Split notification strategies out into modules.

1) Add a Strategy class that defines the interface that a particular
notification strategy must implement.

2) Split each notification strategy out into its own module.

This is in part just an attempt at some "code cleanup", but it also has
an advantage that it is easier to make a particular notification
strategy be optional and not impose a hard dependency on all of glance.

Change-Id: Iab658637c56e764e2b3ec54c67e752db0cbfbe5c

glance/api/v1/images.py

@@ -36,7 +36,6 @@ from glance.api.v1 import controller
 from glance import image_cache
 from glance.common import cfg
 from glance.common import exception
-from glance.common import notifier
 from glance.common import wsgi
 from glance.common import utils
 import glance.store
@@ -51,6 +50,7 @@ from glance.store import (get_from_backend,
                           get_store_from_scheme,
                           UnsupportedBackend)
 from glance import registry
+from glance import notifier
 
 
 logger = logging.getLogger(__name__)

glance/notifier/__init__.py

@@ -0,0 +1,72 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2011, OpenStack LLC.
+# Copyright 2012, Red Hat, 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.
+
+
+import datetime
+import uuid
+import socket
+
+from glance.common import cfg
+from glance.common import exception
+from glance.common import utils
+
+
+_STRATEGIES = {
+    "logging": "glance.notifier.notify_log.LoggingStrategy",
+    "rabbit": "glance.notifier.notify_kombu.RabbitStrategy",
+    "noop": "glance.notifier.notify_noop.NoopStrategy",
+    "default": "glance.notifier.notify_noop.NoopStrategy",
+}
+
+
+class Notifier(object):
+    """Uses a notification strategy to send out messages about events."""
+
+    opts = [
+        cfg.StrOpt('notifier_strategy', default='default')
+    ]
+
+    def __init__(self, conf, strategy=None):
+        conf.register_opts(self.opts)
+        strategy = conf.notifier_strategy
+        try:
+            self.strategy = utils.import_class(_STRATEGIES[strategy])(conf)
+        except KeyError, ImportError:
+            raise exception.InvalidNotifierStrategy(strategy=strategy)
+
+    @staticmethod
+    def generate_message(event_type, priority, payload):
+        return {
+            "message_id": str(uuid.uuid4()),
+            "publisher_id": socket.gethostname(),
+            "event_type": event_type,
+            "priority": priority,
+            "payload": payload,
+            "timestamp": str(datetime.datetime.utcnow()),
+        }
+
+    def warn(self, event_type, payload):
+        msg = self.generate_message(event_type, "WARN", payload)
+        self.strategy.warn(msg)
+
+    def info(self, event_type, payload):
+        msg = self.generate_message(event_type, "INFO", payload)
+        self.strategy.info(msg)
+
+    def error(self, event_type, payload):
+        msg = self.generate_message(event_type, "ERROR", payload)
+        self.strategy.error(msg)

glance/notifier/notify_kombu.py

@@ -1,12 +1,10 @@
 # vim: tabstop=4 shiftwidth=4 softtabstop=4
 
-# Copyright 2011 OpenStack LLC.
-# All Rights Reserved.
+# Copyright 2011, OpenStack LLC.
 #
 #    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
@@ -15,52 +13,17 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import datetime
+
 import json
-import logging
-import socket
-import uuid
 
 import kombu.connection
 import kombu.entity
 
 from glance.common import cfg
-from glance.common import exception
+from glance.notifier import strategy
 
 
-class NoopStrategy(object):
-    """A notifier that does nothing when called."""
-
-    def __init__(self, conf):
-        pass
-
-    def warn(self, msg):
-        pass
-
-    def info(self, msg):
-        pass
-
-    def error(self, msg):
-        pass
-
-
-class LoggingStrategy(object):
-    """A notifier that calls logging when called."""
-
-    def __init__(self, conf):
-        self.logger = logging.getLogger('glance.notifier.logging_notifier')
-
-    def warn(self, msg):
-        self.logger.warn(msg)
-
-    def info(self, msg):
-        self.logger.info(msg)
-
-    def error(self, msg):
-        self.logger.error(msg)
-
-
-class RabbitStrategy(object):
+class RabbitStrategy(strategy.Strategy):
     """A notifier that puts a message on a queue when called."""
 
     opts = [
@@ -122,49 +85,3 @@ class RabbitStrategy(object):
 
     def error(self, msg):
         self._send_message(msg, "ERROR")
-
-
-class Notifier(object):
-    """Uses a notification strategy to send out messages about events."""
-
-    STRATEGIES = {
-        "logging": LoggingStrategy,
-        "rabbit": RabbitStrategy,
-        "noop": NoopStrategy,
-        "default": NoopStrategy,
-    }
-
-    opts = [
-        cfg.StrOpt('notifier_strategy', default='default')
-        ]
-
-    def __init__(self, conf, strategy=None):
-        conf.register_opts(self.opts)
-        strategy = conf.notifier_strategy
-        try:
-            self.strategy = self.STRATEGIES[strategy](conf)
-        except KeyError:
-            raise exception.InvalidNotifierStrategy(strategy=strategy)
-
-    @staticmethod
-    def generate_message(event_type, priority, payload):
-        return {
-            "message_id": str(uuid.uuid4()),
-            "publisher_id": socket.gethostname(),
-            "event_type": event_type,
-            "priority": priority,
-            "payload": payload,
-            "timestamp": str(datetime.datetime.utcnow()),
-        }
-
-    def warn(self, event_type, payload):
-        msg = self.generate_message(event_type, "WARN", payload)
-        self.strategy.warn(msg)
-
-    def info(self, event_type, payload):
-        msg = self.generate_message(event_type, "INFO", payload)
-        self.strategy.info(msg)
-
-    def error(self, event_type, payload):
-        msg = self.generate_message(event_type, "ERROR", payload)
-        self.strategy.error(msg)

glance/notifier/notify_log.py

@@ -0,0 +1,36 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2011, OpenStack LLC.
+#
+#    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 logging
+
+from glance.notifier import strategy
+
+
+class LoggingStrategy(strategy.Strategy):
+    """A notifier that calls logging when called."""
+
+    def __init__(self, conf):
+        self.logger = logging.getLogger('glance.notifier.logging_notifier')
+
+    def warn(self, msg):
+        self.logger.warn(msg)
+
+    def info(self, msg):
+        self.logger.info(msg)
+
+    def error(self, msg):
+        self.logger.error(msg)

glance/notifier/notify_noop.py

@@ -0,0 +1,34 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2011, OpenStack LLC.
+#
+#    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 glance.notifier import strategy
+
+
+class NoopStrategy(strategy.Strategy):
+    """A notifier that does nothing when called."""
+
+    def __init__(self, conf):
+        pass
+
+    def warn(self, msg):
+        pass
+
+    def info(self, msg):
+        pass
+
+    def error(self, msg):
+        pass

glance/notifier/strategy.py

@@ -0,0 +1,32 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2011, OpenStack LLC.
+# Copyright 2012, Red Hat, 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.
+
+
+class Strategy(object):
+    """Base class for a notification strategy"""
+
+    def __init__(self, conf):
+        pass
+
+    def warn(self, msg):
+        raise NotImplementedError()
+
+    def info(self, msg):
+        raise NotImplementedError()
+
+    def error(self, msg):
+        raise NotImplementedError()

glance/tests/unit/test_notifier.py

@@ -19,7 +19,8 @@ import logging
 import unittest
 
 from glance.common import exception
-from glance.common import notifier
+from glance.common import utils as common_utils
+from glance import notifier
 from glance.tests import utils
 
 
@@ -85,8 +86,10 @@ class TestRabbitNotifier(unittest.TestCase):
     """Test AMQP/Rabbit notifier works."""
 
     def setUp(self):
-        notifier.RabbitStrategy._send_message = self._send_message
-        notifier.RabbitStrategy.connect = lambda s: None
+        notify_kombu = common_utils.import_object(
+                                        "glance.notifier.notify_kombu")
+        notify_kombu.RabbitStrategy._send_message = self._send_message
+        notify_kombu.RabbitStrategy.connect = lambda s: None
         self.called = False
         conf = utils.TestConfigOpts({"notifier_strategy": "rabbit"})
         self.notifier = notifier.Notifier(conf)