+
+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:
+
+1. I have been using ikiwiki's `--post-commit` option without apparent problems. I'm the only current user of my wiki, though.
+
+1. 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]]",
+
+1. I have noticed that running `ikiwiki` after a change to the wiki adds files to a directory called `recentchanges` under `$srcdir`. I don't understand why such files are needed; worse, they are not added to mercurial's list of tracked files, so they polute the output of `hg log`. Is this a bug? Should mercurial's commit hook be modified to add these files before the commit?
+
+--buo
+
+> No, those files should not be added to revision control. --[[Joey]]
+
+>> OK. I see two problems:
+
+>> 1. If I clone my wiki, I won't get an exact copy of it: I will lose the recentchanges history. This could be an acceptable limitation but IMO this should be documented.
+
+>>> The history is stored in mercurial. How will it be lost?
+
+>> 2. The output of `hg status` is polluted. This could be solved trivially by adding a line containing `recentchanges` to `.hgignore`. Another alternative would be to store the `recentchanges` directory inside `$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]]