# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@fb.com>
# Date 1417739703 28800
# Node ID acc73273b27e8d8b9599e4b20e486400b5026fbe
# Parent  065c0334846f9cfacb0a8cf3f47b4b9464dd86ba
fncache: document the fact fncache is outdate at hook run time

Using 'addfinalize' to generate 'fncache' means that no pending version of the
file will be generated for the hooks. We would have to use the
'addfilegenerator' method to get such result. However the 'fncachevfs' (who
decide that a write is necessary) have no access to the transaction to register
such file generation at add time. Having the transaction accessible to the 'vfs'
is too much trouble for no benefit. This outdated 'fncache' file at hook time is
not expected to be an issue.

The previous move from 'onclose' to 'addfinalize' had no impact on this timing.
I'm documenting it now because I looked at it.

diff -r 065c0334846f -r acc73273b27e mercurial/localrepo.py
--- a/mercurial/localrepo.py	Thu Dec 04 13:49:45 2014 -0800
+++ b/mercurial/localrepo.py	Thu Dec 04 16:35:03 2014 -0800
@@ -891,7 +891,10 @@
                                      "journal",
                                      aftertrans(renames),
                                      self.store.createmode)
-        tr.addfinalize('repo.store.write', self.store.write)
+        # note: writing the fncache only during finalize mean that the file is
+        # outdated when running hooks. As fncache is used for streaming clone,
+        # this is not expected to break anything that happen during the hooks.
+        tr.addfinalize('flush-fncache', self.store.write)
         self._transref = weakref.ref(tr)
         return tr