Important Update to the Planet Wars Starter Package

Tags: ai, lisp, Date: 2010-10-25

First, is it possible to get something as simple as RESOLVE-BATTLE wrong? Apparently, yes. That's what one gets for trying to port Python code that's pretty foreign in the sense of being far from the way I'd write it.

More importantly, I found out the hard way that sbcl 1.0.11, that's still on the official servers, has a number of bugs in its timer implementation making WITH-TIMEOUT unreliable. Also, it can trigger timeouts recursively, eventually exceeding the maximum interrupt nesting depth. Well, "found out" is not the right way to put it as we did fix most of these bugs ages ago.

In the new starter package (v0.8 in git, latest tarball), you'll find a timer.lisp that's simply backported almost verbatim from sbcl 1.0.41 to sbcl 1.0.11. Seems to work for me, but I also had to lower the timeout to 0.8 from 0.98 because the main server is extremely slow.

The rate at which games are played on the servers is so low that it takes several days to ascend through the leaderboard. Nevertheless, an old buggy version is sitting on the top right now. Mind you, introducing bugs is a great way exlopore the solution space, and it's quite worrisome just how adept I am at this poor man's evolutionary programming. Most of them have since been fixed while the ideas they brought to light remain, making the current version much stronger.