# Some simple queue module tests, plus some failure conditions
# to ensure the Queue locks remain stable.
import queue
import time
import unittest
from test import support
threading = support.import_module('threading')
QUEUE_SIZE = 5
def qfull(q):
return q.maxsize > 0 and q.qsize() == q.maxsize
# A thread to run a function that unclogs a blocked Queue.
class _TriggerThread(threading.Thread):
def __init__(self, fn, args):
self.fn = fn
self.args = args
self.startedEvent = threading.Event()
threading.Thread.__init__(self)
def run(self):
# The sleep isn't necessary, but is intended to give the blocking
# function in the main thread a chance at actually blocking before
# we unclog it. But if the sleep is longer than the timeout-based
# tests wait in their blocking functions, those tests will fail.
# So we give them much longer timeout values compared to the
# sleep here (I aimed at 10 seconds for blocking functions --
# they should never actually wait that long - they should make
# progress as soon as we call self.fn()).
time.sleep(0.1)
self.startedEvent.set()
self.fn(*self.args)
# Execute a function that blocks, and in a separate thread, a function that
# triggers the release. Returns the result of the blocking function. Caution:
# block_func must guarantee to block until trigger_func is called, and
# trigger_func must guarantee to change queue state so that block_func can make
# enough progress to return. In particular, a block_func that just raises an
# exception regardless of whether trigger_func is called will lead to
# timing-dependent sporadic failures, and one of those went rarely seen but
# undiagnosed for years. Now block_func must be unexceptional. If block_func
# is supposed to raise an exception, call do_exceptional_blocking_test()
# instead.
class BlockingTestMixin:
def do_blocking_test(self, block_func, block_args, trigger_func, trigger_args):
thread = _TriggerThread(trigger_func, trigger_args)
thread.start()
try:
self.result = block_func(*block_args)
# If block_func returned before our thread made the call, we failed!
if not thread.startedEvent.is_set():
self.fail("blocking function '%r' appeared not to block" %
block_func)
return self.result
finally:
thread.join(10) # make sure the thread terminates
if thread.is_alive():
self.fail("trigger function '%r' appeared to not return" %
trigger_func)
# Call this instead if block_func is supposed to raise an exception.
def do_exceptional_blocking_test(self,block_func, block_args, trigger_func,
trigger_args, expected_exception_class):
thread = _TriggerThread(trigger_func, trigger_args)
thread.start()
try:
try:
block_func(*block_args)
except expected_exception_class:
raise
else:
self.fail("expected exception of kind %r" %
expected_exception_class)
finally:
thread.join(10) # make sure the thread terminates
if thread.is_alive():
self.fail("trigger function '%r' appeared to not return" %
trigger_func)
if not thread.startedEvent.is_set():
self.fail("trigger thread ended but event never set")
class BaseQueueTestMixin(BlockingTestMixin):
def setUp(self):
self.cum = 0
self.cumlock = threading.Lock()
def simple_queue_test(self, q):
if q.qsize():
raise RuntimeError("Call this function with an empty queue")
self.assertTrue(q.empty())
self.assertFalse(q.full())
# I guess we better check things actually queue correctly a little :)
q.put(111)
q.put(333)
q.put(222)
target_order = dict(Queue = [111, 333, 222],
LifoQueue = [222, 333, 111],
PriorityQueue = [111, 222, 333])
actual_order = [q.get(), q.get(), q.get()]
self.assertEqual(actual_order, target_order[q.__class__.__name__],
"Didn't seem to queue the correct data!")
for i in range(QUEUE_SIZE-1):
q.put(i)
self.assertTrue(q.qsize(), "Queue should not be empty")
self.assertTrue(not qfull(q), "Queue should not be full")
last = 2 * QUEUE_SIZE
full = 3 * 2 * QUEUE_SIZE
q.put(last)
self.assertTrue(qfull(q), "Queue should be full")
self.assertFalse(q.empty())
self.assertTrue(q.full())
try:
q.put(full, block=0)
self.fail("Didn't appear to block with a full queue")
except queue.Full:
pass
try:
q.put(full, timeout=0.01)
self.fail("Didn't appear to time-out with a full queue")
except queue.Full:
pass
# Test a blocking put
self.do_blocking_test(q.put, (full,), q.get, ())
self.do_blocking_test(q.put, (full, True, 10), q.get, ())
# Empty it
for i in range(QUEUE_SIZE):
q.get()
self.assertTrue(not q.qsize(), "Queue should be empty")
try:
q.get(block=0)
self.fail("Didn't appear to block with an empty queue")
except queue.Empty:
pass
try:
q.get(timeout=0.01)
self.fail("Didn't appear to time-out with an empty queue")
except queue.Empty:
pass
# Test a blocking get
self.do_blocking_test(q.get, (), q.put, ('empty',))
self.do_blocking_test(q.get, (True, 10), q.put, ('empty',))
def worker(self, q):
while True:
x = q.get()
if x < 0:
q.task_done()
return
with self.cumlock:
self.cum += x
q.task_done()
def queue_join_test(self, q):
self.cum = 0
threads = []
for i in (0,1):
thread = threading.Thread(target=self.worker, args=(q,))
thread.start()
threads.append(thread)
for i in range(100):
q.put(i)
q.join()
self.assertEqual(self.cum, sum(range(100)),
"q.join() did not block until all tasks were done")
for i in (0,1):
q.put(-1) # instruct the threads to close
q.join() # verify that you can join twice
for thread in threads:
thread.join()
def test_queue_task_done(self):
# Test to make sure a queue task completed successfully.
q = self.type2test()
try:
q.task_done()
except ValueError:
pass
else:
self.fail("Did not detect task count going negative")
def test_queue_join(self):
# Test that a queue join()s successfully, and before anything else
# (done twice for insurance).
q = self.type2test()
self.queue_join_test(q)
self.queue_join_test(q)
try:
q.task_done()
except ValueError:
pass
else:
self.fail("Did not detect task count going negative")
def test_simple_queue(self):
# Do it a couple of times on the same queue.
# Done twice to make sure works with same instance reused.
q = self.type2test(QUEUE_SIZE)
self.simple_queue_test(q)
self.simple_queue_test(q)
def test_negative_timeout_raises_exception(self):
q = self.type2test(QUEUE_SIZE)
with self.assertRaises(ValueError):
q.put(1, timeout=-1)
with self.assertRaises(ValueError):
q.get(1, timeout=-1)
def test_nowait(self):
q = self.type2test(QUEUE_SIZE)
for i in range(QUEUE_SIZE):
q.put_nowait(1)
with self.assertRaises(queue.Full):
q.put_nowait(1)
for i in range(QUEUE_SIZE):
q.get_nowait()
with self.assertRaises(queue.Empty):
q.get_nowait()
def test_shrinking_queue(self):
# issue 10110
q = self.type2test(3)
q.put(1)
q.put(2)
q.put(3)
with self.assertRaises(queue.Full):
q.put_nowait(4)
self.assertEqual(q.qsize(), 3)
q.maxsize = 2 # shrink the queue
with self.assertRaises(queue.Full):
q.put_nowait(4)
class QueueTest(BaseQueueTestMixin, unittest.TestCase):
type2test = queue.Queue
class LifoQueueTest(BaseQueueTestMixin, unittest.TestCase):
type2test = queue.LifoQueue
class PriorityQueueTest(BaseQueueTestMixin, unittest.TestCase):
type2test = queue.PriorityQueue
# A Queue subclass that can provoke failure at a moment's notice :)
class FailingQueueException(Exception):
pass
class FailingQueue(queue.Queue):
def __init__(self, *args):
self.fail_next_put = False
self.fail_next_get = False
queue.Queue.__init__(self, *args)
def _put(self, item):
if self.fail_next_put:
self.fail_next_put = False
raise FailingQueueException("You Lose")
return queue.Queue._put(self, item)
def _get(self):
if self.fail_next_get:
self.fail_next_get = False
raise FailingQueueException("You Lose")
return queue.Queue._get(self)
class FailingQueueTest(BlockingTestMixin, unittest.TestCase):
def failing_queue_test(self, q):
if q.qsize():
raise RuntimeError("Call this function with an empty queue")
for i in range(QUEUE_SIZE-1):
q.put(i)
# Test a failing non-blocking put.
q.fail_next_put = True
try:
q.put("oops", block=0)
self.fail("The queue didn't fail when it should have")
except FailingQueueException:
pass
q.fail_next_put = True
try:
q.put("oops", timeout=0.1)
self.fail("The queue didn't fail when it should have")
except FailingQueueException:
pass
q.put("last")
self.assertTrue(qfull(q), "Queue should be full")
# Test a failing blocking put
q.fail_next_put = True
try:
self.do_blocking_test(q.put, ("full",), q.get, ())
self.fail("The queue didn't fail when it should have")
except FailingQueueException:
pass
# Check the Queue isn't damaged.
# put failed, but get succeeded - re-add
q.put("last")
# Test a failing timeout put
q.fail_next_put = True
try:
self.do_exceptional_blocking_test(q.put, ("full", True, 10), q.get, (),
FailingQueueException)
self.fail("The queue didn't fail when it should have")
except FailingQueueException:
pass
# Check the Queue isn't damaged.
# put failed, but get succeeded - re-add
q.put("last")
self.assertTrue(qfull(q), "Queue should be full")
q.get()
self.assertTrue(not qfull(q), "Queue should not be full")
q.put("last")
self.assertTrue(qfull(q), "Queue should be full")
# Test a blocking put
self.do_blocking_test(q.put, ("full",), q.get, ())
# Empty it
for i in range(QUEUE_SIZE):
q.get()
self.assertTrue(not q.qsize(), "Queue should be empty")
q.put("first")
q.fail_next_get = True
try:
q.get()
self.fail("The queue didn't fail when it should have")
except FailingQueueException:
pass
self.assertTrue(q.qsize(), "Queue should not be empty")
q.fail_next_get = True
try:
q.get(timeout=0.1)
self.fail("The queue didn't fail when it should have")
except FailingQueueException:
pass
self.assertTrue(q.qsize(), "Queue should not be empty")
q.get()
self.assertTrue(not q.qsize(), "Queue should be empty")
q.fail_next_get = True
try:
self.do_exceptional_blocking_test(q.get, (), q.put, ('empty',),
FailingQueueException)
self.fail("The queue didn't fail when it should have")
except FailingQueueException:
pass
# put succeeded, but get failed.
self.assertTrue(q.qsize(), "Queue should not be empty")
q.get()
self.assertTrue(not q.qsize(), "Queue should be empty")
def test_failing_queue(self):
# Test to make sure a queue is functioning correctly.
# Done twice to the same instance.
q = FailingQueue(QUEUE_SIZE)
self.failing_queue_test(q)
self.failing_queue_test(q)
if __name__ == "__main__":
unittest.main()