effect/effect/parallel_async.py at master · python-effect/effect · GitHub

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"""Generic asynchronous performers."""

from functools import partial

from itertools import count

from ._base import perform

from ._intents import FirstError

def perform_parallel_async(dispatcher, intent, box):

"""

A performer for :obj:`ParallelEffects` which works if all child Effects are

already asynchronous. Use this for things like Twisted, asyncio, etc.

WARNING: If this is used when child Effects have blocking performers, it

will run them in serial, not parallel.

"""

effects = list(intent.effects)

if not effects:

box.succeed([])

return

num_results = count()

results = [None] * len(effects)

def succeed(index, result):

results[index] = result

if next(num_results) + 1 == len(effects):

box.succeed(results)

def fail(index, result):

box.fail(FirstError(exception=result, index=index))

for index, effect in enumerate(effects):

perform(

dispatcher,

effect.on(success=partial(succeed, index), error=partial(fail, index)),

)

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