Added TimeoutQueue.

src/structures.py

@@ -37,8 +37,9 @@ __revision__ = "$Id$"
 
 import supybot.fix as fix
 
+import time
 import types
-from itertools import imap
+from itertools import imap, ilen
 
 class RingBuffer(object):
     """Class to represent a fixed-size ring buffer."""
@@ -303,6 +304,39 @@ class smallqueue(list):
         self[:] = []
 
 
+class TimeoutQueue(object):
+    def __init__(self, timeout, queue=None):
+        if queue is None:
+            queue = smallqueue()
+        self.queue = queue
+        self.timeout = timeout
+
+    def _clearOldElements(self):
+        now = time.time()
+        while now - self.queue.peek()[0] > self.timeout:
+            self.queue.dequeue()
+
+    def enqueue(self, elt, at=None):
+        if at is None:
+            at = time.time()
+        self.queue.enqueue((at, elt))
+
+    def dequeue(self):
+        self._clearOldElements()
+        return self.queue.dequeue()[1]
+
+    def __iter__(self):
+        # We could _clearOldElements here, but what happens if someone stores
+        # the resulting generator and elements that should've timed out are
+        # yielded?  Hmm?  What happens then, smarty-pants?
+        for (t, elt) in self.queue:
+            if time.time() - t < self.timeout:
+                yield elt
+
+    def __len__(self):
+        return ilen(self)
+
+
 class MaxLengthQueue(queue):
     __slots__ = ('length',)
     def __init__(self, length, seq=()):

test/test_structures.py

@@ -576,5 +576,18 @@ class TwoWayDictionaryTestCase(SupyTestCase):
         self.failIf('foo' in d)
 
 
+class TestTimeoutQueue(SupyTestCase):
+    def test(self):
+        q = TimeoutQueue(1)
+        q.enqueue(1)
+        self.assertEqual(len(q), 1)
+        q.enqueue(2)
+        self.assertEqual(len(q), 2)
+        q.enqueue(3)
+        self.assertEqual(len(q), 3)
+        time.sleep(1)
+        self.assertEqual(len(q), 0)
+        
+
 # vim:set shiftwidth=4 tabstop=8 expandtab textwidth=78: