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# Licensed under the Revised BSD License, see LICENSE for details.
# SPDX-License-Identifier: BSD-3-Clause
import collections.abc
import inspect
import os
import typing
import warnings
from asyncio import CancelledError, InvalidStateError
import cocotb
import cocotb.triggers
from cocotb import _outcomes
from cocotb._py_compat import cached_property
from cocotb.log import SimLog
from cocotb.utils import extract_coro_stack, remove_traceback_frames
T = typing.TypeVar("T")
Self = typing.TypeVar("Self")
# Sadly the Python standard logging module is very slow so it's better not to
# make any calls by testing a boolean flag first
_debug = "COCOTB_SCHEDULER_DEBUG" in os.environ
class Task(typing.Coroutine[typing.Any, typing.Any, T]):
"""Concurrently executing task.
This class is not intended for users to directly instantiate.
Use :func:`cocotb.create_task` to create a Task object,
or use :func:`cocotb.start_soon` or :func:`cocotb.start` to
create a Task and schedule it to run.
.. versionchanged:: 1.8.0
Moved to the ``cocotb.task`` module.
.. versionchanged:: 2.0
The ``retval``, ``_finished``, and ``__bool__`` methods were removed.
Use :meth:`result`, :meth:`done`, and :meth:`done` methods instead, respectively.
"""
_name: str = "Task" # class name of schedulable task
_id_count = 0 # used by the scheduler for debug
def __init__(self, inst):
if inspect.iscoroutinefunction(inst):
raise TypeError(
f"Coroutine function {inst} should be called prior to being "
"scheduled."
)
elif inspect.isasyncgen(inst):
raise TypeError(
f"{inst.__qualname__} is an async generator, not a coroutine. "
"You likely used the yield keyword instead of await."
)
elif not isinstance(inst, collections.abc.Coroutine):
raise TypeError(f"{inst} isn't a valid coroutine!")
self._coro = inst
self._started = False
self._outcome: _outcomes.Outcome = None
self._trigger: typing.Optional[cocotb.triggers.Trigger] = None
self._cancelled: typing.Optional[CancelledError] = None
self._task_id = self._id_count
type(self)._id_count += 1
self.__name__ = f"{type(self)._name} {self._task_id}"
self.__qualname__ = self.__name__
@cached_property
def log(self) -> SimLog:
# Creating a logger is expensive, only do it if we actually plan to
# log anything
return SimLog(f"cocotb.{self.__qualname__}.{self._coro.__qualname__}")
def __str__(self) -> str:
return f"<{self.__name__}>"
def _get_coro_stack(self) -> typing.Any:
"""Get the coroutine callstack of this Task."""
coro_stack = extract_coro_stack(self._coro)
# Remove Trigger.__await__() from the stack, as it's not really useful
if len(coro_stack) > 0 and coro_stack[-1].name == "__await__":
coro_stack.pop()
return coro_stack
def __repr__(self) -> str:
coro_stack = self._get_coro_stack()
if cocotb.scheduler._current_task is self:
fmt = "<{name} running coro={coro}()>"
elif self.done():
fmt = "<{name} finished coro={coro}() outcome={outcome}>"
elif self._trigger is not None:
fmt = "<{name} pending coro={coro}() trigger={trigger}>"
elif not self._started:
fmt = "<{name} created coro={coro}()>"
else:
raise RuntimeError("Task in unknown state")
try:
coro_name = coro_stack[-1].name
# coro_stack may be empty if:
# - exhausted generator
# - finished coroutine
except IndexError:
try:
coro_name = self._coro.__name__
except AttributeError:
coro_name = type(self._coro).__name__
repr_string = fmt.format(
name=self.__name__,
coro=coro_name,
trigger=self._trigger,
outcome=self._outcome,
)
return repr_string
def _advance(self, outcome: _outcomes.Outcome) -> typing.Any:
"""Advance to the next yield in this coroutine.
Args:
outcome: The :any:`outcomes.Outcome` object to resume with.
Returns:
The object yielded from the coroutine or None if coroutine finished
"""
try:
self._started = True
return outcome.send(self._coro)
except StopIteration as e:
self._outcome = _outcomes.Value(e.value)
except BaseException as e:
self._outcome = _outcomes.Error(
remove_traceback_frames(e, ["_advance", "send"])
)
def send(self, value: typing.Any) -> typing.Any:
return self._coro.send(value)
def throw(self, exc: BaseException) -> typing.Any:
return self._coro.throw(exc)
def close(self) -> None:
return self._coro.close()
def kill(self) -> None:
"""Kill a coroutine."""
if self._outcome is not None:
# already finished, nothing to kill
return
if _debug:
self.log.debug("kill() called on coroutine")
# todo: probably better to throw an exception for anyone waiting on the coroutine
self._outcome = _outcomes.Value(None)
cocotb.scheduler._unschedule(self)
def join(self) -> "cocotb.triggers.Join":
"""Return a trigger that will fire when the wrapped coroutine exits."""
return cocotb.triggers.Join(self)
def has_started(self) -> bool:
"""Return ``True`` if the Task has started executing."""
return self._started
def cancel(self, msg: typing.Optional[str] = None) -> None:
"""Cancel a Task's further execution.
When a Task is cancelled, a :exc:`asyncio.CancelledError` is thrown into the Task.
"""
self._cancelled = CancelledError(msg)
warnings.warn(
"Calling this method will cause a CancelledError to be thrown in the "
"Task sometime in the future.",
FutureWarning,
stacklevel=2,
)
self.kill()
def cancelled(self) -> bool:
"""Return ``True`` if the Task was cancelled."""
return self._cancelled is not None
def done(self) -> bool:
"""Return ``True`` if the Task has finished executing."""
return self._outcome is not None or self.cancelled()
def result(self) -> T:
"""Return the result of the Task.
If the Task ran to completion, the result is returned.
If the Task failed with an exception, the exception is re-raised.
If the Task was cancelled, the CancelledError is re-raised.
If the coroutine is not yet complete, a :exc:`asyncio.InvalidStateError` is raised.
"""
if not self.done():
raise InvalidStateError("result is not yet available")
elif self.cancelled():
raise self._cancelled
else:
return self._outcome.get()
def exception(self) -> typing.Optional[BaseException]:
"""Return the exception of the Task.
If the Task ran to completion, ``None`` is returned.
If the Task failed with an exception, the exception is returned.
If the Task was cancelled, the CancelledError is re-raised.
If the coroutine is not yet complete, a :exc:`asyncio.InvalidStateError` is raised.
"""
if not self.done():
raise InvalidStateError("result is not yet available")
elif self.cancelled():
raise self._cancelled
elif isinstance(self._outcome, _outcomes.Error):
return self._outcome.error
else:
return None
def __await__(self) -> typing.Generator[typing.Any, typing.Any, T]:
# It's tempting to use `return (yield from self._coro)` here,
# which bypasses the scheduler. Unfortunately, this means that
# we can't keep track of the result or state of the coroutine,
# things which we expose in our public API. If you want the
# efficiency of bypassing the scheduler, remove the `@coroutine`
# decorator from your `async` functions.
# Hand the coroutine back to the scheduler trampoline.
return (yield self)
class _RunningTest(Task[None]):
"""
The result of calling a :class:`cocotb.test` decorated object.
All this class does is change ``__name__`` to show "Test" instead of "Task".
.. versionchanged:: 1.8.0
Moved to the ``cocotb.task`` module.
"""
_name: str = "Test"
def __init__(
self, inst: typing.Coroutine[typing.Any, typing.Any, None], name: str
) -> None:
super().__init__(inst)
self.__name__ = f"{type(self)._name} {name}"
self.__qualname__ = self.__name__
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