bpo-27456: asyncio: Fix _set_nodelay() for non-blocking socket

Lib/asyncio/selector_events.py

@@ -42,7 +42,7 @@ def _test_selector_event(selector, fd, event):
 if hasattr(socket, 'TCP_NODELAY'):
     def _set_nodelay(sock):
         if (sock.family in {socket.AF_INET, socket.AF_INET6} and
-                sock.type == socket.SOCK_STREAM and
+                base_events._is_stream_socket(sock) and
                 sock.proto == socket.IPPROTO_TCP):
             sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
 else:

Lib/test/test_asyncio/test_selector_events.py

@@ -17,6 +17,7 @@
 from asyncio.selector_events import _SelectorSslTransport
 from asyncio.selector_events import _SelectorSocketTransport
 from asyncio.selector_events import _SelectorDatagramTransport
+from asyncio.selector_events import _set_nodelay
 
 
 MOCK_ANY = mock.ANY
@@ -1787,5 +1788,31 @@ def test_fatal_error_connected(self, m_exc):
                 'Fatal error on transport\nprotocol:.*\ntransport:.*'),
             exc_info=(ConnectionRefusedError, MOCK_ANY, MOCK_ANY))
 
+
+class TestSelectorUtils(test_utils.TestCase):
+    def check_set_nodelay(self, sock):
+        opt = sock.getsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY)
+        self.assertFalse(opt)
+
+        _set_nodelay(sock)
+
+        opt = sock.getsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY)
+        self.assertTrue(opt)
+
+    @unittest.skipUnless(hasattr(socket, 'TCP_NODELAY'),
+                         'need socket.TCP_NODELAY')
+    def test_set_nodelay(self):
+        sock = socket.socket(family=socket.AF_INET, type=socket.SOCK_STREAM,
+                             proto=socket.IPPROTO_TCP)
+        with sock:
+            self.check_set_nodelay(sock)
+
+        sock = socket.socket(family=socket.AF_INET, type=socket.SOCK_STREAM,
+                             proto=socket.IPPROTO_TCP)
+        with sock:
+            sock.setblocking(False)
+            self.check_set_nodelay(sock)
+
+
 if __name__ == '__main__':
     unittest.main()

Misc/NEWS.d/next/Library/2017-11-02-17-08-02.bpo-27456.wWa1LV.rst

@@ -0,0 +1 @@
+Fix asyncio: Set also the TCP_NODELAY flag on non-blocking sockets.