Make usage_from_instances consider current usage

VirtNUMAHostTopology.usage_from_instances will now consider the current
usage of the passed host, and also accepts a 'free' keyword argument,
which if set to True, will cause the instance usage to be taken out of
the considered host. Also adds better handling of  None and emtpy
params.

Blueprint: virt-driver-numa-placement
Change-Id: I62c59b5e1dcbd4db247282f170c6f2f501bafd3d

nova/tests/virt/test_hardware.py

@@ -920,6 +920,76 @@ class NUMATopologyTest(test.NoDBTestCase):
         self.assertEqual(hostusage.cells[2].cpu_usage, 1)
         self.assertEqual(hostusage.cells[2].memory_usage, 256)
 
+    def test_host_usage_culmulative_with_free(self):
+        hosttopo = hw.VirtNUMAHostTopology([
+            hw.VirtNUMATopologyCellUsage(
+                0, set([0, 1, 2, 3]), 1024, cpu_usage=2, memory_usage=512),
+            hw.VirtNUMATopologyCellUsage(
+                1, set([4, 6]), 512, cpu_usage=1, memory_usage=512),
+            hw.VirtNUMATopologyCellUsage(2, set([5, 7]), 256),
+        ])
+        instance1 = hw.VirtNUMAInstanceTopology([
+            hw.VirtNUMATopologyCell(0, set([0, 1, 2]), 512),
+            hw.VirtNUMATopologyCell(1, set([3]), 256),
+            hw.VirtNUMATopologyCell(2, set([4]), 256)])
+
+        hostusage = hw.VirtNUMAHostTopology.usage_from_instances(
+                hosttopo, [instance1])
+        self.assertIsInstance(hostusage.cells[0],
+                              hw.VirtNUMATopologyCellUsage)
+        self.assertEqual(hostusage.cells[0].cpu_usage, 5)
+        self.assertEqual(hostusage.cells[0].memory_usage, 1024)
+
+        self.assertIsInstance(hostusage.cells[1],
+                              hw.VirtNUMATopologyCellUsage)
+        self.assertEqual(hostusage.cells[1].cpu_usage, 2)
+        self.assertEqual(hostusage.cells[1].memory_usage, 768)
+
+        self.assertIsInstance(hostusage.cells[2],
+                              hw.VirtNUMATopologyCellUsage)
+        self.assertEqual(hostusage.cells[2].cpu_usage, 1)
+        self.assertEqual(hostusage.cells[2].memory_usage, 256)
+
+        # Test freeing of resources
+        hostusage = hw.VirtNUMAHostTopology.usage_from_instances(
+                hostusage, [instance1], free=True)
+        self.assertEqual(hostusage.cells[0].cpu_usage, 2)
+        self.assertEqual(hostusage.cells[0].memory_usage, 512)
+
+        self.assertEqual(hostusage.cells[1].cpu_usage, 1)
+        self.assertEqual(hostusage.cells[1].memory_usage, 512)
+
+        self.assertEqual(hostusage.cells[2].cpu_usage, 0)
+        self.assertEqual(hostusage.cells[2].memory_usage, 0)
+
+    def test_topo_usage_none(self):
+        hosttopo = hw.VirtNUMAHostTopology([
+            hw.VirtNUMATopologyCellUsage(0, set([0, 1]), 512),
+            hw.VirtNUMATopologyCellUsage(1, set([2, 3]), 512),
+        ])
+        instance1 = hw.VirtNUMAInstanceTopology([
+            hw.VirtNUMATopologyCell(0, set([0, 1]), 256),
+            hw.VirtNUMATopologyCell(2, set([2]), 256),
+        ])
+
+        hostusage = hw.VirtNUMAHostTopology.usage_from_instances(
+                None, [instance1])
+        self.assertIsNone(hostusage)
+
+        hostusage = hw.VirtNUMAHostTopology.usage_from_instances(
+                hosttopo, [])
+        self.assertEqual(hostusage.cells[0].cpu_usage, 0)
+        self.assertEqual(hostusage.cells[0].memory_usage, 0)
+        self.assertEqual(hostusage.cells[1].cpu_usage, 0)
+        self.assertEqual(hostusage.cells[1].memory_usage, 0)
+
+        hostusage = hw.VirtNUMAHostTopology.usage_from_instances(
+                hosttopo, None)
+        self.assertEqual(hostusage.cells[0].cpu_usage, 0)
+        self.assertEqual(hostusage.cells[0].memory_usage, 0)
+        self.assertEqual(hostusage.cells[1].cpu_usage, 0)
+        self.assertEqual(hostusage.cells[1].memory_usage, 0)
+
     def _test_to_dict(self, cell_or_topo, expected):
         got = cell_or_topo._to_dict()
         self.assertThat(expected, matchers.DictMatches(got))

nova/virt/hardware.py

@@ -596,6 +596,9 @@ class VirtNUMATopology(object):
         """Defined so that boolean testing works the same as for lists."""
         return len(self.cells)
 
+    def __repr__(self):
+        return "<%s: %s>" % (self.__class__.__name__, str(self._to_dict()))
+
     def _to_dict(self):
         return {'cells': [cell._to_dict() for cell in self.cells]}
 
@@ -742,11 +745,12 @@ class VirtNUMAHostTopology(VirtNUMATopology):
     cell_class = VirtNUMATopologyCellUsage
 
     @classmethod
-    def usage_from_instances(cls, host, instances):
+    def usage_from_instances(cls, host, instances, free=False):
         """Get host topology usage
 
-        :param host: VirtNUMAHostTopology without usage information
+        :param host: VirtNUMAHostTopology with usage information
         :param instances: list of VirtNUMAInstanceTopology
+        :param free: If True usage of the host will be decreased
 
         Sum the usage from all @instances to report the overall
         host topology usage
@@ -754,19 +758,25 @@ class VirtNUMAHostTopology(VirtNUMATopology):
         :returns: VirtNUMAHostTopology including usage information
         """
 
+        if host is None:
+            return
+
+        instances = instances or []
         cells = []
+        sign = -1 if free else 1
         for hostcell in host.cells:
-            memory_usage = 0
-            cpu_usage = 0
+            memory_usage = hostcell.memory_usage
+            cpu_usage = hostcell.cpu_usage
             for instance in instances:
                 for instancecell in instance.cells:
                     if instancecell.id == hostcell.id:
-                        memory_usage = memory_usage + instancecell.memory
-                        cpu_usage = cpu_usage + len(instancecell.cpuset)
+                        memory_usage = (
+                                memory_usage + sign * instancecell.memory)
+                        cpu_usage = cpu_usage + sign * len(instancecell.cpuset)
 
             cell = cls.cell_class(
                 hostcell.id, hostcell.cpuset, hostcell.memory,
-                cpu_usage, memory_usage)
+                max(0, cpu_usage), max(0, memory_usage))
 
             cells.append(cell)