Source code for glance.image_cache.drivers.base
# Copyright 2011 OpenStack Foundation
# 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.
"""
Base attribute driver class
"""
import os.path
from oslo_config import cfg
from oslo_log import log as logging
from glance.common import exception
from glance.common import utils
from glance.i18n import _
LOG = logging.getLogger(__name__)
CONF = cfg.CONF
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class Driver(object):
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def set_paths(self):
"""
Creates all necessary directories under the base cache directory
"""
self.base_dir = CONF.image_cache_dir
if self.base_dir is None:
msg = _('Failed to read %s from config') % 'image_cache_dir'
LOG.error(msg)
driver = self.__class__.__module__
raise exception.BadDriverConfiguration(driver_name=driver,
reason=msg)
self.incomplete_dir = os.path.join(self.base_dir, 'incomplete')
self.invalid_dir = os.path.join(self.base_dir, 'invalid')
self.queue_dir = os.path.join(self.base_dir, 'queue')
dirs = [self.incomplete_dir, self.invalid_dir, self.queue_dir]
for path in dirs:
utils.safe_mkdirs(path)
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def get_cache_size(self):
"""
Returns the total size in bytes of the image cache.
"""
raise NotImplementedError
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def get_cached_images(self):
"""
Returns a list of records about cached images.
The list of records shall be ordered by image ID and shall look like::
[
{
'image_id': <IMAGE_ID>,
'hits': INTEGER,
'last_modified': ISO_TIMESTAMP,
'last_accessed': ISO_TIMESTAMP,
'size': INTEGER
}, ...
]
"""
return NotImplementedError
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def is_cached(self, image_id):
"""
Returns True if the image with the supplied ID has its image
file cached.
:param image_id: Image ID
"""
raise NotImplementedError
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def is_cacheable(self, image_id):
"""
Returns True if the image with the supplied ID can have its
image file cached, False otherwise.
:param image_id: Image ID
"""
raise NotImplementedError
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def is_queued(self, image_id):
"""
Returns True if the image identifier is in our cache queue.
:param image_id: Image ID
"""
raise NotImplementedError
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def delete_all_cached_images(self):
"""
Removes all cached image files and any attributes about the images
and returns the number of cached image files that were deleted.
"""
raise NotImplementedError
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def delete_cached_image(self, image_id):
"""
Removes a specific cached image file and any attributes about the image
:param image_id: Image ID
"""
raise NotImplementedError
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def delete_all_queued_images(self):
"""
Removes all queued image files and any attributes about the images
and returns the number of queued image files that were deleted.
"""
raise NotImplementedError
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def delete_queued_image(self, image_id):
"""
Removes a specific queued image file and any attributes about the image
:param image_id: Image ID
"""
raise NotImplementedError
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def queue_image(self, image_id):
"""
Puts an image identifier in a queue for caching. Return True
on successful add to the queue, False otherwise...
:param image_id: Image ID
"""
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def clean(self, stall_time=None):
"""
Dependent on the driver, clean up and destroy any invalid or incomplete
cached images
"""
raise NotImplementedError
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def get_least_recently_accessed(self):
"""
Return a tuple containing the image_id and size of the least recently
accessed cached file, or None if no cached files.
"""
raise NotImplementedError
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def open_for_write(self, image_id):
"""
Open a file for writing the image file for an image
with supplied identifier.
:param image_id: Image ID
"""
raise NotImplementedError
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def open_for_read(self, image_id):
"""
Open and yield file for reading the image file for an image
with supplied identifier.
:param image_id: Image ID
"""
raise NotImplementedError
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def get_image_filepath(self, image_id, cache_status='active'):
"""
This crafts an absolute path to a specific entry
:param image_id: Image ID
:param cache_status: Status of the image in the cache
"""
if cache_status == 'active':
return os.path.join(self.base_dir, str(image_id))
return os.path.join(self.base_dir, cache_status, str(image_id))
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def get_image_size(self, image_id):
"""
Return the size of the image file for an image with supplied
identifier.
:param image_id: Image ID
"""
path = self.get_image_filepath(image_id)
return os.path.getsize(path)
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def get_queued_images(self):
"""
Returns a list of image IDs that are in the queue. The
list should be sorted by the time the image ID was inserted
into the queue.
"""
raise NotImplementedError
