A rather frustrating and long day coding went like this:

1-3 pm

Wrote a single function, of which all any Haskell programmer needs to know is its type signature:

Lsof.queryDir :: FilePath -> IO [(FilePath, LsofOpenMode, ProcessInfo)]

When I'm spending another hour or two taking a unix utility like lsof and parsing its output, which in this case is in a rather complicated machine-parsable output format, I often wish unix streams were strongly typed, which would avoid this bother.

3-9 pm

Six hours spent making it defer annexing files until the commit thread wakes up and is about to make a commit. Why did it take so horribly long? Well, there were a number of complications, and some really bad bugs involving races that were hard to reproduce reliably enough to deal with.

In other words, I was lost in the weeds for a lot of those hours...

At one point, something glorious happened, and it was always making exactly one commit for batch mode modifications of a lot of files (like untarring them). Unfortunately, I had to lose that gloriousness due to another potential race, which, while unlikely, would have made the program deadlock if it happened.

So, it's back to making 2 or 3 commits per batch mode change. I also have a buglet that causes sometimes a second empty commit after a file is added. I know why (the inotify event for the symlink gets in late, after the commit); will try to improve commit frequency later.

9-11 pm

Put the capstone on the day's work, by calling lsof on a directory full of hardlinks to the files that are about to be annexed, to check if any are still open for write.

This works great! Starting up git annex watch when processes have files open is no longer a problem, and even if you're evil enough to try having multiple processes open the same file, it will complain and not annex it until all the writers close it.

(Well, someone really evil could turn the write bit back on after git annex clears it, and open the file again, but then really evil people can do that to files in .git/annex/objects too, and they'll get their just deserts when git annex fsck runs. So, that's ok..)

Anyway, will beat on it more tomorrow, and if all is well, this will finally go out to the beta testers.