path: root/nova/tests/unit/virt/libvirt/test_imagecache.py

# Copyright 2012 Michael Still and Canonical 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.


import contextlib
import io
import os
import time

import mock
from oslo_concurrency import lockutils
from oslo_concurrency import processutils
from oslo_log import formatters
from oslo_log import log as logging
from oslo_utils.fixture import uuidsentinel as uuids

from nova.compute import manager as compute_manager
import nova.conf
from nova import context
from nova import objects
from nova import test
from nova.tests.unit import fake_instance
from nova import utils
from nova.virt.libvirt import imagecache

CONF = nova.conf.CONF


@contextlib.contextmanager
def intercept_log_messages():
    try:
        mylog = logging.getLogger('nova')
        stream = io.StringIO()
        handler = logging.logging.StreamHandler(stream)
        handler.setFormatter(formatters.ContextFormatter())
        mylog.logger.addHandler(handler)
        yield stream
    finally:
        mylog.logger.removeHandler(handler)


class GetCacheFnameTestCase(test.NoDBTestCase):
    def test_get_cache_fname(self):
        # Ensure a known input to this function produces a known output.

        # This test assures us that, used in the expected manner, the function
        # doesn't raise an exception in either python2 or python3. It also
        # serves as a canary to warn if any change in underlying libraries
        # would produce output incompatible with current usage.

        # Take a known image_id and the pre-calculated hexdigest of its sha1
        image_id = 'fd0cb2f1-8375-44c9-b1f4-3e1f4c4a8ef0'
        expected_cache_name = '0d5e6b61602d758984b3bf038267614d6016eb2a'

        cache_name = imagecache.get_cache_fname(image_id)
        self.assertEqual(expected_cache_name, cache_name)


class ImageCacheManagerTestCase(test.NoDBTestCase):

    def setUp(self):
        super(ImageCacheManagerTestCase, self).setUp()
        self.stock_instance_names = set(['instance-00000001',
                                         'instance-00000002',
                                         'instance-00000003',
                                         'banana-42-hamster'])

    @mock.patch.object(os.path, 'exists', return_value=True)
    @mock.patch.object(time, 'time', return_value=2000000)
    @mock.patch.object(os.path, 'getmtime', return_value=1000000)
    def test_get_age_of_file(self, mock_getmtime, mock_time, mock_exists):
        image_cache_manager = imagecache.ImageCacheManager()
        exists, age = image_cache_manager._get_age_of_file('/tmp')
        self.assertTrue(exists)
        self.assertEqual(1000000, age)

    @mock.patch.object(os.path, 'exists', return_value=False)
    def test_get_age_of_file_not_exists(self, mock_exists):
        image_cache_manager = imagecache.ImageCacheManager()
        exists, age = image_cache_manager._get_age_of_file('/tmp')
        self.assertFalse(exists)
        self.assertEqual(0, age)

    def test_list_base_images(self):
        listing = ['00000001',
                   'ephemeral_20_abcdefg',
                   '00000004',
                   'swap_1000']
        images = ['e97222e91fc4241f49a7f520d1dcf446751129b3_sm',
                  'e09c675c2d1cfac32dae3c2d83689c8c94bc693b_sm',
                  'e97222e91fc4241f49a7f520d1dcf446751129b3',
                  '17d1b00b81642842e514494a78e804e9a511637c',
                  '17d1b00b81642842e514494a78e804e9a511637c_5368709120',
                  '17d1b00b81642842e514494a78e804e9a511637c_10737418240']
        listing.extend(images)

        self.stub_out('os.listdir', lambda x: listing)
        self.stub_out('os.path.isfile', lambda x: True)

        base_dir = '/var/lib/nova/instances/_base'
        self.flags(instances_path='/var/lib/nova/instances')

        image_cache_manager = imagecache.ImageCacheManager()
        image_cache_manager._scan_base_images(base_dir)

        sanitized = []
        for ent in image_cache_manager.unexplained_images:
            sanitized.append(ent.replace(base_dir + '/', ''))

        self.assertEqual(sorted(sanitized), sorted(images))

        expected = os.path.join(base_dir,
                                'e97222e91fc4241f49a7f520d1dcf446751129b3')
        self.assertIn(expected, image_cache_manager.unexplained_images)

        expected = os.path.join(base_dir,
                                '17d1b00b81642842e514494a78e804e9a511637c_'
                                '10737418240')
        self.assertIn(expected, image_cache_manager.unexplained_images)

        unexpected = os.path.join(base_dir, '00000004')
        self.assertNotIn(unexpected, image_cache_manager.unexplained_images)

        for ent in image_cache_manager.unexplained_images:
            self.assertTrue(ent.startswith(base_dir))

        self.assertEqual(len(image_cache_manager.originals), 2)

        expected = os.path.join(base_dir,
                                '17d1b00b81642842e514494a78e804e9a511637c')
        self.assertIn(expected, image_cache_manager.originals)

        unexpected = os.path.join(base_dir,
                                  '17d1b00b81642842e514494a78e804e9a511637c_'
                                '10737418240')
        self.assertNotIn(unexpected, image_cache_manager.originals)

        self.assertEqual(1, len(image_cache_manager.back_swap_images))
        self.assertIn('swap_1000', image_cache_manager.back_swap_images)
        self.assertEqual(1, len(image_cache_manager.back_ephemeral_images))
        self.assertIn(
            'ephemeral_20_abcdefg', image_cache_manager.back_ephemeral_images)

    def test_list_backing_images_small(self):
        self.stub_out('os.listdir',
                      lambda x: ['_base', 'instance-00000001',
                                 'instance-00000002', 'instance-00000003'])
        self.stub_out('os.path.exists',
                      lambda x: x.find('instance-') != -1)
        self.stub_out('nova.virt.libvirt.utils.get_disk_backing_file',
                      lambda x: 'e97222e91fc4241f49a7f520d1dcf446751129b3_sm')

        found = os.path.join(CONF.instances_path,
                             CONF.image_cache.subdirectory_name,
                             'e97222e91fc4241f49a7f520d1dcf446751129b3_sm')

        image_cache_manager = imagecache.ImageCacheManager()
        image_cache_manager.unexplained_images = [found]
        image_cache_manager.instance_names = self.stock_instance_names

        inuse_images = image_cache_manager._list_backing_images()

        self.assertEqual(inuse_images, [found])
        self.assertEqual(len(image_cache_manager.unexplained_images), 0)

    def test_list_backing_images_resized(self):
        self.stub_out('os.listdir',
                      lambda x: ['_base', 'instance-00000001',
                                 'instance-00000002', 'instance-00000003'])
        self.stub_out('os.path.exists',
                      lambda x: x.find('instance-') != -1)
        self.stub_out('nova.virt.libvirt.utils.get_disk_backing_file',
                      lambda x: ('e97222e91fc4241f49a7f520d1dcf446751129b3_'
                                 '10737418240'))

        found = os.path.join(CONF.instances_path,
                             CONF.image_cache.subdirectory_name,
                             'e97222e91fc4241f49a7f520d1dcf446751129b3_'
                             '10737418240')

        image_cache_manager = imagecache.ImageCacheManager()
        image_cache_manager.unexplained_images = [found]
        image_cache_manager.instance_names = self.stock_instance_names

        inuse_images = image_cache_manager._list_backing_images()

        self.assertEqual(inuse_images, [found])
        self.assertEqual(len(image_cache_manager.unexplained_images), 0)

    def test_list_backing_images_instancename(self):
        self.stub_out('os.listdir',
                      lambda x: ['_base', 'banana-42-hamster'])
        self.stub_out('os.path.exists',
                      lambda x: x.find('banana-42-hamster') != -1)
        self.stub_out('nova.virt.libvirt.utils.get_disk_backing_file',
                      lambda x: 'e97222e91fc4241f49a7f520d1dcf446751129b3_sm')

        found = os.path.join(CONF.instances_path,
                             CONF.image_cache.subdirectory_name,
                             'e97222e91fc4241f49a7f520d1dcf446751129b3_sm')

        image_cache_manager = imagecache.ImageCacheManager()
        image_cache_manager.unexplained_images = [found]
        image_cache_manager.instance_names = self.stock_instance_names

        inuse_images = image_cache_manager._list_backing_images()

        self.assertEqual(inuse_images, [found])
        self.assertEqual(len(image_cache_manager.unexplained_images), 0)

    def test_list_backing_images_disk_notexist(self):
        self.stub_out('os.listdir',
                      lambda x: ['_base', 'banana-42-hamster'])
        self.stub_out('os.path.exists',
                      lambda x: x.find('banana-42-hamster') != -1)

        def fake_get_disk(disk_path):
            raise processutils.ProcessExecutionError()

        self.stub_out('nova.virt.libvirt.utils.get_disk_backing_file',
                      fake_get_disk)

        image_cache_manager = imagecache.ImageCacheManager()
        image_cache_manager.unexplained_images = []
        image_cache_manager.instance_names = self.stock_instance_names

        self.assertRaises(processutils.ProcessExecutionError,
                          image_cache_manager._list_backing_images)

    def test_find_base_file_nothing(self):
        self.stub_out('os.path.exists', lambda x: False)

        base_dir = '/var/lib/nova/instances/_base'
        fingerprint = '549867354867'
        image_cache_manager = imagecache.ImageCacheManager()
        res = list(image_cache_manager._find_base_file(base_dir, fingerprint))

        self.assertEqual(0, len(res))

    def test_find_base_file_small(self):
        fingerprint = '968dd6cc49e01aaa044ed11c0cce733e0fa44a6a'
        self.stub_out('os.path.exists',
                       lambda x: x.endswith('%s_sm' % fingerprint))

        base_dir = '/var/lib/nova/instances/_base'
        image_cache_manager = imagecache.ImageCacheManager()
        res = list(image_cache_manager._find_base_file(base_dir, fingerprint))

        base_file = os.path.join(base_dir, fingerprint + '_sm')
        self.assertEqual([base_file], res)

    def test_find_base_file_resized(self):
        fingerprint = '968dd6cc49e01aaa044ed11c0cce733e0fa44a6a'
        listing = ['00000001',
                   'ephemeral_0_20_None',
                   '968dd6cc49e01aaa044ed11c0cce733e0fa44a6a_10737418240',
                   '00000004']

        self.stub_out('os.listdir', lambda x: listing)
        self.stub_out('os.path.exists',
                       lambda x: x.endswith('%s_10737418240' % fingerprint))
        self.stub_out('os.path.isfile', lambda x: True)

        base_dir = '/var/lib/nova/instances/_base'
        image_cache_manager = imagecache.ImageCacheManager()
        image_cache_manager._scan_base_images(base_dir)
        res = list(image_cache_manager._find_base_file(base_dir, fingerprint))

        base_file = os.path.join(base_dir, fingerprint + '_10737418240')
        self.assertEqual([base_file], res)

    def test_find_base_file_all(self):
        fingerprint = '968dd6cc49e01aaa044ed11c0cce733e0fa44a6a'
        listing = ['00000001',
                   'ephemeral_0_20_None',
                   '968dd6cc49e01aaa044ed11c0cce733e0fa44a6a_sm',
                   '968dd6cc49e01aaa044ed11c0cce733e0fa44a6a_10737418240',
                   '00000004']

        self.stub_out('os.listdir', lambda x: listing)
        self.stub_out('os.path.exists', lambda x: True)
        self.stub_out('os.path.isfile', lambda x: True)

        base_dir = '/var/lib/nova/instances/_base'
        image_cache_manager = imagecache.ImageCacheManager()
        image_cache_manager._scan_base_images(base_dir)
        res = list(image_cache_manager._find_base_file(base_dir, fingerprint))

        base_file1 = os.path.join(base_dir, fingerprint)
        base_file2 = os.path.join(base_dir, fingerprint + '_sm')
        base_file3 = os.path.join(base_dir, fingerprint + '_10737418240')
        self.assertEqual([base_file1, base_file2, base_file3], res)

    @contextlib.contextmanager
    def _make_base_file(self, lock=True):
        """Make a base file for testing."""

        with utils.tempdir() as tmpdir:
            self.flags(instances_path=tmpdir)
            fname = os.path.join(tmpdir, 'aaa')

            base_file = open(fname, 'w')
            base_file.write('data')
            base_file.close()

            if lock:
                lockdir = os.path.join(tmpdir, 'locks')
                lockname = os.path.join(lockdir, 'nova-aaa')
                os.mkdir(lockdir)
                lock_file = open(lockname, 'w')
                lock_file.write('data')
                lock_file.close()

            base_file = open(fname, 'r')
            base_file.close()
            yield fname

    def test_remove_base_file(self):
        with self._make_base_file() as fname:
            image_cache_manager = imagecache.ImageCacheManager()
            image_cache_manager._remove_base_file(fname)

            lock_name = 'nova-' + os.path.split(fname)[-1]
            lock_dir = os.path.join(CONF.instances_path, 'locks')
            lock_file = os.path.join(lock_dir, lock_name)

            # Files are initially too new to delete
            self.assertTrue(os.path.exists(fname))
            self.assertTrue(os.path.exists(lock_file))

            # Old files get cleaned up though
            os.utime(fname, (-1, time.time() - 3601))
            image_cache_manager._remove_base_file(fname)

            self.assertFalse(os.path.exists(fname))
            self.assertFalse(os.path.exists(lock_file))

    def test_remove_base_file_original(self):
        with self._make_base_file() as fname:
            image_cache_manager = imagecache.ImageCacheManager()
            image_cache_manager.originals = [fname]
            image_cache_manager._remove_base_file(fname)

            # Files are initially too new to delete
            self.assertTrue(os.path.exists(fname))

            # This file should stay longer than a resized image
            os.utime(fname, (-1, time.time() - 3601))
            image_cache_manager._remove_base_file(fname)

            self.assertTrue(os.path.exists(fname))

            # Originals don't stay forever though
            os.utime(fname, (-1, time.time() - 3600 * 25))
            image_cache_manager._remove_base_file(fname)

            self.assertFalse(os.path.exists(fname))

    def test_remove_base_file_dne(self):
        # This test is solely to execute the "does not exist" code path. We
        # don't expect the method being tested to do anything in this case.
        with utils.tempdir() as tmpdir:
            self.flags(instances_path=tmpdir)

            fname = os.path.join(tmpdir, 'aaa')
            image_cache_manager = imagecache.ImageCacheManager()
            image_cache_manager._remove_base_file(fname)

    def test_remove_base_file_oserror(self):
        with intercept_log_messages() as stream:
            with utils.tempdir() as tmpdir:
                self.flags(instances_path=tmpdir)

                fname = os.path.join(tmpdir, 'aaa')

                os.mkdir(fname)
                os.utime(fname, (-1, time.time() - 3601))

                # This will raise an OSError because of file permissions
                image_cache_manager = imagecache.ImageCacheManager()
                image_cache_manager._remove_base_file(fname)

                self.assertTrue(os.path.exists(fname))
                self.assertNotEqual(stream.getvalue().find('Failed to remove'),
                                    -1)

    @mock.patch('nova.privsep.path.utime')
    def test_mark_in_use(self, mock_utime):
        img = '123'

        with self._make_base_file() as fname:
            image_cache_manager = imagecache.ImageCacheManager()
            image_cache_manager.unexplained_images = [fname]
            image_cache_manager.used_images = {'123': (1, 0, ['banana-42'])}
            image_cache_manager._mark_in_use(img, fname)

            mock_utime.assert_called_once_with(fname)
            self.assertEqual(image_cache_manager.unexplained_images, [])
            self.assertEqual(image_cache_manager.removable_base_files, [])

    @mock.patch('nova.privsep.path.utime')
    @mock.patch.object(lockutils, 'external_lock')
    def test_verify_base_images(self, mock_lock, mock_utime):
        hashed_1 = '356a192b7913b04c54574d18c28d46e6395428ab'
        hashed_21 = '472b07b9fcf2c2451e8781e944bf5f77cd8457c8'
        hashed_22 = '12c6fc06c99a462375eeb3f43dfd832b08ca9e17'
        hashed_42 = '92cfceb39d57d914ed8b14d0e37643de0797ae56'

        self.flags(instances_path='/instance_path')
        self.flags(subdirectory_name='_base', group='image_cache')

        base_file_list = ['00000001',
                          'ephemeral_0_20_None',
                          'e97222e91fc4241f49a7f520d1dcf446751129b3_sm',
                          'e09c675c2d1cfac32dae3c2d83689c8c94bc693b_sm',
                          hashed_42,
                          hashed_1,
                          hashed_21,
                          hashed_22,
                          '%s_5368709120' % hashed_1,
                          '%s_10737418240' % hashed_1,
                          '00000004']

        def fq_path(path):
            return os.path.join('/instance_path/_base/', path)

        # Fake base directory existence
        orig_exists = os.path.exists

        def exists(path):
            # The python coverage tool got angry with my overly broad mocks
            if not path.startswith('/instance_path'):
                return orig_exists(path)

            if path in ['/instance_path',
                        '/instance_path/_base',
                        '/instance_path/instance-1/disk',
                        '/instance_path/instance-2/disk',
                        '/instance_path/instance-3/disk']:
                return True

            for p in base_file_list:
                if path == fq_path(p):
                    return True

            if path in ['/instance_path/_base/%s_sm' % i for i in [hashed_1,
                                                                   hashed_21,
                                                                   hashed_22,
                                                                   hashed_42]]:
                return False

            self.fail('Unexpected path existence check: %s' % path)

        self.stub_out('os.path.exists', lambda x: exists(x))

        # Fake up some instances in the instances directory
        orig_listdir = os.listdir

        def listdir(path):
            # The python coverage tool got angry with my overly broad mocks
            if not path.startswith('/instance_path'):
                return orig_listdir(path)

            if path == '/instance_path':
                return ['instance-1', 'instance-2', 'instance-3', '_base']

            if path == '/instance_path/_base':
                return base_file_list

            self.fail('Unexpected directory listed: %s' % path)

        self.stub_out('os.listdir', lambda x: listdir(x))

        # Fake isfile for these faked images in _base
        orig_isfile = os.path.isfile

        def isfile(path):
            # The python coverage tool got angry with my overly broad mocks
            if not path.startswith('/instance_path'):
                return orig_isfile(path)

            for p in base_file_list:
                if path == fq_path(p):
                    return True

            self.fail('Unexpected isfile call: %s' % path)

        self.stub_out('os.path.isfile', lambda x: isfile(x))

        # Fake the database call which lists running instances
        instances = [{'image_ref': '1',
                      'host': CONF.host,
                      'name': 'instance-1',
                      'uuid': uuids.instance_1,
                      'vm_state': '',
                      'task_state': ''},
                     {'image_ref': '1',
                      'kernel_id': '21',
                      'ramdisk_id': '22',
                      'host': CONF.host,
                      'name': 'instance-2',
                      'uuid': uuids.instance_2,
                      'vm_state': '',
                      'task_state': ''}]
        all_instances = [fake_instance.fake_instance_obj(None, **instance)
                         for instance in instances]
        image_cache_manager = imagecache.ImageCacheManager()

        # Fake the utils call which finds the backing image
        def get_disk_backing_file(path):
            if path in ['/instance_path/instance-1/disk',
                        '/instance_path/instance-2/disk']:
                return fq_path('%s_5368709120' % hashed_1)
            self.fail('Unexpected backing file lookup: %s' % path)

        self.stub_out('nova.virt.libvirt.utils.get_disk_backing_file',
                      lambda x: get_disk_backing_file(x))

        # Fake getmtime as well
        orig_getmtime = os.path.getmtime

        def getmtime(path):
            if not path.startswith('/instance_path'):
                return orig_getmtime(path)

            return 1000000

        self.stub_out('os.path.getmtime', lambda x: getmtime(x))

        # Make sure we don't accidentally remove a real file
        orig_remove = os.remove

        def remove(path):
            if not path.startswith('/instance_path'):
                return orig_remove(path)

            # Don't try to remove fake files
            return

        self.stub_out('os.remove', lambda x: remove(x))

        with mock.patch.object(objects.block_device.BlockDeviceMappingList,
                               'bdms_by_instance_uuid', return_value={}
                               ) as mock_bdms:
            ctxt = context.get_admin_context()
            # And finally we can make the call we're actually testing...
            # The argument here should be a context, but it is mocked out
            image_cache_manager.update(ctxt, all_instances)

            # Verify
            active = [fq_path(hashed_1), fq_path('%s_5368709120' % hashed_1),
                      fq_path(hashed_21), fq_path(hashed_22)]
            for act in active:
                self.assertIn(act, image_cache_manager.active_base_files)
            self.assertEqual(len(image_cache_manager.active_base_files),
                             len(active))

            for rem in [fq_path('e97222e91fc4241f49a7f520d1dcf446751129b3_sm'),
                        fq_path('e09c675c2d1cfac32dae3c2d83689c8c94bc693b_sm'),
                        fq_path(hashed_42),
                        fq_path('%s_10737418240' % hashed_1)]:
                self.assertIn(rem, image_cache_manager.removable_base_files)

            mock_bdms.assert_called_once_with(ctxt,
                [uuids.instance_1, uuids.instance_2])

    def test_verify_base_images_no_base(self):
        self.flags(instances_path='/tmp/no/such/dir/name/please')
        image_cache_manager = imagecache.ImageCacheManager()
        image_cache_manager.update(None, [])

    @mock.patch('nova.objects.InstanceList.get_by_filters')
    def test_run_image_cache_manager_pass(self, mock_instance_list):

        def fake_instances(ctxt):
            instances = []
            for x in range(2):
                instances.append(
                    fake_instance.fake_db_instance(
                        image_ref=uuids.fake_image_ref,
                        uuid=getattr(uuids, 'instance_%s' % x),
                        name='instance-%s' % x,
                        vm_state='',
                        task_state=''))
            return objects.instance._make_instance_list(
                ctxt, objects.InstanceList(), instances, None)

        with utils.tempdir() as tmpdir:
            self.flags(instances_path=tmpdir)
            ctxt = context.get_admin_context()
            mock_instance_list.return_value = fake_instances(ctxt)
            compute = compute_manager.ComputeManager()
            compute._run_image_cache_manager_pass(ctxt)
            filters = {
                'host': ['fake-mini'],
                'deleted': False,
                'soft_deleted': True,
            }
            mock_instance_list.assert_called_once_with(
                ctxt, filters, expected_attrs=[], use_slave=True)

    def test_store_swap_image(self):
        image_cache_manager = imagecache.ImageCacheManager()
        image_cache_manager._store_swap_image('swap_')
        image_cache_manager._store_swap_image('swap_123')
        image_cache_manager._store_swap_image('swap_456')
        image_cache_manager._store_swap_image('swap_abc')
        image_cache_manager._store_swap_image('123_swap')
        image_cache_manager._store_swap_image('swap_129_')

        self.assertEqual(len(image_cache_manager.back_swap_images), 2)
        expect_set = set(['swap_123', 'swap_456'])
        self.assertEqual(image_cache_manager.back_swap_images, expect_set)

    def test_store_ephemeral_image(self):
        image_cache_manager = imagecache.ImageCacheManager()
        image_cache_manager._store_ephemeral_image('ephemeral_')
        image_cache_manager._store_ephemeral_image('ephemeral_123')
        image_cache_manager._store_ephemeral_image('ephemeral_456_40d1d2c')
        image_cache_manager._store_ephemeral_image('ephemeral_abc_40d1f2e')
        image_cache_manager._store_ephemeral_image('123_ephemeral_40e1d2d')
        image_cache_manager._store_ephemeral_image('ephemeral_129_')

        self.assertEqual(len(image_cache_manager.back_ephemeral_images), 1)
        expect_set = set(['ephemeral_456_40d1d2c'])
        self.assertEqual(image_cache_manager.back_ephemeral_images, expect_set)

    @mock.patch.object(lockutils, 'external_lock')
    @mock.patch('os.path.exists')
    @mock.patch('os.path.getmtime')
    @mock.patch('os.remove')
    @mock.patch('nova.privsep.path.utime')
    def test_age_and_verify_swap_images(self, mock_utime, mock_remove,
            mock_getmtime, mock_exist, mock_lock):
        base_dir = '/tmp_age_test'

        image_cache_manager = imagecache.ImageCacheManager()
        expected_remove = set()
        expected_exist = set(['swap_128', 'swap_256'])

        image_cache_manager.back_swap_images.add('swap_128')
        image_cache_manager.back_swap_images.add('swap_256')

        image_cache_manager.used_swap_images.add('swap_128')

        mock_getmtime.side_effect = lambda path: time.time() - 1000000

        mock_exist.side_effect = \
            lambda path: os.path.dirname(path) == base_dir and \
                         os.path.basename(path) in expected_exist

        def removefile(path):
            self.assertEqual(base_dir, os.path.dirname(path),
                             'Attempt to remove unexpected path')

            fn = os.path.basename(path)
            expected_remove.add(fn)
            expected_exist.remove(fn)

        mock_remove.side_effect = removefile

        image_cache_manager._age_and_verify_swap_images(None, base_dir)
        self.assertEqual(set(['swap_128']), expected_exist)
        self.assertEqual(set(['swap_256']), expected_remove)

    @mock.patch.object(lockutils, 'external_lock')
    @mock.patch('os.path.exists')
    @mock.patch('os.path.getmtime')
    @mock.patch('os.remove')
    @mock.patch('nova.privsep.path.utime')
    def test_age_and_verify_ephemeral_images(self, mock_utime, mock_remove,
            mock_getmtime, mock_exist, mock_lock):
        base_dir = '/tmp_age_test'
        image_cache_manager = imagecache.ImageCacheManager()
        expected_remove = set()
        expected_exist = set(['ephemeral_456_40d1d2c', 'ephemeral_2_41e1f2c'])
        image_cache_manager.back_ephemeral_images.add('ephemeral_456_40d1d2c')
        image_cache_manager.back_ephemeral_images.add('ephemeral_2_41e1f2c')
        image_cache_manager.used_ephemeral_images.add('ephemeral_2_41e1f2c')
        mock_getmtime.side_effect = lambda path: time.time() - 1000000
        mock_exist.side_effect = \
            lambda path: os.path.dirname(path) == base_dir and \
                         os.path.basename(path) in expected_exist

        def removefile(path):
            self.assertEqual(base_dir, os.path.dirname(path),
                             'Attempt to remove unexpected path')
            fn = os.path.basename(path)
            expected_remove.add(fn)
            expected_exist.remove(fn)
        mock_remove.side_effect = removefile
        image_cache_manager._age_and_verify_ephemeral_images(None, base_dir)
        self.assertEqual(set(['ephemeral_2_41e1f2c']), expected_exist)
        self.assertEqual(set(['ephemeral_456_40d1d2c']), expected_remove)

    @mock.patch.object(utils, 'synchronized')
    @mock.patch.object(imagecache.ImageCacheManager, '_get_age_of_file',
                       return_value=(True, 100))
    def test_lock_acquired_on_removing_old_enough_files(self, mock_get_age,
                                                        mock_synchronized):
        base_file = '/tmp_age_test'
        lock_path = os.path.join(CONF.instances_path, 'locks')
        lock_file = os.path.split(base_file)[-1]
        image_cache_manager = imagecache.ImageCacheManager()
        image_cache_manager._remove_old_enough_file(base_file, 60,
                                                    remove_lock=False)
        mock_synchronized.assert_called_once_with(lock_file, external=True,
                                                  lock_path=lock_path)

    @mock.patch('os.stat')
    def test_get_disk_usage_cache_is_on_different_disk(self, mock_stat):
        mock_stat.side_effect = [mock.Mock(st_dev=0), mock.Mock(st_dev=1)]
        manager = imagecache.ImageCacheManager()

        self.assertEqual(0, manager.get_disk_usage())

        mock_stat.assert_has_calls([
            mock.call(CONF.instances_path),
            mock.call(
                os.path.join(
                    CONF.instances_path,
                    CONF.image_cache.subdirectory_name))])

    @mock.patch('os.listdir')
    @mock.patch('os.stat')
    def test_get_disk_usage_empty(self, mock_stat, mock_listdir):
        mock_stat.side_effect = [mock.Mock(st_dev=0), mock.Mock(st_dev=0)]
        mock_listdir.return_value = []

        manager = imagecache.ImageCacheManager()

        self.assertEqual(0, manager.get_disk_usage())

    @mock.patch('os.stat')
    @mock.patch('os.listdir')
    def test_get_disk_usage_cache_dir_missing(self, mock_listdir, mock_stat):
        mock_stat.side_effect = [mock.Mock(st_dev=0), FileNotFoundError]

        manager = imagecache.ImageCacheManager()

        self.assertEqual(0, manager.get_disk_usage())
        mock_listdir.assert_not_called()

    @mock.patch('os.path.isfile')
    @mock.patch('os.listdir')
    @mock.patch('os.stat')
    def test_get_disk_usage(self, mock_stat, mock_listdir, mock_isfile):
        mock_stat.side_effect = [
            # cache and instances dirs are on the same dev
            mock.Mock(st_dev=0),
            mock.Mock(st_dev=0),
            # stat calls on each file in the cache directory to get the size
            mock.Mock(st_blocks=10),  # foo
            mock.Mock(st_blocks=20),  # bar
        ]
        mock_listdir.return_value = ['foo', 'bar', 'some-dir']
        mock_isfile.side_effect = [
            True,  # foo
            True,  # bar
            False,  # some-dir
        ]

        manager = imagecache.ImageCacheManager()

        # size is calculated from as st_blocks * 512
        self.assertEqual(10 * 512 + 20 * 512, manager.get_disk_usage())

    @mock.patch('os.path.isfile')
    @mock.patch('os.listdir')
    @mock.patch('os.stat')
    def test_get_disk_usage_io_error_while_reading(
            self, mock_stat, mock_listdir, mock_isfile):
        mock_stat.side_effect = [
            # cache and instances dirs are on the same dev
            mock.Mock(st_dev=0),
            mock.Mock(st_dev=0),
            # stat calls on each file in the cache directory to get the size
            mock.Mock(st_blocks=10),  # foo
            IOError,  # error while checking bar
        ]
        mock_listdir.return_value = ['foo', 'bar', 'some-dir']
        mock_isfile.side_effect = [
            True,  # foo
            True,  # bar
            False,  # some-dir
        ]

        manager = imagecache.ImageCacheManager()

        self.assertEqual(0, manager.get_disk_usage())