calling this done.. hopefully

diff --git a/doc/bugs/locking_fun.mdwn b/doc/bugs/locking_fun.mdwn
index 64d06917f3022ac41276ace5f8c9b31ea8612349..46278b0283030ccc8f2a452bc6c106b0c57480f1 100644 (file)
--- a/doc/bugs/locking_fun.mdwn
+++ b/doc/bugs/locking_fun.mdwn
@@ -7,6 +7,8 @@ This can happen because CGI.pm writes the change, then drops the main wiki
 lock before calling rcs_commit. It can't keep the lock because the commit
 hook needs to be able to lock.
 
+-------
+
 We batted this around for an hour or two on irc. The best solution seems to
 be adding a subsidiary second lock, which is only used to lock the working
 copy and is a blocking read/write lock.
@@ -34,103 +36,7 @@ original race. It should be possible though to use a separate exclusive lock,
 wrapped around these flock calls, to force them to be "atomic" and avoid that
 race.
 
-Sample patch, with stub functions for the new lock:
-
-[[toggle text="expand patch"]]
-[[toggleable text="""
-<pre>
-Index: IkiWiki/CGI.pm
-===================================================================
---- IkiWiki/CGI.pm     (revision 2774)
-+++ IkiWiki/CGI.pm     (working copy)
-@@ -494,9 +494,14 @@
-               $content=~s/\r\n/\n/g;
-               $content=~s/\r/\n/g;
- 
-+              lockwc_exclusive();
-+
-               $config{cgi}=0; # avoid cgi error message
-               eval { writefile($file, $config{srcdir}, $content) };
-               $config{cgi}=1;
-+
-+              lockwc_shared();
-+
-               if ($@) {
-                       $form->field(name => "rcsinfo", value => rcs_prepedit($file),
-                               force => 1);
-Index: IkiWiki/Plugin/poll.pm
-===================================================================
---- IkiWiki/Plugin/poll.pm     (revision 2770)
-+++ IkiWiki/Plugin/poll.pm     (working copy)
-@@ -120,7 +120,9 @@
-               $content =~ s{(\\?)\[\[poll\s+([^]]+)\s*\]\]}{$edit->($1, $2)}seg;
- 
-               # Store their vote, update the page, and redirect to it.
-+              IkiWiki::lockwc_exclusive();
-               writefile($pagesources{$page}, $config{srcdir}, $content);
-+              IkiWiki::lockwc_shared();
-               $session->param($choice_param, $choice);
-               IkiWiki::cgi_savesession($session);
-               $oldchoice=$session->param($choice_param);
-@@ -130,6 +132,10 @@
-                       IkiWiki::rcs_commit($pagesources{$page}, "poll vote ($choice)",
-                               IkiWiki::rcs_prepedit($pagesources{$page}),
-                               $session->param("name"), $ENV{REMOTE_ADDR});
-+                      # Make sure that the repo is up-to-date;
-+                      # locking prevents the post-commit hook
-+                      # from updating it.
-+                      rcs_update();
-               }
-               else {
-                       require IkiWiki::Render;
-Index: ikiwiki.in
-===================================================================
---- ikiwiki.in (revision 2770)
-+++ ikiwiki.in (working copy)
-@@ -121,6 +121,7 @@
-               lockwiki();
-               loadindex();
-               require IkiWiki::Render;
-+              lockwc_shared();
-               rcs_update();
-               refresh();
-               rcs_notify() if $config{notify};
-Index: IkiWiki.pm
-===================================================================
---- IkiWiki.pm (revision 2770)
-+++ IkiWiki.pm (working copy)
-@@ -617,6 +617,29 @@
-       close WIKILOCK;
- } #}}}
- 
-+sub lockwc_exclusive () { #{{{
-+      # Take an exclusive lock on the working copy.
-+      # The lock will be dropped on program exit.
-+      # Note: This lock should only be taken _after_ the main wiki
-+      # lock.
-+      
-+      # TODO
-+} #}}}
-+
-+sub lockwc_shared () { #{{{
-+      # Take a shared lock on the working copy. If an exclusive lock
-+      # already exists, downgrade it to a shared lock.
-+      # The lock will be dropped on program exit.
-+      # Note: This lock should only be taken _after_ the main wiki
-+      # lock.
-+      
-+      # TODO
-+} #}}}
-+
-+sub unlockwc () { #{{{
-+      close WIKIWCLOCK;
-+} #}}}
-+
- sub loadindex () { #{{{
-       open (IN, "$config{wikistatedir}/index") || return;
-       while (<IN>) {
-</pre>
-"""]]
+------
 
 My alternative idea, which seems simpler than all this tricky locking
 stuff, is to introduce a new lock file (really a flag file implemented
@@ -190,3 +96,10 @@ The commit hook takes them in the order (wclock, wikilock). This is a
 classic potential deadlock scenario. _However_, the commit hook should
 close the wclock as soon as it successfully opens it, before taking the
 wikilock, so I think that's ok.
+
+-----
+
+I've committed an implementation of my idea just above, and it seems to
+work, although testing for races etc is tricky. Calling this [[bugs/done]]
+unless someone finds a new bug or finds a problem in my thinking above.
+--[[Joey]]