Mar 24

Python speed optimization in the real world

I shipped reposurgeon 2.29 a few minutes ago. The main improvement in this version is speed – it now reads in and analyzes Subversion repositories at a clip of more than 11,000 commits per minute. This, is, in case you are in any doubt, ridiculously fast – faster than the native Subversion tools do it, and for certain far faster than any of the rival conversion utilities can manage. It’s well over an order of magnitude faster than when I began seriously tuning for speed three weeks ago. I’ve learned some interesting lessons along the way.

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Feb 26

Mode of the Reposturgeon!

It was inevitable, I suppose; reposurgeon now has its own Emacs mode.

The most laborious task in the reposurgeon conversion of a large CVS or Subversion repository is editing the comment history. You want to do this for two reasons: (1) to massage multiline comments into the summary-line + continuation form that plays well with git log and gitk, and (2) lifting Subversion and CVS commit references from, e.g., ‘2345’ to [[SVN:2345]] so reposurgeon can recognize them unambiguously and turn them into action stamps.

In the new release 2.22, there’s a small Emacs mode with several functions that help semi-automate this process.

Fear the reposturgeon!

Feb 02

Is closed source worth it for performance?

The following question appeared in my mailbox today:

If a certain program (that you need) was proprietary, and its open-source counterpart was (currently) 40% slower. Which would you use, the open-source one or the proprietary one?

The answer is: it depends. I’m going to answer this one in public because it’s a useful exercise in thinking about larger tradeoffs.

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Dec 21

robotfindskitten – the Mayan Apocalypse Edition!

Today’s very special non-world-ending software release, triggered if not originated from here at Eric Conspiracy Secret Laboratories is the amazing Zen simulation, Robot Finds Kitten. I bow in respect before Leonard Richardson and the other giants of kitten-finding history and am humbly proud to be counted among the select few who have contributed to this monumental, er, monument.

Get yer hot fresh tarball right here. It will improve your sex life, clear up your financial problems, cure your acne, and make you as a god among men. Would I lie?

Dec 20

Reposturgeon Attacks Tokyo!

Well, er, no. Actually, it attacks CVS.

Yes, that’s right, the just-shipped reposurgeon 2.11 can now read – though not write – CVS repositories. To get it to do this, I got my lunch-hooks on a relatively old program called cvsps that assembles changesets out of CVS repositories for human inspection. I gave it a –fast-export reporting mode that emits a fast-import stream instead, so now CVS has a universal exporter that will talk to any version-control system that speaks import streams. Oh, yes, and I’m maintaining cvsps now too – applause to David Mansfield, who both did a very good job on that code and sees clearly that its original use case is obsolete and –fast-export is a better way forward.

Two substantial releases of different projects in a day is a fast pace even for me. cvsps-3.0 and reposurgeon-2.11; two great tastes that taste great together.

Fear the reposturgeon!

Dec 16

The Reposturgeon That Ate Sheboygan!

Well-designed software suites should not only be correct, they should be able to demonstrate their own correctness. This is why the new 2.10 release of reposurgeon features a new tool called ‘repodiffer’. And yes, that is what it sounds like – a diff tool that operates not on files but entire repository histories. You get a report on which revisions are identical, which are different, and in the latter case where the differences are, down to which files don’t match. Commits to be paired are matched by committer and commit date. Like reposurgeon, it will work on any version-control system that can emit a fast-import stream.

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Dec 02

Beware! The Reposturgeon!

I had said I wasn’t going to do it, but…I experimented, and it turned out to be easier than I thought. Release 2.7 of reposurgeon writes (as well as reading) Subversion repositories. With the untested support for darcs, which should work exactly as well as darcs fast-export and fast-import do, this now brings the set of fully-supported version-control systems to git, hg, bzr, svn, and darcs; reposurgeon can be used for repository surgery and interconversion on any of these.

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Nov 04

reposurgeon 2.0 announcement – the full-orchestra version

I shipped reposurgeon 2.0 a few days ago with the Subversion support feature-complete, and a 2.1 minor bugfix release this morning. My previous release announcement was somewhat rushed, so here is a more detailed one explaining why anybody contemplating moving up from Subversion should care.

To go with this, there is a new version of my DVCS Migration HOWTO.

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Oct 25

Announcing autorevision

autorevision extracts metadata about the head version of your repository. This program is meant to be used by project build systems to extract properties that can be used in software version strings. It can create files containing variable and macro definitions suitable for C, C++, sh, Python, Perl, PHP, lua, Javascript, and header files suitable for use with preprocessing Info.plist files.

This was a sort of spinoff from irker, though I’ve decided it not to use it there because I want to keep irkerd and irkerhook.py in single self-contained files.

No, I don’t know dak180’s real name. He’s a pretty good collaborator, though.

Oct 21

I hate having to be the heavy…

I nearly issued a forking threat a few minutes ago. Only the second time I’ve felt a need to do that and the first was in 1993, so this is not something I do casually. And I drew back from the brink.

But I may have to if the maintainer I’m dealing with doesn’t clean up his act. His library is critical to one of my projects, but his behavior has been increasingly sloppy and erratic lately. He made a serious design mistake which he’s been trying to paper over with kluges; the kluges have made the code unstable and the latest shipped version is actually broken to the point of unusability without a patch.

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Oct 12

End-to-end arguments in software design

My title is, of course, a reference to the 1984 paper End-to-End Arguments in System Design by Reed, Saltzer, and Clark. They enunciated what has since become understood as perhaps the single most central and successful principle of the design of the Internet. If you have not read it, do chase the link; it well deserves its status as a classic.

The authors wrote mostly about the design of communications networks. But the title referred not to “network design” but to system design, and some of the early language in the paper hints that the authors thought they had discovered a design rule with implications beyond networking. I shall argue that indeed they had – there is a version of the end-to-end principle that applies productively and forcefully to the design of (non-networked) software. I shall develop that version, illustrating it with a case study from experience.

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Oct 06

irker is feature-complete

I’ve just shipped irker 1.8, and I think this brings the wild ride I’ve been on for the last eleven days approximately to a close. I consider this release feature-complete; it achieves all the goals I had in mind when the CIA service died and I decided it was up to me to rescue the situation. I expect the development pace to slow down a lot from the almost daily release I’ve been doing.

The last really major feature was irkerhook support for Mercurial repositories. I’d be mildly interested in a bzr extractor class if anyone wanted to contribute one, and that probably wouldn’t be hard – the git and hg extractors are about 70 lines each. But with git, hg, and Subversion covered it’s good enough.

Uptake of irker continues at a pleasingly rapid pace. There’s now a second symbiote application, a poller daemon that watches the log of a specified Subversion repository and uses irkerd to ship notifications from it. This can be useful if you don’t have write access to the repo hooks and thus cannot install irkerhook.

Time for a pause and some reflection on lessons to be learned.

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