# -*- coding: utf-8 -*-
import concurrent.futures
import contextlib
import logging
__all__ = 'Future', 'chain', 'copy_future', 'CancelledError', 'capture_exceptions', 'wait', 'as_completed'
_LOGGER = logging.getLogger(__name__)
CancelledError = concurrent.futures.CancelledError
wait = concurrent.futures.wait # pylint: disable=invalid-name
as_completed = concurrent.futures.as_completed # pylint: disable=invalid-name
Future = concurrent.futures.Future
[docs]def copy_future(source, target):
""" Copy the status of future a to b unless b is already done in
which case return
:param source: The source future
:type source: :class:`kiwipy.Future`
:param target: The target future
:type target: :class:`kiwipy.Future`
"""
if target.done():
return
if source.cancelled():
target.cancel()
else:
with capture_exceptions(target):
target.set_result(source.result())
[docs]def chain(source, target):
"""Chain two futures together so that when one completes, so does the other.
The result (success or failure) of ``a`` will be copied to ``b``, unless
``b`` has already been completed or cancelled by the time ``a`` finishes.
"""
source.add_done_callback(lambda first: copy_future(first, target))
@contextlib.contextmanager
def capture_exceptions(future, ignore=()):
"""
Capture any exceptions in the context and set them as the result of the given future
:param future: The future to the exception on
:type future: :class:`kiwipy.Future`
:param ignore: An optional list of exception types to ignore, these will be raised and not set on the future
"""
try:
yield
except Exception as exception: # pylint: disable=broad-except
if isinstance(exception, ignore):
raise
future.set_exception(exception)
