[Python-checkins] bpo-32311: Implement asyncio.create_task() shortcut (#4848)
Andrew Svetlov
webhook-mailer at python.org
Fri Dec 15 00:04:45 EST 2017
https://github.com/python/cpython/commit/f74ef458ab1f502e4e60bd1502ac1dc0d2cb3847
commit: f74ef458ab1f502e4e60bd1502ac1dc0d2cb3847
branch: master
author: Andrew Svetlov <andrew.svetlov at gmail.com>
committer: GitHub <noreply at github.com>
date: 2017-12-15T07:04:38+02:00
summary:
bpo-32311: Implement asyncio.create_task() shortcut (#4848)
* Implement functionality
* Add documentation
files:
A Lib/asyncio/format_helpers.py
A Misc/NEWS.d/next/Library/2017-12-14-17-28-54.bpo-32311.DL5Ytn.rst
M Doc/library/asyncio-task.rst
M Lib/asyncio/base_futures.py
M Lib/asyncio/constants.py
M Lib/asyncio/coroutines.py
M Lib/asyncio/events.py
M Lib/asyncio/futures.py
M Lib/asyncio/tasks.py
M Lib/test/test_asyncio/test_tasks.py
M Lib/test/test_asyncio/utils.py
M Modules/_asynciomodule.c
diff --git a/Doc/library/asyncio-task.rst b/Doc/library/asyncio-task.rst
index 0d0569f0ba1..72fae5e8559 100644
--- a/Doc/library/asyncio-task.rst
+++ b/Doc/library/asyncio-task.rst
@@ -371,10 +371,21 @@ with the result.
Task
----
+.. function:: create_task(coro)
+
+ Wrap a :ref:`coroutine <coroutine>` *coro* into a task and schedule
+ its execution. Return the task object.
+
+ The task is executed in :func:`get_running_loop` context,
+ :exc:`RuntimeError` is raised if there is no running loop in
+ current thread.
+
+ .. versionadded:: 3.7
+
.. class:: Task(coro, \*, loop=None)
- Schedule the execution of a :ref:`coroutine <coroutine>`: wrap it in a
- future. A task is a subclass of :class:`Future`.
+ A unit for concurrent running of :ref:`coroutines <coroutine>`,
+ subclass of :class:`Future`.
A task is responsible for executing a coroutine object in an event loop. If
the wrapped coroutine yields from a future, the task suspends the execution
@@ -399,7 +410,7 @@ Task
<coroutine>` did not complete. It is probably a bug and a warning is
logged: see :ref:`Pending task destroyed <asyncio-pending-task-destroyed>`.
- Don't directly create :class:`Task` instances: use the :func:`ensure_future`
+ Don't directly create :class:`Task` instances: use the :func:`create_task`
function or the :meth:`AbstractEventLoop.create_task` method.
This class is :ref:`not thread safe <asyncio-multithreading>`.
@@ -547,9 +558,15 @@ Task functions
.. versionchanged:: 3.5.1
The function accepts any :term:`awaitable` object.
+ .. note::
+
+ :func:`create_task` (added in Python 3.7) is the preferable way
+ for spawning new tasks.
+
.. seealso::
- The :meth:`AbstractEventLoop.create_task` method.
+ The :func:`create_task` function and
+ :meth:`AbstractEventLoop.create_task` method.
.. function:: wrap_future(future, \*, loop=None)
diff --git a/Lib/asyncio/base_futures.py b/Lib/asyncio/base_futures.py
index 2ee82c3f057..008812eda91 100644
--- a/Lib/asyncio/base_futures.py
+++ b/Lib/asyncio/base_futures.py
@@ -3,7 +3,7 @@
import concurrent.futures._base
import reprlib
-from . import events
+from . import format_helpers
Error = concurrent.futures._base.Error
CancelledError = concurrent.futures.CancelledError
@@ -38,7 +38,7 @@ def _format_callbacks(cb):
cb = ''
def format_cb(callback):
- return events._format_callback_source(callback, ())
+ return format_helpers._format_callback_source(callback, ())
if size == 1:
cb = format_cb(cb[0])
diff --git a/Lib/asyncio/constants.py b/Lib/asyncio/constants.py
index dfe97f49859..52169c3f8e5 100644
--- a/Lib/asyncio/constants.py
+++ b/Lib/asyncio/constants.py
@@ -6,5 +6,5 @@
# Number of stack entries to capture in debug mode.
# The larger the number, the slower the operation in debug mode
-# (see extract_stack() in events.py).
+# (see extract_stack() in format_helpers.py).
DEBUG_STACK_DEPTH = 10
diff --git a/Lib/asyncio/coroutines.py b/Lib/asyncio/coroutines.py
index bca7fe3a537..e3c0162dd14 100644
--- a/Lib/asyncio/coroutines.py
+++ b/Lib/asyncio/coroutines.py
@@ -9,9 +9,9 @@
from collections.abc import Awaitable, Coroutine
-from . import constants
-from . import events
from . import base_futures
+from . import constants
+from . import format_helpers
from .log import logger
@@ -48,7 +48,7 @@ def __init__(self, gen, func=None):
assert inspect.isgenerator(gen) or inspect.iscoroutine(gen), gen
self.gen = gen
self.func = func # Used to unwrap @coroutine decorator
- self._source_traceback = events.extract_stack(sys._getframe(1))
+ self._source_traceback = format_helpers.extract_stack(sys._getframe(1))
self.__name__ = getattr(gen, '__name__', None)
self.__qualname__ = getattr(gen, '__qualname__', None)
@@ -243,7 +243,7 @@ def _format_coroutine(coro):
func = coro
if coro_name is None:
- coro_name = events._format_callback(func, (), {})
+ coro_name = format_helpers._format_callback(func, (), {})
try:
coro_code = coro.gi_code
@@ -260,7 +260,7 @@ def _format_coroutine(coro):
if (isinstance(coro, CoroWrapper) and
not inspect.isgeneratorfunction(coro.func) and
coro.func is not None):
- source = events._get_function_source(coro.func)
+ source = format_helpers._get_function_source(coro.func)
if source is not None:
filename, lineno = source
if coro_frame is None:
diff --git a/Lib/asyncio/events.py b/Lib/asyncio/events.py
index a00f861a9e5..974a4a22218 100644
--- a/Lib/asyncio/events.py
+++ b/Lib/asyncio/events.py
@@ -11,86 +11,14 @@
'_get_running_loop',
)
-import functools
-import inspect
import os
-import reprlib
import socket
import subprocess
import sys
import threading
-import traceback
from . import constants
-
-
-def _get_function_source(func):
- func = inspect.unwrap(func)
- if inspect.isfunction(func):
- code = func.__code__
- return (code.co_filename, code.co_firstlineno)
- if isinstance(func, functools.partial):
- return _get_function_source(func.func)
- if isinstance(func, functools.partialmethod):
- return _get_function_source(func.func)
- return None
-
-
-def _format_args_and_kwargs(args, kwargs):
- """Format function arguments and keyword arguments.
-
- Special case for a single parameter: ('hello',) is formatted as ('hello').
- """
- # use reprlib to limit the length of the output
- items = []
- if args:
- items.extend(reprlib.repr(arg) for arg in args)
- if kwargs:
- items.extend(f'{k}={reprlib.repr(v)}' for k, v in kwargs.items())
- return '({})'.format(', '.join(items))
-
-
-def _format_callback(func, args, kwargs, suffix=''):
- if isinstance(func, functools.partial):
- suffix = _format_args_and_kwargs(args, kwargs) + suffix
- return _format_callback(func.func, func.args, func.keywords, suffix)
-
- if hasattr(func, '__qualname__'):
- func_repr = getattr(func, '__qualname__')
- elif hasattr(func, '__name__'):
- func_repr = getattr(func, '__name__')
- else:
- func_repr = repr(func)
-
- func_repr += _format_args_and_kwargs(args, kwargs)
- if suffix:
- func_repr += suffix
- return func_repr
-
-
-def _format_callback_source(func, args):
- func_repr = _format_callback(func, args, None)
- source = _get_function_source(func)
- if source:
- func_repr += f' at {source[0]}:{source[1]}'
- return func_repr
-
-
-def extract_stack(f=None, limit=None):
- """Replacement for traceback.extract_stack() that only does the
- necessary work for asyncio debug mode.
- """
- if f is None:
- f = sys._getframe().f_back
- if limit is None:
- # Limit the amount of work to a reasonable amount, as extract_stack()
- # can be called for each coroutine and future in debug mode.
- limit = constants.DEBUG_STACK_DEPTH
- stack = traceback.StackSummary.extract(traceback.walk_stack(f),
- limit=limit,
- lookup_lines=False)
- stack.reverse()
- return stack
+from . import format_helpers
class Handle:
@@ -106,7 +34,8 @@ def __init__(self, callback, args, loop):
self._cancelled = False
self._repr = None
if self._loop.get_debug():
- self._source_traceback = extract_stack(sys._getframe(1))
+ self._source_traceback = format_helpers.extract_stack(
+ sys._getframe(1))
else:
self._source_traceback = None
@@ -115,7 +44,8 @@ def _repr_info(self):
if self._cancelled:
info.append('cancelled')
if self._callback is not None:
- info.append(_format_callback_source(self._callback, self._args))
+ info.append(format_helpers._format_callback_source(
+ self._callback, self._args))
if self._source_traceback:
frame = self._source_traceback[-1]
info.append(f'created at {frame[0]}:{frame[1]}')
@@ -145,7 +75,8 @@ def _run(self):
try:
self._callback(*self._args)
except Exception as exc:
- cb = _format_callback_source(self._callback, self._args)
+ cb = format_helpers._format_callback_source(
+ self._callback, self._args)
msg = f'Exception in callback {cb}'
context = {
'message': msg,
diff --git a/Lib/asyncio/format_helpers.py b/Lib/asyncio/format_helpers.py
new file mode 100644
index 00000000000..39cfcee0c1c
--- /dev/null
+++ b/Lib/asyncio/format_helpers.py
@@ -0,0 +1,75 @@
+import functools
+import inspect
+import reprlib
+import traceback
+
+from . import constants
+
+
+def _get_function_source(func):
+ func = inspect.unwrap(func)
+ if inspect.isfunction(func):
+ code = func.__code__
+ return (code.co_filename, code.co_firstlineno)
+ if isinstance(func, functools.partial):
+ return _get_function_source(func.func)
+ if isinstance(func, functools.partialmethod):
+ return _get_function_source(func.func)
+ return None
+
+
+def _format_callback_source(func, args):
+ func_repr = _format_callback(func, args, None)
+ source = _get_function_source(func)
+ if source:
+ func_repr += f' at {source[0]}:{source[1]}'
+ return func_repr
+
+
+def _format_args_and_kwargs(args, kwargs):
+ """Format function arguments and keyword arguments.
+
+ Special case for a single parameter: ('hello',) is formatted as ('hello').
+ """
+ # use reprlib to limit the length of the output
+ items = []
+ if args:
+ items.extend(reprlib.repr(arg) for arg in args)
+ if kwargs:
+ items.extend(f'{k}={reprlib.repr(v)}' for k, v in kwargs.items())
+ return '({})'.format(', '.join(items))
+
+
+def _format_callback(func, args, kwargs, suffix=''):
+ if isinstance(func, functools.partial):
+ suffix = _format_args_and_kwargs(args, kwargs) + suffix
+ return _format_callback(func.func, func.args, func.keywords, suffix)
+
+ if hasattr(func, '__qualname__'):
+ func_repr = getattr(func, '__qualname__')
+ elif hasattr(func, '__name__'):
+ func_repr = getattr(func, '__name__')
+ else:
+ func_repr = repr(func)
+
+ func_repr += _format_args_and_kwargs(args, kwargs)
+ if suffix:
+ func_repr += suffix
+ return func_repr
+
+
+def extract_stack(f=None, limit=None):
+ """Replacement for traceback.extract_stack() that only does the
+ necessary work for asyncio debug mode.
+ """
+ if f is None:
+ f = sys._getframe().f_back
+ if limit is None:
+ # Limit the amount of work to a reasonable amount, as extract_stack()
+ # can be called for each coroutine and future in debug mode.
+ limit = constants.DEBUG_STACK_DEPTH
+ stack = traceback.StackSummary.extract(traceback.walk_stack(f),
+ limit=limit,
+ lookup_lines=False)
+ stack.reverse()
+ return stack
diff --git a/Lib/asyncio/futures.py b/Lib/asyncio/futures.py
index d46a295197b..b310962f9fe 100644
--- a/Lib/asyncio/futures.py
+++ b/Lib/asyncio/futures.py
@@ -11,6 +11,7 @@
from . import base_futures
from . import events
+from . import format_helpers
CancelledError = base_futures.CancelledError
@@ -79,7 +80,8 @@ def __init__(self, *, loop=None):
self._loop = loop
self._callbacks = []
if self._loop.get_debug():
- self._source_traceback = events.extract_stack(sys._getframe(1))
+ self._source_traceback = format_helpers.extract_stack(
+ sys._getframe(1))
_repr_info = base_futures._future_repr_info
diff --git a/Lib/asyncio/tasks.py b/Lib/asyncio/tasks.py
index c5122f76071..172057e5a29 100644
--- a/Lib/asyncio/tasks.py
+++ b/Lib/asyncio/tasks.py
@@ -1,7 +1,7 @@
"""Support for tasks, coroutines and the scheduler."""
__all__ = (
- 'Task',
+ 'Task', 'create_task',
'FIRST_COMPLETED', 'FIRST_EXCEPTION', 'ALL_COMPLETED',
'wait', 'wait_for', 'as_completed', 'sleep',
'gather', 'shield', 'ensure_future', 'run_coroutine_threadsafe',
@@ -67,13 +67,19 @@ def all_tasks(cls, loop=None):
return {t for t in cls._all_tasks if t._loop is loop}
def __init__(self, coro, *, loop=None):
- assert coroutines.iscoroutine(coro), repr(coro)
super().__init__(loop=loop)
if self._source_traceback:
del self._source_traceback[-1]
- self._coro = coro
- self._fut_waiter = None
+ if not coroutines.iscoroutine(coro):
+ # raise after Future.__init__(), attrs are required for __del__
+ # prevent logging for pending task in __del__
+ self._log_destroy_pending = False
+ raise TypeError(f"a coroutine was expected, got {coro!r}")
+
self._must_cancel = False
+ self._fut_waiter = None
+ self._coro = coro
+
self._loop.call_soon(self._step)
self.__class__._all_tasks.add(self)
@@ -263,6 +269,15 @@ def _wakeup(self, future):
Task = _CTask = _asyncio.Task
+def create_task(coro):
+ """Schedule the execution of a coroutine object in a spawn task.
+
+ Return a Task object.
+ """
+ loop = events.get_running_loop()
+ return loop.create_task(coro)
+
+
# wait() and as_completed() similar to those in PEP 3148.
FIRST_COMPLETED = concurrent.futures.FIRST_COMPLETED
diff --git a/Lib/test/test_asyncio/test_tasks.py b/Lib/test/test_asyncio/test_tasks.py
index a5563ba9c6c..a32dca13118 100644
--- a/Lib/test/test_asyncio/test_tasks.py
+++ b/Lib/test/test_asyncio/test_tasks.py
@@ -2054,6 +2054,43 @@ def coro():
self.assertEqual(self.Task.all_tasks(self.loop), set())
+ def test_create_task_with_noncoroutine(self):
+ with self.assertRaisesRegex(TypeError,
+ "a coroutine was expected, got 123"):
+ self.new_task(self.loop, 123)
+
+ def test_create_task_with_oldstyle_coroutine(self):
+
+ @asyncio.coroutine
+ def coro():
+ pass
+
+ task = self.new_task(self.loop, coro())
+ self.assertIsInstance(task, self.Task)
+ self.loop.run_until_complete(task)
+
+ def test_create_task_with_async_function(self):
+
+ async def coro():
+ pass
+
+ task = self.new_task(self.loop, coro())
+ self.assertIsInstance(task, self.Task)
+ self.loop.run_until_complete(task)
+
+ def test_bare_create_task(self):
+
+ async def inner():
+ return 1
+
+ async def coro():
+ task = asyncio.create_task(inner())
+ self.assertIsInstance(task, self.Task)
+ ret = await task
+ self.assertEqual(1, ret)
+
+ self.loop.run_until_complete(coro())
+
def add_subclass_tests(cls):
BaseTask = cls.Task
diff --git a/Lib/test/test_asyncio/utils.py b/Lib/test/test_asyncio/utils.py
index 560db9f562d..a1a9bb3684c 100644
--- a/Lib/test/test_asyncio/utils.py
+++ b/Lib/test/test_asyncio/utils.py
@@ -28,6 +28,7 @@
from asyncio import base_events
from asyncio import events
+from asyncio import format_helpers
from asyncio import futures
from asyncio import tasks
from asyncio.log import logger
@@ -429,7 +430,7 @@ def __eq__(self, other):
def get_function_source(func):
- source = events._get_function_source(func)
+ source = format_helpers._get_function_source(func)
if source is None:
raise ValueError("unable to get the source of %r" % (func,))
return source
diff --git a/Misc/NEWS.d/next/Library/2017-12-14-17-28-54.bpo-32311.DL5Ytn.rst b/Misc/NEWS.d/next/Library/2017-12-14-17-28-54.bpo-32311.DL5Ytn.rst
new file mode 100644
index 00000000000..e2d10959476
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2017-12-14-17-28-54.bpo-32311.DL5Ytn.rst
@@ -0,0 +1 @@
+Implement asyncio.create_task(coro) shortcut
diff --git a/Modules/_asynciomodule.c b/Modules/_asynciomodule.c
index 01c38b80b95..9ac1c44d48d 100644
--- a/Modules/_asynciomodule.c
+++ b/Modules/_asynciomodule.c
@@ -26,6 +26,7 @@ static PyObject *all_tasks;
static PyObject *current_tasks;
static PyObject *traceback_extract_stack;
static PyObject *asyncio_get_event_loop_policy;
+static PyObject *asyncio_iscoroutine_func;
static PyObject *asyncio_future_repr_info_func;
static PyObject *asyncio_task_repr_info_func;
static PyObject *asyncio_task_get_stack_func;
@@ -1461,16 +1462,38 @@ _asyncio_Task___init___impl(TaskObj *self, PyObject *coro, PyObject *loop)
/*[clinic end generated code: output=9f24774c2287fc2f input=8d132974b049593e]*/
{
PyObject *res;
+ int tmp;
_Py_IDENTIFIER(add);
if (future_init((FutureObj*)self, loop)) {
return -1;
}
+ if (!PyCoro_CheckExact(coro)) {
+ // fastpath failed, perfom slow check
+ // raise after Future.__init__(), attrs are required for __del__
+ res = PyObject_CallFunctionObjArgs(asyncio_iscoroutine_func,
+ coro, NULL);
+ if (res == NULL) {
+ return -1;
+ }
+ tmp = PyObject_Not(res);
+ Py_DECREF(res);
+ if (tmp < 0) {
+ return -1;
+ }
+ if (tmp) {
+ self->task_log_destroy_pending = 0;
+ PyErr_Format(PyExc_TypeError,
+ "a coroutine was expected, got %R",
+ coro, NULL);
+ return -1;
+ }
+ }
+
self->task_fut_waiter = NULL;
self->task_must_cancel = 0;
self->task_log_destroy_pending = 1;
-
Py_INCREF(coro);
self->task_coro = coro;
@@ -2604,6 +2627,7 @@ module_free(void *m)
Py_CLEAR(traceback_extract_stack);
Py_CLEAR(asyncio_get_event_loop_policy);
Py_CLEAR(asyncio_future_repr_info_func);
+ Py_CLEAR(asyncio_iscoroutine_func);
Py_CLEAR(asyncio_task_repr_info_func);
Py_CLEAR(asyncio_task_get_stack_func);
Py_CLEAR(asyncio_task_print_stack_func);
@@ -2645,6 +2669,9 @@ module_init(void)
GET_MOD_ATTR(asyncio_task_get_stack_func, "_task_get_stack")
GET_MOD_ATTR(asyncio_task_print_stack_func, "_task_print_stack")
+ WITH_MOD("asyncio.coroutines")
+ GET_MOD_ATTR(asyncio_iscoroutine_func, "iscoroutine")
+
WITH_MOD("inspect")
GET_MOD_ATTR(inspect_isgenerator, "isgenerator")
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