Lib/test/test_threadsignals.py

   1 """PyUnit testing that threads honor our signal semantics"""
   2
   3 import unittest
   4 import signal
   5 import os
   6 import sys
   7 from test.test_support import run_unittest, import_module
   8 thread = import_module('thread')
   9
  10 if sys.platform[:3] in ('win', 'os2') or sys.platform=='riscos':
  11     raise unittest.SkipTest, "Can't test signal on %s" % sys.platform
  12
  13 process_pid = os.getpid()
  14 signalled_all=thread.allocate_lock()
  15
  16
  17 def registerSignals(for_usr1, for_usr2, for_alrm):
  18     usr1 = signal.signal(signal.SIGUSR1, for_usr1)
  19     usr2 = signal.signal(signal.SIGUSR2, for_usr2)
  20     alrm = signal.signal(signal.SIGALRM, for_alrm)
  21     return usr1, usr2, alrm
  22
  23
  24 # The signal handler. Just note that the signal occurred and
  25 # from who.
  26 def handle_signals(sig,frame):
  27     signal_blackboard[sig]['tripped'] += 1
  28     signal_blackboard[sig]['tripped_by'] = thread.get_ident()
  29
  30 # a function that will be spawned as a separate thread.
  31 def send_signals():
  32     os.kill(process_pid, signal.SIGUSR1)
  33     os.kill(process_pid, signal.SIGUSR2)
  34     signalled_all.release()
  35
  36 class ThreadSignals(unittest.TestCase):
  37     """Test signal handling semantics of threads.
  38        We spawn a thread, have the thread send two signals, and
  39        wait for it to finish. Check that we got both signals
  40        and that they were run by the main thread.
  41     """
  42     def test_signals(self):
  43         signalled_all.acquire()
  44         self.spawnSignallingThread()
  45         signalled_all.acquire()
  46         # the signals that we asked the kernel to send
  47         # will come back, but we don't know when.
  48         # (it might even be after the thread exits
  49         # and might be out of order.)  If we haven't seen
  50         # the signals yet, send yet another signal and
  51         # wait for it return.
  52         if signal_blackboard[signal.SIGUSR1]['tripped'] == 0 \
  53            or signal_blackboard[signal.SIGUSR2]['tripped'] == 0:
  54             signal.alarm(1)
  55             signal.pause()
  56             signal.alarm(0)
  57
  58         self.assertEqual( signal_blackboard[signal.SIGUSR1]['tripped'], 1)
  59         self.assertEqual( signal_blackboard[signal.SIGUSR1]['tripped_by'],
  60                            thread.get_ident())
  61         self.assertEqual( signal_blackboard[signal.SIGUSR2]['tripped'], 1)
  62         self.assertEqual( signal_blackboard[signal.SIGUSR2]['tripped_by'],
  63                            thread.get_ident())
  64         signalled_all.release()
  65
  66     def spawnSignallingThread(self):
  67         thread.start_new_thread(send_signals, ())
  68
  69
  70 def test_main():
  71     global signal_blackboard
  72
  73     signal_blackboard = { signal.SIGUSR1 : {'tripped': 0, 'tripped_by': 0 },
  74                           signal.SIGUSR2 : {'tripped': 0, 'tripped_by': 0 },
  75                           signal.SIGALRM : {'tripped': 0, 'tripped_by': 0 } }
  76
  77     oldsigs = registerSignals(handle_signals, handle_signals, handle_signals)
  78     try:
  79         run_unittest(ThreadSignals)
  80     finally:
  81         registerSignals(*oldsigs)
  82
  83 if __name__ == '__main__':
  84     test_main()