async socket

import socket
from select import select

# select = selectors.DefaultSelector()
to_read = {}
to_write = {}
tasks = []


def server():
    server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    server_socket.bind(("localhost", 5000))
    server_socket.listen()

    while True:
        yield ("read", server_socket)
        client_socket, addr = server_socket.accept()
        print("Connected client", addr)
        tasks.append(client(client_socket))


def client(client_socket):
    while True:
        yield ("read", client_socket)
        request = client_socket.recv(4096)

        if not request:
            break
        else:
            yield ("write", client_socket)
            response = "Hello world\n".encode()
            client_socket.send(response)

    print("Outside from an inner loop")
    client_socket.close()


def event_loop():
    while any([tasks, to_read, to_write]):

        while not tasks:
            ready_to_read, ready_to_write, _ = select(to_read, to_write, [])
            for sock in ready_to_read:
                tasks.append(to_read.pop(sock))
            for sock in ready_to_write:
                tasks.append(to_write.pop(sock))
        try:
            task = tasks.pop(0)
            reason, sock = next(task)

            if reason == "read":
                to_read[sock] = task
            if reason == "write":
                to_write[sock] = task
        except StopIteration:
            print("all done")


if __name__ == "__main__":
    tasks.append(server())
    event_loop()