Loopster

Loopster is a service library that provides mechanisms for executing and managing services, including monitoring their status and automatically restarting them when necessary.

Installation

To install Loopster, you can use pip:

pip install loopster

Usage

Basic Service Example

Here's an example of how to create and run a basic service using Loopster:

from loopster.hubs import base
from loopster.hubs.controllers import panic
from loopster.hubs.drivers import process
from loopster.services import softirq

class BasicService(softirq.SoftIrqService):
    def _step(self):
        print("Hello, world!")

driver = process.ProcessDriver()
controller = panic.PanicController()
hub = base.BaseHub(driver=driver, controller=controller)

hub.add_service(svc_class=BasicService, svc_kwargs={})
hub.serve()

Nested Service Example with MySQLWrapper

Here's an example of how to use a nested service with the mysqlwrapper module:

from restalchemy.storage.sql import engines
from rooster.hubs.controllers import force_state
from loopster.hubs.drivers import process
from loopster.services import mysql
from loopster.services import softirq

class BasicService(softirq.SoftIrqService):
    def _step(self):
        print("Hello, world!")

hub = process.ProcessHub(
    controller=force_state.AlwaysForceTargetStateController())

hub.add_service(
    svc_class=mysql.MySQLStorageWrapper,
    svc_kwargs=dict(
        nested_class=BasicService,
        nested_kwargs=dict(
            step_period=STEP_PERIOD,
        ),
        mysql_connection_url=engines.DBConnectionUrl(CONNECTION_URL)
    )
)

Public Interface

Services

Loopster provides several built-in services, including:

• SoftIrqService: A service with a watchdog that runs in an infinite loop.
• BjoernService: A special server for Bjoern, which implements multiprocessing by itself.

Hubs

The ProcessHub class is used to manage multiple services using one strategy provided by the driver. It inherits from SoftIrqService, so it's a service too!

Hub provides a simple way to start and stop multiple services at once, as well as monitor their status.

Features

• Signal Handling: The ProcessHub can handle signals such as SIGHUP and SIGUSR1, allowing for graceful shutdowns and other terminal actions.
• Multiprocessing Support: By using the multiprocessing module, ProcessHub ensures that services run in separate processes, providing better isolation and resource management.
• State Management: The hub manages the state of each service, ensuring they are running as expected and automatically restarting them when necessary.

Controllers

Loopster includes different controllers that manage the state of services:

• AlwaysForceTargetStateController: A simple controller that always sets states in a loop.
• PanicController: A controller that stops managing on any problem.

Drivers

The ProcessDriver class is used to serve services as child processes. It provides methods for adding, removing, and setting the state of services.