84710606d5
1.add limit and marker param to db.instance_get_all_by_filters()
2.set the filter use marker
3.execute limit before sqlarchmy get_all()
4.add testcase 'test_db_api.test_instance_get_all_by_filters_paginate'
5.related testcase:
test_get_servers_with_marker()
test_get_servers_with_limit_and_marker()
in nova/tests/api/openstack/compute/test_servers.py
test_instance_get_all_by_filters_paginate()
in nova/tests/test_db_api.py
6.add InvalidSortkey exception
Implement bp:efficient-limiting.
Change-Id: Iea3eeb7b51194b6017d624506aafc6469d7338e4
129 lines
4.7 KiB
Python
129 lines
4.7 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
|
|
|
|
# Copyright 2010 United States Government as represented by the
|
|
# Administrator of the National Aeronautics and Space Administration.
|
|
# Copyright 2010-2011 OpenStack LLC.
|
|
# Copyright 2012 Justin Santa Barbara
|
|
# 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.
|
|
|
|
"""Implementation of paginate query."""
|
|
|
|
import sqlalchemy
|
|
|
|
from nova import exception
|
|
from nova.openstack.common import log as logging
|
|
|
|
|
|
LOG = logging.getLogger(__name__)
|
|
|
|
|
|
# copy from glance/db/sqlalchemy/api.py
|
|
def paginate_query(query, model, limit, sort_keys, marker=None,
|
|
sort_dir=None, sort_dirs=None):
|
|
"""Returns a query with sorting / pagination criteria added.
|
|
|
|
Pagination works by requiring a unique sort_key, specified by sort_keys.
|
|
(If sort_keys is not unique, then we risk looping through values.)
|
|
We use the last row in the previous page as the 'marker' for pagination.
|
|
So we must return values that follow the passed marker in the order.
|
|
With a single-valued sort_key, this would be easy: sort_key > X.
|
|
With a compound-values sort_key, (k1, k2, k3) we must do this to repeat
|
|
the lexicographical ordering:
|
|
(k1 > X1) or (k1 == X1 && k2 > X2) or (k1 == X1 && k2 == X2 && k3 > X3)
|
|
|
|
We also have to cope with different sort_directions.
|
|
|
|
Typically, the id of the last row is used as the client-facing pagination
|
|
marker, then the actual marker object must be fetched from the db and
|
|
passed in to us as marker.
|
|
|
|
:param query: the query object to which we should add paging/sorting
|
|
:param model: the ORM model class
|
|
:param limit: maximum number of items to return
|
|
:param sort_keys: array of attributes by which results should be sorted
|
|
:param marker: the last item of the previous page; we returns the next
|
|
results after this value.
|
|
:param sort_dir: direction in which results should be sorted (asc, desc)
|
|
:param sort_dirs: per-column array of sort_dirs, corresponding to sort_keys
|
|
|
|
:rtype: sqlalchemy.orm.query.Query
|
|
:return: The query with sorting/pagination added.
|
|
"""
|
|
|
|
if 'id' not in sort_keys:
|
|
# TODO(justinsb): If this ever gives a false-positive, check
|
|
# the actual primary key, rather than assuming its id
|
|
LOG.warn(_('Id not in sort_keys; is sort_keys unique?'))
|
|
|
|
assert(not (sort_dir and sort_dirs))
|
|
|
|
# Default the sort direction to ascending
|
|
if sort_dirs is None and sort_dir is None:
|
|
sort_dir = 'asc'
|
|
|
|
# Ensure a per-column sort direction
|
|
if sort_dirs is None:
|
|
sort_dirs = [sort_dir for _sort_key in sort_keys]
|
|
|
|
assert(len(sort_dirs) == len(sort_keys))
|
|
|
|
# Add sorting
|
|
for current_sort_key, current_sort_dir in zip(sort_keys, sort_dirs):
|
|
sort_dir_func = {
|
|
'asc': sqlalchemy.asc,
|
|
'desc': sqlalchemy.desc,
|
|
}[current_sort_dir]
|
|
|
|
try:
|
|
sort_key_attr = getattr(model, current_sort_key)
|
|
except AttributeError:
|
|
raise exception.InvalidSortKey()
|
|
query = query.order_by(sort_dir_func(sort_key_attr))
|
|
|
|
# Add pagination
|
|
if marker is not None:
|
|
marker_values = []
|
|
for sort_key in sort_keys:
|
|
v = getattr(marker, sort_key)
|
|
marker_values.append(v)
|
|
|
|
# Build up an array of sort criteria as in the docstring
|
|
criteria_list = []
|
|
for i in xrange(0, len(sort_keys)):
|
|
crit_attrs = []
|
|
for j in xrange(0, i):
|
|
model_attr = getattr(model, sort_keys[j])
|
|
crit_attrs.append((model_attr == marker_values[j]))
|
|
|
|
model_attr = getattr(model, sort_keys[i])
|
|
if sort_dirs[i] == 'desc':
|
|
crit_attrs.append((model_attr < marker_values[i]))
|
|
elif sort_dirs[i] == 'asc':
|
|
crit_attrs.append((model_attr > marker_values[i]))
|
|
else:
|
|
raise ValueError(_("Unknown sort direction, "
|
|
"must be 'desc' or 'asc'"))
|
|
|
|
criteria = sqlalchemy.sql.and_(*crit_attrs)
|
|
criteria_list.append(criteria)
|
|
|
|
f = sqlalchemy.sql.or_(*criteria_list)
|
|
query = query.filter(f)
|
|
|
|
if limit is not None:
|
|
query = query.limit(limit)
|
|
|
|
return query
|