aiomisc - miscellaneous utils for asyncio#

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As a programmer, you are no stranger to the challenges that come with building and maintaining software applications. One area that can be particularly difficult is making architecture of the asynchronous I/O software.

This is where aiomisc comes in. It is a Python library that provides a collection of utility functions and classes for working with asynchronous I/O in a more intuitive and efficient way. It is built on top of the asyncio library and is designed to make it easier for developers to write asynchronous code that is both reliable and scalable.

With aiomisc, you can take advantage of powerful features like worker pools, connection pools, circuit breaker pattern, and retry mechanisms such as asyncbackoff and asyncretry to make your asyncio code more robust and easier to maintain. In this documentation, we’ll take a closer look at what aiomisc has to offer and how it can help you streamline your asyncio service development.

Installation#

Installation is possible in standard ways, such as PyPI or installation from a git repository directly.

Installing from PyPI:

pip3 install aiomisc

Installing from github.com:

# Using git tool
pip3 install git+https://github.com/aiokitchen/aiomisc.git

# Alternative way using http
pip3 install \
    https://github.com/aiokitchen/aiomisc/archive/refs/heads/master.zip

The package contains several extras and you can install additional dependencies if you specify them in this way.

With uvloop:

pip3 install "aiomisc[uvloop]"

With aiohttp:

pip3 install "aiomisc[aiohttp]"

Complete table of extras bellow:

example

description

pip install aiomisc[aiohttp]

For running aiohttp applications.

pip install aiomisc[asgi]

For running ASGI applications

pip install aiomisc[carbon]

Sending metrics to carbon (part of graphite)

pip install aiomisc[cron]

use croniter for scheduling tasks

pip install aiomisc[raven]

Sending exceptions to sentry using raven

pip install aiomisc[rich]

You might using rich for logging

pip install aiomisc[uvicorn]

For running ASGI application using uvicorn

pip install aiomisc[uvloop]

use uvloop as a default event loop

You can combine extras values by separating them with commas, for example:

pip3 install "aiomisc[aiohttp,cron,rich,uvloop]"

Quick Start#

This section will cover how this library creates and uses the event loop and creates services. For more details see Tutorial section, and you can always refer to the Modules and API Reference sections for help.

Event-loop and entrypoint#

Let’s look at this simple example first:

import asyncio
import logging

import aiomisc

log = logging.getLogger(__name__)

async def main():
    log.info('Starting')
    await asyncio.sleep(3)
    log.info('Exiting')


if __name__ == '__main__':
    with aiomisc.entrypoint(log_level="info", log_format="color") as loop:
        loop.run_until_complete(main())

This code declares an asynchronous main() function that exits for 3 seconds. It would seem nothing interesting, but the whole point is in the entrypoint.

At the first glance the entrypoint did not do much, just creates an event-loop and transfers control to the user. However, under the hood, the logger is configured in a separate thread, a pool of threads is created, services are started, but more on that later as there are no services in this example.

Alternatively, you can choose not to use an entrypoint, just create an event-loop and set it as a default for current thread:

import asyncio
import aiomisc

# * Installs uvloop event loop is it's has been installed.
# * Creates and set `aiomisc.thread_pool.ThreadPoolExecutor`
#   as a default executor
# * Sets just created event-loop as a current event-loop for this thread.
aiomisc.new_event_loop()

async def main():
    await asyncio.sleep(1)

if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    loop.run_until_complete(main())

The example above is useful if your code is already using an implicitly created event loop, you will have to modify less code, just add aiomisc.new_event_loop() and all calls to asyncio.get_event_loop() will return the created instance.

However, you can do with one call. Following example closes implicitly created asyncio event loop and install a new one:

import asyncio
import aiomisc

async def main():
    await asyncio.sleep(3)

if __name__ == '__main__':
    loop = aiomisc.new_event_loop()
    loop.run_until_complete(main())

Services#

The main thing that an entrypoint does is start and gracefully stop services.

The service concept within this library means a class derived from the aiosmic.Service class and implementing the async def start(self) -> None: method and optionally the async def stop(self, exc: Optional[ Exception]) -> None method.

The concept of stopping a service is not necessarily is pressing Ctrl+C keys by user, it’s actually just exiting the entrypoint context manager.

The example below shows what your service might look like:

from aiomisc import entrypoint, Service

class MyService(Service):
    async def start(self):
        do_something_when_start()

    async def stop(self, exc):
        do_graceful_shutdown()


with entrypoint(MyService()) as loop:
    loop.run_forever()

The entry point can start as many instances of the service as it likes, and all of them will start concurrently.

There is also a way if the start method is a payload for a service, and then there is no need to implement the stop method, since the running task with the start function will be canceled at the stop stage. But in this case, you will have to notify the entrypoint that the initialization of the service instance is complete and it can continue.

Like this:

import asyncio
from threading import Event
from aiomisc import entrypoint, Service

event = Event()

class MyService(Service):
    async def start(self):
        # Send signal to entrypoint for continue running
        self.start_event.set()
        await asyncio.sleep(3600)


with entrypoint(MyService()) as loop:
    assert event.is_set()

Note

The entrypoint passes control to the body of the context manager only after all service instances have started. As mentioned above, a start is considered to be the completion of the start method or the setting of an start event with self.start_event.set().

The whole power of this library is in the set of already implemented or abstract services. Such as: AIOHTTPService, ASGIService, TCPServer, UDPServer, TCPClient, PeriodicService, CronService and so on.

Unfortunately in this section it is not possible to pay more attention to this, please pay attention to the Tutorial section section, there are more examples and explanations, and of cource you always can find out an answer on the API Reference or in the source code. The authors have tried to make the source code as clear and simple as possible, so feel free to explore it.

Versioning#

This software follows Semantic Versioning

Summary: it’s given a version number MAJOR.MINOR.PATCH, increment the:

  • MAJOR version when you make incompatible API changes

  • MINOR version when you add functionality in a backwards compatible manner

  • PATCH version when you make backwards compatible bug fixes

  • Additional labels for pre-release and build metadata are available as extensions to the MAJOR.MINOR.PATCH format.

In this case, the package version is assigned automatically with poem-plugins, it using on the tag in the repository as a major and minor and the counter, which takes the number of commits between tag to the head of branch.

How to develop?#

This project, like most open source projects, is developed by enthusiasts, you can join the development, submit issues, or send your merge requests.

In order to start developing in this repository, you need to do the following things.

Should be installed:

  • Python 3.7+ as python3

  • Installed Poetry as poetry

For setting up developer environment just execute:

# installing all dependencies
poetry install

# setting up pre-commit hooks
poetry run pre-commit install

# adding poem-plugins to the poetry
poetry self add poem-plugins