Not long ago I pulled the plug on one of the two CVS export utilities I was maintaining. One consequence of this is that I decided I needed to get the other one out of beta and into a state I would be willing to ship as 1.0.
And lo, it has come to pass. I just shipped cvs-fast-export 1.0. It has been well field-tested; a couple of weeks ago I used it to rescue the history of Gnu Troff.
There are several CVS exporters out there that suck pretty badly. (To be fair, the perversity of CVS is such that doing an even half-decent job of lifting CVS histories into a modern version-control system is quite difficult.) Now that this one is shipped I know of exactly two that don’t suck. The other one is Michael Haggerty’s cvs2git, which I’m working with him on improving.
Tradeoffs: cvs2git is slow and a bit clunky to use (I’m improving the latter but can’t fix the former). cvs-fast-export is blazingly fast (like, 3.7K commits a minute) but has a hard repository-size limit – above it you run out of core and the OS reaps the process in mid-flight. (Very few projects will hit this limit.)
For each tool there are weird CVS edge cases that it gets wrong. The sets of edge cases are different. cvs2git’s may be smaller, but I’m not sure of that; we haven’t set up head-to-head testing yet. Most projects will not trip over either set of problems.
cvs-fast-export is better documented, especially around error conditions.
Help stamp out CVS in our lifetime!
I really hadn’t been planning to comment on the Duck Dynasty brouhaha. But conservative gadfly Mark Steyn (a very funny, witty man even if you disagree with his politics) has described the actual strategy of GLAAD and its allies with a pithy phrase that I think describes wider circulation – “de-normalizing dissent”.
OK, let’s get the obvious out of the way first. Judged by his remarks in Esquire, Duck Dynasty patriarch Phil Robertson is an ignorant, bigoted cracker who reifies almost every bad redneck stereotype there is. His religion is barely distinguishable from a psychotic delusional system. Nothing I am about to say should be construed as a defense of the content of his beliefs.
On the other hand, Steyn has a point when he detects something creepy and totalitarian about the attempt to hound Robertson out of his job and out of public life. True, nothing GLAAD has done rises to the level of state coercion – there is no First Amendment issue here, no violence or threat of same in play.
But what GLAAD and its allies are trying to accomplish is not mere moral suasion either; they’re trying to make beliefs they disapprove of unspeakable in polite society by making the consequences of expressing them so unpleasant that people will self-censor. In Steyn’s well-chosen phrase, they’re trying to de-normalize dissent.
There are a lot of things people writing software do in the world of bits that don’t have easy analogs in the world of atoms. Sometimes it can be tremendously clarifying when one of those things gets a name, as for example when Martin Fowler invented the term “refactoring” to describe modifying a codebase with the intent to improve its structure or aesthetics without changing its behavior.
There’s a related thing we do a lot when trying to wrap our heads around large, complicated codebases. Often the most fruitful way to explore code to modify it. Because you don’t really know you have understood a piece of code until you can modify it successfully.
Sometimes – often – this can feel like launching an expedition into the untamed jungle of code, from some base camp on the periphery deeper and deeper into trackless wilderness. It is certainly possible to lose your bearings. And large, old codebases can be very jungly, overgrown and organic – full of half-planned and semi-random modifications, dotted with occasional clearings where the light gets in and things locally make sense.
There’s an ancient Unix maxim to the effect that a tool that gets 85% of your job done now is preferable to one that gets 100% done never. Sometimes chasing corner cases is more work than the problem really justifies.
In today’s dharma lesson, I shall illustrate this principle with a real-world and useful example.
I did something unusual today. I pulled the plug on one of my own projects.
In Solving the CVS-lifting problem and Announcing cvs-fast-export I described how I accidentally ended up maintaining two different CVS-to-something-else exporters.
I finally got enough round tuits to put together two-thirds of the head-to-head comparison I’ve been meaning to do – that is, compare the import-stream output of cvs-fast-export to that of cvsps to see how they rate against each other. I wrote both git-stream output stages, so this was really a comparison of the analysis engines.
I wasn’t surprised which program did a better job; I’ve read and modified both pieces of code, after all. Keith Packard’s analysis engine, in cvs-fast-export, is noticeably more elegant and craftsmanlike than the equivalent in cvsps. (Well, duh. Yeah, that Keith Packard, the co-architect of X.)
What did surprise me was the magnitude of the quality difference once I could actually compare them head-to-head. Bletch. Turns out it’s not a case of a good job versus mildly flaky, but of good job versus suckage.
The comparison, and what I discovered when I tried to patch cvsps to behave less badly, was so damning that I did something I don’t remember ever having felt the need to do before. I shot one of my own projects through the head.
A few days ago I released reposurgeon 2.43. Since then I’ve been finishing up yet another conversion of an ancient repository – groff, this time, from CVS to git at the maintainer’s request. In the process, some ugly features and irregularities in the reposurgeon command language annoyed me enough that I began fixing them.
This, then, is a reposurgeon 3.0 release warning. If you’ve been using 2.43 or earlier versions, be aware that there are already significant non-backwards-compatible changes to the language in the repository head version and may be more before I ship. Explanation follows, embedded in more general thoughts about the art of language design.
If you’re a regular at A&D or on my G+ feed, and even possibly if you aren’t, you’ll have noticed that I ship an awful lot of code. I do get questions about this; between GPSD, reposurgeon, giflib, doclifter, and bimpty-bump other projects it is reasonable that other hackers sometimes wonder how I do it.
Here’s part of my answer: be fanatical about automating away every part of your workflow that you can. Every second you don’t spend on mechanical routines is a second you get to use as creative time.
Soon, after an 11-year alpha period, I’m going to ship version 1.0 of one of my main automation tools. This thing would be my secret weapon if I had secrets. The story of how it came to be, and why it took 11 years to mature, should be interesting to other hackers on several different levels.
Though there haven’t been any huge dramatic improvements since Subversion analysis got good enough to use even on horribly gnarly repositories, reposurgeon continues to quietly get better and faster. I shipped 2.43 a few minutes ago.