我正在尝试建立一个聊天应用程序（一对一）使用node.js，express，mysql和socket为后端和flutter为客户端…问题是当socket没有连接或超时。。。我想用redis来处理这个问题…所以当用户a想给用户b发送消息，但是socket断开时，我想用redis来存储聊天，然后在socket连接后再发送回来。。。我试着搜索一些关于它的资源或文章，但很难找到如何使用redis和socket进行聊天的应用程序。。。有人知道如何使用redis编写socket的资源、文档或代码吗？下面是我的部分代码后，我遵循一些教程

io.on('connection', socket => {
    id = socket.handshake.query.id
    socket.join(id)

    socket.on('sendmessage', x => {
        receiver = x.receiver
        sender = x.sender
        message = x.message
         var d = new Date(),
             dformat = [d.getFullYear(),
             d.getMonth() + 1,
             d.getDate()].join('-') + ' ' +
                 [d.getHours(),
                 d.getMinutes(),
                 d.getSeconds()].join(':');
        connection.query("INSERT INTO chat (sender, receiver, message, date) VALUES ('" + sender + "', '" + receiver + "', '" + message + "', '" + dformat + "')", function (error, result) {
         });

        socket.in(receiver).emit('receivemessage', {
            'message': message,
            'sender': sender,
            'receiver': receiver,
        })
         connection.query("SELECT * FROM chat WHERE (sender = '" + sender + "' AND receiver = '" + receiver + "') OR (sender = '" + receiver + "' AND receiver = '" + sender + "') ORDER BY date", function (err, messages) {
         });
    })
});