Source code for thoth.storages.ceph_cache
#!/usr/bin/env python3
# thoth-storages
# Copyright(C) 2018, 2019, 2020 Fridolin Pokorny
#
# This program is free software: you can redistribute it and / or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""A base class for implementing caches based on Ceph."""
from datetime import datetime
from datetime import timedelta
from datetime import timezone
from .exceptions import CacheMiss
from .exceptions import NotFoundError
from .result_base import ResultStorageBase
[docs]class CephCache(ResultStorageBase):
"""A base class implementing cache interface."""
[docs] def retrieve_document_record(self, document_id: str) -> dict:
"""Check whether the given record exists in the cache for the requested document."""
try:
return self.retrieve_document(document_id)
except NotFoundError as exc:
raise CacheMiss(f"There was no record found in the cache for {document_id!r}") from exc
[docs] def store_document_record(self, document_id: str, document: dict) -> None:
"""Store the given document record in the cache."""
self.ceph.store_document(document, document_id)
[docs] def retrieve_document_ttl(self, document_id: str) -> float:
"""Retrieve the TTL for a cached document."""
# Verify if the document is present in the cache
self.retrieve_document_record(document_id)
# Uses UTC time to be environment agnostic (no timezone)
time_lived = datetime.now(timezone.utc) - self.ceph.retrieve_document_attr(
object_key=document_id, attr="LastModified"
).replace(tzinfo=timezone.utc)
if time_lived <= timedelta(hours=4):
return (timedelta(hours=4) - time_lived).total_seconds()
return 0.0