Add hacking check for oslo namespace usage

We want to make sure that we don't have usage of the old
oslo.concurrency naming slipping in with new changes where
we should be using the oslo_concurrency namespace.  This change
adds a hacking check to avoid use of the deprecated namespace.
As we convert more oslo libraries to the new namespace the check
will be updated to enforce use of the new namespace.

This hacking check is based upon the same N333 hacking check
in Cinder.

Change-Id: Ibec6d09e9d313c9e723f7542cedb9da5772d3de2

HACKING.rst

@@ -13,6 +13,7 @@ Cinder Specific Commandments
 - [N323] Add check for explicit import of _() to ensure proper translation.
 - [N324] Enforce no use of LOG.audit messages.  LOG.info should be used instead.
 - [N327] assert_called_once is not a valid Mock method.
+- [N333] Ensure that oslo namespaces are used for namespaced libraries.
 
 
 General

cinder/hacking/checks.py

@@ -41,6 +41,10 @@ underscore_import_check = re.compile(r"(.)*i18n\s+import\s+_(.)*")
 custom_underscore_check = re.compile(r"(.)*_\s*=\s*(.)*")
 no_audit_log = re.compile(r"(.)*LOG\.audit(.)*")
 
+# NOTE(jsbryant): When other oslo libraries switch over non-namespaced
+# imports, we will need to add them to the regex below.
+oslo_namespace_imports = re.compile(r"from[\s]*oslo[.](concurrency)")
+
 
 def no_vi_headers(physical_line, line_number, lines):
     """Check for vi editor configuration in source files.
@@ -124,6 +128,14 @@ def check_assert_called_once(logical_line, filename):
             yield (pos, msg)
 
 
+def check_oslo_namespace_imports(logical_line):
+    if re.match(oslo_namespace_imports, logical_line):
+        msg = ("N333: '%s' must be used instead of '%s'.") % (
+            logical_line.replace('oslo.', 'oslo_'),
+            logical_line)
+        yield(0, msg)
+
+
 def factory(register):
     register(no_vi_headers)
     register(no_translate_debug_logs)
@@ -131,3 +143,4 @@ def factory(register):
     register(check_explicit_underscore_import)
     register(check_no_log_audit)
     register(check_assert_called_once)
+    register(check_oslo_namespace_imports)

cinder/tests/test_hacking.py

@@ -110,3 +110,9 @@ class HackingTestCase(test.TestCase):
             "LOG.audit('My test audit log')"))), 1)
         self.assertEqual(len(list(checks.check_no_log_audit(
             "LOG.info('My info test log.')"))), 0)
+
+    def test_oslo_namespace_imports_check(self):
+        self.assertEqual(1, len(list(checks.check_oslo_namespace_imports(
+            "from oslo.concurrency import foo"))))
+        self.assertEqual(0, len(list(checks.check_oslo_namespace_imports(
+            "from oslo_concurrency import bar"))))

cinder/volume/targets/iscsi.py

@@ -10,7 +10,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-from oslo.concurrency import processutils
+from oslo_concurrency import processutils
 
 from cinder import exception
 from cinder.i18n import _, _LW, _LE