# Copyright (C) 2025 Red Hat, Inc.
#
# 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.

from oslo_concurrency import lockutils


class Singleton(type):
    _instances = {}
    _semaphores = lockutils.Semaphores()

    def __call__(cls, *args, **kwargs):
        with lockutils.lock('singleton_lock', semaphores=cls._semaphores):
            if cls not in cls._instances:
                cls._instances[cls] = super().__call__(*args, **kwargs)
        return cls._instances[cls]