src/ntfc/parallel.py

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"""Parallel execution utilities for handlers."""

from concurrent.futures import ThreadPoolExecutor
from typing import Any, Callable, List, TypeVar

T = TypeVar("T")


def run_parallel(
    items: List[T],
    fn: Callable[[T], Any],
) -> List[Any]:
    """Run a callable on all items in parallel, preserving order.

    :param items: List of objects to execute on.
    :param fn: Callable invoked with each item as its sole argument.
    :return: List of results in the same order as *items*.
    """
    if not items:
        return []

    with ThreadPoolExecutor(max_workers=len(items)) as executor:
        futures = [executor.submit(fn, item) for item in items]
        return [future.result() for future in futures]