174 

   175 def filteredhash(repo, maxrev):

   176     """build hash of filtered revisions in the current repoview.

   177 

   178     Multiple caches perform up-to-date validation by checking that the

   179     tiprev and tipnode stored in the cache file match the current repository.

   180     However, this is not sufficient for validating repoviews because the set

   181     of revisions in the view may change without the repository tiprev and

   182     tipnode changing.

   183 

   184     This function hashes all the revs filtered from the view and returns

   185     that SHA-1 digest.

   186     """

   187     cl = repo.changelog

   188     if not cl.filteredrevs:

   189         return None

   190     key = None

   191     revs = sorted(r for r in cl.filteredrevs if r <= maxrev)

   192     if revs:

   193         s = util.sha1()

   194         for rev in revs:

   195             s.update('%s;' % rev)

   196         key = s.digest()

   197     return key