c# - 异步套接字调用卡住 UI 线程

Question

我一直在开发客户端到服务器的聊天信使，但遇到了一些有关异步调用的问题。一段时间以来，我一直在尝试修复它们，但没有成功。

问题出在客户端，连接到服务器没有问题，但是一旦调用第一个“BeginSend”方法，整个客户端就会停止响应。(它不会 100% 停止，它偶尔会响应，但是在一个荒谬的响应之后30 秒以上的时间)。其余调用运行良好，但 UI 不会响应。服务器响应也很好。

这是代码，我在此处评论了客户端首先卡住的地方。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Windows.Forms.VisualStyles;
using System.Net.Sockets;
using System.Net;

namespace Client_GUI_Design_Test
{
    public partial class Login : Form
    {
        public Socket clientSocket;
        public string strName;
        public byte[] byteData = new byte[1024];
        public List<String> contacts = new List<String>();
        public Boolean needUpdate = true;
       // public Panel globalPanel;
        public Login()
        {
            InitializeComponent();
        }

        public struct Contact
        {
            public string strName;
        }


        public int num1 = 0;
        public void addContact(String contactName, String message, int status, int imageNum)
        {
            //MessageBox.Show(this.Size.Width.ToString());
            panel1.HorizontalScroll.Enabled = false;
            panel1.HorizontalScroll.Visible = false;
            if (num1 >= panel1.Size.Height - 47)
            {
                panel1.Size = new Size(257, 514);
                this.Size = new Size(277, this.Size.Height);
                panel1.AutoScroll = true;
                panel1.HorizontalScroll.Enabled = false;
                panel1.HorizontalScroll.Visible = false;
                panel1.VerticalScroll.Visible = true;
            }
            panel1.VerticalScroll.Value = 0;
            //Contact Panel
            Panel contactPanel = new Panel();
            contactPanel.Size = new Size(249, 47);
            contactPanel.Margin = new System.Windows.Forms.Padding(0, 0, 0, 0);

            //Name Label
            Label name = new Label();
            //Font
            float size = 12.00f;
            name.Font = new Font("Microsoft Sans Serif", size, FontStyle.Bold);
            //Location
            name.Location = new Point(29, 3);
            //Size
            name.Size = new Size(112, 20);
            name.Text = contactName;
            //Events
            #region
            name.MouseEnter += delegate
            {
                contactPanel.BackColor = Color.Gainsboro;
            };
            name.MouseLeave += delegate
            {
                contactPanel.BackColor = System.Drawing.SystemColors.Control;
            };
            #endregion
            contactPanel.Controls.Add(name);

            //Image Box
            PictureBox image = new PictureBox();
            //Image
            image.Image = imageList1.Images[imageNum];
            //Size
            image.Size = new Size(56, 42);
            //Location
            image.Location = new Point(187, 4);
            //Events
            #region
            image.MouseEnter += delegate
            {
                contactPanel.BackColor = Color.Gainsboro;
            };
            image.MouseLeave += delegate
            {
                contactPanel.BackColor = System.Drawing.SystemColors.Control;
            };
            #endregion
            contactPanel.Controls.Add(image);

            //Status
            PictureBox statusPic = new PictureBox();
            //Image
            statusPic.Image = imageList2.Images[status];
            //Size
            statusPic.Size = new Size(20, 20);
            //Location
            statusPic.Location = new Point(3, 3);
            //Events
            #region
            statusPic.MouseEnter += delegate
            {
                contactPanel.BackColor = Color.Gainsboro;
            };
            statusPic.MouseLeave += delegate
            {
                contactPanel.BackColor = System.Drawing.SystemColors.Control;
            };
            #endregion
            contactPanel.Controls.Add(statusPic);

            //Message Label
            Label messageL = new Label();
            //Font
            float sizem = 11.25f;
            messageL.Font = new Font("Microsoft Sans Serif", sizem, FontStyle.Bold);
            messageL.ForeColor = Color.Gray;
            //Location
            messageL.Location = new Point(29, 23);
            //Size
            messageL.Size = new Size(153, 18);
            //Text
            messageL.Text = message;
            //Events
            #region
            messageL.MouseEnter += delegate
            {
                contactPanel.BackColor = Color.Gainsboro;
            };
            messageL.MouseLeave += delegate
            {
                contactPanel.BackColor = System.Drawing.SystemColors.Control;
            };
            messageL.MouseHover += delegate
            {
                ToolTip tip = new ToolTip();
                tip.Tag = messageL.Text;
                tip.Show(messageL.Text, messageL, 1, 1, 750);
            };
            #endregion

            contactPanel.Controls.Add(messageL);

            contactPanel.Paint += new PaintEventHandler(contactPanel_Paint);
            {


            };
            contactPanel.MouseEnter += delegate
            {
                contactPanel.BackColor = Color.Gainsboro;
            };
            contactPanel.MouseLeave += delegate
            {
                contactPanel.BackColor = System.Drawing.SystemColors.Control;
            };
            contactPanel.Location = new Point(0, num1);
            //globalPanel = contactPanel;
            //panel1.Controls.Add(contactPanel);
            addPanel(contactPanel);
            num1 += 47;


        }

        public delegate void UpdatePanelCallBack(Panel panel);
        private void addPanel(Panel panel)
        {
            if (InvokeRequired)
            {
                object[] pList = { panel };
                panel1.BeginInvoke(new
                   UpdatePanelCallBack(OnUpdatePanel), pList);
            }

            else
            {
                OnUpdatePanel(panel);
            }
        }

        private void OnUpdatePanel(Panel panel)
        {
            panel1.Controls.Add(panel);
        }

        VisualStyleRenderer renderer = new VisualStyleRenderer(VisualStyleElement.Button.PushButton.Normal);
        void contactPanel_Paint(object sender, PaintEventArgs e)
        {
            renderer.DrawEdge(e.Graphics, panel1.ClientRectangle,
                Edges.Top,
                EdgeStyle.Bump, EdgeEffects.Flat);
        }

        private void button3_Click(object sender, EventArgs e)
        {
            try
            {
                clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

                //IPAddress ipAddress = IPAddress.Parse(txtServerIP.Text);
                //Server is listening on port 43594
                IPEndPoint ipEndPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 43594);

                //Connect to the server
                clientSocket.BeginConnect(ipEndPoint, new AsyncCallback(OnConnect), null);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "SGSclient", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }


        }

        private void OnSend(IAsyncResult ar)
        {
            try
            {
                Socket client = (Socket)ar.AsyncState;
                client.EndSend(ar);
                //clientSocket.EndSend(ar);
               //strName = textBox2.Text;
               // DialogResult = DialogResult.OK;
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "SGSclient", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void OnConnect(IAsyncResult ar)
        {
            try
            {
                clientSocket.EndConnect(ar);

                //We are connected so we login into the server
                Data msgToSend = new Data();
                msgToSend.cmdCommand = Command.Login;
                msgToSend.strName = textBox2.Text;
                msgToSend.strMessage = null;

                byte[] b = msgToSend.ToByte();

                //Send the message to the server
                //HERE - Starts freezing the UI thread, continues to do background operations
                clientSocket.BeginSend(b, 0, b.Length, SocketFlags.None, new AsyncCallback(OnSend), clientSocket);

                clientSocket.BeginReceive(byteData,
                                       0,
                                       byteData.Length,
                                       SocketFlags.None,
                                       new AsyncCallback(OnReceive),
                                       clientSocket);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "SGSclient", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }

            panel4.Visible = false;
            panel1.Visible = true;
        }

        public void OnReceive(IAsyncResult ar)
        {
            try
            {
                clientSocket.EndReceive(ar);

                Data msgReceived = new Data(byteData);
                //Accordingly process the message received
                switch (msgReceived.cmdCommand)
                {
                    case Command.Login:
                        //lstChatters.Items.Add(msgReceived.strName);
                        break;

                    case Command.Logout:
                        //lstChatters.Items.Remove(msgReceived.strName);
                        break;

                    case Command.Message:
                        break;

                    case Command.List:
                        MessageBox.Show(msgReceived.strName);
                        //contacts.Add(msgReceived.strName);
                        needUpdate = true;
                        //lstChatters.Items.AddRange(msgReceived.strMessage.Split('*'));
                        //lstChatters.Items.RemoveAt(lstChatters.Items.Count - 1);
                        //txtChatBox.Text += "<<<" + strName + " has joined the room>>>\r\n";

                        break;
                }

                byteData = new byte[1024];

                clientSocket.BeginReceive(byteData,
                                          0,
                                          byteData.Length,
                                          SocketFlags.None,
                                          new AsyncCallback(OnReceive),
                                          clientSocket);

            }
            catch (ObjectDisposedException)
            { }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "SGSclientTCP: " + strName, MessageBoxButtons.OK, MessageBoxIcon.Error);
            }

        }

        private void Login_Load(object sender, EventArgs e)
        {
            CheckForIllegalCrossThreadCalls = false;
            //backgroundWorker1.RunWorkerAsync();

        }

        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            while (true)
            {
                if(needUpdate){

                }
            }
        }


        private void Login_DoubleClick(object sender, EventArgs e)
        {
            MessageBox.Show("");
            foreach (string s in contacts)
            {
                addContact(s, "Random Message", 0, 1);
                needUpdate = false;
            }
        }
    }
}

修复了其他类中的问题，但在 OnReceive 中仍然存在问题(可能有助于更快地识别问题)

public void OnReceive(IAsyncResult ar)
        {
            try
            {
                Socket client = (Socket)ar.AsyncState;
                client.EndReceive(ar);

                Data msgReceived = new Data(byteData);
                //Accordingly process the message received
                switch (msgReceived.cmdCommand)
                {
                    case Command.Login:
                        //lstChatters.Items.Add(msgReceived.strName);
                        break;

                    case Command.Logout:
                        //lstChatters.Items.Remove(msgReceived.strName);
                        break;

                    case Command.Message:
                        break;

                    case Command.List:
                        MessageBox.Show(msgReceived.strName);
                        //contacts.Add(msgReceived.strName);
                        needUpdate = true;
                        //lstChatters.Items.AddRange(msgReceived.strMessage.Split('*'));
                        //lstChatters.Items.RemoveAt(lstChatters.Items.Count - 1);
                        //txtChatBox.Text += "<<<" + strName + " has joined the room>>>\r\n";

                        break;
                }

                byteData = new byte[1024];

               /* client.BeginReceive(byteData,
                                          0,
                                          byteData.Length,
                                          SocketFlags.None,
                                          new AsyncCallback(OnReceive),
                                          client);*/

            }
            catch (ObjectDisposedException)
            { }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "SGSclientTCP: " + strName, MessageBoxButtons.OK, MessageBoxIcon.Error);
            }

        }

我知道这是很多代码，很抱歉，但这是我最后的选择，我完全被卡住了。任何帮助将不胜感激:)

Answer 1

您正在从不同的线程访问 clientSocket。

在 button3_Click 中调用 BeginConnect 像这样传递你的套接字:

//Connect to the server
clientSocket.BeginConnect(ipEndPoint, new AsyncCallback(OnConnect), clientSocket);

在 OnReceive 中从 AsyncState 获取套接字(调用 BeginConnect 时传递到这里):

Socket client = (Socket)ar.AsyncState;
client.EndReceive(ar);

来自 msdn EndConnect

EndConnect是阻塞方法，完成BeginConnect方法中启动的异步远程主机连接请求

在调用 BeginConnect 之前，您需要创建一个实现 AsyncCallback 委托(delegate)的回调方法。此回调方法在单独的线程中执行，并在 BeginConnect 返回后由系统调用。回调方法必须接受 BeginConnect 方法返回的 IAsyncResult 作为参数。

编辑:

正如我在您的代码中看到的那样，您正在使用 byteData 缓冲区，它被声明为类字段并在 BeginReceive 尝试访问它时从另一个线程访问它。查看异步服务器套接字示例，了解如何处理读取部分。

您可以在 msdn Socket Code Examples 上查看此示例

Asynchronous Server Socket Example

Asynchronous Client Socket Example