[PATCH 3 of 3] repoview: add optional hiddencache verification

[David Soria Parra]

# HG changeset patch
# User David Soria Parra <davidsp at fb.com>
# Date 1407430439 25200
#      Thu Aug 07 09:53:59 2014 -0700
# Node ID 5dd7cb3ba93256f916a970a4dc1f1b7e178e4176
# Parent  3da6820d38112cddfc21e2b99ab02957f93d80cf
repoview: add optional hiddencache verification

To ensure our cache approach is correct and users aren't affected, we are
verifying the cache by default. If we don't encounter any user reports of an
invalid cache we will remove the verification and the internal variable.

diff --git a/mercurial/repoview.py b/mercurial/repoview.py
--- a/mercurial/repoview.py
+++ b/mercurial/repoview.py
@@ -86,11 +86,19 @@
         if iscachevalid(repo, hideable):
             data = repo.vfs.read(cachefile)
             hidden = frozenset(struct.unpack('%sI' % (len(data) / 4), data))
+            # internal: don't document as it will be removed in the future.
+            if repo.ui.configbool('repoview', 'verifycache', True):
+                blocked = cl.ancestors(_gethiddenblockers(repo), inclusive=True)
+                computed = frozenset(r for r in hideable if r not in blocked)
+                if computed != hidden:
+                    invalidatecache(repo)
+                    repo.ui.warn(_('Cache inconsistency detected. Please ' +
+                        'open an issue on http://bz.selenic.com.\n'))
+                    hidden = computed
         else:
             # recompute cache
             blocked = cl.ancestors(_gethiddenblockers(repo), inclusive=True)
             hidden = frozenset(r for r in hideable if r not in blocked)
-
             # write cache to file
             try:
                 data = struct.pack('%sI' % len(hidden), *hidden)