generated from daniil-berg/boilerplate-py
improved exception handling/logging in `apply` meta task
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80fc91ec47
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0daed04167
GPG Key ID:
BE187C50903BEE97
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@ -23,7 +23,7 @@ This module should **not** be considered part of the public API.
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from asyncio.streams import StreamReader, StreamWriter
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from pathlib import Path
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from typing import Any, Awaitable, Callable, Iterable, Mapping, Tuple, TypeVar, Union
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from typing import Any, Awaitable, Callable, Coroutine, Iterable, Mapping, Tuple, TypeVar, Union
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T = TypeVar('T')
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@ -32,7 +32,7 @@ ArgsT = Iterable[Any]
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KwArgsT = Mapping[str, Any]
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AnyCallableT = Callable[[...], Union[T, Awaitable[T]]]
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CoroutineFunc = Callable[[...], Awaitable[Any]]
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CoroutineFunc = Callable[[...], Coroutine]
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EndCB = Callable
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CancelCB = Callable
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@ -528,6 +528,8 @@ class BaseTaskPool:
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self._tasks_cancelled.clear()
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self._tasks_running.clear()
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self._closed = True
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# TODO: Turn the `_closed` attribute into an `Event` and add something like a `until_closed` method that will
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# await it to allow blocking until a closing command comes from a server.
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class TaskPool(BaseTaskPool):
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@ -566,36 +568,51 @@ class TaskPool(BaseTaskPool):
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return name
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i += 1
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async def _apply_num(self, group_name: str, func: CoroutineFunc, args: ArgsT = (), kwargs: KwArgsT = None,
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num: int = 1, end_callback: EndCB = None, cancel_callback: CancelCB = None) -> None:
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async def _apply_spawner(self, group_name: str, func: CoroutineFunc, args: ArgsT = (), kwargs: KwArgsT = None,
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num: int = 1, end_callback: EndCB = None, cancel_callback: CancelCB = None) -> None:
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"""
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Creates a coroutine with the supplied arguments and runs it as a new task in the pool.
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Creates coroutines with the supplied arguments and runs them as new tasks in the pool.
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This method blocks, **only if** the pool has not enough room to accommodate `num` new tasks.
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Args:
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group_name:
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Name of the task group to add the new task to.
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Name of the task group to add the new tasks to.
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func:
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The coroutine function to be run as a task within the task pool.
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The coroutine function to be run in `num` tasks within the task pool.
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args (optional):
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The positional arguments to pass into the function call.
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The positional arguments to pass into each function call.
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kwargs (optional):
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The keyword-arguments to pass into the function call.
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The keyword-arguments to pass into each function call.
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num (optional):
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The number of tasks to spawn with the specified parameters.
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end_callback (optional):
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A callback to execute after the task has ended.
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A callback to execute after each task has ended.
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It is run with the task's ID as its only positional argument.
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cancel_callback (optional):
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A callback to execute after cancellation of the task.
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A callback to execute after cancellation of each task.
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It is run with the task's ID as its only positional argument.
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"""
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if kwargs is None:
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kwargs = {}
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# TODO: Add exception logging
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await gather(*(self._start_task(func(*args, **kwargs), group_name=group_name, end_callback=end_callback,
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cancel_callback=cancel_callback) for _ in range(num)))
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for i in range(num):
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try:
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coroutine = func(*args, **kwargs)
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except Exception as e:
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# This means there was probably something wrong with the function arguments.
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log.exception("%s occurred in group '%s' while trying to create coroutine: %s(*%s, **%s)",
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str(e.__class__.__name__), group_name, func.__name__, repr(args), repr(kwargs))
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continue
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try:
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await self._start_task(coroutine, group_name=group_name, end_callback=end_callback,
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cancel_callback=cancel_callback)
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except CancelledError:
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# Either the task group or all tasks were cancelled, so this meta tasks is not supposed to spawn any
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# more tasks and can return immediately.
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log.debug("Cancelled spawning tasks in group '%s' after %s out of %s tasks have been spawned",
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group_name, i, num)
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coroutine.close()
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return
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def apply(self, func: CoroutineFunc, args: ArgsT = (), kwargs: KwArgsT = None, num: int = 1, group_name: str = None,
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end_callback: EndCB = None, cancel_callback: CancelCB = None) -> str:
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@ -650,8 +667,8 @@ class TaskPool(BaseTaskPool):
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raise exceptions.InvalidGroupName(f"Group named {group_name} already exists!")
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self._task_groups.setdefault(group_name, TaskGroupRegister())
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meta_tasks = self._group_meta_tasks_running.setdefault(group_name, set())
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meta_tasks.add(create_task(self._apply_num(group_name, func, args, kwargs, num,
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end_callback=end_callback, cancel_callback=cancel_callback)))
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meta_tasks.add(create_task(self._apply_spawner(group_name, func, args, kwargs, num,
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end_callback=end_callback, cancel_callback=cancel_callback)))
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return group_name
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@staticmethod
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@ -696,6 +713,8 @@ class TaskPool(BaseTaskPool):
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# When the number of running tasks spawned by this method reaches the specified maximum,
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# this next line will block, until one of them ends and releases the semaphore.
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await map_semaphore.acquire()
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# TODO: Clean up exception handling/logging. Cancellation can also occur while awaiting the semaphore.
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# Wrap `star_function` call in a separate `try` block (similar to `_apply_spawner`).
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try:
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await self._start_task(star_function(func, next_arg, arg_stars=arg_stars), group_name=group_name,
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ignore_lock=True, end_callback=release_cb, cancel_callback=cancel_callback)
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@ -455,49 +455,65 @@ class TaskPoolTestCase(CommonTestCase):
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self.assertEqual(expected_output, output)
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@patch.object(pool.TaskPool, '_start_task')
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async def test__apply_num(self, mock__start_task: AsyncMock):
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group_name = FOO + BAR
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mock_awaitable = object()
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mock_func = MagicMock(return_value=mock_awaitable)
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args, kwargs, num = (FOO, BAR), {'a': 1, 'b': 2}, 3
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async def test__apply_spawner(self, mock__start_task: AsyncMock):
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grp_name = FOO + BAR
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mock_awaitable1, mock_awaitable2 = object(), object()
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mock_func = MagicMock(side_effect=[mock_awaitable1, Exception(), mock_awaitable2], __name__='func')
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args, kw, num = (FOO, BAR), {'a': 1, 'b': 2}, 3
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end_cb, cancel_cb = MagicMock(), MagicMock()
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self.assertIsNone(await self.task_pool._apply_num(group_name, mock_func, args, kwargs, num, end_cb, cancel_cb))
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mock_func.assert_has_calls(3 * [call(*args, **kwargs)])
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mock__start_task.assert_has_awaits(3 * [
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call(mock_awaitable, group_name=group_name, end_callback=end_cb, cancel_callback=cancel_cb)
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self.assertIsNone(await self.task_pool._apply_spawner(grp_name, mock_func, args, kw, num, end_cb, cancel_cb))
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mock_func.assert_has_calls(num * [call(*args, **kw)])
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mock__start_task.assert_has_awaits([
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call(mock_awaitable1, group_name=grp_name, end_callback=end_cb, cancel_callback=cancel_cb),
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call(mock_awaitable2, group_name=grp_name, end_callback=end_cb, cancel_callback=cancel_cb),
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])
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mock_func.reset_mock()
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mock_func.reset_mock(side_effect=True)
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mock__start_task.reset_mock()
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self.assertIsNone(await self.task_pool._apply_num(group_name, mock_func, args, None, num, end_cb, cancel_cb))
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mock_func.assert_has_calls(num * [call(*args)])
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mock__start_task.assert_has_awaits(num * [
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call(mock_awaitable, group_name=group_name, end_callback=end_cb, cancel_callback=cancel_cb)
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# Simulate cancellation while the second task is being started.
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mock__start_task.side_effect = [None, CancelledError, None]
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mock_coroutine_to_close = MagicMock()
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mock_func.side_effect = [mock_awaitable1, mock_coroutine_to_close, 'never called']
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self.assertIsNone(await self.task_pool._apply_spawner(grp_name, mock_func, args, None, num, end_cb, cancel_cb))
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mock_func.assert_has_calls(2 * [call(*args)])
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mock__start_task.assert_has_awaits([
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call(mock_awaitable1, group_name=grp_name, end_callback=end_cb, cancel_callback=cancel_cb),
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call(mock_coroutine_to_close, group_name=grp_name, end_callback=end_cb, cancel_callback=cancel_cb),
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])
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mock_coroutine_to_close.close.assert_called_once_with()
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@patch.object(pool, 'create_task')
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@patch.object(pool.TaskPool, '_apply_num', new_callable=MagicMock())
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@patch.object(pool.TaskPool, '_apply_spawner', new_callable=MagicMock())
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@patch.object(pool, 'TaskGroupRegister')
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@patch.object(pool.TaskPool, '_generate_group_name')
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@patch.object(pool.BaseTaskPool, '_check_start')
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def test_apply(self, mock__check_start: MagicMock, mock__generate_group_name: MagicMock,
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mock_reg_cls: MagicMock, mock__apply_num: MagicMock, mock_create_task: MagicMock):
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mock_reg_cls: MagicMock, mock__apply_spawner: MagicMock, mock_create_task: MagicMock):
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mock__generate_group_name.return_value = generated_name = 'name 123'
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mock_group_reg = set_up_mock_group_register(mock_reg_cls)
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mock__apply_num.return_value = mock_apply_coroutine = object()
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mock__apply_spawner.return_value = mock_apply_coroutine = object()
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mock_create_task.return_value = fake_task = object()
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mock_func, num, group_name = MagicMock(), 3, FOO + BAR
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args, kwargs = (FOO, BAR), {'a': 1, 'b': 2}
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end_cb, cancel_cb = MagicMock(), MagicMock()
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self.task_pool._task_groups = {group_name: 'causes error'}
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with self.assertRaises(exceptions.InvalidGroupName):
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self.task_pool.apply(mock_func, args, kwargs, num, group_name, end_cb, cancel_cb)
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mock__check_start.assert_called_once_with(function=mock_func)
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mock__apply_spawner.assert_not_called()
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mock_create_task.assert_not_called()
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mock__check_start.reset_mock()
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self.task_pool._task_groups = {}
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def check_assertions(_group_name, _output):
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self.assertEqual(_group_name, _output)
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mock__check_start.assert_called_once_with(function=mock_func)
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self.assertEqual(mock_group_reg, self.task_pool._task_groups[_group_name])
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mock__apply_num.assert_called_once_with(_group_name, mock_func, args, kwargs, num,
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end_callback=end_cb, cancel_callback=cancel_cb)
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mock__apply_spawner.assert_called_once_with(_group_name, mock_func, args, kwargs, num,
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end_callback=end_cb, cancel_callback=cancel_cb)
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mock_create_task.assert_called_once_with(mock_apply_coroutine)
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self.assertSetEqual({fake_task}, self.task_pool._group_meta_tasks_running[group_name])
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@ -507,7 +523,7 @@ class TaskPoolTestCase(CommonTestCase):
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mock__check_start.reset_mock()
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self.task_pool._task_groups.clear()
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mock__apply_num.reset_mock()
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mock__apply_spawner.reset_mock()
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mock_create_task.reset_mock()
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output = self.task_pool.apply(mock_func, args, kwargs, num, None, end_cb, cancel_cb)
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@ -695,6 +711,7 @@ class SimpleTaskPoolTestCase(CommonTestCase):
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def tearDown(self) -> None:
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self.base_class_init_patcher.stop()
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super().tearDown()
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def test_init(self):
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self.assertEqual(self.TEST_POOL_FUNC, self.task_pool._func)
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