aiosock -- Multiprocess communication sockets for asyncio

This package wraps the socket lib, so that it can be used as part of the non-blocking asyncio event loop. A goal scenario is multiprocess communication with the help of coroutines, i.e., combining multiprocessing and asyncio.

For example, there are two processes in a program: one is Main_Process, and the other is IO_Process. The two processes are running with respective event loops. The Main_Process is asynchronizedly reading messages from IO_Process, and once the IO_Process sends something to the Main_Process, the latter will call a callback function or continue executing a coroutine from the previous break point.

Quick Start

First, install aiosock.

pip install aiosock

Second, import modules

import aiosock
import asyncio

Third, create aio-socket pair

sock1, sock2 = aiosocket.aiosockpair()

Forth, if you wish to use a callback function, initialize the aio-socket(s) with the function. The form of the function should be

def callback(obj_recv: Any, *args: Any): ...

The first argument is the object received from the other socket, and the remainder are arguments passed from where the socket is initialized. For example

def callback_print(obj_recv: Any, num: int): 
    print(f'{num}: {obj_recv}')

sock1.init((callback_print, 0))

Fifth, you may also use await to read something in an async function, rather than using a callback. For example

async def main():
    obj_recv = await sock1.read()

Sixth, you are able to set callbacks for both read and write. the read callback is executed whenever something is received, and the write callback is executed when it is available to write. For example

def callback_print(obj_recv: Any, num: int): 
    print(f'{num}: {obj_recv}')

def callback_writable():
    print('Now writable.')

sock1.init((callback_print, 0), callback_writable)

The defaut values of the callbacks are None.

Seventh, send any object you want, as long as the object is serializable.

sock2.send('Hello asyncio!')

You can call sock2.send(...) in another process and initialized the sock2 in that process, so that multiple processes are able to communicate with each other.

Finally, don't forget to run the event loop, for example

asyncio.get_event_loop().run_forever()

Here is a complete demonstration below.

Demo

Code:

from multiprocessing import Process
import os
from typing import Any, Iterable, Mapping
from aiosock import AioSock, aiosockpair
import asyncio


class IO_Process(Process):
    ''''''
    def __init__(self, sock: AioSock, group = None, name: 'str | None' = None, args: Iterable[Any] = (), kwargs: Mapping[str, Any] = {}, *, daemon: 'bool | None' = None) -> None:
        super().__init__(group, None, name, daemon=daemon)
        self.sock = sock


    def run(self):
        print(f'IO Process PID: {os.getpid()}')
        self.loop = asyncio.get_event_loop()
        self.sock.init(self.on_read)
        self.loop.call_later(3, self.sock.write, f'[sock2 write] PID: {os.getpid()}')
        self.loop.create_task(self.read())
        self.loop.run_forever()


    def on_read(self, obj: Any, *args):
        ''''''
        print(obj)
        print(f'[io on_read] PID: {os.getpid()}')


    async def read(self):
        ''''''
        while True:
            obj = await self.sock.read()
            print(f'[io await read]{str(obj)}')
            print(f'[io await read] PID: {os.getpid()}')


async def main(sock: AioSock):
    ''''''
    sock1.write(f'[sock1 write] PID: {os.getpid()}')
    obj = await sock.read()
    print(obj)
    print(f'[main await read] PID: {os.getpid()}')


if __name__ == '__main__':    
    print('IO Process Read/Write, Main Process Write/Read.')  
    print(f'Main Process PID: {os.getpid()}')
    sock1, sock2 = aiosockpair()
    iop = IO_Process(sock2)
    sock1.init()
    iop.start()
    loop = asyncio.get_event_loop()
    loop.run_until_complete(main(sock1))

Output:

Main Process PID: 15408
IO Process PID: 12324
[sock1 write] PID: 15408
[io on_read] PID: 12324
[io await read][sock1 write] PID: 15408
[io await read] PID: 12324
[sock2 write] PID: 12324
[main await read] PID: 15408