fix(OnceFlag): add isSet and check before waiting (#6316)

src/util/OnceFlag.cpp

@@ -16,6 +16,10 @@ void OnceFlag::set()
 bool OnceFlag::waitFor(std::chrono::milliseconds ms)
 {
     std::unique_lock lock(this->mutex);
+    if (this->flag.load(std::memory_order::relaxed))
+    {
+        return true;
+    }
     return this->condvar.wait_for(lock, ms, [this] {
         return this->flag.load(std::memory_order::relaxed);
     });
@@ -24,9 +28,19 @@ bool OnceFlag::waitFor(std::chrono::milliseconds ms)
 void OnceFlag::wait()
 {
     std::unique_lock lock(this->mutex);
+    if (this->flag.load(std::memory_order::relaxed))
+    {
+        return;
+    }
     this->condvar.wait(lock, [this] {
         return this->flag.load(std::memory_order::relaxed);
     });
 }
 
+bool OnceFlag::isSet()
+{
+    std::unique_lock lock(this->mutex);
+    return this->flag.load(std::memory_order::relaxed);
+}
+
 }  // namespace chatterino

src/util/OnceFlag.hpp

@@ -31,6 +31,9 @@ public:
     /// The calling thread will be suspended during the wait.
     void wait();
 
+    /// Is the flag currently set?
+    bool isSet();
+
 private:
     std::mutex mutex;
     std::condition_variable condvar;