Detect file creation with watchdog

Question

I am trying to detect when a file with a given name is created in a directory. I am doing it thanks to watchdog. The creation is correctly detected but I don't know how to terminate the application properly once the detection is done.

My piece of code is the following:

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import logging
import sys
import time

from watchdog.events import FileSystemEventHandler
from watchdog.observers import Observer

logging.basicConfig(level=logging.ERROR)

class MyEventHandler(FileSystemEventHandler):
    def __init__(self, observer, filename):
        self.observer = observer
        self.filename = filename

    def on_created(self, event):
        print "e=", event
        if not event.is_directory and event.src_path.endswith(self.filename):
            print "file created"
            self.observer.unschedule_all()
            self.observer.stop()

def main(argv=None):
    path = argv[1]
    filename = argv[2]
    observer = Observer()
    event_handler = MyEventHandler(observer, filename)
    observer.schedule(event_handler, path, recursive=False)
    observer.start()
    observer.join()
    return 0

if __name__ == "__main__":
    sys.exit(main(sys.argv))

I am new to python and I cannot figure out what is wrong. The detection seems to be scheduled in a dedicated thread and the join() method is waiting for this thread to terminate. Thus, I suppose that I am not calling the right method on the observer to stop waiting/looping, but the watchdog documentation seems really not clear to point out what are the methods that may be used.

Does someone have an idea how I can achieve my goal?

Answer 1

Finally, after taking a look at the watchdog implementation, it is not necessary to call unschedule_all before stop, this is done automatically. Removing the line containing this method call fixes the issue and the application is running perfectly.