asyncio: Remove asyncio.timeout() context manager.

It will probably be added back in Python 3.6, once its compatibility
issues are resolved; see [1] for more details.

[1] https://mail.python.org/pipermail/async-sig/2016-June/000045.html

Doc/library/asyncio-task.rst

@@ -662,22 +662,6 @@ Task functions
        except CancelledError:
            res = None
 
-.. function:: timeout(timeout, \*, loop=None)
-
-   Return a context manager that cancels a block on *timeout* expiring::
-
-       with timeout(1.5):
-           yield from inner()
-
-   1. If ``inner()`` is executed faster than in ``1.5`` seconds
-      nothing happens.
-   2. Otherwise ``inner()`` is cancelled internally but
-      :exc:`asyncio.TimeoutError` is raised outside of
-      context manager scope.
-
-   Passing ``None`` as *timeout* argument disables the manager logic.
-
-   .. versionadded:: 3.5.2
 
 .. coroutinefunction:: wait(futures, \*, loop=None, timeout=None,\
                             return_when=ALL_COMPLETED)

Doc/whatsnew/3.5.rst

@@ -835,10 +835,6 @@ Updates in 3.5.2:
   method to get the current exception handler.
   (Contributed by Yury Selivanov.)
 
-* New :func:`~asyncio.timeout` context manager to simplify timeouts
-  handling code.
-  (Contributed by Andrew Svetlov.)
-
 * New :meth:`StreamReader.readuntil() <asyncio.StreamReader.readuntil>`
   method to read data from the stream until a separator bytes
   sequence appears.

Lib/asyncio/tasks.py

@@ -4,7 +4,6 @@ __all__ = ['Task',
            'FIRST_COMPLETED', 'FIRST_EXCEPTION', 'ALL_COMPLETED',
            'wait', 'wait_for', 'as_completed', 'sleep', 'async',
            'gather', 'shield', 'ensure_future', 'run_coroutine_threadsafe',
-           'timeout',
            ]
 
 import concurrent.futures
@@ -737,55 +736,3 @@ def run_coroutine_threadsafe(coro, loop):
 
     loop.call_soon_threadsafe(callback)
     return future
-
-
-def timeout(timeout, *, loop=None):
-    """A factory which produce a context manager with timeout.
-
-    Useful in cases when you want to apply timeout logic around block
-    of code or in cases when asyncio.wait_for is not suitable.
-
-    For example:
-
-    >>> with asyncio.timeout(0.001):
-    ...     yield from coro()
-
-
-    timeout: timeout value in seconds or None to disable timeout logic
-    loop: asyncio compatible event loop
-    """
-    if loop is None:
-        loop = events.get_event_loop()
-    return _Timeout(timeout, loop=loop)
-
-
-class _Timeout:
-    def __init__(self, timeout, *, loop):
-        self._timeout = timeout
-        self._loop = loop
-        self._task = None
-        self._cancelled = False
-        self._cancel_handler = None
-
-    def __enter__(self):
-        self._task = Task.current_task(loop=self._loop)
-        if self._task is None:
-            raise RuntimeError('Timeout context manager should be used '
-                               'inside a task')
-        if self._timeout is not None:
-            self._cancel_handler = self._loop.call_later(
-                self._timeout, self._cancel_task)
-        return self
-
-    def __exit__(self, exc_type, exc_val, exc_tb):
-        if exc_type is futures.CancelledError and self._cancelled:
-            self._cancel_handler = None
-            self._task = None
-            raise futures.TimeoutError
-        if self._timeout is not None:
-            self._cancel_handler.cancel()
-            self._cancel_handler = None
-        self._task = None
-
-    def _cancel_task(self):
-        self._cancelled = self._task.cancel()

Lib/test/test_asyncio/test_tasks.py

@@ -2260,192 +2260,5 @@ class SleepTests(test_utils.TestCase):
         self.assertEqual(result, 11)
 
 
-class TimeoutTests(test_utils.TestCase):
-    def setUp(self):
-        self.loop = asyncio.new_event_loop()
-        asyncio.set_event_loop(None)
-
-    def tearDown(self):
-        self.loop.close()
-        self.loop = None
-
-    def test_timeout(self):
-        canceled_raised = [False]
-
-        @asyncio.coroutine
-        def long_running_task():
-            try:
-                yield from asyncio.sleep(10, loop=self.loop)
-            except asyncio.CancelledError:
-                canceled_raised[0] = True
-                raise
-
-        @asyncio.coroutine
-        def go():
-            with self.assertRaises(asyncio.TimeoutError):
-                with asyncio.timeout(0.01, loop=self.loop) as t:
-                    yield from long_running_task()
-                    self.assertIs(t._loop, self.loop)
-
-        self.loop.run_until_complete(go())
-        self.assertTrue(canceled_raised[0], 'CancelledError was not raised')
-
-    def test_timeout_finish_in_time(self):
-        @asyncio.coroutine
-        def long_running_task():
-            yield from asyncio.sleep(0.01, loop=self.loop)
-            return 'done'
-
-        @asyncio.coroutine
-        def go():
-            with asyncio.timeout(0.1, loop=self.loop):
-                resp = yield from long_running_task()
-            self.assertEqual(resp, 'done')
-
-        self.loop.run_until_complete(go())
-
-    def test_timeout_gloabal_loop(self):
-        asyncio.set_event_loop(self.loop)
-
-        @asyncio.coroutine
-        def run():
-            with asyncio.timeout(0.1) as t:
-                yield from asyncio.sleep(0.01)
-                self.assertIs(t._loop, self.loop)
-
-        self.loop.run_until_complete(run())
-
-    def test_timeout_not_relevant_exception(self):
-        @asyncio.coroutine
-        def go():
-            yield from asyncio.sleep(0, loop=self.loop)
-            with self.assertRaises(KeyError):
-                with asyncio.timeout(0.1, loop=self.loop):
-                    raise KeyError
-
-        self.loop.run_until_complete(go())
-
-    def test_timeout_canceled_error_is_converted_to_timeout(self):
-        @asyncio.coroutine
-        def go():
-            yield from asyncio.sleep(0, loop=self.loop)
-            with self.assertRaises(asyncio.CancelledError):
-                with asyncio.timeout(0.001, loop=self.loop):
-                    raise asyncio.CancelledError
-
-        self.loop.run_until_complete(go())
-
-    def test_timeout_blocking_loop(self):
-        @asyncio.coroutine
-        def long_running_task():
-            time.sleep(0.05)
-            return 'done'
-
-        @asyncio.coroutine
-        def go():
-            with asyncio.timeout(0.01, loop=self.loop):
-                result = yield from long_running_task()
-            self.assertEqual(result, 'done')
-
-        self.loop.run_until_complete(go())
-
-    def test_for_race_conditions(self):
-        fut = asyncio.Future(loop=self.loop)
-        self.loop.call_later(0.1, fut.set_result('done'))
-
-        @asyncio.coroutine
-        def go():
-            with asyncio.timeout(0.2, loop=self.loop):
-                resp = yield from fut
-            self.assertEqual(resp, 'done')
-
-        self.loop.run_until_complete(go())
-
-    def test_timeout_time(self):
-        @asyncio.coroutine
-        def go():
-            foo_running = None
-
-            start = self.loop.time()
-            with self.assertRaises(asyncio.TimeoutError):
-                with asyncio.timeout(0.1, loop=self.loop):
-                    foo_running = True
-                    try:
-                        yield from asyncio.sleep(0.2, loop=self.loop)
-                    finally:
-                        foo_running = False
-
-            dt = self.loop.time() - start
-            # tolerate a small delta for slow delta or unstable clocks
-            self.assertTrue(0.09 < dt < 0.12, dt)
-            self.assertFalse(foo_running)
-
-        self.loop.run_until_complete(go())
-
-    def test_timeout_disable(self):
-        @asyncio.coroutine
-        def long_running_task():
-            yield from asyncio.sleep(0.1, loop=self.loop)
-            return 'done'
-
-        @asyncio.coroutine
-        def go():
-            t0 = self.loop.time()
-            with asyncio.timeout(None, loop=self.loop):
-                resp = yield from long_running_task()
-            self.assertEqual(resp, 'done')
-            dt = self.loop.time() - t0
-            # tolerate a time delta for clocks with bad resolution
-            # and slow buildbots
-            self.assertTrue(0.09 < dt < 0.15, dt)
-        self.loop.run_until_complete(go())
-
-    def test_raise_runtimeerror_if_no_task(self):
-        with self.assertRaises(RuntimeError):
-            with asyncio.timeout(0.1, loop=self.loop):
-                pass
-
-    def test_outer_coro_is_not_cancelled(self):
-
-        has_timeout = [False]
-
-        @asyncio.coroutine
-        def outer():
-            try:
-                with asyncio.timeout(0.001, loop=self.loop):
-                    yield from asyncio.sleep(1, loop=self.loop)
-            except asyncio.TimeoutError:
-                has_timeout[0] = True
-
-        @asyncio.coroutine
-        def go():
-            task = asyncio.ensure_future(outer(), loop=self.loop)
-            yield from task
-            self.assertTrue(has_timeout[0])
-            self.assertFalse(task.cancelled())
-            self.assertTrue(task.done())
-
-        self.loop.run_until_complete(go())
-
-    def test_cancel_outer_coro(self):
-        fut = asyncio.Future(loop=self.loop)
-
-        @asyncio.coroutine
-        def outer():
-            fut.set_result(None)
-            yield from asyncio.sleep(1, loop=self.loop)
-
-        @asyncio.coroutine
-        def go():
-            task = asyncio.ensure_future(outer(), loop=self.loop)
-            yield from fut
-            task.cancel()
-            with self.assertRaises(asyncio.CancelledError):
-                yield from task
-            self.assertTrue(task.cancelled())
-            self.assertTrue(task.done())
-
-        self.loop.run_until_complete(go())
-
 if __name__ == '__main__':
     unittest.main()