On Aug 5, 2008, at 0:26 AM, Ketil Malde wrote:
The consequences of moving to the darcs-2 format are a bit unclear to me. For instance, I'd like to keep my main (export) repo in darcs-1 format, in order to make it as accessible as possible (Ubuntu still ships with darcs-1.0.9, and that's a fairly cutting edge distribution.) Can I convert my working repos to darcs-2? Should I? How about darcs-hashed? In short, I'd like to see examples of recommended migration strategies, and associated benefits.
Here's what I recommend, and what I've been doing for months, both with the large Tahoe code base -- http://allmydata.org/trac/tahoe and with numerous smaller codebases -- http://allmydata.org/trac . 1. Upgrade any executables you have to the latest stable version of darcs immediately. The new executables are fully backwards compatible -- you will not have any compatibility problems as a result of upgrading. They are also much less buggy and faster than older darcs executables. (There are at least two known issues with the darcs-2.0.2 executable which cause performance problems -- one is a issue with ghc v6.8.2 and the other is an issue with the latest version of libcurl -- v7.18.2. Hopefully the darcs core team will release darcs-2.0.3 soon to fix these two issues, but even if darcs-2.0.2 is still the current version, I recommend it over any previous version.) If your use of darcs is currently satisfying (fast enough, no bugs getting in your way), then stop at this step. You are now using the latest stable darcs executable while using old-fashioned darcs-v1 repositories. Other people who are using older versions of darcs can continue to share patches with your repositories just like always. 2. If there are problems with this situation of using darcs-2 executables and darcs-1-format repositories, then report it to the darcs-users mailing list, and then make a new hashed-format repository in parallel with your existing darcs-1-format repository, like this: darcs get --hashed ${repo} ${repo}-hashedformat Now people who have new darcs-v2 can push and pull to the - hashedformat repository and people who have darcs-v1 can continue to push and pull to the original repository. You can transfer patches between those repositories with normal darcs push and pull. For those projects of mine which have a high rate of patches I have gone ahead and added post-apply hooks to automatically do a "push --all" to the other one, like this: echo "apply posthook darcs push --all --repodir=/home/source/darcs/ tahoe/${repo}-hashedformat /home/source/darcs/tahoe/${repo}" >> $ {repo}-hashedformat/_darcs/prefs/defaults echo "apply run-posthook" >> ${repo}-hashedformat/_darcs/prefs/defaults echo "apply posthook darcs push --all --repodir=/home/source/darcs/ tahoe/${repo} /home/source/darcs/tahoe/${repo}-hashedformat" >> $ {repo}/_darcs/prefs/defaults echo "apply run-posthook" >> ${repo}/_darcs/prefs/defaults (Note that this is mutually recursive, but it terminates because the post-apply hook doesn't trigger in the case that zero patches were pushed.) If your use of darcs is currently satisfying then stop at this step. You are now using the latest stable darcs executable, and maintaining two darcs repositories -- an old-fashioned darcs-1-format repository for your darcs-1-executable-using friends and a hashed-format repository for your darcs-2-executable using friends. Your post- apply hooks cause these two repositories to get automatically synced with each other. 3. If there are problems with this situation of using darcs-2 executables and a pair of repos -- one of which is darcs-1-format repo for the use of darcs-1-executable-using users and the other of which is a hashed-format repo for the use of darcs-2-executable-using users -- then report it to the darcs-users mailing list and await further instructions. Note that these instructions do not involve any use of darcs-2-format repositories. Those are only for projects which (a) have no darcs-1- executable-using users, and (b) have no extant branches stored in darcs-1-format or hashed-format repositories. Personally step 2 has satisfied all my needs so I use the step 2 strategy for all my publicly shared repositories, although I do tend to create new private repositories with darcs-2-format. If someone wants to adapt this message to the darcs wiki I would be grateful. Regards, Zooko http://allmydata.org -- Tahoe, the Least-Authority Filesystem http://allmydata.com -- back up all your files for $5/month