1 files changed, 54 insertions, 21 deletions

diff --git a/yardstick/benchmark/scenarios/base.py b/yardstick/benchmark/scenarios/base.py
index 7af85834c..ae8bfad71 100644
--- a/yardstick/benchmark/scenarios/base.py
+++ b/yardstick/benchmark/scenarios/base.py
@@ -13,44 +13,76 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-# yardstick comment: this is a modified copy of
-# rally/rally/benchmark/scenarios/base.py
+import abc
+import time
 
-""" Scenario base class
-"""
+import six
+from stevedore import extension
 
-from __future__ import absolute_import
 import yardstick.common.utils as utils
+from yardstick.common import exceptions as y_exc
 
 
+def _iter_scenario_classes(scenario_type=None):
+    """Generator over all 'Scenario' subclasses
+
+    This function will iterate over all 'Scenario' subclasses defined in this
+    project and will load any class introduced by any installed plugin project,
+    defined in 'entry_points' section, under 'yardstick.scenarios' subsection.
+    """
+    extension.ExtensionManager(namespace='yardstick.scenarios',
+                               invoke_on_load=False)
+    for scenario in utils.itersubclasses(Scenario):
+        if not scenario_type:
+            yield scenario
+        elif getattr(scenario, '__scenario_type__', None) == scenario_type:
+            yield scenario
+
+
+@six.add_metaclass(abc.ABCMeta)
 class Scenario(object):
 
     def setup(self):
-        """ default impl for scenario setup """
+        """Default setup implementation for Scenario classes"""
         pass
 
-    def run(self, args):
-        """ catcher for not implemented run methods in subclasses """
-        raise RuntimeError("run method not implemented")
+    @abc.abstractmethod
+    def run(self, *args):
+        """Entry point for scenario classes, called from runner worker"""
+
+    def is_ended(self):
+        return False
 
     def teardown(self):
-        """ default impl for scenario teardown """
+        """Default teardown implementation for Scenario classes"""
+        pass
+
+    def pre_run_wait_time(self, time_seconds):
+        """Time waited before executing the run method"""
         pass
 
+    def post_run_wait_time(self, time_seconds):
+        """Time waited after executing the run method"""
+        time.sleep(time_seconds)
+
+    def verify_SLA(self, condition, error_msg):
+        if not condition:
+            raise y_exc.SLAValidationError(
+                case_name=self.__scenario_type__, error_msg=error_msg)
+
     @staticmethod
     def get_types():
         """return a list of known runner type (class) names"""
         scenarios = []
-        for scenario in utils.itersubclasses(Scenario):
+        for scenario in _iter_scenario_classes():
             scenarios.append(scenario)
         return scenarios
 
     @staticmethod
     def get_cls(scenario_type):
         """return class of specified type"""
-        for scenario in utils.itersubclasses(Scenario):
-            if scenario_type == scenario.__scenario_type__:
-                return scenario
+        for scenario in _iter_scenario_classes(scenario_type):
+            return scenario
 
         raise RuntimeError("No such scenario type %s" % scenario_type)
 
@@ -58,11 +90,8 @@ class Scenario(object):
     def get(scenario_type):
         """Returns instance of a scenario runner for execution type.
         """
-        for scenario in utils.itersubclasses(Scenario):
-            if scenario_type == scenario.__scenario_type__:
-                return scenario.__module__ + "." + scenario.__name__
-
-        raise RuntimeError("No such scenario type %s" % scenario_type)
+        scenario = Scenario.get_cls(scenario_type)
+        return scenario.__module__ + "." + scenario.__name__
 
     @classmethod
     def get_scenario_type(cls):
@@ -78,10 +107,14 @@ class Scenario(object):
         """
         return cls.__doc__.splitlines()[0] if cls.__doc__ else str(None)
 
-    def _push_to_outputs(self, keys, values):
+    @staticmethod
+    def _push_to_outputs(keys, values):
+        """Return a dictionary given the keys and the values"""
         return dict(zip(keys, values))
 
-    def _change_obj_to_dict(self, obj):
+    @staticmethod
+    def _change_obj_to_dict(obj):
+        """Return a dictionary from the __dict__ attribute of an object"""
         dic = {}
         for k, v in vars(obj).items():
             try: