list_instances - cache allocations

When listing instances fetch all allocations to a cache,
fetch each nodes allocation from the cache. This is
significantly faster than calling get_allocation for each
node.

time metealsmith list # 250 nodes:
  real 0m54.970s vs real 1m45.048s without "cached".

Story: 2010571
Task: 47318
Change-Id: Ic4cef61e338fb57bea5de4f96eb3584386cc5152

metalsmith/_provisioner.py

@@ -50,6 +50,8 @@ class Provisioner(object):
         OpenStack API during provisioning.
     """
 
+    allocations_cache = dict()
+
     def __init__(self, session=None, cloud_region=None, dry_run=False):
         if cloud_region is None:
             if session is None:
@@ -630,6 +632,8 @@ class Provisioner(object):
         :return: list of :py:class:`metalsmith.Instance` objects.
         """
         nodes = self.connection.baremetal.nodes(associated=True, details=True)
+        Provisioner.allocations_cache = {
+            a.id: a for a in self.connection.baremetal.allocations()}
         instances = [i for i in map(self._get_instance, nodes)
                      if i.state != _instance.InstanceState.UNKNOWN]
         return instances
@@ -678,13 +682,24 @@ class Provisioner(object):
                 'with a node' % node)
 
     def _get_instance(self, ident):
-        node, allocation = self._find_node_and_allocation(ident)
-        if allocation is None and node.allocation_id:
+        if hasattr(ident, 'allocation_id'):
+            node = ident
             try:
-                allocation = self.connection.baremetal.get_allocation(
-                    node.allocation_id)
+                try:
+                    allocation = Provisioner.allocations_cache[
+                        node.instance_id]
+                except KeyError:
+                    allocation = self.connection.baremetal.get_allocation(
+                        node.allocation_id)
             except os_exc.ResourceNotFound as exc:
                 raise exceptions.InstanceNotFound(str(exc))
-
+        else:
+            node, allocation = self._find_node_and_allocation(ident)
+            if allocation is None and node.allocation_id:
+                try:
+                    allocation = self.connection.baremetal.get_allocation(
+                        node.allocation_id)
+                except os_exc.ResourceNotFound as exc:
+                    raise exceptions.InstanceNotFound(str(exc))
         return _instance.Instance(self.connection, node,
                                   allocation=allocation)

metalsmith/test/test_provisioner.py

@@ -32,6 +32,7 @@ NODE_FIELDS = ['name', 'id', 'instance_info', 'instance_id', 'is_maintenance',
                'maintenance_reason', 'properties', 'provision_state', 'extra',
                'last_error', 'traits', 'resource_class', 'conductor_group',
                'allocation_id']
+ALLOCATION_FIELDS = ['id', 'name', 'node_id']
 
 
 class TestInit(unittest.TestCase):
@@ -2073,14 +2074,16 @@ class TestListInstances(Base):
         self.nodes[0].allocation_id = 'id2'
         self.nodes[6].instance_id = None
         self.api.baremetal.nodes.return_value = self.nodes
+        self.allocations = [mock.Mock(id='id2')]
+        self.api.baremetal.allocations.return_value = self.allocations
 
     def test_list(self):
         instances = self.pr.list_instances()
         self.assertTrue(all(isinstance(i, _instance.Instance)
                             for i in instances))
         self.assertEqual(self.nodes[:6], [i.node for i in instances])
-        self.assertEqual([self.api.baremetal.get_allocation.return_value]
-                         + [None] * 5,
+        self.assertEqual([self.api.baremetal.get_allocation.return_value] * 6,
                          [i.allocation for i in instances])
         self.api.baremetal.nodes.assert_called_once_with(associated=True,
                                                          details=True)
+        self.api.baremetal.allocations.assert_called_once()