doc/todo/mercurial.mdwn



Is the code sufficiently robust? It just warns when mercurial fails.
When rcs_commit is called with a $user that is an openid, it will be
passed through to mercurial -u. Will mercurial choke on this?
Nope. Mercurial doesn't expect any particular format for the username,
though "Name address@domain" is standard. --[[bma]]
The way -u $user is passed to hg commit, there's no way to tell
if a given commit came in over the web or was done directly. So
rcs_recentchanges hardcodes 'committype => "mercurial"'. See the monotone
backend for an example of one that does this right.
The rcs_commit implementation seems not to notice if the file has been
changed since a web edit started. Unlike all the other frontends, which
use the rcstoken to detect if the web commit started editing an earlier
version of the file, and if so, merge the two sets of changes together.
It seems that with the current mercurial commit code, it will always
blindly overwrite the current file with the web edited version, losing
any other changes.
rcs_commit_staged, rcs_rename, rcs_remove, and rcs_diff are not
implemented for mercurial, and so attachments, remove and rename plugins
and recentchangesdiff cannot be used with it. (These should be fairly
easy to add..)

Posthook: in $srcdir/.hg/hgrc, I have the following
[hooks]
incoming.update = hg up
update.ikiwiki = ikiwiki --setup /path/to/ikiwiki.setup --refresh

This should update the working directory and run ikiwiki every time a change is recorded (someone who knows mercurial better than I do may be able to suggest a better way, but this works for me.)

Try running it with --post-commit instead of --refresh. That should
work better, handling both the case where the edit was made via the web
and then committed, and the case where a commit was made directly.
It can deadlock if the post-commit hook runs with --refresh in the
former case. --[[Joey]]

The problem with --post-commit is that if you delete some pages in $SRC, ikiwiki --setup setupfile --post-commit will not delete them in $DEST. --[[users/weakish]]

You should really be using a setup file that has mercurial_wrapper
set, and running the wrapper generated by that from your hook.
That will work. I think that the --setup --post-commit on the command
line is currently broken and does the same expensive rebuild process as --setup
alone (which doesn't delete files from $DEST either). Will fix that.
(fixed)
--[[Joey]]


Mercurial doesn't support put hooks in .hg/hooks/* (like git). In Mercurial, the only way to run
your own hooks is specifying them in the hgrc file. (Or write a new extension.)
I guess use a very long command will work.
(e.g. ikiwiki --post-commit --a-lot-of-switches --set var=value $SRC $DEST)
(Fortunately ikiwiki supports --set var=value so without --setup works.)
Alternative is always editing via cgi or pushing.  Never work on the $SRC/repo directly.
--[[users/weakish]]


I don't see anything preventing you from using a setup file with
mercurial_wrapper => ".hg/ikiwiki-hook", and then modifying the hgrc
to run that wrapper. --[[Joey]]


Thanks for pointing out this.  I have some stupid misunderstanding on the
usage of mercurial_wrapper before.  The wrapper works nicely! --[[weakish]]


I add the following to .hg/hgrc:(I use changegroup since I don't think we need refresh per changeset, please point out if I am wrong.)
[hooks]
changegroup = hg update >&2 && ikiwiki --setup path.to.setup.file --refresh
post-commit = path.to.the.mercurial.wrapper


I have no idea when the deadlock will happen.  --[[users/weakish]]

For the deadlock to occur, a edit has to be made via the web.
Ikiwiki,
running as a CGI, takes a lock on the wiki, and commits the edit,
continuing to run in the background, with the lock still held.
When the edit is committed, the hg hook runs, running ikwiki --refresh.
Nearly the first thing that process does it try to lock the wiki..
which is already locked. This lock is taken in a blocking manner,
thus the deadlock -- the cgi is waiting for the commit to finish before
dropping the lock, and the commit is blocked waiting for the lock to be
released.
--post-commit avoids this problem by checking if the cgi is running
and avoiding doing anything in that case. (While still handing the
refresh if the commit was not made by the CGI.)
So in that case, the commit finishes w/o ikiwiki doing anything,
and the ikiwiki CGI handles the wiki refresh.
--[[Joey]]


I have a few notes on mercurial usage after trying it out for a while:


I have been using ikiwiki's --post-commit option without apparent problems. I'm the only current user of my wiki, though.


The ikiwiki.setup file included in ikiwiki works with mercurial's hgserve, which is not the preferred solution. Mercurial's hgwebdir.cgi is more flexible and doesn't require running a server. I have this in my .setup file:
 # Mercurial stuff.
 rcs => "mercurial",
 historyurl => "http://localhost/cgi-bin/hgwebdir.cgi/ikiwiki/log/tip/\[[file]]",
 diffurl => "http://localhost/cgi-bin/hgwebdir.cgi/ikiwiki/diff/tip/\[[file]]",


I have noticed that running ikiwiki after a change to the wiki adds files to a directory called recentchanges under $srcdir. I don't understand why such files are needed; worse, they are not added to mercurial's list of tracked files, so they polute the output of hg log. Is this a bug? Should mercurial's commit hook be modified to add these files before the commit?


--buo

No, those files should not be added to revision control. --[[Joey]]


OK. I see two problems:


If I clone my wiki, I won't get an exact copy of it: I will lose the recentchanges history. This could be an acceptable limitation but IMO this should be documented.


The history is stored in mercurial. How will it be lost?


The output of hg status is polluted. This could be solved trivially by adding a line containing recentchanges to .hgignore. Another alternative would be to store the recentchanges directory inside $srdcir/.ikiwiki.


I think the ideal solution would be to build $destdir/recentchanges/* directly from the output of hg log. --[[buo]]


That would be 100 times as slow, so I chose not to do that. --[[Joey]]


Since this is confusing people, allow me to clarify: Ikiwiki's
recentchanges generation pulls log information directly out of the VCS as
needed. It caches it in recentchanges/* in the scrdir. These cache
files need not be preserved, should never be checked into VCS, and if
you want to you can configure your VCSignore file to ignore them,
just as you can configure it to ignore the .ikiwiki directory in the
scrdir. --[[Joey]]