# Arti Report 2: July 7 through July 21 It's been a quiet couple of weeks. Most of the team has been on vacation or leave for the last two weeks, so the Arti hacking has been down to me (nick) for this period.
Our last report went out on the same day that our [announcement] went public, and since then we've had an influx of attention and volunteers interest. Thanks to everybody who's been trying out the code! Special thanks to `trinity-1686a` for a [stream-isolation] implementation, `lyuyuan` for work on [RESOLVE and RESOLVE_PTR][resolve], and everybody else who's been submitting patches! ## Circuit timeout inference My own work for this period has focused on [circuit timeout inference][cti]. (I decided to start with this because it's part of the Tor protocol that I've worked with the least in the past.) The approach is kind of complicated: in order to adjust our timeout, we need to observe how long circuits actually take to complete... including the circuits that we don't use because they take longer than our current timeout timeout. So we have to keep building circuits for a while even after they time out, so that we can observe how long it takes them to finish. Then we use an estimator based on a Pareto distribution, and use that to determine our actual cutoffs. The core logic is now [implemented in Arti][pareto-code], and we just have a few more pieces ([persistence][ticket-143], [directory notification][ticket-144], and [testing circuits][ticket-145]) to cover before we can call it done. ## Open problems Our timeout tests rely on using a simulated view of time. (Nobody wants to wait 10 seconds for a simulated 10-second timeout!) For that, we have [testing code][rt-mock-time] to override the asynchronous runtime's view of the passage of time. But we have a bug somewhere that makes these tests unreliable. The [WaitFor] future, which is supposed to run a another future to completion while advancing the current (simulated) time, doesn't seem to be reliable. As implemented, it advances the current time even when the future it's testing _isn't_ blocked on time, and sometimes advances time much too far while the tested future makes no progress. I've kludged it up by making it yield a lot and advance time in tiny increments, but that's just a workaround. Does anybody like [debugging Futures code][ticket-149]? ## Next steps In the next two weeks I hope we can wrap up the outstanding issues above in circuit timeouts, including the ones that require some architectural decisions. I'm also hoping that we can make progress on [guards]: that's the last remaining really big security feature we have to do for our 0.0.1 milestone. Once that's done, we can move on to polishing and infrastructure issues for the rest of the time we have for this milestone. Finally, we're going to be expanding our team! Please have a look at our [job-opening], and share it with anybody you know who is interested in Rust and Tor, and who might be interested in a job. Next update in two weeks! [announcement]: https://blog.torproject.org/announcing-arti [cti]: https://gitlab.torproject.org/tpo/core/torspec/-/blob/master/path-spec.txt#L364 [cti]: https://gitlab.torproject.org/tpo/core/torspec/-/blob/master/guard-spec.txt [job-opening]: https://www.torproject.org/about/jobs/rust-dev/ [pareto-code]: https://gitlab.torproject.org/tpo/core/arti/-/blob/main/tor-circmgr/src/timeouts/pareto.rs [resolve]: https://gitlab.torproject.org/tpo/core/arti/-/merge_requests/39 [rt-mock-time]: https://gitlab.torproject.org/tpo/core/arti/-/blob/main/tor-rtmock/src/time.rs [stream-isolation]: https://gitlab.torproject.org/tpo/core/arti/-/merge_requests/38 [ticket-143]: https://gitlab.torproject.org/tpo/core/arti/-/issues/143 [ticket-144]: https://gitlab.torproject.org/tpo/core/arti/-/issues/144 [ticket-145]: https://gitlab.torproject.org/tpo/core/arti/-/issues/145 [ticket-149]: https://gitlab.torproject.org/tpo/core/arti/-/issues/149 [WaitFor]: https://gitlab.torproject.org/tpo/core/arti/-/blob/main/tor-rtmock/src/sleep_runtime.rs#L123 _______________________________________________ tor-dev mailing list tor-dev@lists.torproject.org https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-dev
