fix(once-flag): make flag atomic (#6237)

CHANGELOG.md

@@ -53,6 +53,7 @@
 - Dev: Fixed incorrect lua generation of static methods for typescript plugins. (#6190, #6223)
 - Dev: Merged top/bottom and left/right notebook layouts. (#6215)
 - Dev: Refactored `Button` and friends. (#6102)
+- Dev: `OnceFlag`'s internal flag is now atomic. (#6237)
 - Dev: Bumped clang-format requirement to 19. (#6236)
 
 ## 2.5.3

src/util/OnceFlag.cpp

@@ -3,13 +3,12 @@
 namespace chatterino {
 
 OnceFlag::OnceFlag() = default;
-OnceFlag::~OnceFlag() = default;
 
 void OnceFlag::set()
 {
     {
         std::unique_lock guard(this->mutex);
-        this->flag = true;
+        this->flag.store(true, std::memory_order::relaxed);
     }
     this->condvar.notify_all();
 }
@@ -18,7 +17,7 @@ bool OnceFlag::waitFor(std::chrono::milliseconds ms)
 {
     std::unique_lock lock(this->mutex);
     return this->condvar.wait_for(lock, ms, [this] {
-        return this->flag;
+        return this->flag.load(std::memory_order::relaxed);
     });
 }
 
@@ -26,7 +25,7 @@ void OnceFlag::wait()
 {
     std::unique_lock lock(this->mutex);
     this->condvar.wait(lock, [this] {
-        return this->flag;
+        return this->flag.load(std::memory_order::relaxed);
     });
 }
 

src/util/OnceFlag.hpp

@@ -14,7 +14,6 @@ class OnceFlag
 {
 public:
     OnceFlag();
-    ~OnceFlag();
 
     /// Set this flag and notify waiters
     void set();
@@ -35,7 +34,7 @@ public:
 private:
     std::mutex mutex;
     std::condition_variable condvar;
-    bool flag = false;
+    std::atomic<bool> flag = false;
 };
 
 }  // namespace chatterino