Add public property from storage to flowdetail.meta

Sometimes you need to access the metadata from listeners
and currently that requires a private property access.

Change-Id: Ib4f15650b15dfe8a04dbb690607d515663371d90
Fixes: #1511086

taskflow/storage.py

@@ -301,6 +301,11 @@ class Storage(object):
         # This never changes (so no read locking needed).
         return self._flowdetail.uuid
 
+    @property
+    def flow_meta(self):
+        """The flow detail metadata this storage unit is associated with."""
+        return self._flowdetail.meta
+
     @property
     def backend(self):
         """The backend this storage unit is associated with."""

taskflow/tests/unit/test_storage.py

@@ -60,11 +60,13 @@ class StorageTestMixin(object):
         s.ensure_atom(test_utils.NoopTask('my_task'))
         self.assertTrue(uuidutils.is_uuid_like(s.get_atom_uuid('my_task')))
 
-    def test_flow_name_and_uuid(self):
+    def test_flow_name_uuid_and_meta(self):
         flow_detail = models.FlowDetail(name='test-fd', uuid='aaaa')
+        flow_detail.meta = {'a': 1}
         s = self._get_storage(flow_detail)
         self.assertEqual('test-fd', s.flow_name)
         self.assertEqual('aaaa', s.flow_uuid)
+        self.assertEqual({'a': 1}, s.flow_meta)
 
     def test_ensure_task(self):
         s = self._get_storage()