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# Copyright (C) 2023 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
from . import events
from . import futures
import asyncio
import collections.abc
import concurrent.futures
import contextvars
import typing
class QAsyncioTask(futures.QAsyncioFuture):
""" https://docs.python.org/3/library/asyncio-task.html """
def __init__(self, coro: typing.Union[collections.abc.Generator, collections.abc.Coroutine], *,
loop: typing.Optional["events.QAsyncioEventLoop"] = None,
name: typing.Optional[str] = None,
context: typing.Optional[contextvars.Context] = None) -> None:
super().__init__(loop=loop, context=context)
self._coro = coro
self._name = name if name else "QtTask"
self._handle = self._loop.call_soon(self._step, context=self._context)
self._cancellation_requests = 0
self._future_to_await: typing.Optional[asyncio.Future] = None
self._cancel_message: typing.Optional[str] = None
self._cancelled = False
asyncio._register_task(self) # type: ignore[arg-type]
def __repr__(self) -> str:
if self._state == futures.QAsyncioFuture.FutureState.PENDING:
state = "Pending"
elif self._state == futures.QAsyncioFuture.FutureState.DONE_WITH_RESULT:
state = "Done"
elif self._state == futures.QAsyncioFuture.FutureState.DONE_WITH_EXCEPTION:
state = f"Done with exception ({repr(self._exception)})"
elif self._state == futures.QAsyncioFuture.FutureState.CANCELLED:
state = "Cancelled"
return f"Task '{self.get_name()}' with state: {state}"
class QtTaskApiMisuseError(Exception):
pass
def set_result(self, result: typing.Any) -> None: # type: ignore[override]
# This function is not inherited from the Future APIs.
raise QAsyncioTask.QtTaskApiMisuseError("Tasks cannot set results")
def set_exception(self, exception: typing.Any) -> None: # type: ignore[override]
# This function is not inherited from the Future APIs.
raise QAsyncioTask.QtTaskApiMisuseError("Tasks cannot set exceptions")
def _step(self,
exception_or_future: typing.Union[
BaseException, futures.QAsyncioFuture, None] = None) -> None:
if self.done():
return
result = None
self._future_to_await = None
if asyncio.futures.isfuture(exception_or_future):
try:
exception_or_future.result()
except BaseException as e:
exception_or_future = e
try:
asyncio._enter_task(self._loop, self) # type: ignore[arg-type]
if isinstance(exception_or_future, BaseException):
result = self._coro.throw(exception_or_future)
else:
result = self._coro.send(None)
except StopIteration as e:
self._state = futures.QAsyncioFuture.FutureState.DONE_WITH_RESULT
self._result = e.value
except (concurrent.futures.CancelledError, asyncio.exceptions.CancelledError) as e:
self._state = futures.QAsyncioFuture.FutureState.CANCELLED
self._exception = e
except BaseException as e:
self._state = futures.QAsyncioFuture.FutureState.DONE_WITH_EXCEPTION
self._exception = e
else:
if asyncio.futures.isfuture(result):
result.add_done_callback(
self._step, context=self._context) # type: ignore[arg-type]
self._future_to_await = result
if self._cancelled:
# If the task was cancelled, then a new future should be
# cancelled as well. Otherwise, in some scenarios like
# a loop inside the task and with bad timing, if the new
# future is not cancelled, the task would continue running
# in this loop despite having been cancelled. This bad
# timing can occur especially if the first future finishes
# very quickly.
self._future_to_await.cancel(self._cancel_message)
elif result is None:
self._loop.call_soon(self._step, context=self._context)
else:
exception = RuntimeError(f"Bad task result: {result}")
self._loop.call_soon(self._step, exception, context=self._context)
finally:
asyncio._leave_task(self._loop, self) # type: ignore[arg-type]
if self._exception:
self._loop.call_exception_handler({
"message": (str(self._exception) if self._exception
else "An exception occurred during task "
"execution"),
"exception": self._exception,
"task": self,
"future": (exception_or_future
if asyncio.futures.isfuture(exception_or_future)
else None)
})
if self.done():
self._schedule_callbacks()
asyncio._unregister_task(self) # type: ignore[arg-type]
def get_stack(self, *, limit=None) -> typing.List[typing.Any]:
# TODO
raise NotImplementedError("QtTask.get_stack is not implemented")
def print_stack(self, *, limit=None, file=None) -> None:
# TODO
raise NotImplementedError("QtTask.print_stack is not implemented")
def get_coro(self) -> typing.Union[collections.abc.Generator, collections.abc.Coroutine]:
return self._coro
def get_name(self) -> str:
return self._name
def set_name(self, value) -> None:
self._name = str(value)
def cancel(self, msg: typing.Optional[str] = None) -> bool:
if self.done():
return False
self._cancel_message = msg
self._handle.cancel()
if self._future_to_await is not None:
self._future_to_await.cancel(msg)
self._cancelled = True
return True
def uncancel(self) -> None:
# TODO
raise NotImplementedError("QtTask.uncancel is not implemented")
def cancelling(self) -> bool:
# TODO
raise NotImplementedError("QtTask.cancelling is not implemented")
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