Support subclass iteration for Workflow controller

Just as task specification list implementation, implement workflow
controllers class hierarchy, this patch includes:

* add two static methods in WorkflowController, _get_class() and
get_controller()
* add a variable for DirectWorkflowController and ReverseWorkflowController
respectively
* use subclasses iteration for WorkflowController
* make use of get_controller() when getting WorkflowController instance
* delete workflow_controller_factory.py
* import DirectWorkflowController and ReverseWorkflowController earlier
for WorkflowController's subclasses iteration
* add some unit tests

Change-Id: I34e61abbbd592f5252a69bd2803041dee1e49768
Implements: bp workflow-handler-design-improvements

mistral/engine1/__init__.py

@@ -0,0 +1,20 @@
+# Copyright 2015 - Huawei Technologies Co. Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+#    you may not use this file except in compliance with the License.
+#    You may obtain a copy of the License at
+#
+#        http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS,
+#    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#    See the License for the specific language governing permissions and
+#    limitations under the License.
+
+from oslo_utils import importutils
+
+
+# NOTE(xylan): import modules for WorkflowHandler subclasses iteration
+importutils.import_module('mistral.workflow.direct_workflow')
+importutils.import_module('mistral.workflow.reverse_workflow')

mistral/engine1/default_engine.py

@@ -26,11 +26,11 @@ from mistral.openstack.common import log as logging
 from mistral import utils as u
 from mistral.utils import wf_trace
 from mistral.workbook import parser as spec_parser
+from mistral.workflow import base as wf_base
 from mistral.workflow import commands
 from mistral.workflow import data_flow
 from mistral.workflow import states
 from mistral.workflow import utils as wf_utils
-from mistral.workflow import workflow_controller_factory as wfc_factory
 
 
 LOG = logging.getLogger(__name__)
@@ -67,7 +67,7 @@ class DefaultEngine(base.Engine):
 
                 wf_trace.info(wf_ex, "Starting workflow: '%s'" % wf_name)
 
-                wf_ctrl = wfc_factory.create_workflow_controller(
+                wf_ctrl = wf_base.WorkflowController.get_controller(
                     wf_ex,
                     wf_spec
                 )
@@ -119,7 +119,7 @@ class DefaultEngine(base.Engine):
             if task_ex.state == states.DELAYED:
                 return
 
-            wf_ctrl = wfc_factory.create_workflow_controller(wf_ex)
+            wf_ctrl = wf_base.WorkflowController.get_controller(wf_ex)
 
             # Calculate commands to process next.
             cmds = wf_ctrl.continue_workflow()
@@ -214,7 +214,7 @@ class DefaultEngine(base.Engine):
 
                 wf_handler.set_execution_state(wf_ex, states.RUNNING)
 
-                wf_ctrl = wfc_factory.create_workflow_controller(wf_ex)
+                wf_ctrl = wf_base.WorkflowController.get_controller(wf_ex)
 
                 # Calculate commands to process next.
                 cmds = wf_ctrl.continue_workflow()

mistral/tests/unit/workflow/test_base.py

@@ -0,0 +1,59 @@
+# Copyright 2015 - Huawei Technologies Co. Ltd
+#
+#    Licensed under the Apache License, Version 2.0 (the "License");
+#    you may not use this file except in compliance with the License.
+#    You may obtain a copy of the License at
+#
+#        http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS,
+#    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#    See the License for the specific language governing permissions and
+#    limitations under the License.
+
+import mock
+
+from mistral import exceptions
+from mistral.tests import base
+from mistral.workflow import base as wf_base
+from mistral.workflow import direct_workflow
+from mistral.workflow import reverse_workflow
+
+
+class WorkflowControllerTest(base.BaseTest):
+    def test_get_class_direct(self):
+        wf_handler_cls = wf_base.WorkflowController._get_class("direct")
+
+        self.assertIs(wf_handler_cls, direct_workflow.DirectWorkflowController)
+
+    def test_get_class_reverse(self):
+        wf_handler_cls = wf_base.WorkflowController._get_class("reverse")
+
+        self.assertIs(wf_handler_cls,
+                      reverse_workflow.ReverseWorkflowController)
+
+    def test_get_class_notfound(self):
+        exc = self.assertRaises(
+            exceptions.NotFoundException,
+            wf_base.WorkflowController._get_class,
+            "invalid"
+        )
+
+        self.assertIn("Failed to find a workflow controller", str(exc))
+
+    @mock.patch("mistral.workbook.parser.get_workflow_spec")
+    @mock.patch("mistral.workflow.base.WorkflowController._get_class")
+    def test_get_handler(self, mock_get_class, mock_get_spec):
+        mock_wf_spec = mock.MagicMock()
+        mock_wf_spec.get_type.return_value = "direct"
+        mock_get_spec.return_value = mock_wf_spec
+        mock_handler_cls = mock.MagicMock()
+        mock_get_class.return_value = mock_handler_cls
+        wf_ex = {"spec": "spec"}
+
+        wf_base.WorkflowController.get_controller(wf_ex)
+
+        mock_get_spec.assert_called_once_with("spec")
+        mock_get_class.assert_called_once_with("direct")
+        mock_handler_cls.assert_called_once_with(wf_ex)

mistral/workflow/base.py

@@ -1,5 +1,6 @@
 # Copyright 2014 - Mirantis, Inc.
 # Copyright 2015 - StackStorm, Inc.
+# Copyright 2015 - Huawei Technologies Co. Ltd
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -16,6 +17,7 @@
 import abc
 import copy
 
+from mistral import exceptions as exc
 from mistral.openstack.common import log as logging
 from mistral import utils as u
 from mistral.workbook import parser as spec_parser
@@ -108,3 +110,26 @@ class WorkflowController(object):
 
     def _is_paused_or_completed(self):
         return states.is_paused_or_completed(self.wf_ex.state)
+
+    @staticmethod
+    def _get_class(wf_type):
+        """Gets a workflow controller class by given workflow type.
+
+        :param wf_type: Workflow type.
+        :returns: Workflow controller class.
+        """
+        for wf_ctrl_cls in u.iter_subclasses(WorkflowController):
+            if wf_type == wf_ctrl_cls.__workflow_type__:
+                return wf_ctrl_cls
+
+        msg = 'Failed to find a workflow controller [type=%s]' % wf_type
+        raise exc.NotFoundException(msg)
+
+    @staticmethod
+    def get_controller(wf_ex, wf_spec=None):
+        if not wf_spec:
+            wf_spec = spec_parser.get_workflow_spec(wf_ex['spec'])
+
+        ctrl_cls = WorkflowController._get_class(wf_spec.get_type())
+
+        return ctrl_cls(wf_ex)

mistral/workflow/direct_workflow.py

@@ -38,6 +38,8 @@ class DirectWorkflowController(base.WorkflowController):
     'A'->'B' and 'A'->'C' evaluate to true.
     """
 
+    __workflow_type__ = "direct"
+
     def _get_upstream_task_executions(self, task_spec):
         return filter(
             lambda t_e: self._is_upstream_task_execution(task_spec, t_e),

mistral/workflow/reverse_workflow.py

@@ -38,6 +38,8 @@ class ReverseWorkflowController(base.WorkflowController):
     when a dependency of 'A' is resolved, will run task 'A'.
     """
 
+    __workflow_type__ = "reverse"
+
     def _find_next_commands(self):
         """Finds all tasks with resolved dependencies and return them
          in the form of workflow commands.

mistral/workflow/workflow_controller_factory.py

@@ -1,47 +0,0 @@
-# -*- coding: utf-8 -*-
-#
-# Copyright 2014 - Mirantis, Inc.
-#
-#    Licensed under the Apache License, Version 2.0 (the "License");
-#    you may not use this file except in compliance with the License.
-#    You may obtain a copy of the License at
-#
-#        http://www.apache.org/licenses/LICENSE-2.0
-#
-#    Unless required by applicable law or agreed to in writing, software
-#    distributed under the License is distributed on an "AS IS" BASIS,
-#    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-#    See the License for the specific language governing permissions and
-#    limitations under the License.
-
-from mistral import exceptions as exc
-from mistral.workbook import parser as spec_parser
-from mistral.workflow import direct_workflow
-from mistral.workflow import reverse_workflow
-
-
-def create_workflow_controller(wf_ex, wf_spec=None):
-    if not wf_spec:
-        wf_spec = spec_parser.get_workflow_spec(wf_ex.spec)
-
-    cls = _select_workflow_controller(wf_spec)
-
-    if not cls:
-        msg = 'Failed to find a workflow controller [wf_spec=%s]' % wf_spec
-        raise exc.WorkflowException(msg)
-
-    return cls(wf_ex)
-
-
-def _select_workflow_controller(wf_spec):
-    # TODO(rakhmerov): This algorithm is actually for DSL v2.
-    # TODO(rakhmerov): Take DSL versions into account.
-    wf_type = wf_spec.get_type() or 'direct'
-
-    if wf_type == 'reverse':
-        return reverse_workflow.ReverseWorkflowController
-
-    if wf_type == 'direct':
-        return direct_workflow.DirectWorkflowController
-
-    return None

requirements.txt

@@ -14,6 +14,7 @@ kombu>=2.4.8
 oslo.config>=1.4.0  # Apache-2.0
 oslo.db>=1.0.0  # Apache-2.0
 oslo.messaging>=1.4.0
+oslo.utils>=1.2.0  # Apache-2.0
 paramiko>=1.13.0
 python-cinderclient>=1.1.0
 python-heatclient>=0.2.9