Method delref

flow/WriteOnlySet.actor.cpp:166–171

	mutable std::atomic<unsigned> _refCount = 1;
	TestObject() { instanceCounter.fetch_add(1); }
	void delref() const {
		if (--_refCount == 0) {
			delete this;
			--instanceCounter;
		}
	}
	void addref() const { ++_refCount; }
};