use selectors instead of select.select (#16)

* use selectors instead of select.select

select.select() cannot work with fd > FDSET_SIZE == 1024
`selectors` uses most efficient implementation of `*poll()`
wherever supported, otherwise fallbacks to `select.select`
eg. in Windows.

* register socket before loop

mockssh/server.py

@@ -1,7 +1,6 @@
 import errno
 import logging
 import os
-import select
 import socket
 import subprocess
 import threading
@@ -11,6 +10,12 @@
 except ImportError:  # Python 2.7
     from Queue import Queue
 
+try:
+    import selectors
+except ImportError:  # Python 2.7
+    import selectors2 as selectors
+
+
 import paramiko
 
 from mockssh import sftp
@@ -129,10 +134,12 @@ def __enter__(self):
 
     def _run(self):
         sock = self._socket
+        selector = selectors.DefaultSelector()
+        selector.register(sock, selectors.EVENT_READ)
         while sock.fileno() > 0:
             self.log.debug("Waiting for incoming connections ...")
-            rlist, _, _ = select.select([sock], [], [], 1.0)
-            if rlist:
+            events = selector.select(timeout=1.0)
+            if events:
                 try:
                     conn, addr = sock.accept()
                 except OSError as ex:

requirements.txt

@@ -1 +1,2 @@
 paramiko
+selectors2; python_version < '3.4'