C＃读取TCP上的数据并不总是读取所有数据

时间：2017-11-19 19:02:39

标签： c# json sockets tcp

这是我的TCP侦听器，它读取收到的数据：

    private void Update()
    {
        //Console.WriteLine("Call");
        if (!serverStarted)
        {
            return;
        }

        foreach (ServerClient c in clients.ToList())
        {
            // Is the client still connected?
            if (!IsConnected(c.tcp))
            {
                c.tcp.Close();
                disconnectList.Add(c);
                Console.WriteLine(c.connectionId + " has disconnected.");
                CharacterLogout(c.connectionId);
                continue;
                //Console.WriteLine("Check for connection?\n");
            }
            else
            {
                // Check for message from Client.

                NetworkStream s = c.tcp.GetStream();
                if (s.DataAvailable)
                {
                    StreamReader reader = new StreamReader(s, true);
                    string data = reader.ReadLine();

                    if (data != null)
                    {
                        OnIncomingData(c, data);
                    }
                }
                //continue;
            }
        }

        for (int i = 0; i < disconnectList.Count - 1; i++)
        {
            clients.Remove(disconnectList[i]);
            disconnectList.RemoveAt(i);
        }


    }

    private bool IsConnected(TcpClient c)
    {
        try
        {
            if (c != null && c.Client != null && c.Client.Connected)
            {
                if (c.Client.Poll(0, SelectMode.SelectRead))
                {
                    return !(c.Client.Receive(new byte[1], SocketFlags.Peek) == 0);
                }

                return true;
            }
            else
            {
                return false;
            }
        }
        catch
        {
            return false;
        }
    }

    private void StartListening()
    {
        server.BeginAcceptTcpClient(OnConnection, server);
    }

通常情况下这很好。 例如，当我每2秒，3秒或更长的时间间隔发送一个请求时，一切正常。

然而，当我发送示例2的请求时，每1秒甚至更少的时间发送3个请求，在开始时它工作正常，一段时间后它只是剪切了收到的数据。

如果我经常发送请求，我会收到问题。以下是收到数据的示例。

Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"257.8289","position.z":"251.5683","position.y":"2.798551"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"257.8895","position.z":"251.6447","position.y":"2.796823"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"257.9507","position.z":"251.7218","position.y":"2.795079"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"258.0536","position.z":"251.8516","position.y":"2.792141"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"258.2184","position.z":"252.0594","position.y":"2.793153"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"258.2699","position.z":"252.1243","position.y":"2.795335"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"258.3738","position.z":"252.2554","position.y":"2.799742"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"258.5936","position.z":"252.5325","position.y":"2.80906"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"258.7353","position.z":"252.7112","position.y":"2.815068"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"258.7883","position.z":"252.778","position.y":"2.817239"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"258.9598","position.z":"252.9942","position.y":"2.809892"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"259.0203","position.z":"253.0705","position.y":"2.806783"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"259.0894","position.z":"253.1577","position.y":"2.803234"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"259.2439","position.z":"253.3524","position.y":"2.795195"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"259.4146","position.z":"253.5677","position.y":"2.784776"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"259.5829","position.z":"253.7799","position.y":"2.772557"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"259.7452","position.z":"253.9845","position.y":"2.762063"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"259.8754","position.z":"254.1487","position.y":"2.760789"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"260.0437","position.z":"254.3609","position.y":"2.759143"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"260.2104","position.z":"254.5711","position.y":"2.757511"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"260.5002","position.z":"254.8992","position.y":"2.756335"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"260.9822","position.z":"255.1375","position.y":"2.765062"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"261.5056","position.z":"255.2772","position.y":"2.787397"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"261.5968","position.z":"255.3015","position.y":"2.791161"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"261.7819","position.z":"255.3509","position.y":"2.797171"},"connectionId":1}
Character position Updated
{"header":"1x008","data":{"characterId":"1","position.x":"261.8941","position.z":"255.3809","position.y":"2.799694"},"connectionId":1}
Character position Updated
ion.z":"255.5631","position.y":"2.815049"},"connectionId":1}

正如您在最后一行中看到的那样，JSON被破坏了。数据无故缩减，它会使我的代码失效。

我可以确认客户端为服务器/侦听器端显示的最后一行发送有效的JSON字符串。

我认为它可能与缓冲区大小相关，但我在这个TCP通信中非常新。

这是来自客户端的发送功能：

public void Send(string header, Dictionary<string, string> data)
{

    if (stream.CanRead)
    {
        socketReady = true;
    }

    if (!socketReady)
    {
        return;
    }
    JsonData SendData = new JsonData();
    SendData.header = "1x" + header;
    foreach (var item in data)
    {
        SendData.data.Add(item.Key.ToString(), item.Value.ToString());
    }
    SendData.connectionId = connectionId;

    string json = JsonConvert.SerializeObject(SendData);
    var howManyBytes = json.Length * sizeof(Char);
    writer.WriteLine(json);
    writer.Flush();

    Debug.Log("Client World:" + json);
}

我的错误在哪里，我该如何解决？

1 个答案:

答案 0 :(得分：1)

A StreamReader包含两个内部缓冲区 - 一个已解码但尚未消耗的字符，以及一个已接收但尚未解码的字节（可能是用于多字节编码的不完整字符）。当它需要数据时，它首先检查缓冲区，如果它没有它需要的东西，那么它会读取＆＃34;一些＆＃34;来自流的数据，直到它可以完成当前请求（ReadLine()或其他）。在某些情况下，使用稀疏消息可能意味着它会完整地读取单个消息，这可能会错误地表明您的代码正在运行。但是，当多个消息靠近在一起时，它可以从套接字 over-read - 接收所有一条消息和另一条消息的一部分。这意味着每个套接字保留 StreamReader非常非常重要 - 否则当您将其放在地板上时，您将丢失套接字消耗的任何数据但未在之前的ReadLine()中阅读。这会使您看到的结果完全。所以：作为一个简单的修复：不是存储套接字，而是使用StreamReader 存储套接字的元组 - 并且每个套接字只创建一个读取器。

或者，你可以写得更好＆＃34;框架＆＃34;代码并手动缓冲数据（某处），直到您的框架完成（在您的情况下为行尾）。然后处理后缓冲区，小心保留帧后剩下的任何额外字节。如果您不熟悉网络代码，第一个选项可能更简单。但是第二个选项更好 - 它可以避免在收到部分帧时阻塞。目前，单个客户端可以通过发送一些没有换行的文本来杀死你的服务器，只是保持套接字打开（可能每隔30秒运行一次额外的字符）。这将导致您的服务器永远停留在ReadLine() - 或直到您的服务器OOM，因为如果传入文本。哎呀，发送一大块没有换行的文本！

这个可能就像（使用C＃vCurrent）

一样简单 
List<(Socket socket, StreamReader reader)> sockets = ...

...


// (adding)
var newSocket = ...
var reader = new StreamReader(...); // on newSocket
sockets.Add((newSocket, reader));
// ...

foreach(var pair in sockets) {
    // ...
    var socket = pair.socket;
    var line = pair.reader.ReadLine();
    if(line != null) {...}
    // ...
}
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