ThePain/Swiftgram
1
0
Fork 0
mirror of https://github.com/Swiftgram/Telegram-iOS.git synced 2026-01-07 05:25:12 +00:00
Code Issues Packages Projects Releases Wiki Activity

[ASTextNode] Fix a deadlock that could occur when enabling experimental ASTextNode2 via ASConfiguration (#903)

Browse Source 
Because multiple threads can enter this allocWithZone: method around the same time, it is possible for one of them to setSuperclass first, and then the second thread would get stuck in an infinite loop. When climbing the inheritance heirarchy, ASTextNode2 would be encountered by this second thread, and it would continue until reaching c == Nil. Since there was no case to catch this, an infinite loop would result. Then the main thread can be deadlocked if a method like waitUntilAllUpdatesAreProcessed is called on ASCollectionView.
This commit is contained in:
appleguy
2018-05-03 03:51:59 -07:00
committed by Adlai Holler
parent 64c9b38a0f
commit 9de33361dc
1 changed files with 2 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
Source/ASTextNode.mm
View File

@@ -1324,8 +1324,9 @@ static NSAttributedString *DefaultTruncationAttributedString()
// We are descended from ASTextNode. We need to change the superclass for the
// ASTextNode subclass to ASTextNode2.
// Walk up the class hierarchy until we find ASTextNode.
// Note: This may be called on multiple threads simultaneously.
Class s;
for (Class c = self; c != [ASTextNode class]; c = s) {
for (Class c = self; c != Nil && c != [ASTextNode class]; c = s) {
s = class_getSuperclass(c);
if (s == [ASTextNode class]) {
#pragma clang diagnostic push