Server_with_select.py

import selectors
import socket
import types


class ServerWithSelect:
    def __init__(self, host_name="localhost", port_num=6379, reuse_port=True):
        self.host_name = host_name
        self.port_num = port_num
        self.reuse_port = reuse_port
        self.selector = selectors.DefaultSelector()
        self.__init_server()

    def __init_server(self):
        sock = socket.create_server((self.host_name, self.port_num), reuse_port=self.reuse_port)
        print(f"Listening on {(self.host_name, self.port_num)}")
        sock.setblocking(False)
        self.selector.register(
            sock, selectors.EVENT_READ, data=None
        )

    def listen_for_connections(self):
        while True:
            events = self.selector.select(timeout=None)
            for key, mask in events:
                if key.data is None:
                    self.__accept_wrapper(key)
                else:
                    self.__service_connection(key, mask)

    def __accept_wrapper(self, key):
        sock = key.fileobj
        print("Listening for Connections")
        conn, addr = sock.accept()  # wait for client
        print(f"Connected by {addr}")
        conn.setblocking(False)
        data = types.SimpleNamespace(addr=addr, inb=b"", outb=b"")
        events = selectors.EVENT_READ | selectors.EVENT_WRITE
        self.selector.register(conn, events, data=data)

    def __service_connection(self, key, mask):
        sock = key.fileobj
        data = key.data
        if mask & selectors.EVENT_READ:
            recv_data = sock.recv(1024)  # Should be ready to read
            if recv_data:
                data.outb += recv_data
            else:
                print(f"Closing connection to {data.addr}")
                self.selector.unregister(sock)
                sock.close()
        if mask & selectors.EVENT_WRITE:
            if data.outb:
                # reply to ping
                sent = sock.send(b"+PONG\r\n")  # Should be ready to write
                # sent = self.__reply_to_ping(key)
                data.outb = data.outb[sent:]

    def __del__(self):
        self.selector.close()

if __name__ == "__main__":
    ServerWithSelect().listen_for_connections()