import _thread
import signal
import time

def alarm_interrupt(sig, frame):
    raise KeyboardInterrupt

# Mimic receiving a SIGINT (KeyboardInterrupt) with SIGALRM while stuck
# in a deadlock.
# XXX this test can fail when the legacy (non-semaphore) implementation
# of locks is used in thread_pthread.h, see issue #11223.
oldalrm = signal.signal(signal.SIGALRM, alarm_interrupt)
try:
    lock = _thread.allocate_lock()
    lock.acquire()
    signal.alarm(1)
    t1 = time.time()
    try:
       lock.acquire(timeout=5)
    except KeyboardInterrupt:
        pass
    else:
        raise Exception("KeyboardInterrupt not raised!")
    dt = time.time() - t1
    # Checking that KeyboardInterrupt was raised is not sufficient.
    # We want to assert that lock.acquire() was interrupted because
    # of the signal, not that the signal handler was called immediately
    # after timeout return of lock.acquire() (which can fool assertRaises).
    if dt > 3.0:
        raise Exception("dt > 3: dt=%s" % dt)
finally:
    signal.signal(signal.SIGALRM, oldalrm)