VirtualConnection: Allow using virt-manager object caches

So when we call into virtinst it doesn't do a whole round of object
lookup and XML fetching.

tests/pylint.cfg

@@ -42,6 +42,7 @@ load-plugins=
 # I0011: Warn about locally disabled pylint msgs
 # R0201: Method could be a function
 #
+# W0108: Lambda may not be necessary
 # W0142: Used * or ** magic*
 # W0603: Using the global statement
 # W0702: No exception type specified for 'catch'
@@ -53,7 +54,7 @@ load-plugins=
 # W1001: Use of 'property' on old style class,
 #        pylint can't detect our Gtk subclasses are new style
 # W0511: FIXME and XXX: messages
-disable=Design,Similarities,C0103,C0111,C0301,C0302,I0011,R0201,W0142,W0603,W0702,W0703,W1401,W1001,W0511
+disable=Design,Similarities,C0103,C0111,C0301,C0302,I0011,R0201,W0108,W0142,W0603,W0702,W0703,W1401,W1001,W0511
 
 
 [REPORTS]

virtManager/connection.py

@@ -127,11 +127,17 @@ class vmmConnection(vmmGObject):
         self.mediadev_error = ""
         self.mediadev_use_libvirt = False
 
+        self._init_virtconn()
+
 
     #################
     # Init routines #
     #################
 
+    def _init_virtconn(self):
+        self._backend.cb_fetch_all_guests = lambda: self.vms.values()
+        self._backend.cb_fetch_all_pools = lambda: self.pools.values()
+
     def _init_netdev(self):
         """
         Determine how we will be polling for net devices (HAL or libvirt)

virtinst/VirtualDisk.py

@@ -469,8 +469,6 @@ class VirtualDisk(VirtualDevice):
         vms = conn.fetch_all_guests()
 
         def count_cb(ctx):
-            c = 0
-
             template = "count(/domain/devices/disk["
             if check_conflict:
                 template += "not(shareable) and "
@@ -478,16 +476,15 @@ class VirtualDisk(VirtualDevice):
 
             for dtype in VirtualDisk._target_props:
                 xpath = template % (dtype, util.xml_escape(path))
-                c += ctx.xpathEval(xpath)
-
-            return c
+                if ctx.xpathEval(xpath):
+                    return True
+            return False
 
         names = []
         for vm in vms:
-            xml = vm.XMLDesc(0)
-            tmpcount = util.get_xml_path(xml, func=count_cb)
-            if tmpcount:
-                names.append(vm.name())
+            xml = vm.get_xml(refresh_if_nec=False)
+            if util.get_xml_path(xml, func=count_cb):
+                names.append(vm.get_backend().name())
 
         return names
 

virtinst/VirtualNetworkInterface.py

@@ -46,26 +46,6 @@ def _compareMAC(p, q):
     return 0
 
 
-def _countMACaddr(vms, searchmac):
-    if not searchmac:
-        return
-
-    def count_cb(ctx):
-        c = 0
-
-        for mac in ctx.xpathEval("/domain/devices/interface/mac"):
-            macaddr = mac.xpathEval("attribute::address")[0].content
-            if macaddr and _compareMAC(searchmac, macaddr) == 0:
-                c += 1
-        return c
-
-    count = 0
-    for vm in vms:
-        xml = vm.XMLDesc(0)
-        count += util.get_xml_path(xml, func=count_cb)
-    return count
-
-
 class VirtualPort(XMLBuilderDomain.XMLBuilderDomain):
 
     def __init__(self, conn, parsexml=None, parsexmlnode=None):
@@ -332,16 +312,22 @@ class VirtualNetworkInterface(VirtualDevice):
             Non fatal collisions (mac addr collides with inactive guest) will
             return (False, "description of collision")
         """
-        mac = mac or self.macaddr
-        if mac is None:
+        searchmac = mac or self.macaddr
+        if searchmac is None:
             return (False, None)
 
-        vms = self.conn.fetch_all_guests()
-
-        if _countMACaddr(vms, mac) > 0:
-            return (True, _("The MAC address '%s' is in use "
-                            "by another virtual machine.") % mac)
+        def count_cb(ctx):
+            for mac in ctx.xpathEval("/domain/devices/interface/mac"):
+                macaddr = mac.xpathEval("attribute::address")[0].content
+                if macaddr and _compareMAC(searchmac, macaddr) == 0:
+                    return True
+            return False
 
+        for vm in self.conn.fetch_all_guests():
+            xml = vm.get_xml(refresh_if_nec=False)
+            if util.get_xml_path(xml, func=count_cb):
+                return (True, _("The MAC address '%s' is in use "
+                                "by another virtual machine.") % searchmac)
         return (False, None)
 
     def setup(self, meter=None):

virtinst/connection.py

@@ -31,6 +31,24 @@ from virtinst.cli import parse_optstr
 _virtinst_uri_magic = "__virtinst_test__"
 
 
+class _FetchObjWrapper(object):
+    """
+    Wrapper to make virDomain etc. objects have a similar XML API as
+    virt-manager objects, so fetch_all* callers get similar results
+    """
+    def __init__(self, backend):
+        self._backend = backend
+        self._xml = None
+
+    def get_xml(self, refresh_if_nec=True):
+        if self._xml is None or refresh_if_nec:
+            self._xml = self._backend.XMLDesc(0)
+        return self._xml
+
+    def get_backend(self):
+        return self._backend
+
+
 class VirtualConnection(object):
     """
     Wrapper for libvirt connection that provides various bits like
@@ -70,6 +88,11 @@ class VirtualConnection(object):
         # isn't hammering the connection over and over
         self.cache_object_fetch = False
 
+        # These let virt-manager register a callback which provides its
+        # own cached object lists, rather than doing fresh calls
+        self.cb_fetch_all_guests = None
+        self.cb_fetch_all_pools = None
+
 
     ##############
     # Properties #
@@ -127,25 +150,35 @@ class VirtualConnection(object):
         self._libvirtconn = conn
 
     def fetch_all_guests(self):
+        # pylint: disable=E1102
+        if self.cb_fetch_all_guests:
+            return self.cb_fetch_all_guests()
+        # pylint: enable=E1102
+
         key = "vms"
         if key in self._fetch_cache:
             return self._fetch_cache[key]
 
         ignore, ignore, ret = pollhelpers.fetch_vms(self, {},
                                                     lambda obj, ignore: obj)
-        ret = ret.values()
+        ret = [_FetchObjWrapper(obj) for obj in ret.values()]
         if self.cache_object_fetch:
             self._fetch_cache[key] = ret
         return ret
 
     def fetch_all_pools(self):
+        # pylint: disable=E1102
+        if self.cb_fetch_all_pools:
+            return self.cb_fetch_all_pools()
+        # pylint: enable=E1102
+
         key = "pools"
         if key in self._fetch_cache:
             return self._fetch_cache[key]
 
         ignore, ignore, ret = pollhelpers.fetch_pools(self, {},
                                                     lambda obj, ignore: obj)
-        ret = ret.values()
+        ret = [_FetchObjWrapper(obj) for obj in ret.values()]
         if self.cache_object_fetch:
             self._fetch_cache[key] = ret
         return ret

virtinst/util.py

@@ -465,14 +465,15 @@ def lookup_pool_by_path(conn, path):
         return None
 
     def check_pool(pool, path):
-        xml_path = get_xml_path(pool.XMLDesc(0), "/pool/target/path")
+        xml_path = get_xml_path(pool.get_xml(refresh_if_nec=False),
+                                "/pool/target/path")
         if xml_path is not None and os.path.abspath(xml_path) == path:
             return pool
 
     for pool in conn.fetch_all_pools():
         p = check_pool(pool, path)
         if p:
-            return p
+            return p.get_backend()
     return None