profiling: add list+deque+cache+islice just to compare with pure slice

--HG--
extra : convert_revision : svn%3Ab85faa78-f9eb-468e-a121-7cced6da292c%40997

scrapy/trunk/profiling/priorityqueue/pq_classes.py

@@ -245,4 +245,21 @@ class PriorityQueue6(object):
         return bool(len(self))
 
 
+from itertools import islice
+class PriorityQueue6b(PriorityQueue6):
+    """Priority queue using a deque for priority 0"""
 
+    def pop(self):
+        cached = self.priolist[self.index]
+        if cached:
+            return (cached.pop(), self.index - self.zero)
+
+        for prio, queue in enumerate(islice(self.priolist, self.index, None), self.index):
+            if queue:
+                self.index = prio
+                return (queue.pop(), prio - self.zero)
+
+        raise IndexError("pop from an empty queue")
+
+
+__all__ = [name for name in globals().keys() if name.startswith('PriorityQueue')]

scrapy/trunk/profiling/priorityqueue/run.py

@@ -15,6 +15,7 @@ TESTCASES = [
        ("deque+defaultdict+deque", PriorityQueue4),
        ('list+deque', PriorityQueue5),
        ('list+deque+cache', PriorityQueue6),
+       ('list+deque+cache+islice', PriorityQueue6b),
        ]