+ def downgrade(self, names=None):
+ """Downgrade a set of resource locks from exclusive to shared mode.
+
+ The locks must have been acquired in exclusive mode.
+
+ """
+ assert self.is_owned(), ("downgrade on lockset %s while not owning any"
+ " lock" % self.name)
+
+ # Support passing in a single resource to downgrade rather than many
+ if isinstance(names, basestring):
+ names = [names]
+
+ owned = self.list_owned()
+
+ if names is None:
+ names = owned
+ else:
+ names = set(names)
+ assert owned.issuperset(names), \
+ ("downgrade() on unheld resources %s (set %s)" %
+ (names.difference(owned), self.name))
+
+ for lockname in names:
+ self.__lockdict[lockname].downgrade()
+
+ # Do we own the lockset in exclusive mode?
+ if self.__lock.is_owned(shared=0):
+ # Have all locks been downgraded?
+ if not compat.any(lock.is_owned(shared=0)
+ for lock in self.__lockdict.values()):
+ self.__lock.downgrade()
+ assert self.__lock.is_owned(shared=1)
+
+ return True
+