lbry-sdk/lbry/extras/daemon/component.py

import asyncio
import logging
from lbry.conf import Config
from lbry.extras.daemon.componentmanager import ComponentManager

log = logging.getLogger(__name__)


class ComponentType(type):
    def __new__(mcs, name, bases, newattrs):
        klass = type.__new__(mcs, name, bases, newattrs)
        if name != "Component" and newattrs['__module__'] != 'lbry.testcase':
            ComponentManager.default_component_classes[klass.component_name] = klass
        return klass


class Component(metaclass=ComponentType):
    """
    lbry-daemon component helper

    Inheriting classes will be automatically registered with the ComponentManager and must implement setup and stop
    methods
    """

    depends_on = []
    component_name = None

    def __init__(self, component_manager):
        self.conf: Config = component_manager.conf
        self.component_manager = component_manager
        self._running = False

    def __lt__(self, other):
        return self.component_name < other.component_name

    @property
    def running(self):
        return self._running

    async def get_status(self): # pylint: disable=no-self-use
        return

    async def start(self):
        raise NotImplementedError()

    async def stop(self):
        raise NotImplementedError()

    @property
    def component(self):
        raise NotImplementedError()

    async def _setup(self):
        try:
            result = await self.start()
            self._running = True
            return result
        except asyncio.CancelledError:
            log.info("Cancelled setup of %s component", self.__class__.__name__)
            raise
        except Exception as err:
            log.exception("Error setting up %s", self.component_name or self.__class__.__name__)
            raise err

    async def _stop(self):
        try:
            result = await self.stop()
            self._running = False
            return result
        except asyncio.CancelledError:
            log.info("Cancelled stop of %s component", self.__class__.__name__)
            raise
        except Exception as err:
            log.exception("Error stopping %s", self.__class__.__name__)
            raise err