Comando para Django que chequea lock

command_locked.py

import logging
import fcntl
import os

from optparse import make_option

from django.core.management.base import BaseCommand

logger = logging.getLogger(__name__)

#
# Recordar cambiar >> default='/tmp/.some_file.lock'
#

class Command(BaseCommand):
    help = "Mensaje de ayuda"
    option_list = BaseCommand.option_list + (
        make_option('--lock', action='store', dest='lock_file',
            default='/tmp/.some_file.lock',
            help='Archivo a usar para lock'),
    )

    def realizar_trabajo():
        raise(Exception("IMPLEMENTAR!"))

    def handle(self, *args, **options):
        lock_file = options.get('lock_file')
        
        FORMAT = "%(asctime)s [{0}] [%(levelname)-5s] %(name)s - %(message)s".format(os.getpid())
        
        if 'DEBUG' in os.environ:
            logging.basicConfig(format=FORMAT, level=logging.DEBUG)
        else:
            logging.basicConfig(format=FORMAT, level=logging.INFO)
        
        if not os.path.exists(lock_file):
            open(lock_file, 'a')
        
        logger.info("Intentando obtener lock...")
        opened_lock_file = open(lock_file, 'a')
        try:
            fcntl.lockf(opened_lock_file, fcntl.LOCK_EX | fcntl.LOCK_NB)
            opened_lock_file.seek(0)
            opened_lock_file.truncate()
            opened_lock_file.write(str(os.getpid()))
            opened_lock_file.flush()
        except IOError:
            try:
                locked_by = open(lock_file, 'r').read()
            except:
                locked_by = '?'
            self.stderr.write(
                self.style.ERROR("No se pudo obtener lock: {0} - "
                    "Archivo de LOCK contiene: '{1}'\n".format(lock_file, locked_by))
            )
            return
        
        logger.info("... lock obtenido!")
        
        from django.db import transaction
        
        logger.info("Iniciando procesamiento...")
        realizar_trabajo()
        
        logger.info("Committing...")
        transaction.commit_unless_managed()
        
        logger.info("FIN")