Bug 37: Implement queue resizing

eventlet/queue.py

@@ -182,6 +182,15 @@ class LightQueue(object):
         """Return the size of the queue."""
         return len(self.queue)
 
+    def resize(self, size):
+        """Resizes the queue's maximum size.
+
+        If the size is increased, and there are putters waiting, they may be woken up."""
+        if size > self.maxsize:
+            # Maybe wake some stuff up
+            self._schedule_unlock()
+        self.maxsize = size
+        
     def putting(self):
         """Returns the number of greenthreads that are blocked waiting to put
         items into the queue."""

tests/queue_test.py

@@ -68,6 +68,33 @@ class TestQueue(LimitedTestCase):
         self.assertEquals(evt.wait(),'done')
         gt.wait()
 
+    def test_resize_up(self):
+        q = eventlet.Queue(0)
+        def sender(evt, q):
+            q.put('hi')
+            evt.send('done')
+
+        evt = event.Event()
+        gt = eventlet.spawn(sender, evt, q)
+        eventlet.sleep(0)
+        self.assert_(not evt.ready())
+        q.resize(1)
+        eventlet.sleep(0)
+        self.assert_(evt.ready())
+        gt.wait()
+
+    def test_resize_down(self):
+        size = 5
+        q = eventlet.Queue(5)
+
+        for i in range(5):
+            q.put(i)
+
+        self.assertEquals(list(q.queue), range(5))
+        q.resize(1)
+        eventlet.sleep(0)
+        self.assertEquals(list(q.queue), range(5))
+
     def test_multiple_waiters(self):
         # tests that multiple waiters get their results back
         q = eventlet.Queue()