How to auto-close a MongoDB connection

mongox.py

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

"""
Handle MongoDB connection.
"""
# Created: 01.11.21

from time import perf_counter, sleep
import logging
import atexit
from typing import Union

from pymongo import MongoClient
from pymongo.database import Database, Collection

from base import the_config
from pythonx import split_seconds


logger = logging.getLogger(__name__)
mongo_client: Union[MongoClient, None] = None


def bye():
    global mongo_client, mongo_db
    if mongo_client:
        mongo_client.close()
        mongo_client = None
        mongo_db = None
        dt = perf_counter() - mongo_pc0
        logger.info(f"closed mongo connection after {split_seconds(dt)}")
        # sleep(2.0) # -> ja, funktionert auch wenn man den Debugger neustartet :)


atexit.register(bye)
logger.info("atexit.register() for MongoDB connection.")

mongo_uri = the_config["mongo"]["uri"]
mongo_dbname = the_config["mongo"]["db"]
logger.info(f"connecting to {mongo_uri}")
mongo_client = MongoClient(mongo_uri)
logger.info(f"choosing database {mongo_dbname}")
mongo_db: Database = mongo_client[mongo_dbname]
mongo_pc0 = perf_counter()


def get_mongo_db(coll: str = None) -> Union[Database, Collection]:
    if coll:
        assert isinstance(coll, str)
        return mongo_db[coll]
    else:
        return mongo_db


def coll(symbol: str) -> Collection:
    return mongo_db[the_config["coll"][symbol]]


#
#       pythonx/split_secnds()
#

def split_seconds(seconds: float) -> str:
    """
    Funny stuff: render a duration like 5d 10m 3.5s.
    :param seconds:
    :return:
    """
    secs = seconds % 60
    seconds //= 60
    seconds = int(round(seconds, 0))
    mins = seconds % 60
    seconds //= 60
    hrs = seconds % 24
    seconds //= 24
    days = seconds
    a = []
    if days:
        a.append(f"{days}d")
    if hrs:
        a.append(f"{hrs}h")
    if mins:
        a.append(f"{mins}m")
    if secs >= 0.1:
        a.append(f"{secs:0.1f}s")
    if a:
        return " ".join(a)
    else:
        return "no time"