Function greenlet_spawn

lib/sqlalchemy/util/concurrency.py:177–224

Runs a sync function ``fn`` in a new greenlet. The sync function can then use :func:`await_` to wait for async functions. :param fn: The sync callable to call. :param \\*args: Positional arguments to pass to the ``fn`` callable. :param \\*\\*kwargs: Keyword arguments to pass to

(
    fn: Callable[..., _T],
    *args: Any,
    _require_await: bool = False,
    **kwargs: Any,
)

async def greenlet_spawn(
    fn: Callable[..., _T],
    *args: Any,
    _require_await: bool = False,
    **kwargs: Any,
) -> _T:
    """Runs a sync function ``fn`` in a new greenlet.

    The sync function can then use :func:`await_` to wait for async
    functions.

    :param fn: The sync callable to call.
    :param \\*args: Positional arguments to pass to the ``fn`` callable.
    :param \\*\\*kwargs: Keyword arguments to pass to the ``fn`` callable.
    """

    result: Any
    context = _concurrency_shim._AsyncIoGreenlet(
        fn, _concurrency_shim.getcurrent()
    )
    # runs the function synchronously in gl greenlet. If the execution
    # is interrupted by await_, context is not dead and result is a
    # coroutine to wait. If the context is dead the function has
    # returned, and its result can be returned.
    switch_occurred = False

    result = context.switch(*args, **kwargs)
    while not context.dead:
        switch_occurred = True
        try:
            # wait for a coroutine from await_ and then return its
            # result back to it.
            value = await result
        except BaseException:
            # this allows an exception to be raised within
            # the moderated greenlet so that it can continue
            # its expected flow.
            result = context.throw(*sys.exc_info())
        else:
            result = context.switch(value)

    if _require_await and not switch_occurred:
        raise exc.AwaitRequired(
            "The current operation required an async execution but none was "
            "detected. This will usually happen when using a non compatible "
            "DBAPI driver. Please ensure that an async DBAPI is used."
        )
    return result  # type: ignore[no-any-return]


class AsyncAdaptedLock: