"""Shared GPU lease and process-group lifecycle helpers."""

from __future__ import annotations

import os
import signal
import subprocess
import threading
from contextlib import suppress


class ResourceBusyError(RuntimeError):
    pass


class GpuLease:
    def __init__(self):
        self.lock = threading.RLock()
        self.owner: str | None = None

    def acquire(self, owner: str) -> None:
        with self.lock:
            if self.owner is not None and self.owner != owner:
                raise ResourceBusyError(f"计算资源正由 {self.owner} 使用")
            self.owner = owner

    def release(self, owner: str) -> None:
        with self.lock:
            if self.owner == owner:
                self.owner = None

    def public(self) -> str | None:
        with self.lock:
            return self.owner


def terminate_process(process: subprocess.Popen[str], grace_seconds: float = 5.0) -> None:
    if process.poll() is not None:
        return
    with suppress(ProcessLookupError):
        os.killpg(process.pid, signal.SIGTERM)
    try:
        process.wait(timeout=grace_seconds)
    except subprocess.TimeoutExpired:
        with suppress(ProcessLookupError):
            os.killpg(process.pid, signal.SIGKILL)