Use a task model and dumb workers

Instead of having smart workers that need to know
about the full logic of how they operate and what
they will do which makes it hard to reuse parts of
those workers switch the model so that workers are
dumb and they just run tasks which themselves can
request additional tasks to run when succesful.

This makes it more consistent when tasks are to
be retried and also makes it easier to know which
task is running and when.

Less specialized workers == good.

Closes-Bug: #1586474

Change-Id: Ie7b7303b8bf2a80b3e26b6d4ffc27787f8c794d6

1 files changed, 42 insertions, 0 deletions

diff --git a/kolla/common/task.py b/kolla/common/task.py
new file mode 100644
index 000000000..255abf85c
--- /dev/null
+++ b/kolla/common/task.py
@@ -0,0 +1,42 @@
+# 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 abc
+
+import six
+
+
+@six.add_metaclass(abc.ABCMeta)
+class Task(object):
+
+    def __init__(self):
+        self.success = False
+
+    @abc.abstractproperty
+    def name(self):
+        pass
+
+    def reset(self):
+        self.success = False
+
+    @property
+    def followups(self):
+        return []
+
+    @abc.abstractmethod
+    def run(self):
+        pass
+
+    @staticmethod
+    def set_status(status):
+        # TODO(harlowja): remove this.
+        pass