glance/glance/image_cache/prefetcher.py

84 lines
2.7 KiB
Python

# 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 eventlet
from glance.common import exception
from glance import context
from glance.image_cache import base
import glance.openstack.common.log as logging
import glance.registry.client.v1.api as registry
import glance.store
LOG = logging.getLogger(__name__)
class Prefetcher(base.CacheApp):
def __init__(self):
super(Prefetcher, self).__init__()
registry.configure_registry_client()
registry.configure_registry_admin_creds()
def fetch_image_into_cache(self, image_id):
ctx = context.RequestContext(is_admin=True, show_deleted=True)
try:
image_meta = registry.get_image_metadata(ctx, image_id)
if image_meta['status'] != 'active':
LOG.warn(_("Image '%s' is not active. Not caching."),
image_id)
return False
except exception.NotFound:
LOG.warn(_("No metadata found for image '%s'"), image_id)
return False
location = image_meta['location']
image_data, image_size = glance.store.get_from_backend(ctx, location)
LOG.debug(_("Caching image '%s'"), image_id)
cache_tee_iter = self.cache.cache_tee_iter(image_id, image_data,
image_meta['checksum'])
# Image is tee'd into cache and checksum verified
# as we iterate
list(cache_tee_iter)
return 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 = eventlet.GreenPool(num_images)
results = pool.imap(self.fetch_image_into_cache, images)
successes = sum([1 for r in results if r is True])
if successes != num_images:
LOG.error(_("Failed to successfully cache all "
"images in queue."))
return False
LOG.info(_("Successfully cached all %d images"), num_images)
return True