Listener sensor reed switch with Raspberry Pi GPIO

reed-switch.py

#!/usr/bin/python

import RPi.GPIO as GPIO
import time
import sys
import signal 

GPIO.setmode(GPIO.BCM)

DOOR_SENSOR_PIN = 18

isOpen = None
oldIsOpen = None

GPIO.setup(DOOR_SENSOR_PIN, GPIO.IN, pull_up_down = GPIO.PUD_UP)

def cleanupLights(signal, frame):
    GPIO.cleanup() 
    sys.exit(0)

def expiredTime(sig, frame):
    print('Door opened timeout')
    signal.alarm(0)

signal.signal(signal.SIGALRM, expiredTime)    
signal.signal(signal.SIGINT, cleanupLights)

while True: 
    oldIsOpen = isOpen 
    isOpen = GPIO.input(DOOR_SENSOR_PIN)

    if (isOpen and (isOpen != oldIsOpen)):
        print('Door open')
        signal.alarm(10)
    elif (isOpen != oldIsOpen):
        print('Door close')
        signal.alarm(0)
    time.sleep(1)