Method readGuard

fdbserver/storageserver.actor.cpp:1445–1451

	template <class Request, class HandleFunction>
	Future<Void> readGuard(const Request& request, const HandleFunction& fun) {
		bool read = shouldRead(request);
		if (!read) {
			return Void();
		}
		return fun(this, request);
	}

	Version minFeedVersionForAddress(const NetworkAddress& addr) {
		auto& clientVersions = changeFeedClientVersions[addr];