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