VirtEventLoop is now a singleton.

This prevents client libvirt version 0.8.8 to segfault when reseting libvirt
event handlers.

cloudcontrol/node/hypervisor/__init__.py

@@ -707,16 +707,6 @@ class Hypervisor(object):
         libvirt.registerErrorHandler(self.vir_error_cb, None)
         # libvirt event loop abstraction
         self.vir_event_loop = VirEventLoop(self.handler.main.evloop)
-        # This tells libvirt what event loop implementation it
-        # should use
-        libvirt.virEventRegisterImpl(
-            self.vir_event_loop.add_handle,
-            self.vir_event_loop.update_handle,
-            self.vir_event_loop.remove_handle,
-            self.vir_event_loop.add_timer,
-            self.vir_event_loop.update_timer,
-            self.vir_event_loop.remove_timer,
-        )
 
         self.vir_con = libvirt.open('qemu:///system')  # currently only support KVM
 

cloudcontrol/node/hypervisor/lib.py

@@ -6,6 +6,8 @@ from itertools import chain
 import pyev
 import libvirt
 
+from cloudcontrol.node.utils import Singleton
+
 
 logger = logging.getLogger(__name__)
 
@@ -162,6 +164,9 @@ class EventLoop(object):
 
     It cannot be used from other threads.
     """
+
+    __metaclass__ = Singleton
+
     def __init__(self, loop):
         """
         :param loop: pyev loop instance
@@ -179,6 +184,17 @@ class EventLoop(object):
         self.handles = dict()
         self.timers = dict()
 
+        # This tells libvirt what event loop implementation it
+        # should use
+        libvirt.virEventRegisterImpl(
+            self.add_handle,
+            self.update_handle,
+            self.remove_handle,
+            self.add_timer,
+            self.update_timer,
+            self.remove_timer,
+        )
+
     def add_handle(self, fd, events, cb, opaque):
         """Registers a new file handle 'fd', monitoring  for 'events' (libvirt
         event constants), firing the callback  cb() when an event occurs.