From 6605764c523787141272fe83c3d46a65aea7649d Mon Sep 17 00:00:00 2001
From: Joey Hess <joey@gnu.kitenet.net>
Date: Mon, 9 Feb 2009 14:58:10 -0500
Subject: [PATCH] Fix unusual --setup --post-commit command line option combo.

---
 debian/changelog        |  1 +
 doc/todo/mercurial.mdwn | 25 +++++++++++++++++++++++++
 ikiwiki.in              |  6 ++++--
 3 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/debian/changelog b/debian/changelog
index c9878c719..d2b701db7 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -8,6 +8,7 @@ ikiwiki (3.04) UNRELEASED; urgency=low
   * Work around XML::Atom strangeness that results in double-encoded posts.
     (smcv) 
   * Updated German translation (Kai Wasserbäch). Closes: #514251
+  * Fix unusual --setup --post-commit command line option combo.
 
  -- Joey Hess <joeyh@debian.org>  Sat, 31 Jan 2009 19:04:45 -0500
 
diff --git a/doc/todo/mercurial.mdwn b/doc/todo/mercurial.mdwn
index 9635b6880..e45629102 100644
--- a/doc/todo/mercurial.mdwn
+++ b/doc/todo/mercurial.mdwn
@@ -31,6 +31,13 @@ This should update the working directory and run ikiwiki every time a change is
 
 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.
 
+> 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.
+> --[[Joey]] 
+
 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]
@@ -49,6 +56,24 @@ No deadlock happens.  (Also I push to the $SRC from another machine, again, no d
 
 Of course these tests are too simple.  The problem is I have no idea when the deadlock will happen. If someone is kind enough to point out, I will run more test.
 
+> 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]]  
 
 ***
 
diff --git a/ikiwiki.in b/ikiwiki.in
index 32a24af84..c79a2bfef 100755
--- a/ikiwiki.in
+++ b/ikiwiki.in
@@ -135,7 +135,8 @@ sub main () {
 
 		if (@{$config{wrappers}} && 
 		    ! $config{render} && ! $config{dumpsetup} &&
-		    (! $config{refresh} || $config{genwrappers})) {
+		    ((! $config{refresh} && ! $config{post_commit})
+		     || $config{genwrappers})) {
 			debug(gettext("generating wrappers.."));
 			require IkiWiki::Wrapper;
 			my %origconfig=(%config);
@@ -157,7 +158,8 @@ sub main () {
 		}
 		
 		# setup implies a wiki rebuild by default
-		if (! $config{refresh} && ! $config{render}) {
+		if (! $config{refresh} && ! $config{render} &&
+		    ! $config{post_commit}) {
 			$config{rebuild}=1;
 		}
 	}
-- 
2.44.0