Synnefo

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from django.conf import settings

from django.core.exceptions import MiddlewareNotUsed

from synnefo.lib.dictconfig import dictConfig

import logging

class NullHandler(logging.Handler):

    def emit(self, record):

        pass

class LoggingConfigMiddleware:

    def __init__(self):

        """Initialise the logging setup from settings.

        Logging setup is initialized only in the first request.

        """

        logging_setting = getattr(settings, 'LOGGING_SETUP', None)

        if logging_setting:

            # Disable handlers that are not used by any logger.

            active_handlers = set()

            loggers = logging_setting.get('loggers', {})

            for logger in loggers.values():

                active_handlers.update(logger.get('handlers', []))

            handlers = logging_setting.get('handlers', {})

            for handler in handlers:

                if handler not in active_handlers:

                    handlers[handler] = {'class': 'logging.NullHandler'}

            logging.NullHandler = NullHandler

            dictConfig(logging_setting)

        raise MiddlewareNotUsed('Logging setup only.')