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#!/usr/bin/env python3
from __future__ import annotations
import concurrent
import concurrent.futures as fut
import logging
import traceback
from typing import Callable, List, Set, TypeVar
from overrides import overrides
import id_generator
# This module is commonly used by others in here and should avoid
# taking any unnecessary dependencies back on them.
from deferred_operand import DeferredOperand
logger = logging.getLogger(__name__)
T = TypeVar('T')
def wait_any(
futures: List[SmartFuture],
*,
callback: Callable = None,
log_exceptions: bool = True,
):
real_futures = []
smart_future_by_real_future = {}
completed_futures: Set[fut.Future] = set()
for x in futures:
assert type(x) == SmartFuture
real_futures.append(x.wrapped_future)
smart_future_by_real_future[x.wrapped_future] = x
while len(completed_futures) != len(real_futures):
newly_completed_futures = concurrent.futures.as_completed(real_futures)
for f in newly_completed_futures:
if callback is not None:
callback()
completed_futures.add(f)
if log_exceptions and not f.cancelled():
exception = f.exception()
if exception is not None:
logger.warning(
f'Future {id(f)} raised an unhandled exception and exited.'
)
logger.exception(exception)
raise exception
yield smart_future_by_real_future[f]
if callback is not None:
callback()
return
def wait_all(
futures: List[SmartFuture],
*,
log_exceptions: bool = True,
) -> None:
real_futures = []
for x in futures:
assert type(x) == SmartFuture
real_futures.append(x.wrapped_future)
(done, not_done) = concurrent.futures.wait(
real_futures, timeout=None, return_when=concurrent.futures.ALL_COMPLETED
)
if log_exceptions:
for f in real_futures:
if not f.cancelled():
exception = f.exception()
if exception is not None:
logger.warning(
f'Future {id(f)} raised an unhandled exception and exited.'
)
logger.exception(exception)
raise exception
assert len(done) == len(real_futures)
assert len(not_done) == 0
class SmartFuture(DeferredOperand):
"""This is a SmartFuture, a class that wraps a normal Future and can
then be used, mostly, like a normal (non-Future) identifier.
Using a FutureWrapper in expressions will block and wait until
the result of the deferred operation is known.
"""
def __init__(self, wrapped_future: fut.Future) -> None:
assert type(wrapped_future) == fut.Future
self.wrapped_future = wrapped_future
self.id = id_generator.get("smart_future_id")
def get_id(self) -> int:
return self.id
def is_ready(self) -> bool:
return self.wrapped_future.done()
# You shouldn't have to call this; instead, have a look at defining a
# method on DeferredOperand base class.
@overrides
def _resolve(self, *, timeout=None) -> T:
return self.wrapped_future.result(timeout)
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