| # |
| # Licensed to the Apache Software Foundation (ASF) under one or more |
| # contributor license agreements. See the NOTICE file distributed with |
| # this work for additional information regarding copyright ownership. |
| # The ASF licenses this file to You 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. |
| # |
| |
| import threading |
| |
| |
| class AtomicRef: |
| def __init__(self, var): |
| self._lock = threading.Lock() |
| self._var = var |
| |
| def get(self): |
| with self._lock: |
| return self._var |
| |
| def set(self, new_var): |
| with self._lock: |
| self._var = new_var |
| |
| def compare_and_set(self, expect, update) -> bool: |
| """ |
| Atomically sets the value to the given updated value if the current value == the expected value |
| |
| :return: return True if success, False if the actual value was not equal to the expected value. |
| """ |
| with self._lock: |
| if self._var == expect: |
| self._var = update |
| return True |
| return False |