lib/logger.py

import logging
from functools import wraps
from threading import Lock


class Logger:
    _instances = {}
    _lock = Lock()

    def __new__(cls, name="root"):
        with cls._lock:
            if name not in cls._instances:
                instance = super().__new__(cls)
                instance._init(name)
                cls._instances[name] = instance
            return cls._instances[name]

    def _init(self, name):
        self.logger = logging.getLogger(name)
        self.logger.setLevel(logging.DEBUG)
        self.logger.propagate = False

        console_handler = logging.StreamHandler()
        console_handler.setLevel(logging.INFO)

        file_handler = logging.FileHandler("app.log")
        file_handler.setLevel(logging.DEBUG)

        formatter = logging.Formatter(
            "%(asctime)s [%(threadName)s] %(levelname)-5s %(name)s - %(message)s",
            datefmt="%Y-%m-%d %H:%M:%S",  # no milliseconds
        )
        console_handler.setFormatter(formatter)
        file_handler.setFormatter(formatter)

        self.logger.addHandler(console_handler)
        self.logger.addHandler(file_handler)

    def _log(self, level, message):
        log_message = f"{message}".strip()
        self.logger.log(level, log_message)

    def debug(self, message, **kwargs):
        self._log(logging.DEBUG, message, **kwargs)

    def info(self, message, **kwargs):
        self._log(logging.INFO, message, **kwargs)

    def warning(self, message, **kwargs):
        self._log(logging.WARNING, message, **kwargs)

    def error(self, message, **kwargs):
        self._log(logging.ERROR, message, **kwargs)

    def critical(self, message, **kwargs):
        self._log(logging.CRITICAL, message, **kwargs)


# decorator for logging function calls
def log_fn(name=None):
    def decorator(fn):
        @wraps(fn)
        def wrapper(*args, **kwargs):
            log = Logger(name or fn.__name__)
            log.info("begin")
            result = fn(*args, **kwargs)
            log.info("end")

            return result

        return wrapper

    return decorator