Source code for Exscript.util.sigint

#
# Copyright (C) 2010-2017 Samuel Abels
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"""
A class for catching SIGINT, such that CTRL+c works.
"""
from __future__ import print_function
from builtins import object
import os
import sys
import signal


[docs]class SigIntWatcher(object): """ This class solves two problems with multithreaded programs in Python: - A signal might be delivered to any thread and - if the thread that gets the signal is waiting, the signal is ignored (which is a bug). This class forks and catches sigint for Exscript. The watcher is a concurrent process (not thread) that waits for a signal and the process that contains the threads. Works on Linux, Solaris, MacOS, and AIX. Known not to work on Windows. """
[docs] def __init__(self): """ Creates a child process, which returns. The parent process waits for a KeyboardInterrupt and then kills the child process. """ try: self.child = os.fork() except AttributeError: # platforms that don't have os.fork self.child = 0 except RuntimeError: # prevent "not holding the import lock" on some systems self.child = 0 if self.child: self.watch()
[docs] def watch(self): try: pid, status = os.wait() except KeyboardInterrupt: print('********** SIGINT RECEIVED - SHUTTING DOWN! **********') self.kill() sys.exit(1) sys.exit(status >> 8)
[docs] def kill(self): try: os.kill(self.child, signal.SIGKILL) except OSError: pass