# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
# Copyright (c) 2010 Citrix Systems, Inc.
#
#    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.

"""
A fake (in-memory) hypervisor+api.

Allows nova testing w/o a hypervisor.  This module also documents the
semantics of real hypervisor connections.

"""

import collections
import contextlib
import time
import uuid

import fixtures
import os_resource_classes as orc
from oslo_log import log as logging
from oslo_serialization import jsonutils
from oslo_utils.fixture import uuidsentinel as uuids
from oslo_utils import versionutils

from nova.compute import power_state
from nova.compute import task_states
from nova.compute import vm_states
import nova.conf
from nova.console import type as ctype
from nova import context as nova_context
from nova import exception
from nova import objects
from nova.objects import diagnostics as diagnostics_obj
from nova.objects import fields as obj_fields
from nova.objects import migrate_data
from nova.virt import driver
from nova.virt import hardware
from nova.virt.ironic import driver as ironic
import nova.virt.node
from nova.virt import virtapi

CONF = nova.conf.CONF

LOG = logging.getLogger(__name__)


class FakeInstance(object):

    def __init__(self, name, state, uuid):
        self.name = name
        self.state = state
        self.uuid = uuid

    def __getitem__(self, key):
        return getattr(self, key)


class Resources(object):
    vcpus = 0
    memory_mb = 0
    local_gb = 0
    vcpus_used = 0
    memory_mb_used = 0
    local_gb_used = 0

    def __init__(self, vcpus=8, memory_mb=8000, local_gb=500):
        self.vcpus = vcpus
        self.memory_mb = memory_mb
        self.local_gb = local_gb

    def claim(self, vcpus=0, mem=0, disk=0):
        self.vcpus_used += vcpus
        self.memory_mb_used += mem
        self.local_gb_used += disk

    def release(self, vcpus=0, mem=0, disk=0):
        self.vcpus_used -= vcpus
        self.memory_mb_used -= mem
        self.local_gb_used -= disk

    def dump(self):
        return {
            'vcpus': self.vcpus,
            'memory_mb': self.memory_mb,
            'local_gb': self.local_gb,
            'vcpus_used': self.vcpus_used,
            'memory_mb_used': self.memory_mb_used,
            'local_gb_used': self.local_gb_used
        }


class FakeDriver(driver.ComputeDriver):
    # These must match the traits in
    # nova.tests.functional.integrated_helpers.ProviderUsageBaseTestCase
    capabilities = {
        "has_imagecache": True,
        "supports_evacuate": True,
        "supports_migrate_to_same_host": False,
        "supports_attach_interface": True,
        "supports_device_tagging": True,
        "supports_tagged_attach_interface": True,
        "supports_tagged_attach_volume": True,
        "supports_extend_volume": True,
        "supports_multiattach": True,
        "supports_trusted_certs": True,
        "supports_pcpus": False,
        "supports_accelerators": True,
        "supports_remote_managed_ports": True,
        "supports_address_space_passthrough": True,
        "supports_address_space_emulated": True,

        # Supported image types
        "supports_image_type_raw": True,
        "supports_image_type_vhd": False,
        }

    # Since we don't have a real hypervisor, pretend we have lots of
    # disk and ram so this driver can be used to test large instances.
    vcpus = 1000
    memory_mb = 800000
    local_gb = 600000

    """Fake hypervisor driver."""

    def __init__(self, virtapi, read_only=False):
        super(FakeDriver, self).__init__(virtapi)
        self.instances = {}
        self.resources = Resources(
            vcpus=self.vcpus,
            memory_mb=self.memory_mb,
            local_gb=self.local_gb)
        self.host_status_base = {
            'hypervisor_type': 'fake',
            'hypervisor_version': versionutils.convert_version_to_int('1.0'),
            'hypervisor_hostname': CONF.host,
            'cpu_info': {},
            'disk_available_least': 0,
            'supported_instances': [(
                obj_fields.Architecture.X86_64,
                obj_fields.HVType.FAKE,
                obj_fields.VMMode.HVM)],
            'numa_topology': None,
          }
        self._mounts = {}
        self._interfaces = {}
        self.active_migrations = {}
        self._host = None
        self._nodes = None

    def init_host(self, host):
        self._host = host
        # NOTE(gibi): this is unnecessary complex and fragile but this is
        # how many current functional sample tests expect the node name.
        self._set_nodes(['fake-mini'] if self._host == 'compute'
                        else [self._host])

    def _set_nodes(self, nodes):
        # NOTE(gibi): this is not part of the driver interface but used
        # by our tests to customize the discovered nodes by the fake
        # driver.
        self._nodes = nodes

    def list_instances(self):
        return [self.instances[uuid].name for uuid in self.instances.keys()]

    def list_instance_uuids(self):
        return list(self.instances.keys())

    def plug_vifs(self, instance, network_info):
        """Plug VIFs into networks."""
        pass

    def unplug_vifs(self, instance, network_info):
        """Unplug VIFs from networks."""
        pass

    def spawn(self, context, instance, image_meta, injected_files,
              admin_password, allocations, network_info=None,
              block_device_info=None, power_on=True, accel_info=None):

        if network_info:
            for vif in network_info:
                # simulate a real driver triggering the async network
                # allocation as it might cause an error
                vif.fixed_ips()
                # store the vif as attached so we can allow detaching it later
                # with a detach_interface() call.
                self._interfaces[vif['id']] = vif

        uuid = instance.uuid
        state = power_state.RUNNING if power_on else power_state.SHUTDOWN
        flavor = instance.flavor
        self.resources.claim(
            vcpus=flavor.vcpus,
            mem=flavor.memory_mb,
            disk=flavor.root_gb)
        fake_instance = FakeInstance(instance.name, state, uuid)
        self.instances[uuid] = fake_instance

    def snapshot(self, context, instance, image_id, update_task_state):
        if instance.uuid not in self.instances:
            raise exception.InstanceNotRunning(instance_id=instance.uuid)
        update_task_state(task_state=task_states.IMAGE_UPLOADING)

    def reboot(self, context, instance, network_info, reboot_type,
               block_device_info=None, bad_volumes_callback=None,
               accel_info=None):
        # If the guest is not on the hypervisor and we're doing a hard reboot
        # then mimic the libvirt driver by spawning the guest.
        if (instance.uuid not in self.instances and
                reboot_type.lower() == 'hard'):
            injected_files = admin_password = allocations = None
            self.spawn(context, instance, instance.image_meta, injected_files,
                       admin_password, allocations,
                       block_device_info=block_device_info)
        else:
            # Just try to power on the guest.
            self.power_on(context, instance, network_info,
                          block_device_info=block_device_info)

    def get_host_ip_addr(self):
        return '192.168.0.1'

    def set_admin_password(self, instance, new_pass):
        pass

    def resume_state_on_host_boot(self, context, instance, network_info,
                                  block_device_info=None):
        pass

    def rescue(self, context, instance, network_info, image_meta,
               rescue_password, block_device_info):
        pass

    def unrescue(
        self,
        context: nova_context.RequestContext,
        instance: 'objects.Instance',
    ):
        self.instances[instance.uuid].state = power_state.RUNNING

    def poll_rebooting_instances(self, timeout, instances):
        pass

    def migrate_disk_and_power_off(self, context, instance, dest,
                                   flavor, network_info,
                                   block_device_info=None,
                                   timeout=0, retry_interval=0):
        pass

    def finish_revert_migration(self, context, instance, network_info,
                                migration, block_device_info=None,
                                power_on=True):
        state = power_state.RUNNING if power_on else power_state.SHUTDOWN
        self.instances[instance.uuid] = FakeInstance(
            instance.name, state, instance.uuid)

    def post_live_migration_at_destination(self, context, instance,
                                           network_info,
                                           block_migration=False,
                                           block_device_info=None):
        # Called from the destination host after a successful live migration
        # so spawn the instance on this host to track it properly.
        image_meta = injected_files = admin_password = allocations = None
        self.spawn(context, instance, image_meta, injected_files,
                   admin_password, allocations)

    def power_off(self, instance, timeout=0, retry_interval=0):
        if instance.uuid in self.instances:
            self.instances[instance.uuid].state = power_state.SHUTDOWN
        else:
            raise exception.InstanceNotFound(instance_id=instance.uuid)

    def power_on(self, context, instance, network_info,
                 block_device_info=None, accel_info=None):
        if instance.uuid in self.instances:
            self.instances[instance.uuid].state = power_state.RUNNING
        else:
            raise exception.InstanceNotFound(instance_id=instance.uuid)

    def trigger_crash_dump(self, instance):
        pass

    def soft_delete(self, instance):
        pass

    def restore(self, instance):
        pass

    def pause(self, instance):
        pass

    def unpause(self, instance):
        pass

    def suspend(self, context, instance):
        pass

    def resume(self, context, instance, network_info, block_device_info=None):
        pass

    def destroy(self, context, instance, network_info, block_device_info=None,
                destroy_disks=True, destroy_secrets=True):
        key = instance.uuid
        if key in self.instances:
            flavor = instance.flavor
            self.resources.release(
                vcpus=flavor.vcpus,
                mem=flavor.memory_mb,
                disk=flavor.root_gb)
            del self.instances[key]
        else:
            LOG.warning("Key '%(key)s' not in instances '%(inst)s'",
                        {'key': key,
                         'inst': self.instances}, instance=instance)

    def cleanup(self, context, instance, network_info, block_device_info=None,
                destroy_disks=True, migrate_data=None, destroy_vifs=True,
                destroy_secrets=True):
        # cleanup() should not be called when the guest has not been destroyed.
        if instance.uuid in self.instances:
            raise exception.InstanceExists(
                "Instance %s has not been destroyed." % instance.uuid)

    def attach_volume(self, context, connection_info, instance, mountpoint,
                      disk_bus=None, device_type=None, encryption=None):
        """Attach the disk to the instance at mountpoint using info."""
        instance_name = instance.name
        if instance_name not in self._mounts:
            self._mounts[instance_name] = {}
        self._mounts[instance_name][mountpoint] = connection_info

    def detach_volume(self, context, connection_info, instance, mountpoint,
                      encryption=None):
        """Detach the disk attached to the instance."""
        try:
            del self._mounts[instance.name][mountpoint]
        except KeyError:
            pass

    def swap_volume(self, context, old_connection_info, new_connection_info,
                    instance, mountpoint, resize_to):
        """Replace the disk attached to the instance."""
        instance_name = instance.name
        if instance_name not in self._mounts:
            self._mounts[instance_name] = {}
        self._mounts[instance_name][mountpoint] = new_connection_info

    def extend_volume(self, context, connection_info, instance,
                      requested_size):
        """Extend the disk attached to the instance."""
        pass

    def attach_interface(self, context, instance, image_meta, vif):
        if vif['id'] in self._interfaces:
            raise exception.InterfaceAttachFailed(
                    instance_uuid=instance.uuid)
        self._interfaces[vif['id']] = vif

    def detach_interface(self, context, instance, vif):
        try:
            del self._interfaces[vif['id']]
        except KeyError:
            raise exception.InterfaceDetachFailed(
                    instance_uuid=instance.uuid)

    def get_info(self, instance, use_cache=True):
        if instance.uuid not in self.instances:
            raise exception.InstanceNotFound(instance_id=instance.uuid)
        i = self.instances[instance.uuid]
        return hardware.InstanceInfo(state=i.state)

    def get_diagnostics(self, instance):
        return {'cpu0_time': 17300000000,
                'memory': 524288,
                'vda_errors': -1,
                'vda_read': 262144,
                'vda_read_req': 112,
                'vda_write': 5778432,
                'vda_write_req': 488,
                'vnet1_rx': 2070139,
                'vnet1_rx_drop': 0,
                'vnet1_rx_errors': 0,
                'vnet1_rx_packets': 26701,
                'vnet1_tx': 140208,
                'vnet1_tx_drop': 0,
                'vnet1_tx_errors': 0,
                'vnet1_tx_packets': 662,
        }

    def get_instance_diagnostics(self, instance):
        diags = diagnostics_obj.Diagnostics(
            state='running', driver='libvirt', hypervisor='kvm',
            hypervisor_os='ubuntu', uptime=46664, config_drive=True)
        diags.add_cpu(id=0, time=17300000000, utilisation=15)
        diags.add_nic(mac_address='01:23:45:67:89:ab',
                      rx_octets=2070139,
                      rx_errors=100,
                      rx_drop=200,
                      rx_packets=26701,
                      rx_rate=300,
                      tx_octets=140208,
                      tx_errors=400,
                      tx_drop=500,
                      tx_packets = 662,
                      tx_rate=600)
        diags.add_disk(read_bytes=262144,
                       read_requests=112,
                       write_bytes=5778432,
                       write_requests=488,
                       errors_count=1)
        diags.memory_details = diagnostics_obj.MemoryDiagnostics(
            maximum=524288, used=0)
        return diags

    def get_all_volume_usage(self, context, compute_host_bdms):
        """Return usage info for volumes attached to vms on
           a given host.
        """
        volusage = []
        if compute_host_bdms:
            volusage = [{'volume': compute_host_bdms[0][
                                       'instance_bdms'][0]['volume_id'],
                         'instance': compute_host_bdms[0]['instance'],
                         'rd_bytes': 0,
                         'rd_req': 0,
                         'wr_bytes': 0,
                         'wr_req': 0}]

        return volusage

    def get_host_cpu_stats(self):
        stats = {'kernel': 5664160000000,
                'idle': 1592705190000000,
                'user': 26728850000000,
                'iowait': 6121490000000}
        stats['frequency'] = 800
        return stats

    def block_stats(self, instance, disk_id):
        return [0, 0, 0, 0, None]

    def get_console_output(self, context, instance):
        return 'FAKE CONSOLE OUTPUT\nANOTHER\nLAST LINE'

    def get_vnc_console(self, context, instance):
        return ctype.ConsoleVNC(internal_access_path='FAKE',
                                host='fakevncconsole.com',
                                port=6969)

    def get_spice_console(self, context, instance):
        return ctype.ConsoleSpice(internal_access_path='FAKE',
                                  host='fakespiceconsole.com',
                                  port=6969,
                                  tlsPort=6970)

    def get_rdp_console(self, context, instance):
        return ctype.ConsoleRDP(internal_access_path='FAKE',
                                host='fakerdpconsole.com',
                                port=6969)

    def get_serial_console(self, context, instance):
        return ctype.ConsoleSerial(internal_access_path='FAKE',
                                   host='fakerdpconsole.com',
                                   port=6969)

    def get_mks_console(self, context, instance):
        return ctype.ConsoleMKS(internal_access_path='FAKE',
                                host='fakemksconsole.com',
                                port=6969)

    def get_available_resource(self, nodename):
        """Updates compute manager resource info on ComputeNode table.

           Since we don't have a real hypervisor, pretend we have lots of
           disk and ram.
        """
        cpu_info = collections.OrderedDict([
            ('arch', 'x86_64'),
            ('model', 'Nehalem'),
            ('vendor', 'Intel'),
            ('features', ['pge', 'clflush']),
            ('topology', {
                'cores': 1,
                'threads': 1,
                'sockets': 4,
                }),
            ])
        if nodename not in self.get_available_nodes():
            return {}

        host_status = self.host_status_base.copy()
        host_status.update(self.resources.dump())
        host_status['hypervisor_hostname'] = nodename
        host_status['host_hostname'] = nodename
        host_status['host_name_label'] = nodename
        host_status['cpu_info'] = jsonutils.dumps(cpu_info)
        # NOTE(danms): Because the fake driver runs on the same host
        # in tests, potentially with multiple nodes, we need to
        # control our node uuids. Make sure we return a unique and
        # consistent uuid for each node we are responsible for to
        # avoid the persistent local node identity from taking over.
        host_status['uuid'] = str(getattr(uuids, 'node_%s' % nodename))
        return host_status

    def update_provider_tree(self, provider_tree, nodename, allocations=None):
        # NOTE(yikun): If the inv record does not exists, the allocation_ratio
        # will use the CONF.xxx_allocation_ratio value if xxx_allocation_ratio
        # is set, and fallback to use the initial_xxx_allocation_ratio
        # otherwise.
        inv = provider_tree.data(nodename).inventory
        ratios = self._get_allocation_ratios(inv)
        inventory = {
            'VCPU': {
                'total': self.vcpus,
                'min_unit': 1,
                'max_unit': self.vcpus,
                'step_size': 1,
                'allocation_ratio': ratios[orc.VCPU],
                'reserved': CONF.reserved_host_cpus,
            },
            'MEMORY_MB': {
                'total': self.memory_mb,
                'min_unit': 1,
                'max_unit': self.memory_mb,
                'step_size': 1,
                'allocation_ratio': ratios[orc.MEMORY_MB],
                'reserved': CONF.reserved_host_memory_mb,
            },
            'DISK_GB': {
                'total': self.local_gb,
                'min_unit': 1,
                'max_unit': self.local_gb,
                'step_size': 1,
                'allocation_ratio': ratios[orc.DISK_GB],
                'reserved': self._get_reserved_host_disk_gb_from_config(),
            },
        }
        provider_tree.update_inventory(nodename, inventory)

    def get_instance_disk_info(self, instance, block_device_info=None):
        return

    def live_migration(self, context, instance, dest,
                       post_method, recover_method, block_migration=False,
                       migrate_data=None):
        post_method(context, instance, dest, block_migration,
                            migrate_data)
        return

    def live_migration_force_complete(self, instance):
        return

    def live_migration_abort(self, instance):
        return

    def cleanup_live_migration_destination_check(self, context,
                                                 dest_check_data):
        return

    def check_can_live_migrate_destination(self, context, instance,
                                           src_compute_info, dst_compute_info,
                                           block_migration=False,
                                           disk_over_commit=False):
        data = migrate_data.LibvirtLiveMigrateData()
        data.filename = 'fake'
        data.image_type = CONF.libvirt.images_type
        data.graphics_listen_addr_vnc = CONF.vnc.server_listen
        data.graphics_listen_addr_spice = CONF.spice.server_listen
        data.serial_listen_addr = None
        # Notes(eliqiao): block_migration and disk_over_commit are not
        # nullable, so just don't set them if they are None
        if block_migration is not None:
            data.block_migration = block_migration
        if disk_over_commit is not None:
            data.disk_over_commit = disk_over_commit
        data.disk_available_mb = 100000
        data.is_shared_block_storage = True
        data.is_shared_instance_path = True

        return data

    def check_can_live_migrate_source(self, context, instance,
                                      dest_check_data, block_device_info=None):
        return dest_check_data

    def finish_migration(self, context, migration, instance, disk_info,
                         network_info, image_meta, resize_instance,
                         allocations, block_device_info=None, power_on=True):
        injected_files = admin_password = None
        # Finish migration is just like spawning the guest on a destination
        # host during resize/cold migrate, so re-use the spawn() fake to
        # claim resources and track the instance on this "hypervisor".
        self.spawn(context, instance, image_meta, injected_files,
                   admin_password, allocations,
                   block_device_info=block_device_info, power_on=power_on)

    def confirm_migration(self, context, migration, instance, network_info):
        # Confirm migration cleans up the guest from the source host so just
        # destroy the guest to remove it from the list of tracked instances
        # unless it is a same-host resize.
        if migration.source_compute != migration.dest_compute:
            self.destroy(context, instance, network_info)

    def pre_live_migration(self, context, instance, block_device_info,
                           network_info, disk_info, migrate_data):
        return migrate_data

    def rollback_live_migration_at_destination(self, context, instance,
                                               network_info,
                                               block_device_info,
                                               destroy_disks=True,
                                               migrate_data=None):
        return

    def _test_remove_vm(self, instance_uuid):
        """Removes the named VM, as if it crashed. For testing."""
        self.instances.pop(instance_uuid)

    def host_power_action(self, action):
        """Reboots, shuts down or powers up the host."""
        return action

    def host_maintenance_mode(self, host, mode):
        """Start/Stop host maintenance window. On start, it triggers
        guest VMs evacuation.
        """
        if not mode:
            return 'off_maintenance'
        return 'on_maintenance'

    def set_host_enabled(self, enabled):
        """Sets the specified host's ability to accept new instances."""
        if enabled:
            return 'enabled'
        return 'disabled'

    def get_volume_connector(self, instance):
        return {'ip': CONF.my_block_storage_ip,
                'initiator': 'fake',
                'host': self._host}

    def get_available_nodes(self, refresh=False):
        return self._nodes

    def get_nodenames_by_uuid(self, refresh=False):
        return {str(getattr(uuids, 'node_%s' % n)): n
                for n in self.get_available_nodes()}

    def instance_on_disk(self, instance):
        return False

    def quiesce(self, context, instance, image_meta):
        pass

    def unquiesce(self, context, instance, image_meta):
        pass


class FakeVirtAPI(virtapi.VirtAPI):
    @contextlib.contextmanager
    def wait_for_instance_event(self, instance, event_names, deadline=300,
                                error_callback=None):
        # NOTE(danms): Don't actually wait for any events, just
        # fall through
        yield

    def exit_wait_early(self, events):
        # We never wait, so there is nothing to exit early
        pass

    def update_compute_provider_status(self, context, rp_uuid, enabled):
        pass


class SmallFakeDriver(FakeDriver):
    # The api samples expect specific cpu memory and disk sizes. In order to
    # allow the FakeVirt driver to be used outside of the unit tests, provide
    # a separate class that has the values expected by the api samples. So
    # instead of requiring new samples every time those
    # values are adjusted allow them to be overwritten here.

    vcpus = 2
    memory_mb = 8192
    local_gb = 1028


class MediumFakeDriver(FakeDriver):
    # Fake driver that has enough resources to host more than one instance
    # but not that much that cannot be exhausted easily

    vcpus = 10
    memory_mb = 8192
    local_gb = 1028


class SameHostColdMigrateDriver(MediumFakeDriver):
    """MediumFakeDriver variant that supports same-host cold migrate."""
    capabilities = dict(FakeDriver.capabilities,
                        supports_migrate_to_same_host=True)


class RescueBFVDriver(MediumFakeDriver):
    capabilities = dict(FakeDriver.capabilities, supports_bfv_rescue=True)


class PowerUpdateFakeDriver(SmallFakeDriver):
    # A specific fake driver for the power-update external event testing.

    def __init__(self, virtapi):
        super(PowerUpdateFakeDriver, self).__init__(virtapi=None)
        self.driver = ironic.IronicDriver(virtapi=virtapi)

    def power_update_event(self, instance, target_power_state):
        """Update power state of the specified instance in the nova DB."""
        self.driver.power_update_event(instance, target_power_state)


class MediumFakeDriverWithNestedCustomResources(MediumFakeDriver):
    # A MediumFakeDriver variant that also reports CUSTOM_MAGIC resources on
    # a nested resource provider
    vcpus = 10
    memory_mb = 8192
    local_gb = 1028
    child_resources = {
            'CUSTOM_MAGIC': {
                'total': 10,
                'reserved': 0,
                'min_unit': 1,
                'max_unit': 10,
                'step_size': 1,
                'allocation_ratio': 1,
            }
    }

    def update_provider_tree(self, provider_tree, nodename, allocations=None):
        super(
            MediumFakeDriverWithNestedCustomResources,
            self).update_provider_tree(
                provider_tree, nodename,
                allocations=allocations)

        if not provider_tree.exists(nodename + '-child'):
            provider_tree.new_child(name=nodename + '-child',
                                    parent=nodename)

        provider_tree.update_inventory(nodename + '-child',
                                       self.child_resources)


class FakeFinishMigrationFailDriver(FakeDriver):
    """FakeDriver variant that will raise an exception from finish_migration"""

    def finish_migration(self, *args, **kwargs):
        raise exception.VirtualInterfaceCreateException()


class PredictableNodeUUIDDriver(SmallFakeDriver):
    """SmallFakeDriver variant that reports a predictable node uuid in
    get_available_resource, like IronicDriver.
    """

    def get_available_resource(self, nodename):
        resources = super(
            PredictableNodeUUIDDriver, self).get_available_resource(nodename)
        # This is used in ComputeNode.update_from_virt_driver which is called
        # from the ResourceTracker when creating a ComputeNode.
        resources['uuid'] = str(uuid.uuid5(uuid.NAMESPACE_DNS, nodename))
        return resources


class FakeRescheduleDriver(FakeDriver):
    """FakeDriver derivative that triggers a reschedule on the first spawn
    attempt. This is expected to only be used in tests that have more than
    one compute service.
    """
    # dict, keyed by instance uuid, mapped to a boolean telling us if the
    # instance has been rescheduled or not
    rescheduled = {}

    def spawn(self, context, instance, image_meta, injected_files,
              admin_password, allocations, network_info=None,
              block_device_info=None, power_on=True, accel_info=None):
        if not self.rescheduled.get(instance.uuid, False):
            # We only reschedule on the first time something hits spawn().
            self.rescheduled[instance.uuid] = True
            raise exception.ComputeResourcesUnavailable(
                reason='FakeRescheduleDriver')
        super(FakeRescheduleDriver, self).spawn(
            context, instance, image_meta, injected_files,
            admin_password, allocations, network_info, block_device_info,
            power_on)


class FakeRescheduleDriverWithNestedCustomResources(
        FakeRescheduleDriver, MediumFakeDriverWithNestedCustomResources):
    pass


class FakeBuildAbortDriver(FakeDriver):
    """FakeDriver derivative that always fails on spawn() with a
    BuildAbortException so no reschedule is attempted.
    """

    def spawn(self, context, instance, image_meta, injected_files,
              admin_password, allocations, network_info=None,
              block_device_info=None, power_on=True, accel_info=None):
        raise exception.BuildAbortException(
            instance_uuid=instance.uuid, reason='FakeBuildAbortDriver')


class FakeBuildAbortDriverWithNestedCustomResources(
    FakeBuildAbortDriver, MediumFakeDriverWithNestedCustomResources):
    pass


class FakeUnshelveSpawnFailDriver(FakeDriver):
    """FakeDriver derivative that always fails on spawn() with a
    VirtualInterfaceCreateException when unshelving an offloaded instance.
    """

    def spawn(self, context, instance, image_meta, injected_files,
              admin_password, allocations, network_info=None,
              block_device_info=None, power_on=True, accel_info=None):
        if instance.vm_state == vm_states.SHELVED_OFFLOADED:
            raise exception.VirtualInterfaceCreateException(
                'FakeUnshelveSpawnFailDriver')
        # Otherwise spawn normally during the initial build.
        super(FakeUnshelveSpawnFailDriver, self).spawn(
            context, instance, image_meta, injected_files,
            admin_password, allocations, network_info, block_device_info,
            power_on)


class FakeUnshelveSpawnFailDriverWithNestedCustomResources(
    FakeUnshelveSpawnFailDriver, MediumFakeDriverWithNestedCustomResources):
    pass


class FakeLiveMigrateDriver(FakeDriver):
    """FakeDriver derivative to handle force_complete and abort calls.

    This module serves those tests that need to abort or force-complete
    the live migration, thus the live migration will never be finished
    without the force_complete_migration or delete_migration API calls.

    """

    def __init__(self, virtapi, read_only=False):
        super(FakeLiveMigrateDriver, self).__init__(virtapi, read_only)
        self._migrating = True
        self._abort_migration = True

    def live_migration(self, context, instance, dest,
                       post_method, recover_method, block_migration=False,
                       migrate_data=None):
        self._abort_migration = False
        self._migrating = True
        count = 0
        while self._migrating and count < 50:
            time.sleep(0.1)
            count = count + 1

        if self._abort_migration:
            recover_method(context, instance, dest, migrate_data,
                           migration_status='cancelled')
        else:
            post_method(context, instance, dest, block_migration,
                        migrate_data)

    def live_migration_force_complete(self, instance):
        self._migrating = False
        if instance.uuid in self.instances:
            del self.instances[instance.uuid]

    def live_migration_abort(self, instance):
        self._abort_migration = True
        self._migrating = False

    def post_live_migration(self, context, instance, block_device_info,
                            migrate_data=None):
        # Runs on the source host, called from
        # ComputeManager._post_live_migration so just delete the instance
        # from being tracked on the source host.
        self.destroy(context, instance, network_info=None,
                     block_device_info=block_device_info)


class FakeLiveMigrateDriverWithNestedCustomResources(
        FakeLiveMigrateDriver, MediumFakeDriverWithNestedCustomResources):
    pass


class FakeDriverWithPciResources(SmallFakeDriver):
    """NOTE: this driver provides symmetric compute nodes. Each compute will
    have the same resources with the same addresses. It is dangerous as using
    this driver can hide issues when in an asymmetric environment nova fails to
    update entities according to the host specific addresses (e.g. pci_slot of
    the neutron port bindings).

    The current non virt driver specific functional test environment has many
    shortcomings making it really hard to simulate host specific virt drivers.

    1) The virt driver is instantiated by the service logic from the name of
    the driver class. This makes passing input to the driver instance from the
    test at init time pretty impossible. This could be solved with some
    fixtures around nova.virt.driver.load_compute_driver()

    2) The compute service access the hypervisor not only via the virt
    interface but also reads the sysfs of the host. So simply providing a fake
    virt driver instance is not enough to isolate simulated compute services
    that are running on the same host. Also these low level sysfs reads are not
    having host specific information in the call params. So simply mocking the
    low level call does not give a way to provide host specific return values.

    3) CONF is global, and it is read dynamically by the driver. So
    providing host specific CONF to driver instances without race conditions
    between the drivers are extremely hard especially if periodic tasks are
    enabled.

    The libvirt based functional test env under nova.tests.functional.libvirt
    has better support to create asymmetric environments. So please consider
    using that if possible instead.
    """

    PCI_ADDR_PF1 = '0000:01:00.0'
    PCI_ADDR_PF1_VF1 = '0000:01:00.1'
    PCI_ADDR_PF2 = '0000:02:00.0'
    PCI_ADDR_PF2_VF1 = '0000:02:00.1'
    PCI_ADDR_PF3 = '0000:03:00.0'
    PCI_ADDR_PF3_VF1 = '0000:03:00.1'

    # NOTE(gibi): Always use this fixture along with the
    # FakeDriverWithPciResources to make the necessary configuration for the
    # driver.
    class FakeDriverWithPciResourcesConfigFixture(fixtures.Fixture):
        def setUp(self):
            super(FakeDriverWithPciResources.
                  FakeDriverWithPciResourcesConfigFixture, self).setUp()
            # Set device_spec before the compute node starts to match
            # with the PCI devices reported by this fake driver.

            # NOTE(gibi): 0000:01:00 is tagged to physnet1 and therefore not a
            # match based on physnet to our sriov port
            # 'port_with_sriov_resource_request' as the network of that port
            # points to physnet2 with the attribute
            # 'provider:physical_network'. Nova pci handling already enforces
            # this rule.
            #
            # 0000:02:00 and 0000:03:00 are both tagged to physnet2 and
            # therefore a good match for our sriov port based on physnet.
            # Having two PFs on the same physnet will allow us to test the
            # placement allocation - physical allocation matching based on the
            # bandwidth allocation in the future.
            CONF.set_override('device_spec', override=[
                jsonutils.dumps(
                    {
                        "address": {
                            "domain": "0000",
                            "bus": "01",
                            "slot": "00",
                            "function": ".*"},
                        "physical_network": "physnet1",
                    }
                ),
                jsonutils.dumps(
                    {
                        "address": {
                            "domain": "0000",
                            "bus": "02",
                            "slot": "00",
                            "function": ".*"},
                        "physical_network": "physnet2",
                    }
                ),
                jsonutils.dumps(
                    {
                        "address": {
                            "domain": "0000",
                            "bus": "03",
                            "slot": "00",
                            "function": ".*"},
                        "physical_network": "physnet2",
                    }
                ),
            ],
                             group='pci')

            # These mocks should be removed after bug
            # https://bugs.launchpad.net/nova/+bug/1961587 has been fixed and
            # every SRIOV device related information is transferred through the
            # virt driver and the PciDevice object instead of queried with
            # sysfs calls by the network.neutron.API code.
            self.useFixture(fixtures.MockPatch(
                'nova.pci.utils.get_mac_by_pci_address',
                return_value='52:54:00:1e:59:c6'))

            self.useFixture(fixtures.MockPatch(
                'nova.pci.utils.get_vf_num_by_pci_address',
                return_value=1))

    def get_available_resource(self, nodename):
        host_status = super(
            FakeDriverWithPciResources, self).get_available_resource(nodename)
        # 01:00.0 - PF - ens1
        #  |---- 01:00.1 - VF
        #
        # 02:00.0 - PF - ens2
        #  |---- 02:00.1 - VF
        #
        # 03:00.0 - PF - ens3
        #  |---- 03:00.1 - VF
        host_status['pci_passthrough_devices'] = jsonutils.dumps([
            {
                'address': self.PCI_ADDR_PF1,
                'product_id': 'fake-product_id',
                'vendor_id': 'fake-vendor_id',
                'status': 'available',
                'dev_type': 'type-PF',
                'parent_addr': None,
                'numa_node': 0,
                'label': 'fake-label',
            },
            {
                'address': self.PCI_ADDR_PF1_VF1,
                'product_id': 'fake-product_id',
                'vendor_id': 'fake-vendor_id',
                'status': 'available',
                'dev_type': 'type-VF',
                'parent_addr': self.PCI_ADDR_PF1,
                'numa_node': 0,
                'label': 'fake-label',
                "parent_ifname": self._host + "-ens1",
            },
            {
                'address': self.PCI_ADDR_PF2,
                'product_id': 'fake-product_id',
                'vendor_id': 'fake-vendor_id',
                'status': 'available',
                'dev_type': 'type-PF',
                'parent_addr': None,
                'numa_node': 0,
                'label': 'fake-label',
            },
            {
                'address': self.PCI_ADDR_PF2_VF1,
                'product_id': 'fake-product_id',
                'vendor_id': 'fake-vendor_id',
                'status': 'available',
                'dev_type': 'type-VF',
                'parent_addr': self.PCI_ADDR_PF2,
                'numa_node': 0,
                'label': 'fake-label',
                "parent_ifname": self._host + "-ens2",
            },
            {
                'address': self.PCI_ADDR_PF3,
                'product_id': 'fake-product_id',
                'vendor_id': 'fake-vendor_id',
                'status': 'available',
                'dev_type': 'type-PF',
                'parent_addr': None,
                'numa_node': 0,
                'label': 'fake-label',
            },
            {
                'address': self.PCI_ADDR_PF3_VF1,
                'product_id': 'fake-product_id',
                'vendor_id': 'fake-vendor_id',
                'status': 'available',
                'dev_type': 'type-VF',
                'parent_addr': self.PCI_ADDR_PF3,
                'numa_node': 0,
                'label': 'fake-label',
                "parent_ifname": self._host + "-ens3",
            },
        ])
        return host_status


class FakeLiveMigrateDriverWithPciResources(
        FakeLiveMigrateDriver, FakeDriverWithPciResources):
    """FakeDriver derivative to handle force_complete and abort calls.

    This module serves those tests that need to abort or force-complete
    the live migration, thus the live migration will never be finished
    without the force_complete_migration or delete_migration API calls.

    """


class FakeDriverWithCaching(FakeDriver):
    def __init__(self, *a, **k):
        super(FakeDriverWithCaching, self).__init__(*a, **k)
        self.cached_images = set()

    def cache_image(self, context, image_id):
        if image_id in self.cached_images:
            return False
        else:
            self.cached_images.add(image_id)
            return True


class EphEncryptionDriver(MediumFakeDriver):
    capabilities = dict(
        FakeDriver.capabilities,
        supports_ephemeral_encryption=True)


class EphEncryptionDriverLUKS(MediumFakeDriver):
    capabilities = dict(
        FakeDriver.capabilities,
        supports_ephemeral_encryption=True,
        supports_ephemeral_encryption_luks=True)


class EphEncryptionDriverPLAIN(MediumFakeDriver):
    capabilities = dict(
        FakeDriver.capabilities,
        supports_ephemeral_encryption=True,
        supports_ephemeral_encryption_plain=True)


class FakeDriverWithoutFakeNodes(FakeDriver):
    """FakeDriver that behaves like a real single-node driver.

    This behaves like a real virt driver from the perspective of its
    nodes, with a stable nodename and use of the global node identity
    stuff to provide a stable node UUID.
    """

    def get_available_resource(self, nodename):
        resources = super().get_available_resource(nodename)
        resources['uuid'] = nova.virt.node.get_local_node_uuid()
        return resources

    def get_nodenames_by_uuid(self, refresh=False):
        return {
            nova.virt.node.get_local_node_uuid(): self.get_available_nodes()[0]
        }
