def test_infinite_loop_stops(self):
"""An infinite loop can be stopped after 10 iterations."""
class Countdown(Runnable):
"""Countdown runnable that sets a semaphore on reaching zero."""
def __init__(self):
super(Countdown, self).__init__()
self.ring = threading.Event()
def next(self, state):
output = state.updated(cnt=state.cnt - 1)
if output.cnt <= 0:
self.ring.set()
return output
countdown = Countdown()
loop = LoopWhileNoImprovement(countdown)
state = loop.run(State(cnt=10))
# stop only AFTER countdown reaches zero (10 iterations)
# timeout in case Countdown failed before setting the flag
countdown.ring.wait(timeout=1)
loop.stop()
self.assertTrue(state.result().cnt <= 0)
def test_dynamic_validation(self):
class simo(traits.SIMO, Runnable):
def next(self, state):
return States(state, state)
with self.assertRaises(StateDimensionalityError):
LoopWhileNoImprovement(simo()).run(State()).result()
with self.assertRaises(StateDimensionalityError):
LoopWhileNoImprovement(simo()).run(States()).result()
def test_no_improvement_tries(self):
class Inc(Runnable):
def next(self, state):
return state.updated(cnt=state.cnt + 1)
loop = LoopWhileNoImprovement(Inc(), max_tries=10, key=lambda _: 0)
state = loop.run(State(cnt=0)).result()
self.assertEqual(len(loop.runnable.timers['dispatch.next']), 10)
self.assertEqual(state.cnt, 1)
def test_terminate_predicate(self):
class Inc(Runnable):
def next(self, state):
return state.updated(cnt=state.cnt + 1)
it = LoopWhileNoImprovement(Inc(),
key=lambda state: state.cnt,
terminate=lambda key: key >= 3)
s = it.run(State(cnt=0)).result()
self.assertEqual(s.cnt, 3)
def test_end_of_stream_termination(self):
class Inc(Runnable):
def next(self, state, **kw):
cnt = state.cnt + 1
if cnt > state.maxcnt:
raise EndOfStream
return state.updated(cnt=cnt)
loop = LoopWhileNoImprovement(Inc())
state = loop.run(State(cnt=0, maxcnt=3)).result()
self.assertEqual(state.cnt, 3)
def test_validation(self):
class simo(Runnable, traits.SIMO):
def next(self, state):
return States(state, state)
with self.assertRaises(TypeError):
LoopWhileNoImprovement(simo())
