[virt-tools-list] [virt-manager PATCH v2 3/9] inspection: simplify VMs visit

[Pino Toscano]

Currently, the handling of the 'vm_added' element in the queue (added as
consequence of the 'vm-added' signal) is to act as trigger to rescan
every VM in every local connection; this operation is "fast" because
every VM except the newly added is already marked as visited. Still, it
is an not really efficient way to visit new VMs.

Instead, just push in the queue all the data we get in vm_added, so when
processing the queue we can process each VM straight away.  Because of
this, make sure to gracefully handle VMs that were removed while the
'vm_added' item for them was sitting in the queue (which is something
the old code did not handle properly).
---
 virtManager/inspection.py | 33 ++++++++++++++++++---------------
 1 file changed, 18 insertions(+), 15 deletions(-)

diff --git a/virtManager/inspection.py b/virtManager/inspection.py
index 298aa47..f0aa578 100644
--- a/virtManager/inspection.py
+++ b/virtManager/inspection.py
@@ -64,9 +64,7 @@ class vmmInspection(vmmGObject):
 
     # Called by the main thread whenever a VM is added to vmlist.
     def vm_added(self, conn, connkey):
-        ignore = conn
-        ignore = connkey
-        obj = ("vm_added")
+        obj = ("vm_added", conn.get_uri(), connkey)
         self._q.put(obj)
 
     def start(self):
@@ -84,7 +82,6 @@ class vmmInspection(vmmGObject):
     def _run(self):
         while True:
             self._process_queue()
-            self._process_vms()
 
     # Process everything on the queue.  If the queue is empty when
     # called, block.
@@ -107,21 +104,27 @@ class vmmInspection(vmmGObject):
                 uri = conn.get_uri()
                 self._conns[uri] = conn
                 conn.connect("vm-added", self.vm_added)
+                # No need to push the VMs of the newly added
+                # connection manually into the queue, as the above
+                # connect() will emit vm-added signals for all of
+                # its VMs.
         elif obj[0] == "conn_removed":
             uri = obj[1]
             del self._conns[uri]
         elif obj[0] == "vm_added":
-            # Nothing - just a signal for the inspection thread to wake up.
-            pass
-
-    # Any VMs we've not seen yet?  If so, process them.
-    def _process_vms(self):
-        for conn in self._conns.itervalues():
-            for vm in conn.list_vms():
-                if not conn.is_active():
-                    break
-
-                self._process_vm(conn, vm)
+            uri = obj[1]
+            if not (uri in self._conns):
+                # This connection disappeared in the meanwhile.
+                return
+            conn = self._conns[uri]
+            if not conn.is_active():
+                return
+            connkey = obj[2]
+            vm = conn.get_vm(connkey)
+            if not vm:
+                # The VM was removed in the meanwhile.
+                return
+            self._process_vm(conn, vm)
 
     # Try processing a single VM, keeping into account whether it was
     # visited already, and whether there are cached data for it.
-- 
2.9.3