Sync asyncio changes from the main repo.

Author: Yury Selivanov

Lib/asyncio/base_events.py

@@ -197,6 +197,7 @@ def __init__(self):
         # exceed this duration in seconds, the slow callback/task is logged.
         self.slow_callback_duration = 0.1
         self._current_handle = None
+        self._task_factory = None
 
     def __repr__(self):
         return ('<%s running=%s closed=%s debug=%s>'
@@ -209,11 +210,32 @@ def create_task(self, coro):
         Return a task object.
         """
         self._check_closed()
-        task = tasks.Task(coro, loop=self)
-        if task._source_traceback:
-            del task._source_traceback[-1]
+        if self._task_factory is None:
+            task = tasks.Task(coro, loop=self)
+            if task._source_traceback:
+                del task._source_traceback[-1]
+        else:
+            task = self._task_factory(self, coro)
         return task
 
+    def set_task_factory(self, factory):
+        """Set a task factory that will be used by loop.create_task().
+
+        If factory is None the default task factory will be set.
+
+        If factory is a callable, it should have a signature matching
+        '(loop, coro)', where 'loop' will be a reference to the active
+        event loop, 'coro' will be a coroutine object.  The callable
+        must return a Future.
+        """
+        if factory is not None and not callable(factory):
+            raise TypeError('task factory must be a callable or None')
+        self._task_factory = factory
+
+    def get_task_factory(self):
+        """Return a task factory, or None if the default one is in use."""
+        return self._task_factory
+
     def _make_socket_transport(self, sock, protocol, waiter=None, *,
                                extra=None, server=None):
         """Create socket transport."""
@@ -465,25 +487,25 @@ def call_soon_threadsafe(self, callback, *args):
         self._write_to_self()
         return handle
 
-    def run_in_executor(self, executor, callback, *args):
-        if (coroutines.iscoroutine(callback)
-        or coroutines.iscoroutinefunction(callback)):
+    def run_in_executor(self, executor, func, *args):
+        if (coroutines.iscoroutine(func)
+        or coroutines.iscoroutinefunction(func)):
             raise TypeError("coroutines cannot be used with run_in_executor()")
         self._check_closed()
-        if isinstance(callback, events.Handle):
+        if isinstance(func, events.Handle):
             assert not args
-            assert not isinstance(callback, events.TimerHandle)
-            if callback._cancelled:
+            assert not isinstance(func, events.TimerHandle)
+            if func._cancelled:
                 f = futures.Future(loop=self)
                 f.set_result(None)
                 return f
-            callback, args = callback._callback, callback._args
+            func, args = func._callback, func._args
         if executor is None:
             executor = self._default_executor
             if executor is None:
                 executor = concurrent.futures.ThreadPoolExecutor(_MAX_WORKERS)
                 self._default_executor = executor
-        return futures.wrap_future(executor.submit(callback, *args), loop=self)
+        return futures.wrap_future(executor.submit(func, *args), loop=self)
 
     def set_default_executor(self, executor):
         self._default_executor = executor

Lib/asyncio/events.py

@@ -277,7 +277,7 @@ def create_task(self, coro):
     def call_soon_threadsafe(self, callback, *args):
         raise NotImplementedError
 
-    def run_in_executor(self, executor, callback, *args):
+    def run_in_executor(self, executor, func, *args):
         raise NotImplementedError
 
     def set_default_executor(self, executor):
@@ -438,6 +438,14 @@ def add_signal_handler(self, sig, callback, *args):
     def remove_signal_handler(self, sig):
         raise NotImplementedError
 
+    # Task factory.
+
+    def set_task_factory(self, factory):
+        raise NotImplementedError
+
+    def get_task_factory(self):
+        raise NotImplementedError
+
     # Error handlers.
 
     def set_exception_handler(self, handler):

Lib/test/test_asyncio/test_base_events.py

@@ -16,10 +16,15 @@
 from asyncio import test_utils
 try:
     from test import support
-    from test.script_helper import assert_python_ok
 except ImportError:
     from asyncio import test_support as support
-    from asyncio.test_support import assert_python_ok
+try:
+    from test.support.script_helper import assert_python_ok
+except ImportError:
+    try:
+        from test.script_helper import assert_python_ok
+    except ImportError:
+        from asyncio.test_support import assert_python_ok
 
 
 MOCK_ANY = mock.ANY
@@ -623,6 +628,42 @@ def custom_handler(loop, context):
             self.assertIs(type(_context['context']['exception']),
                           ZeroDivisionError)
 
+    def test_set_task_factory_invalid(self):
+        with self.assertRaisesRegex(
+            TypeError, 'task factory must be a callable or None'):
+
+            self.loop.set_task_factory(1)
+
+        self.assertIsNone(self.loop.get_task_factory())
+
+    def test_set_task_factory(self):
+        self.loop._process_events = mock.Mock()
+
+        class MyTask(asyncio.Task):
+            pass
+
+        @asyncio.coroutine
+        def coro():
+            pass
+
+        factory = lambda loop, coro: MyTask(coro, loop=loop)
+
+        self.assertIsNone(self.loop.get_task_factory())
+        self.loop.set_task_factory(factory)
+        self.assertIs(self.loop.get_task_factory(), factory)
+
+        task = self.loop.create_task(coro())
+        self.assertTrue(isinstance(task, MyTask))
+        self.loop.run_until_complete(task)
+
+        self.loop.set_task_factory(None)
+        self.assertIsNone(self.loop.get_task_factory())
+
+        task = self.loop.create_task(coro())
+        self.assertTrue(isinstance(task, asyncio.Task))
+        self.assertFalse(isinstance(task, MyTask))
+        self.loop.run_until_complete(task)
+
     def test_env_var_debug(self):
         code = '\n'.join((
             'import asyncio',

Lib/test/test_asyncio/test_tasks.py

@@ -15,10 +15,15 @@
 from asyncio import test_utils
 try:
     from test import support
-    from test.script_helper import assert_python_ok
 except ImportError:
     from asyncio import test_support as support
-    from asyncio.test_support import assert_python_ok
+try:
+    from test.support.script_helper import assert_python_ok
+except ImportError:
+    try:
+        from test.script_helper import assert_python_ok
+    except ImportError:
+        from asyncio.test_support import assert_python_ok
 
 
 PY34 = (sys.version_info >= (3, 4))

Misc/NEWS

@@ -42,6 +42,8 @@ Core and Builtins
 
 - Issue #21354: PyCFunction_New function is exposed by python DLL again.
 
+- asyncio: New event loop APIs: set_task_factory() and get_task_factory()
+
 Library
 -------