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Accelerator module for asyncio
This class is *almost* compatible with concurrent.futures.Future.
Differences:
- result() and exception() do not take a timeout argument and
raise an exception when the future isn't done yet.
- Callbacks registered with add_done_callback() are always called
via the event loop's call_soon_threadsafe().
- This class is not compatible with the wait() and as_completed()
methods in the concurrent.futures package.
add_done_callback(...) Add a callback to be run when the future becomes done. The callback is called with a single argument - the future object. If the future is already done when this is called, the callback is scheduled with call_soon.
cancel(self, /, msg=None) Cancel the future and schedule callbacks. If the future is already done or cancelled, return False. Otherwise, change the future's state to cancelled, schedule the callbacks and return True.
cancelled(self, /) Return True if the future was cancelled.
done(self, /) Return True if the future is done. Done means either that a result / exception are available, or that the future was cancelled.
exception(self, /) Return the exception that was set on this future. The exception (or None if no exception was set) is returned only if the future is done. If the future has been cancelled, raises CancelledError. If the future isn't done yet, raises InvalidStateError.
get_loop(self, /) Return the event loop the Future is bound to.
remove_done_callback(self, fn, /) Remove all instances of a callback from the "call when done" list. Returns the number of callbacks removed.
result(self, /) Return the result this future represents. If the future has been cancelled, raises CancelledError. If the future's result isn't yet available, raises InvalidStateError. If the future is done and has an exception set, this exception is raised.
set_exception(self, exception, /) Mark the future done and set an exception. If the future is already done when this method is called, raises InvalidStateError.
set_result(self, result, /) Mark the future done and set its result. If the future is already done when this method is called, raises InvalidStateError.
A coroutine wrapped in a Future.
add_done_callback(...) Add a callback to be run when the future becomes done. The callback is called with a single argument - the future object. If the future is already done when this is called, the callback is scheduled with call_soon.
cancel(self, /, msg=None) Request that this task cancel itself. This arranges for a CancelledError to be thrown into the wrapped coroutine on the next cycle through the event loop. The coroutine then has a chance to clean up or even deny the request using try/except/finally. Unlike Future.cancel, this does not guarantee that the task will be cancelled: the exception might be caught and acted upon, delaying cancellation of the task or preventing cancellation completely. The task may also return a value or raise a different exception. Immediately after this method is called, Task.cancelled() will not return True (unless the task was already cancelled). A task will be marked as cancelled when the wrapped coroutine terminates with a CancelledError exception (even if cancel() was not called).
cancelled(self, /) Return True if the future was cancelled.
done(self, /) Return True if the future is done. Done means either that a result / exception are available, or that the future was cancelled.
exception(self, /) Return the exception that was set on this future. The exception (or None if no exception was set) is returned only if the future is done. If the future has been cancelled, raises CancelledError. If the future isn't done yet, raises InvalidStateError.
get_coro(self, /)
get_loop(self, /) Return the event loop the Future is bound to.
get_name(self, /)
get_stack(self, /, *, limit=None) Return the list of stack frames for this task's coroutine. If the coroutine is not done, this returns the stack where it is suspended. If the coroutine has completed successfully or was cancelled, this returns an empty list. If the coroutine was terminated by an exception, this returns the list of traceback frames. The frames are always ordered from oldest to newest. The optional limit gives the maximum number of frames to return; by default all available frames are returned. Its meaning differs depending on whether a stack or a traceback is returned: the newest frames of a stack are returned, but the oldest frames of a traceback are returned. (This matches the behavior of the traceback module.) For reasons beyond our control, only one stack frame is returned for a suspended coroutine.
print_stack(self, /, *, limit=None, file=None) Print the stack or traceback for this task's coroutine. This produces output similar to that of the traceback module, for the frames retrieved by get_stack(). The limit argument is passed to get_stack(). The file argument is an I/O stream to which the output is written; by default output is written to sys.stderr.
remove_done_callback(self, fn, /) Remove all instances of a callback from the "call when done" list. Returns the number of callbacks removed.
result(self, /) Return the result this future represents. If the future has been cancelled, raises CancelledError. If the future's result isn't yet available, raises InvalidStateError. If the future is done and has an exception set, this exception is raised.
set_exception(self, exception, /)
set_name(self, value, /)
set_result(self, result, /)
get_event_loop() Return an asyncio event loop. When called from a coroutine or a callback (e.g. scheduled with call_soon or similar API), this function will always return the running event loop. If there is no running event loop set, the function will return the result of `get_event_loop_policy().get_event_loop()` call.
get_running_loop() Return the running event loop. Raise a RuntimeError if there is none. This function is thread-specific.