python 3 asyncio example: periodic check mongodb collection names

periodic_check_mongodb_collection_names.py

import asyncio
from pymongo import MongoClient

@asyncio.coroutine
def periodic(wait_seconds=2):
    while True:
        names = client['local'].collection_names()
        for name in names:
            print(name)
        yield from asyncio.sleep(wait_seconds)

def stop():
    task.cancel()

task = asyncio.Task(periodic(wait_seconds=2))

if __name__ == '__main__':
    client = MongoClient('localhost', 27017)
    loop = asyncio.get_event_loop()
    loop.call_later(60, stop)        # Breaks out after 1 minute

    try:
        loop.run_until_complete(task)
    except asyncio.CancelledError:
        pass