# Some simple Queue module tests, plus some failure conditions
# to ensure the Queue locks remain stable.
import Queue
import sys
import threading
import time
from test.test_support import verify, TestFailed, verbose
QUEUE_SIZE = 5
# 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 _doExceptionalBlockingTest() instead.
def _doBlockingTest(block_func, block_args, trigger_func, trigger_args):
t = _TriggerThread(trigger_func, trigger_args)
t.start()
result = block_func(*block_args)
# If block_func returned before our thread made the call, we failed!
if not t.startedEvent.isSet():
raise TestFailed("blocking function '%r' appeared not to block" %
block_func)
t.join(10) # make sure the thread terminates
if t.isAlive():
raise TestFailed("trigger function '%r' appeared to not return" %
trigger_func)
return result
# Call this instead if block_func is supposed to raise an exception.
def _doExceptionalBlockingTest(block_func, block_args, trigger_func,
trigger_args, expected_exception_class):
t = _TriggerThread(trigger_func, trigger_args)
t.start()
try:
try:
block_func(*block_args)
except expected_exception_class:
raise
else:
raise TestFailed("expected exception of kind %r" %
expected_exception_class)
finally:
t.join(10) # make sure the thread terminates
if t.isAlive():
raise TestFailed("trigger function '%r' appeared to not return" %
trigger_func)
if not t.startedEvent.isSet():
raise TestFailed("trigger thread ended but event never set")
# 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)
def FailingQueueTest(q):
if not q.empty():
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)
raise TestFailed("The queue didn't fail when it should have")
except FailingQueueException:
pass
q.fail_next_put = True
try:
q.put("oops", timeout=0.1)
raise TestFailed("The queue didn't fail when it should have")
except FailingQueueException:
pass
q.put("last")
verify(q.full(), "Queue should be full")
# Test a failing blocking put
q.fail_next_put = True
try:
_doBlockingTest(q.put, ("full",), q.get, ())
raise TestFailed("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:
_doExceptionalBlockingTest(q.put, ("full", True, 10), q.get, (),
FailingQueueException)
raise TestFailed("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")
verify(q.full(), "Queue should be full")
q.get()
verify(not q.full(), "Queue should not be full")
q.put("last")
verify(q.full(), "Queue should be full")
# Test a blocking put
_doBlockingTest( q.put, ("full",), q.get, ())
# Empty it
for i in range(QUEUE_SIZE):
q.get()
verify(q.empty(), "Queue should be empty")
q.put("first")
q.fail_next_get = True
try:
q.get()
raise TestFailed("The queue didn't fail when it should have")
except FailingQueueException:
pass
verify(not q.empty(), "Queue should not be empty")
q.fail_next_get = True
try:
q.get(timeout=0.1)
raise TestFailed("The queue didn't fail when it should have")
except FailingQueueException:
pass
verify(not q.empty(), "Queue should not be empty")
q.get()
verify(q.empty(), "Queue should be empty")
q.fail_next_get = True
try:
_doExceptionalBlockingTest(q.get, (), q.put, ('empty',),
FailingQueueException)
raise TestFailed("The queue didn't fail when it should have")
except FailingQueueException:
pass
# put succeeded, but get failed.
verify(not q.empty(), "Queue should not be empty")
q.get()
verify(q.empty(), "Queue should be empty")
def SimpleQueueTest(q):
if not q.empty():
raise RuntimeError, "Call this function with an empty queue"
# I guess we better check things actually queue correctly a little :)
q.put(111)
q.put(222)
verify(q.get() == 111 and q.get() == 222,
"Didn't seem to queue the correct data!")
for i in range(QUEUE_SIZE-1):
q.put(i)
verify(not q.empty(), "Queue should not be empty")
verify(not q.full(), "Queue should not be full")
q.put("last")
verify(q.full(), "Queue should be full")
try:
q.put("full", block=0)
raise TestFailed("Didn't appear to block with a full queue")
except Queue.Full:
pass
try:
q.put("full", timeout=0.01)
raise TestFailed("Didn't appear to time-out with a full queue")
except Queue.Full:
pass
# Test a blocking put
_doBlockingTest(q.put, ("full",), q.get, ())
_doBlockingTest(q.put, ("full", True, 10), q.get, ())
# Empty it
for i in range(QUEUE_SIZE):
q.get()
verify(q.empty(), "Queue should be empty")
try:
q.get(block=0)
raise TestFailed("Didn't appear to block with an empty queue")
except Queue.Empty:
pass
try:
q.get(timeout=0.01)
raise TestFailed("Didn't appear to time-out with an empty queue")
except Queue.Empty:
pass
# Test a blocking get
_doBlockingTest(q.get, (), q.put, ('empty',))
_doBlockingTest(q.get, (True, 10), q.put, ('empty',))
cum = 0
cumlock = threading.Lock()
def worker(q):
global cum
while True:
x = q.get()
if x is None:
q.task_done()
return
cumlock.acquire()
try:
cum += x
finally:
cumlock.release()
q.task_done()
def QueueJoinTest(q):
global cum
cum = 0
for i in (0,1):
threading.Thread(target=worker, args=(q,)).start()
for i in xrange(100):
q.put(i)
q.join()
verify(cum==sum(range(100)), "q.join() did not block until all tasks were done")
for i in (0,1):
q.put(None) # instruct the threads to close
q.join() # verify that you can join twice
def QueueTaskDoneTest(q):
try:
q.task_done()
except ValueError:
pass
else:
raise TestFailed("Did not detect task count going negative")
def test():
q = Queue.Queue()
QueueTaskDoneTest(q)
QueueJoinTest(q)
QueueJoinTest(q)
QueueTaskDoneTest(q)
q = Queue.Queue(QUEUE_SIZE)
# Do it a couple of times on the same queue
SimpleQueueTest(q)
SimpleQueueTest(q)
if verbose:
print "Simple Queue tests seemed to work"
q = FailingQueue(QUEUE_SIZE)
FailingQueueTest(q)
FailingQueueTest(q)
if verbose:
print "Failing Queue tests seemed to work"
test()
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