storagepool: Don't double invoke 'refresh' when events are present

We need to tweak refresh() handling to work similar to the shared
XML and status caching in libvirtobject.py: when the user manually
invokes the refresh() operation, and storage events are set up,
we just invoke the refresh() but let the event loop handle
refreshing the cache.

This fixes a backtrace when invoking a manual refresh via the
host details dialog

virtManager/connection.py

@@ -778,9 +778,10 @@ class vmmConnection(vmmGObject):
         name = pool.name()
         logging.debug("storage pool lifecycle event: storage=%s event=%s "
             "reason=%s", name, event, reason)
+        is_event_refreshed = (event == getattr(
+            libvirt, "VIR_STORAGE_POOL_EVENT_REFRESHED", 4))
 
-        if (not self.is_active() and
-            event == getattr(libvirt, "VIR_STORAGE_POOL_EVENT_REFRESHED", 4)):
+        if is_event_refreshed and not self.is_active():
             # We refresh() pools during connection startup, and this spams
             # the logs, so skip it.
             return
@@ -788,7 +789,10 @@ class vmmConnection(vmmGObject):
         obj = self.get_pool(name)
 
         if obj:
-            self.idle_add(obj.recache_from_event_loop)
+            if is_event_refreshed:
+                self.idle_add(obj.refresh_pool_cache_from_event_loop)
+            else:
+                self.idle_add(obj.recache_from_event_loop)
         else:
             self.schedule_priority_tick(pollpool=True, force=True)
 

virtManager/storagepool.py

@@ -153,7 +153,7 @@ class vmmStoragePool(vmmLibvirtObject):
             # since the pools may be out of date. But if a storage pool
             # shows up while the conn is connected, this means it was
             # just 'defined' recently and doesn't need to be refreshed.
-            self.refresh(_do_refresh_xml=False)
+            self.refresh(_from_object_init=True)
         for vol in self.get_volumes():
             vol.init_libvirt_state()
 
@@ -180,16 +180,27 @@ class vmmStoragePool(vmmLibvirtObject):
         self._backend.undefine()
         self._backend = None
 
-    def refresh(self, _do_refresh_xml=True):
+    def refresh(self, _from_object_init=False):
         """
-        :param _do_refresh_xml: We want this by default. It's only skipped
-            to avoid double updating XML via init_libvirt_state
+        :param _from_object_init: Only used for the refresh() call from
+            _init_libvirt_state. Tells us to not refresh the XML, since
+            we just updated it.
         """
         if not self.is_active():
             return
 
         self._backend.refresh(0)
-        if _do_refresh_xml:
+        if self._using_events() and not _from_object_init:
+            # If we are using events, we let the event loop trigger
+            # the cache update for us. Except if from init_libvirt_state,
+            # we want the update to be done immediately
+            return
+
+        self.refresh_pool_cache_from_event_loop(
+            _from_object_init=_from_object_init)
+
+    def refresh_pool_cache_from_event_loop(self, _from_object_init=False):
+        if not _from_object_init:
             self.ensure_latest_xml()
         self._update_volumes(force=True)
         self.idle_emit("refreshed")
@@ -220,8 +231,7 @@ class vmmStoragePool(vmmLibvirtObject):
         if not force and self._volumes is not None:
             return
 
-        self._volumes = []
-        keymap = dict((o.get_connkey(), o) for o in self._volumes)
+        keymap = dict((o.get_connkey(), o) for o in self._volumes or [])
         (ignore, ignore, allvols) = pollhelpers.fetch_volumes(
             self.conn.get_backend(), self.get_backend(), keymap,
             lambda obj, key: vmmStorageVolume(self.conn, obj, key))