"""Shared joblib parallel grid runner (spec: specs/exp00_core.md)."""

import os

from joblib import Parallel, delayed


def get_n_jobs():
    return int(os.environ.get("JOB_CORES", "1"))


def _run_one(func, item):
    os.environ["OMP_NUM_THREADS"] = "1"
    return func(item)


def run_grid(func, items, n_jobs=None):
    """Run func(item) over items via joblib loky backend, correct (only slower) at n_jobs=1."""
    if n_jobs is None:
        n_jobs = get_n_jobs()
    return Parallel(n_jobs=n_jobs, backend="loky")(
        delayed(_run_one)(func, item) for item in items
    )