Python 3: dict.iteritems() and dict.itervalues()

* Replace dict.itervalues() with dict.values(). The Python 3 dict
  type has no itervalues() method, the old itervalues() method was
  renamed to values().
* Same change for dict.iteritems(), replaced with dict.items()
* Exception: use six.itervalues() to yield on sock_data_by_port

Using six.itervalues() and six.iteritems() would make the code less
readable. The overhead of creating a temporary list is considered as
negligible:
http://lists.openstack.org/pipermail/openstack-dev/2015-June/066391.html

Change-Id: Ifbe7faa16d419e7fe26f1fb464019b83c9171c45

swift/common/wsgi.py

@@ -31,6 +31,7 @@ import eventlet.debug
 from eventlet import greenio, GreenPool, sleep, wsgi, listen, Timeout
 from paste.deploy import loadwsgi
 from eventlet.green import socket, ssl, os as green_os
+import six
 from six import BytesIO
 from six import StringIO
 from six.moves.urllib.parse import unquote
@@ -643,7 +644,10 @@ class PortPidState(object):
         Yield all current listen sockets.
         """
 
-        for orphan_data in self.sock_data_by_port.itervalues():
+        # Use six.itervalues() instead of calling directly the .values() method
+        # on Python 2 to avoid a temporary list, because sock_data_by_port
+        # comes from users and can be large.
+        for orphan_data in six.itervalues(self.sock_data_by_port):
             yield orphan_data['sock']
 
     def forget_port(self, port):

swift/container/backend.py

@@ -861,7 +861,7 @@ class ContainerBroker(DatabaseBroker):
                     'DELETE FROM object WHERE ' + query_mod +
                     'name=? AND storage_policy_index=?',
                     ((rec['name'], rec['storage_policy_index'])
-                     for rec in to_delete.itervalues()))
+                     for rec in to_delete.values()))
             if to_add:
                 curs.executemany(
                     'INSERT INTO object (name, created_at, size, content_type,'
@@ -870,7 +870,7 @@ class ContainerBroker(DatabaseBroker):
                     ((rec['name'], rec['created_at'], rec['size'],
                       rec['content_type'], rec['etag'], rec['deleted'],
                       rec['storage_policy_index'])
-                     for rec in to_add.itervalues()))
+                     for rec in to_add.values()))
             if source:
                 # for replication we rely on the remote end sending merges in
                 # order with no gaps to increment sync_points

test/unit/common/middleware/test_recon.py

@@ -300,7 +300,7 @@ class TestReconSuccess(TestCase):
                 array.array('H', [4, 2, 4, 3])]
         }
 
-        for ringfn, replica_map in rings.iteritems():
+        for ringfn, replica_map in rings.items():
             ringpath = os.path.join(self.tempdir, ringfn)
             self._create_ring(ringpath, replica_map, self.ring_devs,
                               self.ring_part_shift)

test/unit/common/test_db.py

@@ -691,9 +691,9 @@ class TestDatabaseBroker(unittest.TestCase):
         self.assertTrue(stub_called[0])
         # ensure that metadata was cleared
         m2 = broker.metadata
-        self.assertTrue(not any(v[0] for v in m2.itervalues()))
+        self.assertTrue(not any(v[0] for v in m2.values()))
         self.assertTrue(all(v[1] == normalize_timestamp('2')
-                            for v in m2.itervalues()))
+                            for v in m2.values()))
 
     def test_get(self):
         broker = DatabaseBroker(':memory:')