Method lock

fdbserver/VersionedBTree.actor.cpp:162–179

	}

	Future<Lock> lock(int priority = 0) {
		prioritylock_printf("lock begin %s\n", toString().c_str());

		// This shortcut may enable a waiter to jump the line when the releaser loop yields
		if (available > 0) {
			--available;
			Lock p;
			addRunner(p);
			prioritylock_printf("lock exit immediate %s\n", toString().c_str());
			return p;
		}

		Waiter w;
		waiters[priority].push_back(w);
		++waiting;
		prioritylock_printf("lock exit queued %s\n", toString().c_str());
		return w.lockPromise.getFuture();
	}

	std::string toString() const {
		int runnersDone = 0;