initial version

Change-Id: I699e0ab082657880998d8618fe29eb7f56c6c661

watcher/common/messaging/events/event.py

@@ -0,0 +1,48 @@
+# -*- encoding: utf-8 -*-
+# Copyright (c) 2015 b<>com
+#
+# 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 Event(object):
+    """Generic event to use with EventDispatcher"""
+
+    def __init__(self, event_type=None, data=None, request_id=None):
+        """Default constructor
+
+        :param event_type: the type of the event
+        :param data: a dictionary which contains data
+        :param request_id: a string which represent the uuid of the request
+        """
+        self._type = event_type
+        self._data = data
+        self._request_id = request_id
+
+    def get_type(self):
+        return self._type
+
+    def set_type(self, type):
+        self._type = type
+
+    def get_data(self):
+        return self._data
+
+    def set_data(self, data):
+        self._data = data
+
+    def set_request_id(self, id):
+        self._request_id = id
+
+    def get_request_id(self):
+        return self._request_id

watcher/common/messaging/events/event_dispatcher.py

@@ -0,0 +1,78 @@
+# -*- encoding: utf-8 -*-
+# Copyright (c) 2015 b<>com
+#
+# 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 watcher.decision_engine.framework.messaging.events import Events
+from watcher.openstack.common import log
+
+LOG = log.getLogger(__name__)
+
+
+class EventDispatcher(object):
+    """Generic event dispatcher which listen and dispatch events"""
+
+    def __init__(self):
+        self._events = dict()
+
+    def __del__(self):
+        self._events = None
+
+    def has_listener(self, event_type, listener):
+        """Return true if listener is register to event_type """
+        # Check for event type and for the listener
+        if event_type in self._events.keys():
+            return listener in self._events[event_type]
+        else:
+            return False
+
+    def dispatch_event(self, event):
+        LOG.debug("dispatch evt : %s" % str(event.get_type()))
+        """
+        Dispatch an instance of Event class
+        """
+        if Events.ALL in self._events.keys():
+            listeners = self._events[Events.ALL]
+            for listener in listeners:
+                listener(event)
+
+        # Dispatch the event to all the associated listeners
+        if event.get_type() in self._events.keys():
+            listeners = self._events[event.get_type()]
+            for listener in listeners:
+                listener(event)
+
+    def add_event_listener(self, event_type, listener):
+        """Add an event listener for an event type"""
+        # Add listener to the event type
+        if not self.has_listener(event_type, listener):
+            listeners = self._events.get(event_type, [])
+            listeners.append(listener)
+            self._events[event_type] = listeners
+
+    def remove_event_listener(self, event_type, listener):
+        """Remove event listener. """
+        # Remove the listener from the event type
+        if self.has_listener(event_type, listener):
+            listeners = self._events[event_type]
+
+            if len(listeners) == 1:
+                # Only this listener remains so remove the key
+                del self._events[event_type]
+
+            else:
+                # Update listeners chain
+                listeners.remove(listener)
+                self._events[event_type] = listeners