# -*- coding: utf-8 -*-
from __future__ import (
absolute_import,
division,
print_function,
unicode_literals,
)
import signal
from .exceptions import JobTimeoutException
class BaseDeathPenalty(object):
"""Base class to setup job timeouts."""
def __init__(self, timeout):
self._timeout = timeout
def __enter__(self):
self.setup_death_penalty()
def __exit__(self, type, value, traceback):
# Always cancel immediately, since we're done
try:
self.cancel_death_penalty()
except JobTimeoutException:
# Weird case: we're done with the with body, but now the alarm is
# fired. We may safely ignore this situation and consider the
# body done.
pass
# __exit__ may return True to suppress further exception handling. We
# don't want to suppress any exceptions here, since all errors should
# just pass through, JobTimeoutException being handled normally to the
# invoking context.
return False
def setup_death_penalty(self):
raise NotImplementedError()
def cancel_death_penalty(self):
raise NotImplementedError()
class UnixSignalDeathPenalty(BaseDeathPenalty):
def handle_death_penalty(self, signum, frame):
raise JobTimeoutException(
'Job exceeded maximum timeout '
'value (%d seconds).' % self._timeout
)
def setup_death_penalty(self):
"""Sets up an alarm signal and a signal handler that raises
a JobTimeoutException after the timeout amount (expressed in
seconds).
"""
signal.signal(signal.SIGALRM, self.handle_death_penalty)
signal.setitimer(signal.ITIMER_REAL, self._timeout)
def cancel_death_penalty(self):
"""Removes the death penalty alarm and puts back the system into
default signal handling.
"""
signal.alarm(0)
signal.signal(signal.SIGALRM, signal.SIG_DFL)
