218 lines
6.4 KiB
Python
218 lines
6.4 KiB
Python
# Copyright 2011 OpenStack Foundation
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""
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Base attribute driver class
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"""
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import os.path
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from oslo.config import cfg
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from glance.common import exception
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from glance.common import utils
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import glance.openstack.common.log as logging
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LOG = logging.getLogger(__name__)
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CONF = cfg.CONF
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class Driver(object):
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def configure(self):
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"""
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Configure the driver to use the stored configuration options
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Any store that needs special configuration should implement
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this method. If the store was not able to successfully configure
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itself, it should raise `exception.BadDriverConfiguration`
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"""
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# Here we set up the various file-based image cache paths
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# that we need in order to find the files in different states
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# of cache management.
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self.set_paths()
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def set_paths(self):
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"""
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Creates all necessary directories under the base cache directory
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"""
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self.base_dir = CONF.image_cache_dir
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if self.base_dir is None:
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msg = _('Failed to read %s from config') % 'image_cache_dir'
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LOG.error(msg)
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driver = self.__class__.__module__
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raise exception.BadDriverConfiguration(driver_name=driver,
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reason=msg)
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self.incomplete_dir = os.path.join(self.base_dir, 'incomplete')
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self.invalid_dir = os.path.join(self.base_dir, 'invalid')
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self.queue_dir = os.path.join(self.base_dir, 'queue')
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dirs = [self.incomplete_dir, self.invalid_dir, self.queue_dir]
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for path in dirs:
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utils.safe_mkdirs(path)
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def get_cache_size(self):
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"""
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Returns the total size in bytes of the image cache.
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"""
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raise NotImplementedError
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def get_cached_images(self):
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"""
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Returns a list of records about cached images.
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The list of records shall be ordered by image ID and shall look like::
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[
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{
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'image_id': <IMAGE_ID>,
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'hits': INTEGER,
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'last_modified': ISO_TIMESTAMP,
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'last_accessed': ISO_TIMESTAMP,
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'size': INTEGER
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}, ...
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]
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"""
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return NotImplementedError
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def is_cached(self, image_id):
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"""
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Returns True if the image with the supplied ID has its image
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file cached.
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:param image_id: Image ID
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"""
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raise NotImplementedError
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def is_cacheable(self, image_id):
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"""
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Returns True if the image with the supplied ID can have its
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image file cached, False otherwise.
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:param image_id: Image ID
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"""
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raise NotImplementedError
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def is_queued(self, image_id):
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"""
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Returns True if the image identifier is in our cache queue.
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:param image_id: Image ID
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"""
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raise NotImplementedError
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def delete_all_cached_images(self):
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"""
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Removes all cached image files and any attributes about the images
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and returns the number of cached image files that were deleted.
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"""
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raise NotImplementedError
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def delete_cached_image(self, image_id):
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"""
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Removes a specific cached image file and any attributes about the image
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:param image_id: Image ID
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"""
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raise NotImplementedError
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def delete_all_queued_images(self):
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"""
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Removes all queued image files and any attributes about the images
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and returns the number of queued image files that were deleted.
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"""
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raise NotImplementedError
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def delete_queued_image(self, image_id):
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"""
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Removes a specific queued image file and any attributes about the image
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:param image_id: Image ID
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"""
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raise NotImplementedError
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def queue_image(self, image_id):
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"""
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Puts an image identifier in a queue for caching. Return True
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on successful add to the queue, False otherwise...
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:param image_id: Image ID
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"""
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def clean(self, stall_time=None):
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"""
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Dependent on the driver, clean up and destroy any invalid or incomplete
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cached images
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"""
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raise NotImplementedError
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def get_least_recently_accessed(self):
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"""
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Return a tuple containing the image_id and size of the least recently
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accessed cached file, or None if no cached files.
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"""
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raise NotImplementedError
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def open_for_write(self, image_id):
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"""
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Open a file for writing the image file for an image
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with supplied identifier.
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:param image_id: Image ID
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"""
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raise NotImplementedError
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def open_for_read(self, image_id):
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"""
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Open and yield file for reading the image file for an image
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with supplied identifier.
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:param image_id: Image ID
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"""
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raise NotImplementedError
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def get_image_filepath(self, image_id, cache_status='active'):
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"""
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This crafts an absolute path to a specific entry
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:param image_id: Image ID
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:param cache_status: Status of the image in the cache
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"""
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if cache_status == 'active':
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return os.path.join(self.base_dir, str(image_id))
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return os.path.join(self.base_dir, cache_status, str(image_id))
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def get_image_size(self, image_id):
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"""
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Return the size of the image file for an image with supplied
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identifier.
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:param image_id: Image ID
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"""
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path = self.get_image_filepath(image_id)
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return os.path.getsize(path)
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def get_queued_images(self):
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"""
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Returns a list of image IDs that are in the queue. The
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list should be sorted by the time the image ID was inserted
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into the queue.
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"""
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raise NotImplementedError
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