Update state sequence for failed flows

When flow failes, it now transitions to FAILURE state, and then
goes throgh REVERTING to REVERTED. So, flows that failed and were
reverted are now left in REVERTED state.

Change-Id: Ieb9135673847eb4942afa61696975d013b809819

taskflow/engines/action_engine/engine.py

@@ -26,6 +26,7 @@ from taskflow.engines import base
 
 from taskflow import decorators
 from taskflow import exceptions as exc
+from taskflow.openstack.common import excutils
 from taskflow import states
 from taskflow import storage as t_storage
 
@@ -50,15 +51,20 @@ class ActionEngine(base.EngineBase):
         self.notifier = misc.TransitionNotifier()
         self.task_notifier = misc.TransitionNotifier()
 
-    def _revert(self, current_failure):
+    def _revert(self, current_failure=None):
         self._change_state(states.REVERTING)
-        state = self._root.revert(self)
+        try:
+            state = self._root.revert(self)
+        except Exception:
+            with excutils.save_and_reraise_exception():
+                self._change_state(states.FAILURE)
+
         self._change_state(state)
         if state == states.SUSPENDED:
             return
-        self._change_state(states.FAILURE)
         misc.Failure.reraise_if_any(self._failures)
-        current_failure.reraise()
+        if current_failure:
+            current_failure.reraise()
 
     def _reset(self):
         self._failures = []
@@ -82,7 +88,7 @@ class ActionEngine(base.EngineBase):
                 raise exc.MissingDependencies(self._flow, sorted(missing))
             self._run()
         elif self._failures:
-            self._revert(self._failures[-1])
+            self._revert()
         else:
             self._run()
 
@@ -91,6 +97,7 @@ class ActionEngine(base.EngineBase):
         try:
             state = self._root.execute(self)
         except Exception:
+            self._change_state(states.FAILURE)
             self._revert(misc.Failure())
         else:
             self._change_state(state)

taskflow/tests/unit/test_action_engine.py

@@ -199,13 +199,13 @@ class EngineTaskTest(EngineTestBase):
             ['flow RUNNING',
              'fail RUNNING',
              'fail FAILURE',
+             'flow FAILURE',
              'flow REVERTING',
              'fail REVERTING',
              'fail reverted(Failure: exceptions.RuntimeError: Woot!)',
              'fail REVERTED',
              'fail PENDING',
-             'flow REVERTED',
-             'flow FAILURE'])
+             'flow REVERTED'])
 
     def test_invalid_flow_raises(self):
         value = 'i am string, not task/flow, sorry'
@@ -638,7 +638,7 @@ class SuspendFlowTest(EngineTestBase):
              'b reverted(5)'])
         with self.assertRaisesRegexp(RuntimeError, '^Woot'):
             engine.run()
-        self.assertEquals(engine.storage.get_flow_state(), states.FAILURE)
+        self.assertEquals(engine.storage.get_flow_state(), states.REVERTED)
         self.assertEquals(
             self.values,
             ['a',

taskflow/tests/unit/test_linear_flow.py

@@ -89,9 +89,9 @@ class LinearFlowTest(test.TestCase):
 
         expected_states = [
             states.RUNNING,
+            states.FAILURE,
             states.REVERTING,
             states.REVERTED,
-            states.FAILURE,
         ]
         self.assertEquals(expected_states, changes)
         expected_states = [