如何在 python 中不等待地使用套接字

Question

I create a game in Python, the game consists of several snakes each controlled by a different computer. Each computer sends to the server computer the angle to which the snake is directed.

The problem is that the command

client_mess = client_socket.recv(1024)

greatly inhibits server operation and causes the game to run very slowly. I am looking for a way to use the user message sent by the user, and if no message has been sent since the previous one the server will use the previous message and not wait for another message.

These are the relevant sections of my code:

Server:

server_socket = socket.socket()
server_socket.bind(('0.0.0.0', 5050))
server_socket.listen(1)
print("Server is up and running")

while not done:
    server_socket = socket.socket()
    server_socket.bind(('0.0.0.0', 5050))
    server_socket.listen(1)
    print("Server is up and running")

Client:

while not done:
    
    for event in pygame.event.get():  # User did something
        if event.type == pygame.QUIT:  # If user clicked close
            done = True  # Flag that we are done so we exit this loop
    siz = type(siz)
    my_socket=socket.socket(socket.AF_INET, socket.SOCK_STREAM)

    my_socket.connect(('127.0.0.1', 5050))

    message = str(siz)

    my_socket.send(message.encode())

Answer 1

You can use sockets in non-blocking mode:

import pygame as pg
import socket

pg.init()

client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client.connect(("localhost", 55555)) # Connect to server
client.setblocking(False) # Prevent socket from waiting for input

W, H = 640, 480
FLAGS = 0

screen = pg.display.set_mode((W, H), FLAGS)
W, H = screen.get_size()

font = pg.font.SysFont("arial", 30)

text = ""

running = True
while running:
    for event in pg.event.get():
        if event.type == pg.QUIT:
            running = False
        elif event.type == pg.KEYDOWN and event.key == pg.K_ESCAPE:
            running = False

    try:
        raw = client.recv(1024)
    except BlockingIOError:
        pass # No new data. Reuse old data
    else:
        text = raw.decode("utf-8") # New data has arrived. Use it

    screen.fill((0, 0, 0))
    img = font.render(text, True, (255, 255, 255))
    r = img.get_rect(center=(W // 2, H // 2))
    screen.blit(img, r)
    pg.display.update()

This assumes a simple server script like this:

import socket

server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

server.bind(("localhost", 55555))
server.listen()

while True:
    client, address = server.accept()
    print("Connected to", address)
    while True:
        line = input("> ")
        try:
            client.send(line.encode("utf-8"))
        except ConnectionError as e:
            print(e)
            print("Disconnecting")
            client.close()
            break

It will display whatever line of text you entered on the server in the center of the pygame window.

---

If you want t he reverse situation, where the server has a pygame window open, you can use these pieces of code:

server:

import socket

import pygame as pg

pg.init()

W, H = 640, 480
FLAGS = 0

screen = pg.display.set_mode((W, H), FLAGS)
W, H = screen.get_size()

server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.bind(("localhost", 55556))
server.listen(1)
server.setblocking(False)
client = None

font = pg.font.SysFont("arial", 30)

text = ""

clock = pg.time.Clock()
running = True
while running:
    for event in pg.event.get():
        if event.type == pg.QUIT:
            running = False
        elif event.type == pg.KEYDOWN and event.key == pg.K_ESCAPE:
            running = False
        elif event.type == pg.VIDEORESIZE:
            screen = pg.display.set_mode(event.size, FLAGS)
            W, H = screen.get_size()
    # Logic
    dt = clock.tick()

    if client is None:
        try:
            client, address = server.accept()
        except BlockingIOError:
            pass
    else:
        try:
            raw = client.recv(1024)
        except BlockingIOError:
            pass
        else:
            text = raw.decode("utf-8")


    # Render
    screen.fill((0, 0, 0))
    img = font.render(text, True, (255, 255, 255))
    r = img.get_rect(center=(W // 2, H // 2))
    screen.blit(img, r)

    pg.display.update()
    pg.display.set_caption(f"FPS: {clock.get_fps():.2f}")

client

import socket

client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

client.connect(("localhost", 55556))

try:
    while True:
        line = input("> ")
        try:
            client.send(line.encode("utf-8"))
        except ConnectionError as e:
            print(e)
            print("Disconnecting")
            break
finally:
    client.close()

If you want both to have pygames windows, I would suggest considering using multiple clients and one non-pygame server instead. But similar code should work anyway.