Source code for glance.image_cache.prefetcher
# 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.
"""
Prefetches images into the Image Cache
"""
import glance_store
from oslo_concurrency import lockutils
from oslo_config import cfg
from oslo_log import log as logging
from glance.api import common as api_common
from glance.common import exception
from glance import context
from glance.i18n import _LI, _LW
from glance.image_cache import base
CONF = cfg.CONF
LOG = logging.getLogger(__name__)
[docs]
class Prefetcher(base.CacheApp):
def __init__(self):
# NOTE(abhishekk): Importing the glance.gateway just in time to avoid
# import loop during initialization
import glance.gateway # noqa
super(Prefetcher, self).__init__()
self.gateway = glance.gateway.Gateway()
[docs]
def fetch_image_into_cache(self, image_id):
ctx = context.RequestContext(is_admin=True, show_deleted=True,
roles=['admin'])
try:
image_repo = self.gateway.get_repo(ctx)
image = image_repo.get(image_id)
except exception.NotFound:
LOG.warning(_LW("Image '%s' not found"), image_id)
return False
if image.status != 'active':
LOG.warning(_LW("Image '%s' is not active. Not caching."),
image_id)
return False
for loc in image.locations:
if CONF.enabled_backends:
image_data, image_size = glance_store.get(loc['url'],
None,
context=ctx)
else:
image_data, image_size = glance_store.get_from_backend(
loc['url'], context=ctx)
LOG.debug("Caching image '%s'", image_id)
cache_tee_iter = self.cache.cache_tee_iter(image_id, image_data,
image.checksum)
# Image is tee'd into cache and checksum verified
# as we iterate
list(cache_tee_iter)
return True
[docs]
@lockutils.lock('glance-cache', external=True)
def run(self):
images = self.cache.get_queued_images()
if not images:
LOG.debug("Nothing to prefetch.")
return True
num_images = len(images)
LOG.debug("Found %d images to prefetch", num_images)
pool = api_common.get_thread_pool('prefetcher', size=num_images)
results = pool.map(self.fetch_image_into_cache, images)
successes = sum([1 for r in results if r is True])
if successes != num_images:
LOG.warning(_LW("Failed to successfully cache all "
"images in queue."))
return False
LOG.info(_LI("Successfully cached all %d images"), num_images)
return True