from __future__ import annotations

from contextlib import contextmanager
from pathlib import Path
import fcntl


@contextmanager
def exclusive(db_path: Path):
    """Cross-process lock for destructive dedupe operations."""
    lock_path = Path(str(db_path) + ".lock")
    lock_path.parent.mkdir(parents=True, exist_ok=True)
    with lock_path.open("w") as handle:
        fcntl.flock(handle.fileno(), fcntl.LOCK_EX)
        try:
            yield
        finally:
            fcntl.flock(handle.fileno(), fcntl.LOCK_UN)