asyncio: use directly socket.socketpair() (#4597)

Since Python 3.5, socket.socketpair() is also available on Windows,
and so can be used directly, rather than using
asyncio.windows_utils.socketpair().

Lib/asyncio/proactor_events.py

@@ -446,9 +446,6 @@ class BaseProactorEventLoop(base_events.BaseEventLoop):
     def sock_accept(self, sock):
         return self._proactor.accept(sock)
 
-    def _socketpair(self):
-        raise NotImplementedError
-
     def _close_self_pipe(self):
         if self._self_reading_future is not None:
             self._self_reading_future.cancel()
@@ -461,7 +458,7 @@ class BaseProactorEventLoop(base_events.BaseEventLoop):
 
     def _make_self_pipe(self):
         # A self-socket, really. :-)
-        self._ssock, self._csock = self._socketpair()
+        self._ssock, self._csock = socket.socketpair()
         self._ssock.setblocking(False)
         self._csock.setblocking(False)
         self._internal_fds += 1

Lib/asyncio/selector_events.py

@@ -96,9 +96,6 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
             self._selector.close()
             self._selector = None
 
-    def _socketpair(self):
-        raise NotImplementedError
-
     def _close_self_pipe(self):
         self._remove_reader(self._ssock.fileno())
         self._ssock.close()
@@ -109,7 +106,7 @@ class BaseSelectorEventLoop(base_events.BaseEventLoop):
 
     def _make_self_pipe(self):
         # A self-socket, really. :-)
-        self._ssock, self._csock = self._socketpair()
+        self._ssock, self._csock = socket.socketpair()
         self._ssock.setblocking(False)
         self._csock.setblocking(False)
         self._internal_fds += 1

Lib/asyncio/unix_events.py

@@ -55,9 +55,6 @@ class _UnixSelectorEventLoop(selector_events.BaseSelectorEventLoop):
         super().__init__(selector)
         self._signal_handlers = {}
 
-    def _socketpair(self):
-        return socket.socketpair()
-
     def close(self):
         super().close()
         for sig in list(self._signal_handlers):
@@ -677,7 +674,7 @@ class _UnixSubprocessTransport(base_subprocess.BaseSubprocessTransport):
             # socket (which we use in order to detect closing of the
             # other end).  Notably this is needed on AIX, and works
             # just fine on other platforms.
-            stdin, stdin_w = self._loop._socketpair()
+            stdin, stdin_w = socket.socketpair()
 
             # Mark the write end of the stdin pipe as non-inheritable,
             # needed by close_fds=False on Python 3.3 and older

Lib/asyncio/windows_events.py

@@ -296,9 +296,6 @@ class PipeServer(object):
 class _WindowsSelectorEventLoop(selector_events.BaseSelectorEventLoop):
     """Windows version of selector event loop."""
 
-    def _socketpair(self):
-        return windows_utils.socketpair()
-
 
 class ProactorEventLoop(proactor_events.BaseProactorEventLoop):
     """Windows version of proactor event loop using IOCP."""
@@ -308,9 +305,6 @@ class ProactorEventLoop(proactor_events.BaseProactorEventLoop):
             proactor = IocpProactor()
         super().__init__(proactor)
 
-    def _socketpair(self):
-        return windows_utils.socketpair()
-
     @coroutine
     def create_pipe_connection(self, protocol_factory, address):
         f = self._proactor.connect_pipe(address)