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Patch queues in bzr

The response to bazaar-ng so far has been very positive. Many people are contributing bugs to fix platform problems or to add features they urgently want. It's a very pleasant experience.

One consequence is that, as for many other projects, there are patches submitted that I haven't tested and merged yet. One thing to do would be to put them in an issue tracking system of some kind, but not every project wants that. So I was thinking about what bzr can do to help within this source management problem.

Very shortly we plan to allow submission of changesets by email, as regular diffs with extra annotations. When those come in, they can be stored in a directory on my laptop or on the webserver. Because the changesets have universally unique IDs and descriptive metadata we can then ask interesting questions about the patches:

• Which ones have now been merged into the mainline, and can be deleted from the "pending" queue?
• Which ones still apply to the head of the mainline? Which of those pass all the regression tests? These might be the easiest ones to merge -- though I still have the option of merging one that isn't a perfect fit and fixing it up myself.
• What is the dependency graph between them? Maybe one patch supersedes or updates another, or depends on some infrastructure work.

This queue could be filled by a robot that looks for patches on a mailing list, or in the public trees of past contributors. Although I call it a queue it's not necessarily a FIFO queue; the integrator (me) can pull things out in whatever order. As well as the branches that are normally captured by scm systems, bazaar-ng also helps you manage a bag of patches that don't necessarily fit together yet.

In general: human integrators have a valuable role but a tool can help make them more productive.

You can imagine extending this towards something like Rusty's trivial patch monkey, or perhaps towards filtering out security critical patches as candidates for merging into a stable series.

posted Fri 15 Apr 2005 in /software/vc/bzr | link

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