Add unregister and reset to DictRegistry and use

unregister allows us to unregister things, so that applying
configuration changes will affect the reporting.

Change-Id: I35932c95784060349c60a11b523bf6897fb80090

cloudinit/registry.py

@@ -1,3 +1,7 @@
+# Copyright 2015 Canonical Ltd.
+# This file is part of cloud-init.  See LICENCE file for license information.
+#
+# vi: ts=4 expandtab
 import copy
 
 
@@ -5,6 +9,9 @@ class DictRegistry(object):
     """A simple registry for a mapping of objects."""
 
     def __init__(self):
+        self.reset()
+
+    def reset(self):
         self._items = {}
 
     def register_item(self, key, item):
@@ -14,6 +21,13 @@ class DictRegistry(object):
                 'Item already registered with key {0}'.format(key))
         self._items[key] = item
 
+    def unregister_item(self, key, force=True):
+        """Remove item from the registry."""
+        if key in self._items:
+            del self._items[key]
+        elif not force:
+            raise KeyError("%s: key not present to unregister" % key)
+
     @property
     def registered_items(self):
         """All the items that have been registered.

cloudinit/reporting/__init__.py

@@ -20,8 +20,6 @@ DEFAULT_CONFIG = {
     'logging': {'type': 'log'},
 }
 
-instantiated_handler_registry = DictRegistry()
-
 
 class _nameset(set):
     def __getattr__(self, name):
@@ -46,6 +44,11 @@ class ReportingEvent(object):
         return '{0}: {1}: {2}'.format(
             self.event_type, self.name, self.description)
 
+    def as_dict(self):
+        """The event represented as a dictionary."""
+        return {'name': self.name, 'description': self.description,
+                'event_type': self.event_type}
+
 
 class FinishReportingEvent(ReportingEvent):
 
@@ -60,9 +63,26 @@ class FinishReportingEvent(ReportingEvent):
         return '{0}: {1}: {2}: {3}'.format(
             self.event_type, self.name, self.result, self.description)
 
+    def as_dict(self):
+        """The event represented as json friendly."""
+        data = super(FinishReportingEvent, self).as_dict()
+        data['result'] = self.result
+        return data
 
-def add_configuration(config):
+
+def update_configuration(config):
+    """Update the instanciated_handler_registry.
+
+    :param config:
+        The dictionary containing changes to apply.  If a key is given
+        with a False-ish value, the registered handler matching that name
+        will be unregistered.
+    """
     for handler_name, handler_config in config.items():
+        if not handler_config:
+            instantiated_handler_registry.unregister_item(
+                handler_name, force=True)
+            continue
         handler_config = handler_config.copy()
         cls = available_handlers.registered_items[handler_config.pop('type')]
         instance = cls(**handler_config)
@@ -214,4 +234,5 @@ class ReportEventStack(object):
             report_finish_event(self.fullname, msg, result)
 
 
-add_configuration(DEFAULT_CONFIG)
+instantiated_handler_registry = DictRegistry()
+update_configuration(DEFAULT_CONFIG)

cloudinit/tests/test_reporting.py

@@ -96,6 +96,23 @@ class TestReportingEvent(TestCase):
             [event_type, name, description])
         self.assertEqual(expected_string_representation, event.as_string())
 
+    def test_as_dict(self):
+        event_type, name, desc = 'test_type', 'test_name', 'test_desc'
+        event = reporting.ReportingEvent(event_type, name, desc)
+        self.assertEqual(
+            {'event_type': event_type, 'name': name, 'description': desc},
+            event.as_dict())
+
+
+class TestFinishReportingEvent(TestCase):
+    def test_as_has_result(self):
+        result = reporting.status.SUCCESS
+        name, desc = 'test_name', 'test_desc'
+        event = reporting.FinishReportingEvent(name, desc, result)
+        ret = event.as_dict()
+        self.assertTrue('result' in ret)
+        self.assertEqual(ret['result'], result)
+
 
 class TestBaseReportingHandler(TestCase):
 
@@ -148,7 +165,7 @@ class TestReportingConfiguration(TestCase):
     @mock.patch.object(reporting, 'instantiated_handler_registry')
     def test_empty_configuration_doesnt_add_handlers(
             self, instantiated_handler_registry):
-        reporting.add_configuration({})
+        reporting.update_configuration({})
         self.assertEqual(
             0, instantiated_handler_registry.register_item.call_count)
 
@@ -160,7 +177,7 @@ class TestReportingConfiguration(TestCase):
         handler_cls = mock.Mock()
         available_handlers.registered_items = {handler_type_name: handler_cls}
         handler_name = 'my_test_handler'
-        reporting.add_configuration(
+        reporting.update_configuration(
             {handler_name: {'type': handler_type_name}})
         self.assertEqual(
             {handler_name: handler_cls.return_value},
@@ -178,7 +195,7 @@ class TestReportingConfiguration(TestCase):
         handler_config = extra_kwargs.copy()
         handler_config.update({'type': handler_type_name})
         handler_name = 'my_test_handler'
-        reporting.add_configuration({handler_name: handler_config})
+        reporting.update_configuration({handler_name: handler_config})
         self.assertEqual(
             handler_cls.return_value,
             reporting.instantiated_handler_registry.registered_items[
@@ -195,9 +212,25 @@ class TestReportingConfiguration(TestCase):
         available_handlers.registered_items = {handler_type_name: handler_cls}
         handler_config = {'type': handler_type_name, 'foo': 'bar'}
         expected_handler_config = handler_config.copy()
-        reporting.add_configuration({'my_test_handler': handler_config})
+        reporting.update_configuration({'my_test_handler': handler_config})
         self.assertEqual(expected_handler_config, handler_config)
 
+    @mock.patch.object(
+        reporting, 'instantiated_handler_registry', reporting.DictRegistry())
+    @mock.patch.object(reporting, 'available_handlers')
+    def test_handlers_removed_if_falseish_specified(self, available_handlers):
+        handler_type_name = 'test_handler'
+        handler_cls = mock.Mock()
+        available_handlers.registered_items = {handler_type_name: handler_cls}
+        handler_name = 'my_test_handler'
+        reporting.update_configuration(
+            {handler_name: {'type': handler_type_name}})
+        self.assertEqual(
+            1, len(reporting.instantiated_handler_registry.registered_items))
+        reporting.update_configuration({handler_name: None})
+        self.assertEqual(
+            0, len(reporting.instantiated_handler_registry.registered_items))
+
 
 class TestReportingEventStack(TestCase):
     @mock.patch('cloudinit.reporting.report_finish_event')