/usr/lib/python3/dist-packages/pymongo/server_selectors.py is in python3-pymongo 3.4.0-1.
This file is owned by root:root, with mode 0o644.
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#
# 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.
"""Criteria to select some ServerDescriptions from a TopologyDescription."""
from pymongo.server_type import SERVER_TYPE
class Selection(object):
"""Input or output of a server selector function."""
@classmethod
def from_topology_description(cls, topology_description):
known_servers = topology_description.known_servers
primary = None
for sd in known_servers:
if sd.server_type == SERVER_TYPE.RSPrimary:
primary = sd
break
return Selection(topology_description,
topology_description.known_servers,
topology_description.common_wire_version,
primary)
def __init__(self,
topology_description,
server_descriptions,
common_wire_version,
primary):
self.topology_description = topology_description
self.server_descriptions = server_descriptions
self.primary = primary
self.common_wire_version = common_wire_version
def with_server_descriptions(self, server_descriptions):
return Selection(self.topology_description,
server_descriptions,
self.common_wire_version,
self.primary)
def secondary_with_max_last_write_date(self):
secondaries = secondary_server_selector(self)
if secondaries.server_descriptions:
return max(secondaries.server_descriptions,
key=lambda sd: sd.last_write_date)
@property
def primary_selection(self):
primaries = [self.primary] if self.primary else []
return self.with_server_descriptions(primaries)
@property
def heartbeat_frequency(self):
return self.topology_description.heartbeat_frequency
@property
def topology_type(self):
return self.topology_description.topology_type
def __bool__(self):
return bool(self.server_descriptions)
__nonzero__ = __bool__ # Python 2.
def __getitem__(self, item):
return self.server_descriptions[item]
def any_server_selector(selection):
return selection
def readable_server_selector(selection):
return selection.with_server_descriptions(
[s for s in selection.server_descriptions if s.is_readable])
def writable_server_selector(selection):
return selection.with_server_descriptions(
[s for s in selection.server_descriptions if s.is_writable])
def secondary_server_selector(selection):
return selection.with_server_descriptions(
[s for s in selection.server_descriptions
if s.server_type == SERVER_TYPE.RSSecondary])
def arbiter_server_selector(selection):
return selection.with_server_descriptions(
[s for s in selection.server_descriptions
if s.server_type == SERVER_TYPE.RSArbiter])
def writable_preferred_server_selector(selection):
"""Like PrimaryPreferred but doesn't use tags or latency."""
return (writable_server_selector(selection) or
secondary_server_selector(selection))
def apply_single_tag_set(tag_set, selection):
"""All servers matching one tag set.
A tag set is a dict. A server matches if its tags are a superset:
A server tagged {'a': '1', 'b': '2'} matches the tag set {'a': '1'}.
The empty tag set {} matches any server.
"""
def tags_match(server_tags):
for key, value in tag_set.items():
if key not in server_tags or server_tags[key] != value:
return False
return True
return selection.with_server_descriptions(
[s for s in selection.server_descriptions if tags_match(s.tags)])
def apply_tag_sets(tag_sets, selection):
"""All servers match a list of tag sets.
tag_sets is a list of dicts. The empty tag set {} matches any server,
and may be provided at the end of the list as a fallback. So
[{'a': 'value'}, {}] expresses a preference for servers tagged
{'a': 'value'}, but accepts any server if none matches the first
preference.
"""
for tag_set in tag_sets:
with_tag_set = apply_single_tag_set(tag_set, selection)
if with_tag_set:
return with_tag_set
return selection.with_server_descriptions([])
def secondary_with_tags_server_selector(tag_sets, selection):
"""All near-enough secondaries matching the tag sets."""
return apply_tag_sets(tag_sets, secondary_server_selector(selection))
def member_with_tags_server_selector(tag_sets, selection):
"""All near-enough members matching the tag sets."""
return apply_tag_sets(tag_sets, readable_server_selector(selection))
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