Lib/test/test_queue.py

   1 # Some simple Queue module tests, plus some failure conditions
   2 # to ensure the Queue locks remain stable
   3 import Queue
   4 import sys
   5 import threading
   6 import time
   7
   8 from test_support import verify, TestFailed, verbose
   9
  10 queue_size = 5
  11
  12 # Execute a function that blocks, and in a seperate thread, a function that
  13 # triggers the release.  Returns the result of the blocking function.
  14 class _TriggerThread(threading.Thread):
  15     def __init__(self, fn, args):
  16         self.fn = fn
  17         self.args = args
  18         self.startedEvent = threading.Event()
  19         threading.Thread.__init__(self)
  20     def run(self):
  21         time.sleep(.1)
  22         self.startedEvent.set()
  23         self.fn(*self.args)
  24
  25 def _doBlockingTest( block_func, block_args, trigger_func, trigger_args):
  26     t = _TriggerThread(trigger_func, trigger_args)
  27     t.start()
  28     try:
  29         return block_func(*block_args)
  30     finally:
  31         # If we unblocked before our thread made the call, we failed!
  32         if not t.startedEvent.isSet():
  33             raise TestFailed("blocking function '%r' appeared not to block" % (block_func,))
  34         t.join(1) # make sure the thread terminates
  35         if t.isAlive():
  36             raise TestFailed("trigger function '%r' appeared to not return" % (trigger_func,))
  37
  38 # A Queue subclass that can provoke failure at a moment's notice :)
  39 class FailingQueueException(Exception):
  40     pass
  41
  42 class FailingQueue(Queue.Queue):
  43     def __init__(self, *args):
  44         self.fail_next_put = False
  45         self.fail_next_get = False
  46         Queue.Queue.__init__(self, *args)
  47     def _put(self, item):
  48         if self.fail_next_put:
  49             self.fail_next_put = False
  50             raise FailingQueueException, "You Lose"
  51         return Queue.Queue._put(self, item)
  52     def _get(self):
  53         if self.fail_next_get:
  54             self.fail_next_get = False
  55             raise FailingQueueException, "You Lose"
  56         return Queue.Queue._get(self)
  57
  58 def FailingQueueTest(q):
  59     if not q.empty():
  60         raise RuntimeError, "Call this function with an empty queue"
  61     for i in range(queue_size-1):
  62         q.put(i)
  63     q.fail_next_put = True
  64     # Test a failing non-blocking put.
  65     try:
  66         q.put("oops", block=0)
  67         raise TestFailed("The queue didn't fail when it should have")
  68     except FailingQueueException:
  69         pass
  70     q.put("last")
  71     verify(q.full(), "Queue should be full")
  72     q.fail_next_put = True
  73     # Test a failing blocking put
  74     try:
  75         _doBlockingTest( q.put, ("full",), q.get, ())
  76         raise TestFailed("The queue didn't fail when it should have")
  77     except FailingQueueException:
  78         pass
  79     # Check the Queue isn't damaged.
  80     # put failed, but get succeeded - re-add
  81     q.put("last")
  82     verify(q.full(), "Queue should be full")
  83     q.get()
  84     verify(not q.full(), "Queue should not be full")
  85     q.put("last")
  86     verify(q.full(), "Queue should be full")
  87     # Test a blocking put
  88     _doBlockingTest( q.put, ("full",), q.get, ())
  89     # Empty it
  90     for i in range(queue_size):
  91         q.get()
  92     verify(q.empty(), "Queue should be empty")
  93     q.put("first")
  94     q.fail_next_get = True
  95     try:
  96         q.get()
  97         raise TestFailed("The queue didn't fail when it should have")
  98     except FailingQueueException:
  99         pass
 100     verify(not q.empty(), "Queue should not be empty")
 101     q.get()
 102     verify(q.empty(), "Queue should be empty")
 103     q.fail_next_get = True
 104     try:
 105         _doBlockingTest( q.get, (), q.put, ('empty',))
 106         raise TestFailed("The queue didn't fail when it should have")
 107     except FailingQueueException:
 108         pass
 109     # put succeeded, but get failed.
 110     verify(not q.empty(), "Queue should not be empty")
 111     q.get()
 112     verify(q.empty(), "Queue should be empty")
 113
 114 def SimpleQueueTest(q):
 115     if not q.empty():
 116         raise RuntimeError, "Call this function with an empty queue"
 117     # I guess we better check things actually queue correctly a little :)
 118     q.put(111)
 119     q.put(222)
 120     verify(q.get()==111 and q.get()==222, "Didn't seem to queue the correct data!")
 121     for i in range(queue_size-1):
 122         q.put(i)
 123     verify(not q.full(), "Queue should not be full")
 124     q.put("last")
 125     verify(q.full(), "Queue should be full")
 126     try:
 127         q.put("full", block=0)
 128         raise TestFailed("Didn't appear to block with a full queue")
 129     except Queue.Full:
 130         pass
 131     # Test a blocking put
 132     _doBlockingTest( q.put, ("full",), q.get, ())
 133     # Empty it
 134     for i in range(queue_size):
 135         q.get()
 136     verify(q.empty(), "Queue should be empty")
 137     try:
 138         q.get(block=0)
 139         raise TestFailed("Didn't appear to block with an empty queue")
 140     except Queue.Empty:
 141         pass
 142     # Test a blocking get
 143     _doBlockingTest( q.get, (), q.put, ('empty',))
 144
 145 def test():
 146     q=Queue.Queue(queue_size)
 147     # Do it a couple of times on the same queue
 148     SimpleQueueTest(q)
 149     SimpleQueueTest(q)
 150     if verbose:
 151         print "Simple Queue tests seemed to work"
 152     q = FailingQueue(queue_size)
 153     FailingQueueTest(q)
 154     FailingQueueTest(q)
 155     if verbose:
 156         print "Failing Queue tests seemed to work"
 157
 158 test()