generic timeout construct

timeout.py

import signal
import contextlib
import os
from threading import Thread
from time import sleep
from datetime import datetime


class CustomInterrupt(Exception):
    SIG = 63


def handle_custom_interrupt(signum, _):
    raise CustomInterrupt


signal.signal(CustomInterrupt.SIG, handle_custom_interrupt)


@contextlib.contextmanager
def timeout(seconds: float = 3.0):
    class TimedOut:
        def __init__(self, seconds_: float):
            self.seconds: float = seconds_
            self.state: bool | None = None
            self.thread = Thread(target=self._task)

        def _task(self):
            sleep(self.seconds)
            if self.state is None:
                os.kill(os.getpid(), CustomInterrupt.SIG)

        def start(self):
            self.thread.start()

        def __bool__(self):
            if self.state is None:
                raise ValueError(
                    "Can't decide yet, value only becomes meaningful on exit.")
            return self.state

    timed_out = TimedOut(seconds)
    try:
        timed_out.start()
        yield timed_out
        timed_out.state = False
    except CustomInterrupt:
        timed_out.state = True
    finally:
        timed_out.thread.join()  # tbh, no idea why I'm doing this


start = datetime.now()
print(1, (datetime.now()-start).seconds)
with timeout(1) as timed_out:
    while True:
        pass
print(2, (datetime.now()-start).seconds)

with timeout(1) as timed_out:
    sleep(5)
print(3, (datetime.now()-start).seconds)
# output:
# 1 0
# 2 1
# 3 2