'requires' should take a string or list

* 'requires' can be a task name, or a list of task names. No
use case for a dictionary.
* added convenience methods to get requires.
* minor fix with TaskSpec: get_dict... returns {} not None.

Change-Id: I1c9ef4ab41679e10d8aab38dfae68f169608bd22

mistral/db/sqlalchemy/models.py

@@ -87,7 +87,7 @@ class Task(mb.MistralBase):
 
     id = _id_column()
     name = sa.Column(sa.String(80))
-    requires = sa.Column(st.JsonDictType())
+    requires = sa.Column(st.JsonListType())
     workbook_name = sa.Column(sa.String(80))
     execution_id = sa.Column(sa.String(36))
     description = sa.Column(sa.String(200))

mistral/engine/__init__.py

@@ -303,7 +303,7 @@ class Engine(object):
 
             db_task = db_api.task_create(workbook_name, execution_id, {
                 "name": task.name,
-                "requires": task.requires,
+                "requires": task.get_requires(),
                 "task_spec": task.to_dict(),
                 "action_spec": {} if not action_spec
                 else action_spec.to_dict(),

mistral/engine/workflow.py

@@ -42,7 +42,22 @@ def find_workflow_tasks(workbook, task_name):
 
 def find_resolved_tasks(tasks):
     # We need to analyse graph and see which tasks are ready to start
-    return _get_resolved_tasks(tasks)
+    resolved_tasks = []
+    delayed_tasks = []
+    allows = []
+    for t in tasks:
+        if t['state'] == states.SUCCESS:
+            allows += [t['name']]
+    allow_set = set(allows)
+    for t in tasks:
+        deps = t.get('requires', [])
+        if len(set(deps) - allow_set) == 0:
+        # all required tasks, if any, are SUCCESS
+            if t['state'] == states.IDLE:
+                resolved_tasks.append(t)
+            elif t['state'] == states.DELAYED:
+                delayed_tasks.append(t)
+    return resolved_tasks, delayed_tasks
 
 
 def _get_checked_tasks(target_tasks):
@@ -134,21 +149,3 @@ def _update_dependencies(tasks, graph):
     for task in tasks:
         for dep in _get_dependency_tasks(tasks, task):
             graph.add_edge(dep, task)
-
-
-def _get_resolved_tasks(tasks):
-    resolved_tasks = []
-    delayed_tasks = []
-    allows = []
-    for t in tasks:
-        if t['state'] == states.SUCCESS:
-            allows += [t['name']]
-    allow_set = set(allows)
-    for t in tasks:
-        deps = t.get('requires', {}).keys()
-        if len(set(deps) - allow_set) == 0:
-            if t['state'] == states.IDLE:
-                resolved_tasks.append(t)
-            elif t['state'] == states.DELAYED:
-                delayed_tasks.append(t)
-    return resolved_tasks, delayed_tasks

mistral/tests/resources/control_flow/require_flow.yaml

@@ -45,7 +45,7 @@ Workflow:
         flavor_id: 42
 
     attach-volumes:
-      requires: attach-volumes
+      requires: create-vms
       action: MyRest.attach-volume
       parameters:
         size: 1234
@@ -58,7 +58,8 @@ Workflow:
         server_id: 123
 
     backup-vms:
-      requires: [create-vms]
+      requires: 
+        - create-vms
       action: MyRest.backup-vm
       parameters:
         server_id: 123

mistral/tests/unit/db/test_sqlalchemy_db_api.py

@@ -232,7 +232,7 @@ TASKS = [
         'execution_id': '1',
         'name': 'my_task1',
         'description': 'my description',
-        'requires': {'my_task2': '', 'my_task3': ''},
+        'requires': ['my_task2', 'my_task3'],
         'task_spec': None,
         'action_spec': None,
         'action': {'name': 'Nova:create-vm'},
@@ -250,7 +250,7 @@ TASKS = [
         'execution_id': '1',
         'name': 'my_task2',
         'description': 'my description',
-        'requires': {'my_task4': '', 'my_task5': ''},
+        'requires': ['my_task4', 'my_task5'],
         'task_spec': None,
         'action_spec': None,
         'action': {'name': 'Cinder:create-volume'},

mistral/tests/unit/engine/default/test_executor.py

@@ -79,7 +79,7 @@ SAMPLE_TASK = {
     'task_spec': {
         'action': 'MyRest.my-action',
         'name': TASK_NAME},
-    'requires': {},
+    'requires': [],
     'state': states.IDLE}
 
 SAMPLE_CONTEXT = {

mistral/tests/unit/engine/test_workflow.py

@@ -31,7 +31,7 @@ TASKS = [
         'state': states.SUCCESS
     },
     {
-        'requires': {'create-vms': ''},
+        'requires': ['create-vms'],
         'name': 'attach-volume',
         'state': states.IDLE
     }

mistral/workbook/tasks.py

@@ -42,11 +42,11 @@ class TaskSpec(base.BaseSpec):
             elif isinstance(req, dict):
                 task['requires'] = req
 
-    def _get_on_state(self, key):
+    def _get_as_dict(self, key):
         tasks = self.get_property(key)
 
         if not tasks:
-            return None
+            return {}
 
         if isinstance(tasks, dict):
             return tasks
@@ -61,14 +61,17 @@ class TaskSpec(base.BaseSpec):
     def get_property(self, property_name, default=None):
         return self._data.get(property_name, default)
 
+    def get_requires(self):
+        return self._get_as_dict('requires').keys()
+
     def get_on_error(self):
-        return self._get_on_state("on-error")
+        return self._get_as_dict("on-error")
 
     def get_on_success(self):
-        return self._get_on_state("on-success")
+        return self._get_as_dict("on-success")
 
     def get_on_finish(self):
-        return self._get_on_state("on-finish")
+        return self._get_as_dict("on-finish")
 
     def get_action_namespace(self):
         return self.action.split('.')[0]