# 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()