Method with_lock

library/cpp/threading/future/core/future-inl.h:146–157

                TSystemEvent* readyEvent = nullptr;

                with_lock (StateLock) {
                    TAtomicBase state = AtomicGet(State);
                    if (Y_UNLIKELY(state != NotReady)) {
                        return false;
                    }

                    new (&Value) T(std::forward<TT>(value));

                    readyEvent = ReadyEvent.Get();

                    AtomicSet(State, ValueSet);
                }

                if (readyEvent) {
                    readyEvent->Signal();