From mboxrd@z Thu Jan 1 00:00:00 1970 To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> In-reply-to: Your message of "Thu, 22 May 2014 07:36:54 +0200." References: Date: Wed, 21 May 2014 23:00:08 -0700 From: Bakul Shah Message-Id: <20140522060008.6058CB827@mail.bitblocks.com> Subject: Re: [9fans] CMS/MMS (VCS/SCM/DSCM) [was: syscall 53] Topicbox-Message-UUID: ec4b744a-ead8-11e9-9d60-3106f5b1d025 On Thu, 22 May 2014 07:36:54 +0200 lucio@proxima.alt.za wrote: > > Though the idea of a scmfs (for checkins as well) and using > > vac/venti as a backend is starting to appeal to me : ) > > Let's open the discussion, Plan 9 has some baseline tools other OSes > are still thinking about and will probably implement stupidly. Since > RCS I've been thinking that there has to be a better way and CVS went > a long way to satisfy my personal requirements. Now may well be the > time to look at fresher options. I am attaching an excerpt from an old email (May 26, 2011) that I never sent. These ideas are not even half baked. But may be they will trigger some creative thoughts. On Thu, 26 May 2011 20:16:11 EDT erik quanstrom wrote: > > file servers are great, but hg concepts aren't really file-system oriented. > it might be nice to be able to > diff -c (default mybranch)^/sys/src/9/pc/mp.c > but hg diff figures out all the alloying stuff, like the top-level of the > repo anyway. also, ideas like push, pull, update, etc., don't map very well. > so a hg file server seems to me a bit like, "have hammer, see nail". I thik the filesystem model is more like an electric motor that powers all sorts of things given the right attachments! > if i'm missing why this is an interesting idea, i'd love to know what > i don't see. I partially agree with you; hence the suggestion about editor integration. It is just that I have wondering about just how far the FS model can be pushed or extended seamlessly in various directions. In the context of SCMs, we can map a specific file version to one specific path -- this is what hgfs above does. But what about push/pull/commit etc.? One idea is to to map them to operations on "magic" files. For example, - local file copies appear as normal files. - cat .hg/status == hg status - cat > .hg/commit == hg commit - cat .hg/log == hg log - echo -a > .hg/revert == hg revert -a - echo $url > .hg/push == hg push $url - echo $url > .hg/pull == hg push -u $url - ls .hg/help - cat .hg/help/push In fact the backend SCM need not be mercurial; it can git, venti etc. Can we come up with a minimal set of features? Do we gain anything by mapping $SCM commands to special files? The same question can be asked about many of existing plan9 filesystems. At least for me visualizing new uses is easier when more things can be fitted in a simpler model. Features such as atomic commits, changesets, branches, push, pull, merge etc. can be useful in multiple contexts so it would be nice if they can integrated smoothly in an FS. Example uses: - A backup is nothing but a previous commit. A nightly backup cron job to do "echo `{date} > .commit" - an offsite backup is a `push'. - Initial system install is like a clone. - An OS upgrade is like a pull. - Installing a package is like a pull (or if you built it locally, a commit) - Uinstall is reverting the change. - Each machine's config can be in its own branch. - You can use clone to create sandboxes. - A commit makes your private temp view permanent and potentially visible to others. - Conversely old commits can be spilled to a backup media (current SCMs want the entire history online). - Without needing a permanent connection you can `pull' data. [never have to do `9fs sources; ls /n/sources/contrib'.] A better integration can inspire new uses: - a timemachine like a gui can help quickly scroll through changes in some file (or even a bird's eye view of changes in all the files). - combining versioning + auto push/pull with other filesystems can open up new uses. You can keep your own daily archive of http://nyt.com/ or see how a story develops by scrolling through changes. Just some things I was mulling about. As you can see there are lots of open questions & half-baked ideas to sort through.