async_handlers option for asyncio servers

Author: miguelgrinberg

socketio/asyncio_manager.py

@@ -23,8 +23,9 @@ async def emit(self, event, data, namespace, room=None, skip_sid=None,
                     id = None
                 tasks.append(self.server._emit_internal(sid, event, data,
                                                         namespace, id))
-        if tasks != []:
-            await asyncio.wait(tasks)
+        if tasks == []:  # pragma: no cover
+            return
+        await asyncio.wait(tasks)
 
     async def close_room(self, room, namespace):
         """Remove all participants from a room.

socketio/asyncio_server.py

@@ -24,6 +24,9 @@ class AsyncServer(server.Server):
                  packets. Custom json modules must have ``dumps`` and ``loads``
                  functions that are compatible with the standard library
                  versions.
+    :param async_handlers: If set to ``True``, event handlers are executed in
+                           separate threads. To run handlers synchronously,
+                           set to ``False``. The default is ``False``.
     :param kwargs: Connection parameters for the underlying Engine.IO server.
 
     The Engine.IO configuration supports the following settings:
@@ -55,11 +58,13 @@ class AsyncServer(server.Server):
                             a logger object to use. To disable logging set to
                             ``False``.
     """
-    def __init__(self, client_manager=None, logger=False, json=None, **kwargs):
+    def __init__(self, client_manager=None, logger=False, json=None,
+                 async_handlers=False, **kwargs):
         if client_manager is None:
             client_manager = asyncio_manager.AsyncManager()
         super().__init__(client_manager=client_manager, logger=logger,
-                         binary=False, json=json, **kwargs)
+                         binary=False, json=json,
+                         async_handlers=async_handlers, **kwargs)
 
     def is_asyncio_based(self):
         return True
@@ -280,7 +285,11 @@ async def _handle_event(self, sid, namespace, id, data):
         namespace = namespace or '/'
         self.logger.info('received event "%s" from %s [%s]', data[0], sid,
                          namespace)
-        await self._handle_event_internal(self, sid, data, namespace, id)
+        if self.async_handlers:
+            self.start_background_task(self._handle_event_internal, self, sid,
+                                       data, namespace, id)
+        else:
+            await self._handle_event_internal(self, sid, data, namespace, id)
 
     async def _handle_event_internal(self, server, sid, data, namespace, id):
         r = await server._trigger_event(data[0], namespace, sid, *data[1:])

tests/test_asyncio_server.py

@@ -56,14 +56,15 @@ def _get_mock_manager(self):
     def test_create(self, eio):
         eio.return_value.handle_request = AsyncMock()
         mgr = self._get_mock_manager()
-        s = asyncio_server.AsyncServer(client_manager=mgr, foo='bar')
+        s = asyncio_server.AsyncServer(client_manager=mgr,
+                                       async_handlers=True, foo='bar')
         _run(s.handle_request({}))
         _run(s.handle_request({}))
         eio.assert_called_once_with(**{'foo': 'bar', 'async_handlers': False})
         self.assertEqual(s.manager, mgr)
         self.assertEqual(s.eio.on.call_count, 3)
         self.assertEqual(s.binary, False)
-        self.assertEqual(s.async_handlers, False)
+        self.assertEqual(s.async_handlers, True)
 
     def test_attach(self, eio):
         s = asyncio_server.AsyncServer()
@@ -581,12 +582,18 @@ def loads(*args, **kwargs):
         # restore the default JSON module
         packet.Packet.json = json
 
+    def test_async_handlers(self, eio):
+        s = asyncio_server.AsyncServer(async_handlers=True)
+        _run(s._handle_eio_message('123', '2["my message","a","b","c"]'))
+        s.eio.start_background_task.assert_called_once_with(
+            s._handle_event_internal, s, '123', ['my message', 'a', 'b', 'c'],
+            '/', None)
+
     def test_start_background_task(self, eio):
-        eio.return_value.start_background_task = AsyncMock()
         s = asyncio_server.AsyncServer()
-        _run(s.start_background_task('foo', 'bar', baz='baz'))
-        s.eio.start_background_task.mock.assert_called_once_with('foo', 'bar',
-                                                                 baz='baz')
+        s.start_background_task('foo', 'bar', baz='baz')
+        s.eio.start_background_task.assert_called_once_with('foo', 'bar',
+                                                            baz='baz')
 
     def test_sleep(self, eio):
         eio.return_value.sleep = AsyncMock()