How can C TCP set heartbeat packets to be elegant?

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One 、 explain

Why set the heartbeat ？

The heartbeat mechanism sends a customized message at regular intervals Structure ( Heartbeat bag ), Let the other person know that they are still alive , To ensure the validity of the connection . The data received and sent in the network are all from the operating system SOCKET To implement . But if this Socket It's disconnected , There must be problems when sending and receiving data . But how to judge whether this socket can still be used ？ This requires creating a heartbeat mechanism in the system . Actually TCP A mechanism called heartbeat has been implemented for us in .

But this mechanism is limited by the operating system , And it's easy to make false positives . So it is rarely used by everyone .

The most used , Is to design the data package by yourself , Then reserve the heartbeat format , When the other party receives the heartbeat packet , Just return the response package directly .

that , In this way , Let's use RRQMSocket Elegant realization .

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Two 、 Assembly source code

2.1 Source location

• Gitee
• Github

2.2 documentation

The front page of the document

3、 ... and 、 install

Nuget install RRQMSocket that will do , See link blog for specific steps .

VS、Unity Installation and use Nuget package

Four 、 data format

4.1 Design data format

Before using heartbeat , The data format must be clear , Never confuse business data . Generally, it fits Plc When waiting for ready-made modules , They have a fixed data format , At this time, you can refer to Data processing adapter , Quickly parse data .

But in this article , There is no prescribed format , So we need to design a simple and efficient data format first .

as follows ：

Data length	data type	Load data
2 byte （Ushort）	1 byte （Byte）	n byte （<65535）

4.2 Parse data format

class MyFixedHeaderDataHandlingAdapter : CustomFixedHeaderDataHandlingAdapter<MyRequestInfo>
{
    
    public override int HeaderLength => 3;

    protected override MyRequestInfo GetInstance()
    {
    
        return new MyRequestInfo();
    }
}

class MyRequestInfo : IFixedHeaderRequestInfo
{
    
    public DataType DataType {
     get; set; }
    public byte[] Data {
     get; set; }

    public int BodyLength {
     get; private set; }

    public bool OnParsingBody(byte[] body)
    {
    
        if (body.Length == this.BodyLength)
        {
    
            this.Data = body;
            return true;
        }
        return false;
    }

    public bool OnParsingHeader(byte[] header)
    {
    
        if (header.Length == 3)
        {
    
            this.BodyLength = RRQMBitConverter.Default.ToUInt16(header, 0)-1;
            this.DataType = (DataType)header[2];
            return true;
        }
        return false;
    }

    public void Package(ByteBlock byteBlock)
    {
    
        byteBlock.Write((ushort)((this.Data == null ? 0 : this.Data.Length) + 1));
        byteBlock.Write((byte)this.DataType);
        byteBlock.Write(Data);
    }

    public byte[] PackageAsBytes()
    {
    
        using ByteBlock byteBlock = new ByteBlock();
        this.Package(byteBlock);
        return byteBlock.ToArray();
    }

    public override string ToString()
    {
    
        return $" data type ={
      this.DataType}, data ={
      (this.Data==null?"null":Encoding.UTF8.GetString(this.Data))}";
    }
}

enum DataType : byte
{
    
    Ping,
    Pong,
    Data
}

5、 ... and 、 Create an extension class

/// <summary>
///  A heartbeat counter extension .
/// </summary>
static class DependencyExtensions
{
    
    public static readonly DependencyProperty HeartbeatTimerProperty =
        DependencyProperty.Register("HeartbeatTimer", typeof(Timer), typeof(DependencyExtensions), null);

    public static bool Ping<TClient>(this TClient client)where TClient:ITcpClientBase
    {
    
        try
        {
    
            client.Send(new MyRequestInfo() {
     DataType = DataType.Ping }.PackageAsBytes());
            return true;
        }
        catch(Exception ex)
        {
    
            client.Logger.Exception(ex);
        }

        return false;
    }

    public static bool Pong<TClient>(this TClient client) where TClient : ITcpClientBase
    {
    
        try
        {
    
            client.Send(new MyRequestInfo() {
     DataType = DataType.Pong }.PackageAsBytes());
            return true;
        }
        catch (Exception ex)
        {
    
            client.Logger.Exception(ex);
        }

        return false;
    }
}

6、 ... and 、 Create heartbeat plug-in class

class HeartbeatAndReceivePlugin : TcpPluginBase
{
    
    private readonly int m_timeTick;

    [DependencyInject(1000*5)]
    public HeartbeatAndReceivePlugin(int timeTick)
    {
    
        this.m_timeTick = timeTick;
    }

    protected override void OnConnecting(ITcpClientBase client, ClientOperationEventArgs e)
    {
    
        client.SetDataHandlingAdapter(new MyFixedHeaderDataHandlingAdapter());// Setup adapter .
        base.OnConnecting(client, e);
    }

    protected override void OnConnected(ITcpClientBase client, RRQMEventArgs e)
    {
    
        if (client is ISocketClient)
        {
    
            return;// It can be judged here , If it is a server , Do not use heartbeat .
        }

        if (client.GetValue<Timer>(DependencyExtensions.HeartbeatTimerProperty) is Timer timer)
        {
    
            timer.Dispose();
        }

        client.SetValue(DependencyExtensions.HeartbeatTimerProperty,new Timer((o)=> 
        {
    
            client.Ping();
        },null,0, m_timeTick));

        base.OnConnected(client, e);
    }

    protected override void OnDisconnected(ITcpClientBase client, ClientDisconnectedEventArgs e)
    {
    
        base.OnDisconnected(client, e);
        if (client.GetValue<Timer>(DependencyExtensions.HeartbeatTimerProperty) is Timer timer)
        {
    
            timer.Dispose();
            client.SetValue(DependencyExtensions.HeartbeatTimerProperty,null);
        }
    }

    protected override void OnReceivedData(ITcpClientBase client, ReceivedDataEventArgs e)
    {
    
        if (e.RequestInfo is MyRequestInfo myRequest)
        {
    
            client.Logger.Message(myRequest.ToString());
            if (myRequest.DataType== DataType.Ping)
            {
    
                client.Pong();
            }
        }
        base.OnReceivedData(client, e);
    }
}

7、 ... and 、 test 、 start-up

class Program
{
    
    static TcpService service = new TcpService();
    static TcpClient tcpClient = new TcpClient();
    static void Main(string[] args)
    {
    
        ConsoleAction consoleAction = new ConsoleAction();

        service.Setup(new RRQMConfig()// Load configuration  
            .SetListenIPHosts(new IPHost[] {
     new IPHost("127.0.0.1:7789"), new IPHost(7790) })// Listen to two addresses at the same time 
            .SetMaxCount(10000)
            .UsePlugin()
            .SetThreadCount(10))
            .Start();// start-up 

        service.AddPlugin<HeartbeatAndReceivePlugin>();
        service.Logger.Message(" Server started successfully ");


        tcpClient.Setup(new RRQMConfig()
            .SetRemoteIPHost(new IPHost("127.0.0.1:7789"))
            .UsePlugin()
            .SetBufferLength(1024 * 10));

        tcpClient.AddPlugin<HeartbeatAndReceivePlugin>();

        tcpClient.Connect();
        tcpClient.Logger.Message(" Client successfully connected ");

        consoleAction.OnException += ConsoleAction_OnException;
        consoleAction.Add("1", " Send a heartbeat ", () =>
          {
    
              tcpClient.Ping();
          });
        consoleAction.Add("2", " send data ", () =>
          {
    
              tcpClient.Send(new MyRequestInfo()
              {
    
                  DataType = DataType.Data,
                  Data = Encoding.UTF8.GetBytes(Console.ReadLine())
              }
              .PackageAsBytes());
          });
        consoleAction.ShowAll();
        while (true)
        {
    
            consoleAction.Run(Console.ReadLine());
        }
    }

    private static void ConsoleAction_OnException(Exception obj)
    {
    
        Console.WriteLine(obj);
    }
}

8、 ... and 、 effect

this paper Example demo