Use asyncio.ensure_future() instead of asyncio.async() with conservative approach to support Python < 3.4.4. Fixes https://github.com/GNS3/gns3-gui/issues/2566

gns3server/utils/asyncio/telnet_server.py

@@ -20,6 +20,8 @@ import asyncio
 import asyncio.subprocess
 import struct
 
+from gns3server.utils.asyncio import asyncio_ensure_future
+
 import logging
 log = logging.getLogger(__name__)
 
@@ -212,9 +214,12 @@ class AsyncioTelnetServer:
     @asyncio.coroutine
     def close(self):
         for writer, connection in self._connections.items():
-            writer.write_eof()
-            yield from writer.drain()
-        
+            try:
+                writer.write_eof()
+                yield from writer.drain()
+            except ConnectionResetError:
+                continue
+
     @asyncio.coroutine
     def client_connected_hook(self):
         pass
@@ -229,13 +234,13 @@ class AsyncioTelnetServer:
                 self._reader_process = network_reader
             if self._reader:
                 if self._reader_process == network_reader:
-                    self._current_read = asyncio.async(self._reader.read(READ_SIZE))
+                    self._current_read = asyncio_ensure_future(self._reader.read(READ_SIZE))
                     return self._current_read
         return None
 
     @asyncio.coroutine
     def _process(self, network_reader, network_writer, connection):
-        network_read = asyncio.async(network_reader.read(READ_SIZE))
+        network_read = asyncio_ensure_future(network_reader.read(READ_SIZE))
         reader_read = yield from self._get_reader(network_reader)
 
         while True:
@@ -261,7 +266,7 @@ class AsyncioTelnetServer:
                     if network_reader.at_eof():
                         raise ConnectionResetError()
 
-                    network_read = asyncio.async(network_reader.read(READ_SIZE))
+                    network_read = asyncio_ensure_future(network_reader.read(READ_SIZE))
 
                     if IAC in data:
                         data = yield from self._IAC_parser(data, network_reader, network_writer, connection)
@@ -418,10 +423,10 @@ if __name__ == '__main__':
     logging.basicConfig(level=logging.DEBUG)
     loop = asyncio.get_event_loop()
 
-    process = loop.run_until_complete(asyncio.async(asyncio.subprocess.create_subprocess_exec("/bin/sh", "-i",
-                                                                                              stdout=asyncio.subprocess.PIPE,
-                                                                                              stderr=asyncio.subprocess.STDOUT,
-                                                                                              stdin=asyncio.subprocess.PIPE)))
+    process = loop.run_until_complete(asyncio_ensure_future(asyncio.subprocess.create_subprocess_exec("/bin/sh", "-i",
+                                                                                                      stdout=asyncio.subprocess.PIPE,
+                                                                                                      stderr=asyncio.subprocess.STDOUT,
+                                                                                                      stdin=asyncio.subprocess.PIPE)))
     server = AsyncioTelnetServer(reader=process.stdout, writer=process.stdin, binary=False, echo=False)
 
     coro = asyncio.start_server(server.run, '127.0.0.1', 4444, loop=loop)