#
# Copyright (c) 2008-2015 Thierry Florac <tflorac AT ulthar.net>
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
__docformat__ = 'restructuredtext'
# import standard library
import time
import weakref
# import interfaces
# import packages
MINUTES = 60
HOURS = 60 * MINUTES
STORAGE_TIDS = weakref.WeakKeyDictionary()
[docs]def expired(cache_dict, cache_for):
if 'last_update' not in cache_dict:
return True
return time.time() > cache_dict['last_update'] + cache_for
[docs]def getStorageTids(storage, cache_for=5 * MINUTES):
cache_dict = STORAGE_TIDS.setdefault(storage, {})
if expired(cache_dict, cache_for):
if cache_dict.get('tids'):
first = cache_dict['tids'][-1]
last = cache_dict['tids'][-1]
try:
first_record = next(storage.iterator())
except StopIteration:
first_record = None
if first_record and first_record.tid == first:
# okay, look for new transactions appended at the end
new = [t.tid for t in storage.iterator(start=last)]
if new and new[0] == last:
del new[0]
cache_dict['tids'].extend(new)
else:
# first record changed, we must've packed the DB
cache_dict['tids'] = [t.tid for t in storage.iterator()]
else:
cache_dict['tids'] = [t.tid for t in storage.iterator()]
cache_dict['last_update'] = time.time()
return cache_dict['tids']