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import os
import signal
import subprocess
import sys
import time
import unittest
class SIGUSR1Exception(Exception):
pass
class InterProcessSignalTests(unittest.TestCase):
def setUp(self):
self.got_signals = {'SIGHUP': 0, 'SIGUSR1': 0, 'SIGALRM': 0}
def sighup_handler(self, signum, frame):
self.got_signals['SIGHUP'] += 1
def sigusr1_handler(self, signum, frame):
self.got_signals['SIGUSR1'] += 1
raise SIGUSR1Exception
def wait_signal(self, child, signame, exc_class=None):
try:
if child is not None:
# This wait should be interrupted by exc_class
# (if set)
child.wait()
timeout = 10.0
deadline = time.monotonic() + timeout
while time.monotonic() < deadline:
if self.got_signals[signame]:
return
signal.pause()
except BaseException as exc:
if exc_class is not None and isinstance(exc, exc_class):
# got the expected exception
return
raise
self.fail('signal %s not received after %s seconds'
% (signame, timeout))
def subprocess_send_signal(self, pid, signame):
code = 'import os, signal; os.kill(%s, signal.%s)' % (pid, signame)
args = [sys.executable, '-I', '-c', code]
return subprocess.Popen(args)
def test_interprocess_signal(self):
# Install handlers. This function runs in a sub-process, so we
# don't worry about re-setting the default handlers.
signal.signal(signal.SIGHUP, self.sighup_handler)
signal.signal(signal.SIGUSR1, self.sigusr1_handler)
signal.signal(signal.SIGUSR2, signal.SIG_IGN)
signal.signal(signal.SIGALRM, signal.default_int_handler)
# Let the sub-processes know who to send signals to.
pid = str(os.getpid())
with self.subprocess_send_signal(pid, "SIGHUP") as child:
self.wait_signal(child, 'SIGHUP')
self.assertEqual(self.got_signals, {'SIGHUP': 1, 'SIGUSR1': 0,
'SIGALRM': 0})
with self.subprocess_send_signal(pid, "SIGUSR1") as child:
self.wait_signal(child, 'SIGUSR1', SIGUSR1Exception)
self.assertEqual(self.got_signals, {'SIGHUP': 1, 'SIGUSR1': 1,
'SIGALRM': 0})
with self.subprocess_send_signal(pid, "SIGUSR2") as child:
# Nothing should happen: SIGUSR2 is ignored
child.wait()
try:
signal.alarm(1)
self.wait_signal(None, 'SIGALRM', KeyboardInterrupt)
self.assertEqual(self.got_signals, {'SIGHUP': 1, 'SIGUSR1': 1,
'SIGALRM': 0})
finally:
signal.alarm(0)
if __name__ == "__main__":
unittest.main()
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