31–40 of 162 posts
I suspect the “l” parameter is for observed latency as the client displays observed latency from the server.
To do that, the server needs some measure of “how long does the client think the player actually took to make a move”, to later subtract latency not attributable to actual thinking from the clock.
I wonder why this protocol needs an ack? a websocket wrapped in a tls should be perfectly capable of guaranteeing the integrity of the message
20 years later I still think "female lich" whenever I see the word lichess, even though I know it's li chess.
- "While these moves could be calculated client-side, providing them server-side ensures consistency - especially for complex or esoteric chess variants - and optimizes performance on clients with limited processing capabilities or energy restrictions." Just a wild guess: might be intended to lower the implementation barrier for new open-source software clients on new platforms, and/or preempt them from implementing…
Edit: also includes move count but not repetition.
Regardless, one thing I find maddening about chess.com is the time architecture of the game. I haven't seen the underlying code, but it feels like the SERVER is tracking the time. This completely neglects transport time & latency meaning that 1s to move isn't really a second. Playing on the mobile client is an exercise in frustration if you are playing timed games and down to the wire. Even when you aren't, your clock will jump on normal moves and it is most obvious during the opening.
This could also be due to general poor network code as well. The number of errors I get during puzzles is also frustrating. Do they really not retry a send automatically??
Chess.com has the brand and the names... but dang, the tech feels SO rough to me.
Interesting that they accumulate and periodically store game state. Unfortunately it is not very clear, where they store ongoing game state - in redis or on server itself. Also cost breakdown doesn't have server for redis, only for DB.
BTW, their github has better architectural picture, than overly simplified one in the article: https://raw.githubusercontent.com/lichess-org/lila/master/pu.... Unfortunately, I'm afraid, drawing something like that during interview may not land a job at faang =(
Note that they have cost per game fairly low: $0.00027, 3,671 games per dollar.
Their cost breakdown, for ones who are curious https://docs.google.com/spreadsheets/d/1Si3PMUJGR9KrpE5lngSk...
p.s. I'm not saying that Lichess's approach is the best or faang is the worst. Remember, lichess had 10 hours outage exactly because of the architecture chosen (single datacenter dependency). https://lichess.org/@/Lichess/blog/post-mortem-of-our-longes... . And outages like that are exactly the reasons why multi-datacenter and multi-region architectures are drilled down into faang engineers.
My point is is that there are cases when this approach is legit, but typical interview is laser focused on different things, and most probably won't appreciate the "old style" approach to the problem. I'm sure that if Thibault will ever decide to land in faang he will neither do whiteboard coding nor system design.
lichess is one of the best sites on the internet. very happy to contribute my $5/mo
If you consider this to be true, you would seem to have a rather low standard. There are many aspects in which they are not the best.
Ad-free, compute intensive, non-CRUD, massively scaled, complex cheat moderation, infinite puzzles/analysis, educational (studies/tactics/openings explorer), etc. All this for free. I'm curious what's the best website in your opinion
- "While these moves could be calculated client-side, providing them server-side ensures consistency - especially for complex or esoteric chess variants - and optimizes performance on clients with limited processing capabilities or energy restrictions." Just a wild guess: might be intended to lower the implementation barrier for new open-source software clients on new platforms, and/or preempt them from implementing…
For those curious about the illegal move, it seems like it's allowing queen side castling through the king side rook (or vice versa). eg. if this is the first rank, R _ _ R K _ _ _, then you could make the move O-O-O and end up with _ _ _ R K _ _ _ Naturally, it's not possible to view this move anymore, but this game ( https://lichess.org/XDQeUk6j#48 ) has everything up until the last legal move right before the ille…
Also that linked game is pretty entertaining. It's not a good game, but it can be fun watching lower ranked players make moves that you'd never see in higher level games. Like, who plays Bb5+ against the Scandinavian? Amazing stuff.
- "While these moves could be calculated client-side, providing them server-side ensures consistency - especially for complex or esoteric chess variants - and optimizes performance on clients with limited processing capabilities or energy restrictions." Just a wild guess: might be intended to lower the implementation barrier for new open-source software clients on new platforms, and/or preempt them from implementing…
Another wild guess: Lichess could be pre-calculating and caching the legal moves for the most common chess positions. While pre-calculating every possible legal move for every position would be impossible, you could pre-calculate the most common openings and endgames, which could cover a lot of real-world positions. This cache could easily be larger then practical for the client, but a server could hold onto it no pr…
