Add memoization to expensive emulator calls

Drivers of Redfish emulator now cache the
outcome of a select calls choosing either the
two policies:

* Cache the information for the lifetime of the
  emulator process if it's unlikely for such
  data to get out of sync
* Cache the more dynamic information just for
  the duration of a single Redfish REST API
  call

This change improves emulator responsiveness.

Change-Id: Ief46a0a7b82900ccf6d4c9ebb417f711a9b00513

sushy_tools/emulator/drivers/base.py

@@ -21,6 +21,25 @@ import six
 class AbstractDriver(object):
     """Base class for all virtualization drivers"""
 
+    @classmethod
+    def initialize(cls, **kwargs):
+        """Initialize class attributes
+
+        Since drivers may need to cache thing short-term. The emulator
+        instantiates the driver every time it serves a client query.
+
+        Driver objects can cache whenever it makes sense for the duration
+        of a single session. It is guaranteed that the driver object will
+        never be reused for any other session.
+
+        The `initialize` method is provided to set up the driver in a way
+        that would affect all the subsequent sessions.
+
+        :params **kwargs: driver-specific parameters
+        :returns: initialized driver class
+        """
+        return cls
+
     @abc.abstractproperty
     def driver(self):
         """Return human-friendly driver information

sushy_tools/emulator/drivers/libvirtdriver.py

@@ -13,12 +13,13 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from collections import namedtuple
 import logging
 import uuid
 import xml.etree.ElementTree as ET
 
-from collections import namedtuple
 from sushy_tools.emulator.drivers.base import AbstractDriver
+from sushy_tools.emulator.drivers import memoize
 from sushy_tools import error
 
 try:
@@ -102,15 +103,17 @@ class LibvirtDriver(AbstractDriver):
                                "NicBoot1": "NetworkBoot",
                                "ProcTurboMode": "Enabled"}
 
-    def __init__(self, config, uri=None):
+    @classmethod
-        self._config = config
+    def initialize(cls, config, uri=None):
-        self._uri = uri or self.LIBVIRT_URI
+        cls._config = config
-        self.BOOT_LOADER_MAP = self._config.get(
+        cls._uri = uri or cls.LIBVIRT_URI
-            'SUSHY_EMULATOR_BOOT_LOADER_MAP', self.BOOT_LOADER_MAP)
+        cls.BOOT_LOADER_MAP = cls._config.get(
-        self.KNOWN_BOOT_LOADERS = set(y
+            'SUSHY_EMULATOR_BOOT_LOADER_MAP', cls.BOOT_LOADER_MAP)
-                                      for x in self.BOOT_LOADER_MAP.values()
+        cls.KNOWN_BOOT_LOADERS = set(y for x in cls.BOOT_LOADER_MAP.values()
                                      for y in x.values())
+        return cls
 
+    @memoize.memoize()
     def _get_domain(self, identity, readonly=False):
         with libvirt_open(self._uri, readonly=readonly) as conn:
             try:
@@ -517,6 +520,7 @@ class LibvirtDriver(AbstractDriver):
                                                update_existing_attributes)
 
         if result.attributes_written:
+
             try:
                 with libvirt_open(self._uri) as conn:
                     conn.defineXML(ET.tostring(result.tree).decode('utf-8'))

sushy_tools/emulator/drivers/memoize.py

@@ -0,0 +1,56 @@
+# Copyright 2018 Red Hat, Inc.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+from functools import wraps
+
+
+def memoize(permanent_cache=None):
+    """Cache the return value of the decorated method.
+
+    :param permanent_cache: a `dict` like object to use as a cache.
+        If not given, the `._cache` attribute would be added to
+        the object of the decorated method pointing to a newly
+        created `dict`.
+    :return: decorated function
+    """
+
+    def decorator(method):
+
+        @wraps(method)
+        def wrapped(self, *args, **kwargs):
+            if permanent_cache is None:
+                try:
+                    cache = self._cache
+
+                except AttributeError:
+                    cache = self._cache = {}
+
+            else:
+                cache = permanent_cache
+
+            method_cache = cache.setdefault(method, {})
+
+            key = frozenset(args), frozenset(kwargs)
+
+            try:
+                return method_cache[key]
+
+            except KeyError:
+                rv = method(self, *args, **kwargs)
+                method_cache[key] = rv
+                return rv
+
+        return wrapped
+
+    return decorator

sushy_tools/emulator/drivers/novadriver.py

@@ -17,6 +17,7 @@ import logging
 import math
 
 from sushy_tools.emulator.drivers.base import AbstractDriver
+from sushy_tools.emulator.drivers import memoize
 from sushy_tools import error
 
 try:
@@ -51,11 +52,16 @@ class OpenStackDriver(AbstractDriver):
 
     BOOT_MODE_MAP_REV = {v: k for k, v in BOOT_MODE_MAP.items()}
 
-    def __init__(self, config, os_cloud, readonly=False):
+    PERMANENT_CACHE = {}
-        self._cc = openstack.connect(cloud=os_cloud)
-        self._os_cloud = os_cloud
-        self._config = config
 
+    @classmethod
+    def initialize(cls, config, os_cloud, readonly=False):
+        cls._cc = openstack.connect(cloud=os_cloud)
+        cls._os_cloud = os_cloud
+        cls._config = config
+        return cls
+
+    @memoize.memoize()
     def _get_instance(self, identity):
         instance = self._cc.get_server(identity)
         if instance:
@@ -72,10 +78,20 @@ class OpenStackDriver(AbstractDriver):
 
         raise error.FishyError(msg)
 
+    @memoize.memoize(permanent_cache=PERMANENT_CACHE)
     def _get_flavor(self, identity):
         instance = self._get_instance(identity)
-        flavor = self._cc.get_flavor(instance.flavor.id)
+        return self._cc.get_flavor(instance.flavor.id)
-        return flavor
+
+    @memoize.memoize(permanent_cache=PERMANENT_CACHE)
+    def _get_image_info(self, identity):
+        return self._cc.image.find_image(identity)
+
+    def _get_server_metadata(self, identity):
+        return self._cc.compute.get_server_metadata(identity).to_dict()
+
+    def _set_server_metadata(self, identity, metadata):
+        self._cc.compute.set_server_metadata(identity, metadata)
 
     @property
     def driver(self):
@@ -190,7 +206,7 @@ class OpenStackDriver(AbstractDriver):
         except error.FishyError:
             return
 
-        metadata = self._cc.compute.get_server_metadata(instance.id).to_dict()
+        metadata = self._get_server_metadata(instance.id)
 
         # NOTE(etingof): the following probably only works with
         # libvirt-backed compute nodes
@@ -224,7 +240,6 @@ class OpenStackDriver(AbstractDriver):
 
         # NOTE(etingof): the following probably only works with
         # libvirt-backed compute nodes
-
         self._cc.compute.set_server_metadata(
             instance.id, **{'libvirt:pxe-first': '1'
                             if target == 'network' else ''}
@@ -238,7 +253,7 @@ class OpenStackDriver(AbstractDriver):
         """
         instance = self._get_instance(identity)
 
-        image = self._cc.image.find_image(instance.image['id'])
+        image = self._get_image_info(instance.image['id'])
 
         hw_firmware_type = getattr(image, 'hw_firmware_type', None)
 

sushy_tools/emulator/main.py

@@ -14,6 +14,7 @@
 #    under the License.
 
 import argparse
+import contextlib
 import functools
 import json
 import os
@@ -32,22 +33,22 @@ app = flask.Flask(__name__)
 # Turn off strict_slashes on all routes
 app.url_map.strict_slashes = False
 
-driver = None
+DRIVER = None
 
 
 def init_virt_driver(decorated_func):
     @functools.wraps(decorated_func)
     def decorator(*args, **kwargs):
-        global driver
+        global DRIVER
 
-        if driver is None:
+        if DRIVER is None:
 
             if 'OS_CLOUD' in os.environ:
                 if not novadriver.is_loaded:
                     app.logger.error('Nova driver not loaded')
                     sys.exit(1)
 
-                driver = novadriver.OpenStackDriver(
+                DRIVER = novadriver.OpenStackDriver.initialize(
                     app.config, os.environ['OS_CLOUD'])
 
             else:
@@ -55,7 +56,7 @@ def init_virt_driver(decorated_func):
                     app.logger.error('libvirt driver not loaded')
                     sys.exit(1)
 
-                driver = libvirtdriver.LibvirtDriver(
+                DRIVER = libvirtdriver.LibvirtDriver.initialize(
                     app.config,
                     os.environ.get(
                         'SUSHY_EMULATOR_LIBVIRT_URI',
@@ -63,7 +64,7 @@ def init_virt_driver(decorated_func):
                         os.environ.get('SUSHY_EMULATOR_LIBVIRT_URL'))
                 )
 
-                app.logger.debug('Running with %s', driver.driver)
+            app.logger.debug('Running with %s', DRIVER.driver)
 
         return decorated_func(*args, **kwargs)
 
@@ -99,6 +100,11 @@ def ensure_instance_access(decorated_func):
     return decorator
 
 
+@contextlib.contextmanager
+def virt_driver():
+    yield DRIVER()
+
+
 def returns_json(decorated_func):
     @functools.wraps(decorated_func)
     def decorator(*args, **kwargs):
@@ -135,6 +141,7 @@ def root_resource():
 @init_virt_driver
 @returns_json
 def system_collection_resource():
+    with virt_driver() as driver:
         systems = [system for system in driver.systems
                    if not instance_denied(identity=system)]
 
@@ -153,10 +160,9 @@ def system_resource(identity):
 
         app.logger.debug('Serving resources for system "%s"', identity)
 
+        with virt_driver() as driver:
             return flask.render_template(
-            'system.json',
+                'system.json', identity=identity,
-            identity=identity,
-            name=driver.name(identity),
                 uuid=driver.uuid(identity),
                 power_state=driver.get_power_state(identity),
                 total_memory_gb=driver.get_total_memory(identity),
@@ -170,6 +176,8 @@ def system_resource(identity):
         if not boot:
             return 'PATCH only works for the Boot element', 400
 
+        with virt_driver() as driver:
+
             target = boot.get('BootSourceOverrideTarget')
 
             if target:
@@ -203,7 +211,9 @@ def system_resource(identity):
 @ensure_instance_access
 @returns_json
 def ethernet_interfaces_collection(identity):
+    with virt_driver() as driver:
         nics = driver.get_nics(identity)
+
     return flask.render_template(
         'ethernet_interfaces_collection.json', identity=identity,
         nics=nics)
@@ -215,7 +225,9 @@ def ethernet_interfaces_collection(identity):
 @ensure_instance_access
 @returns_json
 def ethernet_interface(identity, nic_id):
+    with virt_driver() as driver:
         nics = driver.get_nics(identity)
+
     for nic in nics:
         if nic['id'] == nic_id:
             return flask.render_template(
@@ -232,6 +244,7 @@ def ethernet_interface(identity, nic_id):
 def system_reset_action(identity):
     reset_type = flask.request.json.get('ResetType')
 
+    with virt_driver() as driver:
         driver.set_power_state(identity, reset_type)
 
     app.logger.info('System "%s" power state set to "%s"',
@@ -245,6 +258,7 @@ def system_reset_action(identity):
 @ensure_instance_access
 @returns_json
 def bios(identity):
+    with virt_driver() as driver:
         bios = driver.get_bios(identity)
 
     app.logger.debug('Serving BIOS for system "%s"', identity)
@@ -263,6 +277,7 @@ def bios(identity):
 def bios_settings(identity):
 
     if flask.request.method == 'GET':
+        with virt_driver() as driver:
             bios = driver.get_bios(identity)
 
         app.logger.debug('Serving BIOS Settings for system "%s"', identity)
@@ -275,7 +290,9 @@ def bios_settings(identity):
     elif flask.request.method == 'PATCH':
         attributes = flask.request.json.get('Attributes')
 
+        with virt_driver() as driver:
             driver.set_bios(identity, attributes)
+
         app.logger.info('System "%s" BIOS attributes "%s" updated',
                         identity, attributes)
         return '', 204
@@ -288,8 +305,11 @@ def bios_settings(identity):
 @returns_json
 def system_reset_bios(identity):
 
+    with virt_driver() as driver:
         driver.reset_bios(identity)
+
     app.logger.info('BIOS for system "%s" reset', identity)
+
     return '', 204
 
 
@@ -336,7 +356,7 @@ def parse_args():
 
 
 def main():
-    global driver
+    global DRIVER
 
     args = parse_args()
 
@@ -350,20 +370,21 @@ def main():
             app.logger.error('Nova driver not loaded')
             return 1
 
-        driver = novadriver.OpenStackDriver(app.config, os_cloud)
+        DRIVER = novadriver.OpenStackDriver.initialize(
+            app.config, args.os_cloud)
 
     else:
         if not libvirtdriver.is_loaded:
             app.logger.error('libvirt driver not loaded')
             return 1
 
-        driver = libvirtdriver.LibvirtDriver(
+        DRIVER = libvirtdriver.LibvirtDriver.initialize(
             app.config,
             args.libvirt_uri or
             app.config.get('SUSHY_EMULATOR_LIBVIRT_URI', '')
         )
 
-    app.logger.debug('Running with %s', driver.driver)
+    app.logger.debug('Running with %s', DRIVER.driver)
 
     ssl_context = None
 

sushy_tools/tests/unit/emulator/test_libvirt.py

@@ -25,7 +25,8 @@ class LibvirtDriverTestCase(base.BaseTestCase):
     uuid = 'c7a5fdbd-cdaf-9455-926a-d65c16db1809'
 
     def setUp(self):
-        self.test_driver = LibvirtDriver({})
+        test_driver_class = LibvirtDriver.initialize({})
+        self.test_driver = test_driver_class()
         super(LibvirtDriverTestCase, self).setUp()
 
     @mock.patch('libvirt.open', autospec=True)

sushy_tools/tests/unit/emulator/test_main.py

@@ -16,23 +16,24 @@ from six.moves import mock
 from sushy_tools.emulator import main
 
 
-@mock.patch('sushy_tools.emulator.main.driver', autospec=True)
+@mock.patch.object(main, 'DRIVER')  # This enables libvirt driver
 class EmulatorTestCase(base.BaseTestCase):
 
     name = 'QEmu-fedora-i686'
     uuid = 'c7a5fdbd-cdaf-9455-926a-d65c16db1809'
 
     def setUp(self):
-        main.driver = None
+        main.DRIVER = None
         self.app = main.app.test_client()
 
         super(EmulatorTestCase, self).setUp()
 
     def test_error(self, driver_mock):
-        driver_mock.get_power_state.side_effect = Exception('Fish is dead')
+        driver_mock.return_value.get_power_state.side_effect = (
+            Exception('Fish is dead'))
         response = self.app.get('/redfish/v1/Systems/' + self.uuid)
 
-        self.assertEqual('500 INTERNAL SERVER ERROR', response.status)
+        self.assertEqual(500, response.status_code)
 
     def test_root_resource(self, driver_mock):
         response = self.app.get('/redfish/v1/')
@@ -40,7 +41,7 @@ class EmulatorTestCase(base.BaseTestCase):
         self.assertEqual('RedvirtService', response.json['Id'])
 
     def test_collection_resource(self, driver_mock):
-        type(driver_mock).systems = mock.PropertyMock(
+        type(driver_mock.return_value).systems = mock.PropertyMock(
             return_value=['host0', 'host1'])
         response = self.app.get('/redfish/v1/Systems')
         self.assertEqual(200, response.status_code)
@@ -50,12 +51,12 @@ class EmulatorTestCase(base.BaseTestCase):
                          response.json['Members'][1])
 
     def test_system_resource_get(self, driver_mock):
-        driver_mock.uuid.return_value = 'zzzz-yyyy-xxxx'
+        driver_mock.return_value.uuid.return_value = 'zzzz-yyyy-xxxx'
-        driver_mock.get_power_state.return_value = 'On'
+        driver_mock.return_value.get_power_state.return_value = 'On'
-        driver_mock.get_total_memory.return_value = 1
+        driver_mock.return_value.get_total_memory.return_value = 1
-        driver_mock.get_total_cpus.return_value = 2
+        driver_mock.return_value.get_total_cpus.return_value = 2
-        driver_mock.get_boot_device.return_value = 'Cd'
+        driver_mock.return_value.get_boot_device.return_value = 'Cd'
-        driver_mock.get_boot_mode.return_value = 'Legacy'
+        driver_mock.return_value.get_boot_mode.return_value = 'Legacy'
 
         response = self.app.get('/redfish/v1/Systems/xxxx-yyyy-zzzz')
 
@@ -76,7 +77,7 @@ class EmulatorTestCase(base.BaseTestCase):
         response = self.app.patch('/redfish/v1/Systems/xxxx-yyyy-zzzz',
                                   json=data)
         self.assertEqual(204, response.status_code)
-        set_boot_device = driver_mock.set_boot_device
+        set_boot_device = driver_mock.return_value.set_boot_device
         set_boot_device.assert_called_once_with('xxxx-yyyy-zzzz', 'Cd')
 
     def test_system_reset_action_on(self, driver_mock):
@@ -85,7 +86,7 @@ class EmulatorTestCase(base.BaseTestCase):
             '/redfish/v1/Systems/xxxx-yyyy-zzzz/Actions/ComputerSystem.Reset',
             json=data)
         self.assertEqual(204, response.status_code)
-        set_power_state = driver_mock.set_power_state
+        set_power_state = driver_mock.return_value.set_power_state
         set_power_state.assert_called_once_with('xxxx-yyyy-zzzz', 'On')
 
     def test_system_reset_action_forceon(self, driver_mock):
@@ -94,7 +95,7 @@ class EmulatorTestCase(base.BaseTestCase):
             '/redfish/v1/Systems/xxxx-yyyy-zzzz/Actions/ComputerSystem.Reset',
             json=data)
         self.assertEqual(204, response.status_code)
-        set_power_state = driver_mock.set_power_state
+        set_power_state = driver_mock.return_value.set_power_state
         set_power_state.assert_called_once_with('xxxx-yyyy-zzzz', 'ForceOn')
 
     def test_system_reset_action_forceoff(self, driver_mock):
@@ -103,7 +104,7 @@ class EmulatorTestCase(base.BaseTestCase):
             '/redfish/v1/Systems/xxxx-yyyy-zzzz/Actions/ComputerSystem.Reset',
             json=data)
         self.assertEqual(204, response.status_code)
-        set_power_state = driver_mock.set_power_state
+        set_power_state = driver_mock.return_value.set_power_state
         set_power_state.assert_called_once_with('xxxx-yyyy-zzzz', 'ForceOff')
 
     def test_system_reset_action_shutdown(self, driver_mock):
@@ -112,7 +113,7 @@ class EmulatorTestCase(base.BaseTestCase):
             '/redfish/v1/Systems/xxxx-yyyy-zzzz/Actions/ComputerSystem.Reset',
             json=data)
         self.assertEqual(204, response.status_code)
-        set_power_state = driver_mock.set_power_state
+        set_power_state = driver_mock.return_value.set_power_state
         set_power_state.assert_called_once_with(
             'xxxx-yyyy-zzzz', 'GracefulShutdown')
 
@@ -122,7 +123,7 @@ class EmulatorTestCase(base.BaseTestCase):
             '/redfish/v1/Systems/xxxx-yyyy-zzzz/Actions/ComputerSystem.Reset',
             json=data)
         self.assertEqual(204, response.status_code)
-        set_power_state = driver_mock.set_power_state
+        set_power_state = driver_mock.return_value.set_power_state
         set_power_state.assert_called_once_with(
             'xxxx-yyyy-zzzz', 'GracefulRestart')
 
@@ -132,7 +133,7 @@ class EmulatorTestCase(base.BaseTestCase):
             '/redfish/v1/Systems/xxxx-yyyy-zzzz/Actions/ComputerSystem.Reset',
             json=data)
         self.assertEqual(204, response.status_code)
-        set_power_state = driver_mock.set_power_state
+        set_power_state = driver_mock.return_value.set_power_state
         set_power_state.assert_called_once_with(
             'xxxx-yyyy-zzzz', 'ForceRestart')
 
@@ -142,7 +143,7 @@ class EmulatorTestCase(base.BaseTestCase):
             '/redfish/v1/Systems/xxxx-yyyy-zzzz/Actions/ComputerSystem.Reset',
             json=data)
         self.assertEqual(204, response.status_code)
-        set_power_state = driver_mock.set_power_state
+        set_power_state = driver_mock.return_value.set_power_state
         set_power_state.assert_called_once_with('xxxx-yyyy-zzzz', 'Nmi')
 
     @mock.patch.dict(main.app.config, {}, clear=True)
@@ -170,19 +171,20 @@ class EmulatorTestCase(base.BaseTestCase):
         self.assertTrue(main.instance_denied(identity='b'))
 
     def test_get_bios(self, driver_mock):
-        driver_mock.get_bios.return_value = {"attribute 1": "value 1",
+        driver_mock.return_value.get_bios.return_value = {
+            "attribute 1": "value 1",
             "attribute 2": "value 2"}
         response = self.app.get('/redfish/v1/Systems/' + self.uuid + '/BIOS')
 
-        self.assertEqual('200 OK', response.status)
+        self.assertEqual(200, response.status_code)
         self.assertEqual('BIOS', response.json['Id'])
         self.assertEqual({"attribute 1": "value 1",
                           "attribute 2": "value 2"},
                          response.json['Attributes'])
 
     def test_get_bios_existing(self, driver_mock):
-        driver_mock.get_bios.return_value = {"attribute 1": "value 1",
+        driver_mock.return_value.get_bios.return_value = {
-                                             "attribute 2": "value 2"}
+            "attribute 1": "value 1", "attribute 2": "value 2"}
         response = self.app.get(
             '/redfish/v1/Systems/' + self.uuid + '/BIOS/Settings')
 
@@ -194,39 +196,33 @@ class EmulatorTestCase(base.BaseTestCase):
 
     def test_bios_settings_patch(self, driver_mock):
         data = {'Attributes': {'key': 'value'}}
-        self.app.driver = driver_mock
         response = self.app.patch(
             '/redfish/v1/Systems/xxxx-yyyy-zzzz/BIOS/Settings',
             json=data)
-
         self.assertEqual(204, response.status_code)
-        driver_mock.set_bios.assert_called_once_with('xxxx-yyyy-zzzz',
+        driver_mock.return_value.set_bios.assert_called_once_with(
-                                                     {'key': 'value'})
+            'xxxx-yyyy-zzzz', {'key': 'value'})
 
     def test_set_bios(self, driver_mock):
         data = {'Attributes': {'key': 'value'}}
-        self.app.driver = driver_mock
         response = self.app.patch(
             '/redfish/v1/Systems/xxxx-yyyy-zzzz/BIOS/Settings',
             json=data)
 
         self.assertEqual(204, response.status_code)
-        driver_mock.set_bios.assert_called_once_with(
+        driver_mock.return_value.set_bios.assert_called_once_with(
             'xxxx-yyyy-zzzz', data['Attributes'])
 
     def test_reset_bios(self, driver_mock):
-        self.app.driver = driver_mock
         response = self.app.post('/redfish/v1/Systems/' + self.uuid +
                                  '/BIOS/Actions/Bios.ResetBios')
-
         self.assertEqual(204, response.status_code)
-        driver_mock.reset_bios.assert_called_once_with(self.uuid)
+        driver_mock.return_value.reset_bios.assert_called_once_with(self.uuid)
 
     def test_ethernet_interfaces_collection(self, driver_mock):
-        driver_mock.get_nics.return_value = [{'id': 'nic1',
+        driver_mock.return_value.get_nics.return_value = [
-                                              'mac': '52:54:00:4e:5d:37'},
+            {'id': 'nic1', 'mac': '52:54:00:4e:5d:37'},
-                                             {'id': 'nic2',
+            {'id': 'nic2', 'mac': '00:11:22:33:44:55'}]
-                                              'mac': '00:11:22:33:44:55'}]
         response = self.app.get('redfish/v1/Systems/' + self.uuid +
                                 '/EthernetInterfaces')
 
@@ -241,7 +237,7 @@ class EmulatorTestCase(base.BaseTestCase):
                          [m['@odata.id'] for m in response.json['Members']])
 
     def test_ethernet_interfaces_collection_empty(self, driver_mock):
-        driver_mock.get_nics.return_value = []
+        driver_mock.return_value.get_nics.return_value = []
         response = self.app.get('redfish/v1/Systems/' + self.uuid +
                                 '/EthernetInterfaces')
 
@@ -252,10 +248,9 @@ class EmulatorTestCase(base.BaseTestCase):
         self.assertEqual([], response.json['Members'])
 
     def test_ethernet_interface(self, driver_mock):
-        driver_mock.get_nics.return_value = [{'id': 'nic1',
+        driver_mock.return_value.get_nics.return_value = [
-                                              'mac': '52:54:00:4e:5d:37'},
+            {'id': 'nic1', 'mac': '52:54:00:4e:5d:37'},
-                                             {'id': 'nic2',
+            {'id': 'nic2', 'mac': '00:11:22:33:44:55'}]
-                                              'mac': '00:11:22:33:44:55'}]
         response = self.app.get('/redfish/v1/Systems/' + self.uuid +
                                 '/EthernetInterfaces/nic2')
 
@@ -271,10 +266,9 @@ class EmulatorTestCase(base.BaseTestCase):
                          response.json['@odata.id'])
 
     def test_ethernet_interface_not_found(self, driver_mock):
-        driver_mock.get_nics.return_value = [{'id': 'nic1',
+        driver_mock.return_value.get_nics.return_value = [
-                                              'mac': '52:54:00:4e:5d:37'},
+            {'id': 'nic1', 'mac': '52:54:00:4e:5d:37'},
-                                             {'id': 'nic2',
+            {'id': 'nic2', 'mac': '00:11:22:33:44:55'}]
-                                             'mac': '00:11:22:33:44:55'}]
         response = self.app.get('/redfish/v1/Systems/' + self.uuid +
                                 '/EthernetInterfaces/nic3')
 

sushy_tools/tests/unit/emulator/test_memoize.py

@@ -0,0 +1,81 @@
+# Copyright 2018 Red Hat, Inc.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from oslotest import base
+
+from sushy_tools.emulator.drivers import memoize
+
+
+class MemoizeTestCase(base.BaseTestCase):
+
+    def test_local_cache(self):
+
+        class Driver(object):
+            call_count = 0
+
+            @memoize.memoize()
+            def fun(self, *args, **kwargs):
+                self.call_count += 1
+                return args, kwargs
+
+        driver = Driver()
+
+        result = driver.fun(1, x=2)
+        self.assertEqual(((1,), {'x': 2}), result)
+
+        result = driver.fun(1, x=2)
+        self.assertEqual(((1,), {'x': 2}), result)
+
+        # Due to memoization, expect just one call
+        self.assertEqual(1, driver.call_count)
+
+        driver = Driver()
+
+        result = driver.fun(1, x=2)
+        self.assertEqual(((1,), {'x': 2}), result)
+
+        # Due to volatile cache, expect one more call
+        self.assertEqual(1, driver.call_count)
+
+    def test_external_cache(self):
+
+        permanent_cache = {}
+
+        class Driver(object):
+            call_count = 0
+
+            @memoize.memoize(permanent_cache=permanent_cache)
+            def fun(self, *args, **kwargs):
+                self.call_count += 1
+                return args, kwargs
+
+        driver = Driver()
+
+        result = driver.fun(1, x=2)
+        self.assertEqual(((1,), {'x': 2}), result)
+
+        result = driver.fun(1, x=2)
+        self.assertEqual(((1,), {'x': 2}), result)
+
+        # Due to memoization, expect just one call
+        self.assertEqual(1, driver.call_count)
+
+        driver = Driver()
+
+        result = driver.fun(1, x=2)
+        self.assertEqual(((1,), {'x': 2}), result)
+
+        # Due to permanent cache, expect no more calls
+        self.assertEqual(0, driver.call_count)

sushy_tools/tests/unit/emulator/test_nova.py

@@ -21,6 +21,7 @@ from sushy_tools.emulator.drivers.novadriver import OpenStackDriver
 from sushy_tools import error
 
 
+@mock.patch.dict(OpenStackDriver.PERMANENT_CACHE)
 class NovaDriverTestCase(base.BaseTestCase):
 
     name = 'QEmu-fedora-i686'
@@ -30,7 +31,8 @@ class NovaDriverTestCase(base.BaseTestCase):
         self.nova_patcher = mock.patch('openstack.connect', autospec=True)
         self.nova_mock = self.nova_patcher.start()
 
-        self.test_driver = OpenStackDriver({}, 'fake-cloud')
+        test_driver_class = OpenStackDriver.initialize({}, 'fake-cloud')
+        self.test_driver = test_driver_class()
 
         super(NovaDriverTestCase, self).setUp()
 
@@ -145,6 +147,7 @@ class NovaDriverTestCase(base.BaseTestCase):
         self.nova_mock.return_value.get_server.return_value = server
 
         image = mock.Mock(hw_firmware_type='bios')
+
         self.nova_mock.return_value.image.find_image.return_value = image
 
         boot_mode = self.test_driver.get_boot_mode(self.uuid)
@@ -216,7 +219,9 @@ class NovaDriverTestCase(base.BaseTestCase):
 
         server = mock.Mock(id=self.uuid, addresses=addresses)
         self.nova_mock.return_value.get_server.return_value = server
+
         nics = self.test_driver.get_nics(self.uuid)
+
         self.assertEqual([{'id': 'fa:16:3e:22:18:31',
                            'mac': 'fa:16:3e:22:18:31'},
                           {'id': 'fa:16:3e:46:e3:ac',