blob: 3558f29ac6722dda01fb6c5892653cd96446f7f0 [file] [log] [blame]
# Copyright 2015 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
import threading
class WeakConstant(object):
"""A thread-safe, lazily initialized object.
This does not support modification after initialization. The intended
constant nature of the object is not enforced, though, hence the "weak".
def __init__(self, initializer):
self._initialized = False
self._initializer = initializer
self._lock = threading.Lock()
self._val = None
def read(self):
"""Get the object, creating it if necessary."""
if self._initialized:
return self._val
with self._lock:
if not self._initialized:
self._val = self._initializer()
self._initialized = True
return self._val