refactor daemons to use common base class in preparation for network refactor

1 files changed, 103 insertions, 0 deletions

diff --git a/nova/node.py b/nova/node.py
new file mode 100644
index 000000000..852344da9
--- /dev/null
+++ b/nova/node.py
@@ -0,0 +1,103 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# All Rights Reserved.
+#
+#    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.
+
+"""
+Generic Node baseclass for all workers that run on hosts
+"""
+
+import inspect
+import logging
+import os
+
+from twisted.internet import defer
+from twisted.internet import task
+from twisted.application import service
+
+from nova import datastore
+from nova import flags
+from nova import rpc
+from nova.compute import model
+
+
+FLAGS = flags.FLAGS
+
+flags.DEFINE_integer('report_interval', 10,
+                     'seconds between nodes reporting state to cloud',
+                     lower_bound=1)
+
+class Node(object, service.Service):
+    """Base class for workers that run on hosts"""
+
+    @classmethod
+    def create(cls,
+               report_interval=None, # defaults to flag
+               bin_name=None, # defaults to basename of executable
+               topic=None): # defaults to basename - "nova-" part
+        """Instantiates class and passes back application object"""
+        if not report_interval:
+            # NOTE(vish): set here because if it is set to flag in the
+            #             parameter list, it wrongly uses the default
+            report_interval = FLAGS.report_interval
+        # NOTE(vish): magic to automatically determine bin_name and topic
+        if not bin_name:
+            bin_name = os.path.basename(inspect.stack()[-1][1])
+        if not topic:
+            topic = bin_name.rpartition("nova-")[2]
+        logging.warn("Starting %s node" % topic)
+        node_instance = cls()
+
+        conn = rpc.Connection.instance()
+        consumer_all = rpc.AdapterConsumer(
+                connection=conn,
+                topic='%s' % topic,
+                proxy=node_instance)
+
+        consumer_node = rpc.AdapterConsumer(
+                connection=conn,
+                topic='%s.%s' % (topic, FLAGS.node_name),
+                proxy=node_instance)
+
+        pulse = task.LoopingCall(node_instance.report_state,
+                                 FLAGS.node_name,
+                                 bin_name)
+        pulse.start(interval=report_interval, now=False)
+
+        consumer_all.attach_to_twisted()
+        consumer_node.attach_to_twisted()
+
+        # This is the parent service that twistd will be looking for when it
+        # parses this file, return it so that we can get it into globals below
+        application = service.Application(bin_name)
+        node_instance.setServiceParent(application)
+        return application
+
+    @defer.inlineCallbacks
+    def report_state(self, nodename, daemon):
+        # TODO(termie): make this pattern be more elegant. -todd
+        try:
+            record = model.Daemon(nodename, daemon)
+            record.heartbeat()
+            if getattr(self, "model_disconnected", False):
+                self.model_disconnected = False
+                logging.error("Recovered model server connection!")
+
+        except datastore.ConnectionError, ex:
+            if not getattr(self, "model_disconnected", False):
+                self.model_disconnected = True
+                logging.exception("model server went away")
+        yield