A pynsq Reader that polls for a file to transparently enable/disable

disabled_nsq_reader.py

import os.path
import logging
import tornado.ioloop
from nsq import Reader as BaseReader
from nsq import run

class Reader(BaseReader):

    def __init__(self, *args, **kwargs):
        max_in_flight = kwargs['max_in_flight']
        kwargs['max_in_flight'] = 0
        
        def check_disabled():
            if os.path.exists("queuereaders/disable"):
                if self.max_in_flight == max_in_flight:
                    logging.info('[%s] disabling. setting max_in_flight = 0', self.name)
                    self.set_max_in_flight(0)
            else:
                if self.max_in_flight == 0:
                    logging.info('[%s] enabling. setting max_in_flight = %d', self.name, max_in_flight)
                    self.set_max_in_flight(max_in_flight)
        # poll every second for the disabled file, and adjust max_in_flight as appropriate
        self.disabled_watcher = tornado.ioloop.PeriodicCallback(check_disabled, 1000)

        super(Reader, self).__init__(*args, **kwargs)
        self.disabled_watcher.start()