * It's possible that in some cases concurrent modification can happen on [ChatModel.chats] list.
+         * In this case only error log will be printed here (no crash).
+         * TODO: Re-write [ChatModel.chats] logic to a new list assignment instead of changing content of mutableList to prevent that
+         * */
+        try {
+          chatModel.chats.firstOrNull { chat -> chat.chatInfo.id == chatModel.chatId.value }
+        } catch (e: ConcurrentModificationException) {
+          Log.e(TAG, e.stackTraceToString())
+          null
         }
+      }
+        .distinctUntilChanged()
+        // Only changed chatInfo is important thing. Other properties can be skipped for reducing recompositions
+        .filter { it?.chatInfo != activeChat.value?.chatInfo && it != null }
+        .collect { activeChat.value = it }
     }
   }
   val view = LocalView.current