forked from rucio/rucio
/
expiring_list.py
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/
expiring_list.py
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# Copyright European Organization for Nuclear Research (CERN) since 2012
#
# 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.
"""
Utility classes for C3PO
"""
from collections import deque
from threading import Lock, Timer
class ExpiringList:
"""
Simple list with time based element expiration
"""
def __init__(self, timeout=1):
self._lock = Lock()
self._timeout = timeout
self._items = deque()
def add(self, item):
"""Add event time
"""
with self._lock:
self._items.append(item)
Timer(self._timeout, self._expire).start()
def __len__(self):
"""
Return number of active events
"""
with self._lock:
return len(self._items)
def _expire(self):
"""
Remove any expired events
"""
with self._lock:
self._items.popleft()
def to_set(self):
"""
Return items as a set
"""
return set(self._items)
def __str__(self):
with self._lock:
return str(self._items)