Python asyncio.coroutines() Examples

def _run_coroutine_threadsafe(coro, loop):
        """
        Patch to create task in the same thread instead of in the callback. This ensures that contextvars get copied.
        Python 3.7 copies contextvars without this.
        """
        if not asyncio.coroutines.iscoroutine(coro):
            raise TypeError('A coroutine object is required')
        future = concurrent.futures.Future()  # type: concurrent.futures.Future

        # This is the only change to this function: Creating the task here, in the caller thread, instead of within
        # `callback`, which is executed in the loop's thread. This does not run the task; it just _creates_ it.
        task = asyncio.ensure_future(coro, loop=loop)

        def callback():
            try:
                # noinspection PyProtectedMember,PyUnresolvedReferences
                asyncio.futures._chain_future(task, future)  # type: ignore
            except Exception as exc:
                if future.set_running_or_notify_cancel():
                    future.set_exception(exc)
                raise

        loop.call_soon_threadsafe(callback)
        return future 

def test_yield_from_corowrapper_send(self):
        def foo():
            a = yield
            return a

        def call(arg):
            cw = asyncio.coroutines.CoroWrapper(foo())
            cw.send(None)
            try:
                cw.send(arg)
            except StopIteration as ex:
                return ex.args[0]
            else:
                raise AssertionError('StopIteration was expected')

        self.assertEqual(call((1, 2)), (1, 2))
        self.assertEqual(call('spam'), 'spam') 

def test_yield_from_corowrapper_send(self):
        def foo():
            a = yield
            return a

        def call(arg):
            cw = asyncio.coroutines.CoroWrapper(foo())
            cw.send(None)
            try:
                cw.send(arg)
            except StopIteration as ex:
                return ex.args[0]
            else:
                raise AssertionError('StopIteration was expected')

        self.assertEqual(call((1, 2)), (1, 2))
        self.assertEqual(call('spam'), 'spam') 

def test_yield_from_corowrapper_send(self):
        def foo():
            a = yield
            return a

        def call(arg):
            cw = asyncio.coroutines.CoroWrapper(foo())
            cw.send(None)
            try:
                cw.send(arg)
            except StopIteration as ex:
                return ex.args[0]
            else:
                raise AssertionError('StopIteration was expected')

        self.assertEqual(call((1, 2)), (1, 2))
        self.assertEqual(call('spam'), 'spam') 

def _run_coroutine_threadsafe(coro, loop):
    """
    Patch to create task in the same thread instead of in the callback.
    This ensures that contextvars get copied. Python 3.7 copies contextvars
    without this.
    """
    if not asyncio.coroutines.iscoroutine(coro):
        raise TypeError("A coroutine object is required")
    future = concurrent.futures.Future()
    task = asyncio.ensure_future(coro, loop=loop)

    def callback() -> None:
        try:
            # noinspection PyProtectedMember,PyUnresolvedReferences
            # pylint:disable=protected-access
            asyncio.futures._chain_future(task, future)
        except Exception as exc:
            if future.set_running_or_notify_cancel():
                future.set_exception(exc)
            raise

    loop.call_soon_threadsafe(callback)
    return future 

def test_corowrapper_weakref(self):
        wd = weakref.WeakValueDictionary()
        def foo(): yield from []
        cw = asyncio.coroutines.CoroWrapper(foo())
        wd['cw'] = cw  # Would fail without __weakref__ slot.
        cw.gen = None  # Suppress warning from __del__. 

def test_env_var_debug(self):
        aio_path = os.path.dirname(os.path.dirname(asyncio.__file__))

        code = '\n'.join((
            'import asyncio.coroutines',
            'print(asyncio.coroutines._DEBUG)'))

        # Test with -E to not fail if the unit test was run with
        # PYTHONASYNCIODEBUG set to a non-empty string
        sts, stdout, stderr = assert_python_ok('-E', '-c', code,
                                               PYTHONPATH=aio_path)
        self.assertEqual(stdout.rstrip(), b'False')

        sts, stdout, stderr = assert_python_ok('-c', code,
                                               PYTHONASYNCIODEBUG='',
                                               PYTHONPATH=aio_path)
        self.assertEqual(stdout.rstrip(), b'False')

        sts, stdout, stderr = assert_python_ok('-c', code,
                                               PYTHONASYNCIODEBUG='1',
                                               PYTHONPATH=aio_path)
        self.assertEqual(stdout.rstrip(), b'True')

        sts, stdout, stderr = assert_python_ok('-E', '-c', code,
                                               PYTHONASYNCIODEBUG='1',
                                               PYTHONPATH=aio_path)
        self.assertEqual(stdout.rstrip(), b'False') 

def test_corowrapper_weakref(self):
        wd = weakref.WeakValueDictionary()
        def foo(): yield from []
        cw = asyncio.coroutines.CoroWrapper(foo())
        wd['cw'] = cw  # Would fail without __weakref__ slot.
        cw.gen = None  # Suppress warning from __del__. 

def test_current_task_with_interleaving_tasks(self):
        self.assertIsNone(asyncio.Task.current_task(loop=self.loop))

        fut1 = asyncio.Future(loop=self.loop)
        fut2 = asyncio.Future(loop=self.loop)

        @asyncio.coroutine
        def coro1(loop):
            self.assertTrue(asyncio.Task.current_task(loop=loop) is task1)
            yield from fut1
            self.assertTrue(asyncio.Task.current_task(loop=loop) is task1)
            fut2.set_result(True)

        @asyncio.coroutine
        def coro2(loop):
            self.assertTrue(asyncio.Task.current_task(loop=loop) is task2)
            fut1.set_result(True)
            yield from fut2
            self.assertTrue(asyncio.Task.current_task(loop=loop) is task2)

        task1 = asyncio.Task(coro1(self.loop), loop=self.loop)
        task2 = asyncio.Task(coro2(self.loop), loop=self.loop)

        self.loop.run_until_complete(asyncio.wait((task1, task2),
                                                  loop=self.loop))
        self.assertIsNone(asyncio.Task.current_task(loop=self.loop))

    # Some thorough tests for cancellation propagation through
    # coroutines, tasks and wait(). 

def set_coroutine_debug(enabled):
    coroutines = asyncio.coroutines

    old_debug = coroutines._DEBUG
    try:
        coroutines._DEBUG = enabled
        yield
    finally:
        coroutines._DEBUG = old_debug 

def _set_is_coroutine(self, value):
    # property setters and getters are overridden by Mock(), we need to
    # update the dict to add values
    value = _is_coroutine if bool(value) else False
    self.__dict__['_mock_is_coroutine'] = value


# _mock_add_spec() is the actual private implementation in unittest.mock, we
# override it to support coroutines in the metaclass. 

def run(self, *coros: CoroWrapper):
        """
        Runs an arbitrary list of coroutines in order and then quits the loop,
        if not running as a context manager.
        """
        if not self.running:
            raise RuntimeError("not running!")

        async def wrapper():
            results = []
            for coro in coros:
                try:
                    if inspect.isawaitable(coro):
                        results.append(await coro)
                    elif inspect.isfunction(coro):
                        res = coro()
                        if inspect.isawaitable(res):
                            results.append(await res)
                        else:
                            results.append(res)
                    else:
                        raise RuntimeError(
                            "don't know how to run {}".format(coro))
                except Exception as ex:
                    logger.error("Error while running coroutine {}: {}".format(coro.__name__, ex.__repr__()))
                    raise ex
            if len(results) == 1:
                return results[0]
            return results
        if coros:
            what = wrapper()
        else:
            # if no coros supplied, then assume we run forever
            what = self.runFut
        return self.loop.run_until_complete(what) 

def test_current_task_with_interleaving_tasks(self):
        self.assertIsNone(asyncio.Task.current_task(loop=self.loop))

        fut1 = asyncio.Future(loop=self.loop)
        fut2 = asyncio.Future(loop=self.loop)

        @asyncio.coroutine
        def coro1(loop):
            self.assertTrue(asyncio.Task.current_task(loop=loop) is task1)
            yield from fut1
            self.assertTrue(asyncio.Task.current_task(loop=loop) is task1)
            fut2.set_result(True)

        @asyncio.coroutine
        def coro2(loop):
            self.assertTrue(asyncio.Task.current_task(loop=loop) is task2)
            fut1.set_result(True)
            yield from fut2
            self.assertTrue(asyncio.Task.current_task(loop=loop) is task2)

        task1 = asyncio.Task(coro1(self.loop), loop=self.loop)
        task2 = asyncio.Task(coro2(self.loop), loop=self.loop)

        self.loop.run_until_complete(asyncio.wait((task1, task2),
                                                  loop=self.loop))
        self.assertIsNone(asyncio.Task.current_task(loop=self.loop))

    # Some thorough tests for cancellation propagation through
    # coroutines, tasks and wait(). 

def set_coroutine_debug(enabled):
    coroutines = asyncio.coroutines

    old_debug = coroutines._DEBUG
    try:
        coroutines._DEBUG = enabled
        yield
    finally:
        coroutines._DEBUG = old_debug 

def test_corowrapper_weakref(self):
        wd = weakref.WeakValueDictionary()
        def foo(): yield from []
        cw = asyncio.coroutines.CoroWrapper(foo())
        wd['cw'] = cw  # Would fail without __weakref__ slot.
        cw.gen = None  # Suppress warning from __del__. 

def test_current_task_with_interleaving_tasks(self):
        self.assertIsNone(asyncio.Task.current_task(loop=self.loop))

        fut1 = asyncio.Future(loop=self.loop)
        fut2 = asyncio.Future(loop=self.loop)

        @asyncio.coroutine
        def coro1(loop):
            self.assertTrue(asyncio.Task.current_task(loop=loop) is task1)
            yield from fut1
            self.assertTrue(asyncio.Task.current_task(loop=loop) is task1)
            fut2.set_result(True)

        @asyncio.coroutine
        def coro2(loop):
            self.assertTrue(asyncio.Task.current_task(loop=loop) is task2)
            fut1.set_result(True)
            yield from fut2
            self.assertTrue(asyncio.Task.current_task(loop=loop) is task2)

        task1 = asyncio.Task(coro1(self.loop), loop=self.loop)
        task2 = asyncio.Task(coro2(self.loop), loop=self.loop)

        self.loop.run_until_complete(asyncio.wait((task1, task2),
                                                  loop=self.loop))
        self.assertIsNone(asyncio.Task.current_task(loop=self.loop))

    # Some thorough tests for cancellation propagation through
    # coroutines, tasks and wait(). 

def set_coroutine_debug(enabled):
    coroutines = asyncio.coroutines

    old_debug = coroutines._DEBUG
    try:
        coroutines._DEBUG = enabled
        yield
    finally:
        coroutines._DEBUG = old_debug 

def test_task_repr(self):
        self.loop.set_debug(False)

        @asyncio.coroutine
        def notmuch():
            yield from []
            return 'abc'

        # test coroutine function
        self.assertEqual(notmuch.__name__, 'notmuch')
        if PY35:
            self.assertEqual(notmuch.__qualname__,
                             'TaskTests.test_task_repr.<locals>.notmuch')
        self.assertEqual(notmuch.__module__, __name__)

        filename, lineno = test_utils.get_function_source(notmuch)
        src = "%s:%s" % (filename, lineno)

        # test coroutine object
        gen = notmuch()
        if coroutines._DEBUG or PY35:
            coro_qualname = 'TaskTests.test_task_repr.<locals>.notmuch'
        else:
            coro_qualname = 'notmuch'
        self.assertEqual(gen.__name__, 'notmuch')
        if PY35:
            self.assertEqual(gen.__qualname__,
                             coro_qualname)

        # test pending Task
        t = asyncio.Task(gen, loop=self.loop)
        t.add_done_callback(Dummy())

        coro = format_coroutine(coro_qualname, 'running', src,
                                t._source_traceback, generator=True)
        self.assertEqual(repr(t),
                         '<Task pending %s cb=[<Dummy>()]>' % coro)

        # test cancelling Task
        t.cancel()  # Does not take immediate effect!
        self.assertEqual(repr(t),
                         '<Task cancelling %s cb=[<Dummy>()]>' % coro)

        # test cancelled Task
        self.assertRaises(asyncio.CancelledError,
                          self.loop.run_until_complete, t)
        coro = format_coroutine(coro_qualname, 'done', src,
                                t._source_traceback)
        self.assertEqual(repr(t),
                         '<Task cancelled %s>' % coro)

        # test finished Task
        t = asyncio.Task(notmuch(), loop=self.loop)
        self.loop.run_until_complete(t)
        coro = format_coroutine(coro_qualname, 'done', src,
                                t._source_traceback)
        self.assertEqual(repr(t),
                         "<Task finished %s result='abc'>" % coro) 

def test_task_repr(self):
        self.loop.set_debug(False)

        @asyncio.coroutine
        def notmuch():
            yield from []
            return 'abc'

        # test coroutine function
        self.assertEqual(notmuch.__name__, 'notmuch')
        if PY35:
            self.assertEqual(notmuch.__qualname__,
                             'TaskTests.test_task_repr.<locals>.notmuch')
        self.assertEqual(notmuch.__module__, __name__)

        filename, lineno = test_utils.get_function_source(notmuch)
        src = "%s:%s" % (filename, lineno)

        # test coroutine object
        gen = notmuch()
        if coroutines._DEBUG or PY35:
            coro_qualname = 'TaskTests.test_task_repr.<locals>.notmuch'
        else:
            coro_qualname = 'notmuch'
        self.assertEqual(gen.__name__, 'notmuch')
        if PY35:
            self.assertEqual(gen.__qualname__,
                             coro_qualname)

        # test pending Task
        t = asyncio.Task(gen, loop=self.loop)
        t.add_done_callback(Dummy())

        coro = format_coroutine(coro_qualname, 'running', src,
                                t._source_traceback, generator=True)
        self.assertEqual(repr(t),
                         '<Task pending %s cb=[<Dummy>()]>' % coro)

        # test cancelling Task
        t.cancel()  # Does not take immediate effect!
        self.assertEqual(repr(t),
                         '<Task cancelling %s cb=[<Dummy>()]>' % coro)

        # test cancelled Task
        self.assertRaises(asyncio.CancelledError,
                          self.loop.run_until_complete, t)
        coro = format_coroutine(coro_qualname, 'done', src,
                                t._source_traceback)
        self.assertEqual(repr(t),
                         '<Task cancelled %s>' % coro)

        # test finished Task
        t = asyncio.Task(notmuch(), loop=self.loop)
        self.loop.run_until_complete(t)
        coro = format_coroutine(coro_qualname, 'done', src,
                                t._source_traceback)
        self.assertEqual(repr(t),
                         "<Task finished %s result='abc'>" % coro) 

def test_task_repr(self):
        self.loop.set_debug(False)

        @asyncio.coroutine
        def notmuch():
            yield from []
            return 'abc'

        # test coroutine function
        self.assertEqual(notmuch.__name__, 'notmuch')
        if PY35:
            self.assertEqual(notmuch.__qualname__,
                             'TaskTests.test_task_repr.<locals>.notmuch')
        self.assertEqual(notmuch.__module__, __name__)

        filename, lineno = test_utils.get_function_source(notmuch)
        src = "%s:%s" % (filename, lineno)

        # test coroutine object
        gen = notmuch()
        if coroutines._DEBUG or PY35:
            coro_qualname = 'TaskTests.test_task_repr.<locals>.notmuch'
        else:
            coro_qualname = 'notmuch'
        self.assertEqual(gen.__name__, 'notmuch')
        if PY35:
            self.assertEqual(gen.__qualname__,
                             coro_qualname)

        # test pending Task
        t = asyncio.Task(gen, loop=self.loop)
        t.add_done_callback(Dummy())

        coro = format_coroutine(coro_qualname, 'running', src,
                                t._source_traceback, generator=True)
        self.assertEqual(repr(t),
                         '<Task pending %s cb=[<Dummy>()]>' % coro)

        # test cancelling Task
        t.cancel()  # Does not take immediate effect!
        self.assertEqual(repr(t),
                         '<Task cancelling %s cb=[<Dummy>()]>' % coro)

        # test cancelled Task
        self.assertRaises(asyncio.CancelledError,
                          self.loop.run_until_complete, t)
        coro = format_coroutine(coro_qualname, 'done', src,
                                t._source_traceback)
        self.assertEqual(repr(t),
                         '<Task cancelled %s>' % coro)

        # test finished Task
        t = asyncio.Task(notmuch(), loop=self.loop)
        self.loop.run_until_complete(t)
        coro = format_coroutine(coro_qualname, 'done', src,
                                t._source_traceback)
        self.assertEqual(repr(t),
                         "<Task finished %s result='abc'>" % coro)