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
#    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

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 =, 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"Successfully cached all %d images"), num_images) return True