PYTHON-307 Replace select with poll on platforms that support it.

Author: aherlihy

pymongo/network.py

@@ -17,6 +17,17 @@
 import select
 import struct
 
+_HAS_POLL = True
+_poller = None
+_EVENT_MASK = 0
+try:
+    from select import poll
+    _poller = poll()
+    _EVENT_MASK = (select.POLLIN | select.POLLPRI | select.POLLERR |
+                   select.POLLHUP | select.POLLNVAL)
+except ImportError:
+    _HAS_POLL = False
+
 from pymongo import helpers, message
 from pymongo.errors import AutoReconnect
 
@@ -93,7 +104,12 @@ def socket_closed(sock):
     """Return True if we know socket has been closed, False otherwise.
     """
     try:
-        rd, _, _ = select.select([sock], [], [], 0)
+        if _HAS_POLL:
+            _poller.register(sock, _EVENT_MASK)
+            rd = _poller.poll(0)
+            _poller.unregister(sock)
+        else:
+            rd, _, _ = select.select([sock], [], [], 0)
     # Any exception here is equally bad (select.error, ValueError, etc.).
     except:
         return True

test/test_pooling.py

@@ -241,6 +241,14 @@ def test_pool_removes_dead_socket(self):
         with cx_pool.get_socket({}):
             pass
 
+    def test_socket_closed(self):
+        import socket
+        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        s.connect(('localhost', 27017))
+        self.assertFalse(socket_closed(s))
+        s.close()
+        self.assertTrue(socket_closed(s))
+
     def test_return_socket_after_reset(self):
         pool = self.create_pool()
         with pool.get_socket({}) as sock: