Created
October 27, 2020 23:13
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Python Utils
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import logging | |
import signal | |
logger = logging.getLogger(__name__) | |
class ExitSignalHandler(metaclass=Singleton): | |
def __init__(self): | |
self._cleanup_functions = [] | |
handled_signals = signal.SIGINT, signal.SIGTERM | |
for handled_signal in handled_signals: | |
self._attach_new_handler(handled_signal, self.run_cleanup_functions) | |
def add_cleanup_function(self, function): | |
self._cleanup_functions.append(function) | |
def run_cleanup_functions(self, signum, frame): | |
logger.info("Caught kill signal: {}".format(signum)) | |
for function in self._cleanup_functions: | |
function() | |
@staticmethod | |
def _attach_new_handler(sig, new_handler): | |
old_handler = signal.getsignal(sig) if callable(signal.getsignal(sig)) else None | |
def handle_exit_signal(*args, **kwargs): | |
new_handler(*args, **kwargs) | |
if old_handler is not None: | |
old_handler(*args, **kwargs) | |
signal.signal(sig, handle_exit_signal) # NOQA | |
import functools | |
def run_first(preceding_func): | |
""" Runs some function before running decorated function """ | |
def wrapper_decorator(func): | |
@functools.wraps(func) | |
def decorator(*args, **kwargs): | |
preceding_func() | |
returned_value = func(*args, **kwargs) | |
return returned_value | |
return decorator | |
return wrapper_decorator | |
def run_once(func): | |
""" Runs the function only once (caches the return value for subsequent runs) """ | |
@functools.wraps(func) | |
def decorator(*args, **kwargs): | |
if decorator.has_run: | |
return decorator.result | |
decorator.result = func(*args, **kwargs) | |
decorator.has_run = True | |
return decorator.result | |
decorator.has_run = False | |
decorator.result = None | |
return decorator | |
class Singleton(type): | |
_instances = {} | |
def __call__(cls, *args, **kwargs): | |
if cls not in cls._instances: | |
cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs) | |
return cls._instances[cls] |
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