Question

所以我是节点js的新手，我试图移植现有的API。这个函数我只是简单地使用udp来查询远程服务器并等待响应，但是当我循环大量随机生成的查询时，很多都会开始计时。

当我检查服务器日志时，我注意到并非所有查询请求都能通过。这种情况只有在我循环几百次或更多次时才会发生，当数量较小时，很少发生。

var dgram = require("dgram");
var randomstring = require("randomstring");
var xml2js = require("xml2js");
var naTools = require("./NATools.js")

var ipVersion = 5;
var apiId = 7;

/**
 *
 * @param queryParamArray query params
 * @param callback function provided by user
 */
exports.queryServer = function(queryParamArray, callback) {
    //set socket type and query string
    var client = dgram.createSocket("udp4");
    var transactionId = randomstring.generate({
        length : 20,
        charset : "alphanumeric"
    });
    var queryString = queryParamArray[0] + ";" + queryParamArray[1] + ";" + queryParamArray[2] + ";" + ipVersion + ";" + apiId + ";" + transactionId + ";";
    var responseObject;
    var bufferMsg = new Buffer(queryString);

//if the request times out, close the client and call the callback function with the response
var timeoutObject = setTimeout(function() {
    client.close();
    responseObject = "Error : Request timed out after " + queryParamArray[4] + " milliseconds for transaction : " + transactionId;
    callback(responseObject);
}, queryParamArray[4]);

//parses the message received from the netacuity server and calls a function that generates the response objects and calls the callback function
client.on("message", function(message) {
    client.close();
    clearTimeout(timeoutObject);
    var msg = message.toString();
    var delimitedArray = msg.split(";");

    //find the transactionId section, followed by the error, and then the fields - sometimes netacuity server pads with an extra field
    var index = 0;
    while(delimitedArray[index] != transactionId && index<delimitedArray.length){
        index++;
    }

    if(index >= delimitedArray.length) {
        responseObject = "Error : transaction id from response does not match transaction id of request.";
        callback(responseObject);
        return;
    }

    if(delimitedArray[index+1] == '') { //make sure error field is empty
        var responseArray = delimitedArray.slice(index+2, delimitedArray.length-1);
        var paramArray = [queryParamArray[0], transactionId, queryParamArray[2]];
        naTools.generateResponseObject(paramArray, responseArray, callback);
    } else {
        responseObject = "Error : " + delimitedArray[index+1];
        callback(responseObject);
        return;
    }
});
//send the request
client.send(bufferMsg, 0, bufferMsg.length, 5400, queryParamArray[3], function() {
    console.log("Querying Server : " + queryString);
});

}

naTools.generateResponseObject只是一个基于paramArray [0]的switch语句，它生成一个带有数据的Object，并在其上调用传入的回调函数。

以下是测试用例:(假设所有必需的导入都在那里）

 var databaseEnums = {
 xxx             : 3,
 xxx             : 4,
 xxx             : 5,
 xxx             : 6,
 xxx             : 7,
 xxx             : 8,
 xxx             : 9,
 xxx             : 10,
 xxx             : 11,
 xxx             : 12,
 xxx             : 14,
 xxx             : 15,
 xxx             : 17,
 xxx             : 18,
 xxx             : 19,
 xxx             : 24,
 xxx             : 25,
 xxx             : 26
 };

var incompleteIp = "2.242.71."; //put some c class ip here
var randomIp = incompleteIp;
for(var i = 0; i < 500; i++) { //running x test queries
    for(var j = 0; j < 3; j++) {
        var randomNumber = j == 0 ? Math.floor(Math.random() * 3) : Math.floor(Math.random() * 6);
        randomIp += randomNumber;
    }
    var propertyList = Object.keys(databaseEnums);
    var randomPropertyName = propertyList[Math.floor(Math.random()*propertyList.length)];
    var randomFeatureCode = databaseEnums[randomPropertyName];
    api.queryServer([randomFeatureCode, 64, randomIp, "192.168.11.28", 2000, 5400], function(response) {
        console.log(response);
    });
    randomIp = incompleteIp;
}

我不明白为什么有些查询无法进入服务器并且for循环超过300时会超时？有时它会发生，有时它们都会完成。我做错了什么阻止了事件循环？

缩放时节点JS UDP数据报API挂起

0 个答案: