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# 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.
import errno
import io
import os
import signal
import sys
from oslo_concurrency import lockutils
from oslo_service._i18n import _
from oslo_service.backend.base import ServiceBase
def is_daemon():
try:
return os.getpgrp() != os.tcgetpgrp(sys.stdout.fileno())
except io.UnsupportedOperation:
return True
except OSError as err:
return err.errno == errno.ENOTTY or False
def is_sighup_and_daemon(signo, signal_handler):
return (signal_handler.is_signal_supported('SIGHUP') and
signo == signal.SIGHUP and is_daemon())
def get_signal_mappings():
signals_by_name = {
name: getattr(signal, name)
for name in dir(signal)
if name.startswith('SIG') and
isinstance(getattr(signal, name), signal.Signals)
}
signals_to_name = {v: k for k, v in signals_by_name.items()}
return signals_by_name, signals_to_name
class SignalExit(SystemExit):
"""Raised to indicate a signal-based exit.
This exception is commonly raised when the process receives a termination
signal (e.g., SIGTERM, SIGINT). The signal number is stored in `signo`.
"""
def __init__(self, signo, exccode=1):
super().__init__(exccode)
self.signo = signo
def check_service_base(service):
if not isinstance(service, ServiceBase):
raise TypeError(
_("Service %(service)s must be an instance of %(base)s!")
% {'service': service, 'base': ServiceBase})
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]
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