Merge "Formalize base service classes"

neutron_lib/api/extensions.py

@@ -106,7 +106,8 @@ class ExtensionDescriptor(object):
     def get_plugin_interface(self):
         """Returns an abstract class which defines contract for the plugin.
 
-        The abstract class should inherit from extensions.PluginInterface,
+        The abstract class should inherit from
+        neutron_lib.services.base.ServicePluginBase.
         Methods in this abstract class should be decorated as abstractmethod
         """
 

neutron_lib/services/base.py

@@ -15,32 +15,7 @@ import abc
 import six
 
 
-@six.add_metaclass(abc.ABCMeta)
-class _PluginInterface(object):
-
-    @classmethod
-    def __subclasshook__(cls, klass):
-        """Checking plugin class.
-
-        The __subclasshook__ method is a class method
-        that will be called every time a class is tested
-        using issubclass(klass, _PluginInterface).
-        In that case, it will check that every method
-        marked with the abstractmethod decorator is
-        provided by the plugin class.
-        """
-
-        if not cls.__abstractmethods__:
-            return NotImplemented
-
-        for method in cls.__abstractmethods__:
-            if any(method in base.__dict__ for base in klass.__mro__):
-                continue
-            return NotImplemented
-        return True
-
-
-class _WorkerSupportServiceMixin(object):
+class WorkerBase(object):
 
     @property
     def _workers(self):
@@ -74,11 +49,31 @@ class _WorkerSupportServiceMixin(object):
 
 
 @six.add_metaclass(abc.ABCMeta)
-class ServicePluginBase(_PluginInterface,
-                        _WorkerSupportServiceMixin):
+class ServicePluginBase(WorkerBase):
     """Define base interface for any Advanced Service plugin."""
     supported_extension_aliases = []
 
+    @classmethod
+    def __subclasshook__(cls, klass):
+        """Checking plugin class.
+
+        The __subclasshook__ method is a class method
+        that will be called every time a class is tested
+        using issubclass(klass, ServicePluginBase).
+        In that case, it will check that every method
+        marked with the abstractmethod decorator is
+        provided by the plugin class.
+        """
+
+        if not cls.__abstractmethods__:
+            return NotImplemented
+
+        for method in cls.__abstractmethods__:
+            if any(method in base.__dict__ for base in klass.__mro__):
+                continue
+            return NotImplemented
+        return True
+
     @abc.abstractmethod
     def get_plugin_type(self):
         """Return one of predefined service types.

neutron_lib/tests/unit/services/test_base.py

@@ -16,7 +16,7 @@ from neutron_lib.services import base
 from neutron_lib.tests import _base as test_base
 
 
-class _Worker(base._WorkerSupportServiceMixin):
+class _Worker(base.WorkerBase):
     pass
 
 
@@ -43,14 +43,21 @@ class Test_WorkerSupportServiceMixin(test_base.BaseTestCase):
         self.assertSequenceEqual(workers, self.worker.get_workers())
 
 
-class Test_PluginInterface(test_base.BaseTestCase):
+class TestPluginInterface(test_base.BaseTestCase):
+
+    class ServicePluginStub(base.ServicePluginBase):
+        def get_plugin_type(self):
+            pass
+
+        def get_plugin_description(self):
+            pass
 
     def test_issubclass_hook(self):
-        class A(object):
+        class A(TestPluginInterface.ServicePluginStub):
             def f(self):
                 pass
 
-        class B(base._PluginInterface):
+        class B(base.ServicePluginBase):
             @abc.abstractmethod
             def f(self):
                 pass
@@ -62,18 +69,18 @@ class Test_PluginInterface(test_base.BaseTestCase):
             def f(self):
                 pass
 
-        class B(base._PluginInterface):
+        class B(base.ServicePluginBase):
             def f(self):
                 pass
 
         self.assertFalse(issubclass(A, B))
 
     def test_issubclass_hook_not_all_methods_implemented(self):
-        class A(object):
+        class A(TestPluginInterface.ServicePluginStub):
             def f(self):
                 pass
 
-        class B(base._PluginInterface):
+        class B(base.ServicePluginBase):
             @abc.abstractmethod
             def f(self):
                 pass

releasenotes/notes/public-service-classes-e52d7c79a075b799.yaml

@@ -0,0 +1,10 @@
+---
+features:
+  - The ``neutron_lib.api.extensions.ExtensionDescriptor`` class's
+    ``get_plugin_interface`` method now formally only supports
+    ``neutron_lib.services.base.ServicePluginBase``. This change reflects
+    the existing usage by consumers as almost all are returning
+    instances of ``ServicePluginBase`` already.
+  - The class ``WorkerBase`` is now available and provides the same
+    functionality that's provided by
+    ``neutron.worker.WorkerSupportServiceMixin``.