如何使用回调发出Flask SocketIO请求,这些回调在用户重新加入并更改sid后仍然有效



总结问题

我正在使用Flask SocketIO作为一个项目,基本上是想让用户重新加入一个房间;从他们停止的地方继续;更具体地说:

  1. 服务器向客户端发出一个请求,其中包含一个处理响应的回调和1秒的超时。这是在一个循环中完成的,以便在用户重新加入房间时重新发送请求
  2. 用户";重新加入";房间被定义为加入一个房间的用户,该房间的名称与之前与该房间断开连接的用户的名称相同。在这种情况下,用户被赋予他们的新SID,并且向客户端的请求被发送到新SID

我看到的是:

  1. 如果用户加入会议室并正常执行所有操作,则回调将在服务器上得到正确处理。

  2. 如果用户在服务器发送请求时重新加入房间,然后提交响应,JavaScript方面的一切都很好,服务器收到ack,但实际上并没有运行它应该运行的回调:

    uV7BTVtBXwQ6oopnAAAE: Received packet MESSAGE data 313["#000000"]
    received ack from Ac8wmpy2lK-kTQL7AAAF [/]
    

这个问题和我的类似,但他们的解决方案是更新Flask SocketIO,我运行的版本比他们的更新:python Flask SocketIO服务器收到消息,但没有';t触发事件

显示某些代码

我已经创建了一个存储库;最小";示例如下:https://github.com/eshapiro42/socketio-example.

如果将来该链接发生了什么事情,以下是相关的位:

# app.py
from gevent import monkey
monkey.patch_all()
import flask_socketio
from collections import defaultdict
from flask import Flask, request, send_from_directory
from user import User

app = Flask(__name__)
socketio = flask_socketio.SocketIO(app, async_mode="gevent", logger=True, engineio_logger=True)

@app.route("/")
def base():
return send_from_directory("static", "index.html")
@app.route("/<path:path>")
def home(path):
return send_from_directory("static", path)
# Global dictionary of users, indexed by room
connected_users = defaultdict(list)
# Global dictionary of disconnected users, indexed by room
disconnected_users = defaultdict(list)

@socketio.on("join room")
def join_room(data):
sid = request.sid
username = data["username"]
room = data["room"]
flask_socketio.join_room(room)
# If the user is rejoining, change their sid
for room, users in disconnected_users.items():
for user in users:
if user.name == username:
socketio.send(f"{username} has rejoined the room.", room=room)
user.sid = sid
# Add the user back to the connected users list
connected_users[room].append(user)
# Remove the user from the disconnected list
disconnected_users[room].remove(user)
return True
# If the user is new, create a new user
socketio.send(f"{username} has joined the room.", room=room)
user = User(username, socketio, room, sid)
connected_users[room].append(user)
return True

@socketio.on("disconnect")
def disconnect():
sid = request.sid
# Find the room and user with this sid
user_found = False
for room, users in connected_users.items():
for user in users:
if user.sid == sid:
user_found = True
break
if user_found:
break
# If a matching user was not found, do nothing
if not user_found:
return
room = user.room
socketio.send(f"{user.name} has left the room.", room=room)
# Remove the user from the room
connected_users[room].remove(user)
# Add the user to the disconnected list
disconnected_users[room].append(user)
flask_socketio.leave_room(room)

@socketio.on("collect colors")
def collect_colors(data):
room = data["room"]
for user in connected_users[room]:
color = user.call("send color", data)
print(f"{user.name}'s color is {color}.")

if __name__ == "__main__":
socketio.run(app, debug=True)
# user.py
from threading import Event # Monkey patched
class User:
def __init__(self, name, socketio, room, sid):
self.name = name
self.socketio = socketio
self.room = room
self._sid = sid
@property
def sid(self):
return self._sid
@sid.setter
def sid(self, new_sid):
self._sid = new_sid
def call(self, event_name, data):
"""
Send a request to the player and wait for a response.
"""
event = Event()
response = None
# Create callback to run when a response is received
def ack(response_data):
print("WHY DOES THIS NOT RUN AFTER A REJOIN?")
nonlocal event
nonlocal response
response = response_data
event.set()

# Try in a loop with a one second timeout in case an event gets missed or a network error occurs
tries = 0
while True:
# Send request
self.socketio.emit(
event_name,
data, 
to=self.sid,
callback=ack,
)
# Wait for response
if event.wait(1):
# Response was received
break
tries += 1
if tries % 10 == 0:
print(f"Still waiting for input after {tries} seconds")
return response
// static/client.js
var socket = io.connect();
var username = null;
var room = null;
var joined = false;
var colorCallback = null;
function joinedRoom(success) {
if (success) {
joined = true;
$("#joinForm").hide();
$("#collectColorsButton").show();
$("#gameRoom").text(`Room: ${room}`);
}
}
socket.on("connect", () => {
console.log("You are connected to the server.");
});
socket.on("connect_error", (data) => {
console.log(`Unable to connect to the server: ${data}.`);
});
socket.on("disconnect", () => {
console.log("You have been disconnected from the server.");
});
socket.on("message", (data) => {
console.log(data);
});
socket.on("send color", (data, callback) => {
$("#collectColorsButton").hide();
$("#colorForm").show();
console.log(`Callback set to ${callback}`);
colorCallback = callback;
});
$("#joinForm").on("submit", (event) => {
event.preventDefault();
username = $("#usernameInput").val();
room = $("#roomInput").val()
socket.emit("join room", {username: username, room: room}, joinedRoom);
});
$("#colorForm").on("submit", (event) => {
event.preventDefault();
var color = $("#colorInput").val();
$("#colorForm").hide();
colorCallback(color);
});
$("#collectColorsButton").on("click", () => {
socket.emit("collect colors", {username: username, room: room});
});
<!-- static/index.html  -->
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<title>Socket.IO Example</title>
</head>
<body>
<p id="gameRoom"></p>
<form id="joinForm">
<input id="usernameInput" type="text" placeholder="Your Name" autocomplete="off" required>
<input id="roomInput" type="text" placeholder="Room ID" autocomplete="off" required>
<button id="joinGameSubmitButton" type="submit" btn btn-dark">Join Room</button>
</form>
<button id="collectColorsButton" style="display: none;">Collect Colors</button>
<form id="colorForm" style="display: none;">
<p>Please select a color.</p>
<input id="colorInput" type="color" required>
<button id="colorSubmitButton" type="submit">Send Color</button>
</form>
<script src="https://code.jquery.com/jquery-3.3.1.min.js" integrity="sha256-FgpCb/KJQlLNfOu91ta32o/NMZxltwRo8QtmkMRdAu8=" crossorigin="anonymous"></script>
<script src="https://cdn.socket.io/4.4.1/socket.io.min.js" integrity="sha384-fKnu0iswBIqkjxrhQCTZ7qlLHOFEgNkRmK2vaO/LbTZSXdJfAu6ewRBdwHPhBo/H" crossorigin="anonymous"></script>
<script src="client.js"></script>
</body>
</html>

编辑

再现步骤

  1. 启动服务器python app.py并在浏览器中访问localhost:5000
  2. 输入任何用户名和房间ID并点击";加入会议室">
  3. 单击";收集颜色">
  4. 选择一种颜色并单击";发送"选择器应该消失,服务器应该打印出一个确认
  5. 重新加载所有内容
  6. 重复步骤2和3,然后复制房间ID
  7. 退出页面,然后导航回该页面
  8. 输入与步骤6中相同的用户名和房间ID,然后单击";加入会议室">
  9. 选择一种颜色并单击";发送"选择器短暂地消失了,但随后又回来了,因为服务器没有正确处理响应,而是一直发送请求

编辑2

我设法解决了(而不是解决(这个问题,在服务器端添加了更多的状态变量,并实现了更多的事件,以避免完全使用回调。我仍然很想知道基于回调的方法出了什么问题,因为使用它对我来说似乎更干净

这些回调不起作用的原因是,您正在从基于旧的和断开连接的套接字的上下文中进行发射。

回调与request.sid标识的套接字相关联。通过将回调与套接字关联,Flask SocketIO可以在调用回调时安装正确的应用程序和请求上下文。

您对颜色提示进行编码的方式并不好,因为您有一个长时间运行的事件处理程序,它在客户端离开并在不同的套接字上重新连接后继续运行。更好的设计是客户端在自己的事件中发送选定的颜色,而不是作为回调响应发送到服务器。

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