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| -rw-r--r-- | doc/commit-internals.mdwn | 20 | ||||
| -rw-r--r-- | doc/features.mdwn | 3 |
2 files changed, 23 insertions, 0 deletions
diff --git a/doc/commit-internals.mdwn b/doc/commit-internals.mdwn new file mode 100644 index 000000000..3a464ffbf --- /dev/null +++ b/doc/commit-internals.mdwn @@ -0,0 +1,20 @@ +Saving this irc transcript here, since it's a fairly in-depth discussion of +how ikiwiki handles commits, locking, etc, and avoids some races while +doing so. + + <tschwinge> What happens if I edit a page and in the underground a new version is installed into the svn repository? + <tschwinge> The revision when I started editing was saved, right? + <joeyh> what happens, exactly is: + <joeyh> 1. the new version that was committed first get into svn, and ikiwiki updates its WC to have the new version + <joeyh> 2. When you save your edit, ikiwiki detects a conflict. + <joeyh> 3. It uses svn merge to try to resolve it; if it's resolved it adds your changes transparently + <joeyh> 4. If the conflict needs manual resolution, it displays the page with conflict markers in the editor for you to resolve + <tschwinge> Ok. + <joeyh> Note that in step 2, it detects the conflict by using svn info to get the current Revision of the page in the WC, and compares that to a revision that is stored when you start to edit the page + <joeyh> that's why rcs_prepedit exists, to get that revision info + <tschwinge> But isn't there a race condition? + <joeyh> well, there is locking going on too + <joeyh> ikiwiki won't update the WC in step 1. if another instance of itself is getting the Revision info + <tschwinge> Is that lockwiki()? + <joeyh> yeah + <joeyh> note that when it gets the current Revision info of a page during its conflict detection, svn could have changed the page in the repo, and the WC not been updated yet due to the lock, but this isn't a race since the commit will then fail due to a regular svn conflict and the conflict detction will still work. diff --git a/doc/features.mdwn b/doc/features.mdwn index a1a69f22c..e762b27a9 100644 --- a/doc/features.mdwn +++ b/doc/features.mdwn @@ -97,6 +97,9 @@ Some of ikiwiki's features: shown in the file to resolve the conflict, so if you're already familiar with that there's no new commit marker syntax to learn. + For all the gory details of how ikiwiki handles this behind the scenes, + see [[commit-internals]]. + * page locking Wiki admins can lock pages so that only other admins can edit them. |