A few bits about the RCS backends
Terminology
``web-edit'' means that a page is edited by using the web (CGI) interface
as opposed to using a editor and the RCS interface.
[[Subversion]]
Subversion was the first RCS to be supported by ikiwiki.
How does it work internally?
Master repository M.
RCS commits from the outside are installed into M.
There is a working copy of M (a checkout of M): W.
HTML is generated from W. rcs_update() will update from M to W.
CGI operates on W. rcs_commit() will commit from W to M.
For all the gory details of how ikiwiki handles this behind the scenes,
see [[commit-internals]].
You browse and web-edit the wiki on W.
darcs (not yet included)
Support for using darcs as a backend is being worked on by Thomas
Schwinge.
How will it work internally?
``Master'' repository R1.
RCS commits from the outside are installed into R1.
HTML is generated from R1. HTML is automatically generated (by using a
``post-hook'') each time a new change is installed into R1. It follows
that rcs_update() is not needed.
There is a working copy of R1: R2.
CGI operates on R2. rcs_commit() will push from R2 to R1.
You browse the wiki on R1 and web-edit it on R2. This means for example
that R2 needs to be updated from R1 if you are going to web-edit a page,
as the user otherwise might be irritated otherwise...
How do changes get from R1 to R2? Currently only internally in
rcs_commit(). Is rcs_prepedit() suitable?
It follows that the HTML rendering and the CGI handling can be completely
separated parts in ikiwiki.
What repository should [[RecentChanges]] and [[History]] work on? R1?
Rationale for doing it differently than in the Subversion case
darcs is a distributed RCS, which means that every checkout of a
repository is equal to the repository it was checked-out from. There is
no forced hierarchy.
R1 is nevertheless called the master repository. It's used for
collecting all the changes and publishing them: on the one hand via the
rendered HTML and on the other via the standard darcs RCS interface.
R2, the repository the CGI operates on, is just a checkout of R1 and
doesn't really differ from the other checkouts that people will branch
off from R1.
(To be continued.)
[[Git]]
Regarding the Git support, Recai says:
I have been testing it for the past few days and it seems satisfactory. I
haven't observed any race condition regarding the concurrent blog commits
and it handles merge conflicts gracefully as far as I can see.
As you may notice from the patch size, GIT support is not so trivial to
implement (for me, at least). Being a fairly fresh code base it has some
bugs. It also has some drawbacks (especially wrt merge which was the hard
part). GIT doesn't have a similar functionality like 'svn merge -rOLD:NEW
FILE' (please see the relevant comment in mergepast for more details), so I
had to invent an ugly hack just for the purpose.
