vcsserver/lib/statsd_client.py

# RhodeCode VCSServer provides access to different vcs backends via network.
# Copyright (C) 2014-2020 RhodeCode GmbH
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software Foundation,
# Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA

from vcsserver.lib._vendor.statsd import client_from_config


class StatsdClientNotInitialised(Exception):
    pass


class _Singleton(type):
    """A metaclass that creates a Singleton base class when called."""

    _instances = {}

    def __call__(cls, *args, **kwargs):
        if cls not in cls._instances:
            cls._instances[cls] = super().__call__(*args, **kwargs)
        return cls._instances[cls]


class Singleton(_Singleton("SingletonMeta", (object,), {})):
    pass


class StatsdClientClass(Singleton):
    setup_run = False
    statsd_client = None
    statsd = None
    strict_mode_init = False

    def __getattribute__(self, name):

        if name.startswith("statsd"):
            if self.setup_run:
                return super().__getattribute__(name)
            else:
                if self.strict_mode_init:
                    raise StatsdClientNotInitialised(f"requested key was {name}")
                return None

        return super().__getattribute__(name)

    def setup(self, settings):
        """
        Initialize the client
        """
        strict_init_mode = settings.pop('statsd_strict_init', False)

        statsd = client_from_config(settings)
        self.statsd = statsd
        self.statsd_client = statsd
        self.setup_run = True


StatsdClient = StatsdClientClass()