从Node.js中的TCP套接字读取字符串时出现问题 [英] Issues when reading a string from TCP socket in Node.js

问题描述

我已经实现了使用TCP套接字进行通信的客户端/服务器.我要写入套接字的数据是字符串化的JSON.最初，一切都按预期工作，但是，随着我提高写入速度，我最终遇到JSON解析错误，其中客户端的开头在旧的结尾接收了新的写入的开头.

I've implemented a client/server that communicate using a TCP socket. The data that I'm writing to the socket is stringified JSON. Initially everything works as expected, however, as I increase the rate of writes I eventually encounter JSON parse errors where the beginning on the client receives the beginning of the new write on the end of the old one.

这是服务器代码:

var data = {};
data.type = 'req';
data.id = 1;
data.size = 2;
var string = JSON.stringify(data);
client.write(string, callback());

这是我在客户端服务器上接收此代码的方式:

Here is how I am receiving this code on the client server:

client.on('data', function(req) {
    var data = req.toString();
    try {
        json = JSON.parse(data);
    } catch (err) {
         console.log("JSON parse error:" + err);
    } 
});

随着费率增加，我收到的错误是:

The error that I'm receiving as the rate increases is:

SyntaxError: Unexpected token {

这似乎是下一个被标记为当前请求末尾的请求的开始.

Which appears to be the beginning of the next request being tagged onto the end of the current one.

我尝试使用;作为每个JSON请求末尾的分隔符，然后使用:

I've tried using ; as a delimiter on the end of each JSON request and then using:

 var data = req.toString().substring(0,req.toString().indexOf(';'));

但是，这种方法并没有导致JSON解析错误，而是随着我将每秒写入速度提高了300次，似乎导致客户端完全丢失了一些请求.

However this approach, instead of resulting in JSON parse errors seems to result in completely missing some requests on the client side as I increase the rate of writes over 300 per second.

是否有最佳实践或更有效的方法来限制通过TCP套接字的传入请求?

Are there any best practices or more efficient ways to delimit incoming requests via TCP sockets?

谢谢！

推荐答案

感谢大家的解释，他们帮助我更好地理解了通过TCP套接字发送和接收数据的方式.下面是我最后使用的代码的简要概述:

Thanks everyone for the explanations, they helped me to better understand the way in which data is sent and received via TCP sockets. Below is a brief overview of the code that I used in the end:

var chunk = "";
client.on('data', function(data) {
    chunk += data.toString(); // Add string on the end of the variable 'chunk'
    d_index = chunk.indexOf(';'); // Find the delimiter

    // While loop to keep going until no delimiter can be found
    while (d_index > -1) {         
        try {
            string = chunk.substring(0,d_index); // Create string up until the delimiter
            json = JSON.parse(string); // Parse the current string
            process(json); // Function that does something with the current chunk of valid json.        
        }
        chunk = chunk.substring(d_index+1); // Cuts off the processed chunk
        d_index = chunk.indexOf(';'); // Find the new delimiter
    }      
});

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