我刚开始使用 Node.js，我现在正尝试让我的脚本每 10 秒在后台运行一次，就像守护进程等待做某事一样，当有事情要从数据库中运行时，它会从中读取输出程序并根据输出执行某些任务。

这是我到目前为止能做的，它按我的预期工作，但即使在后台也只能运行一次。我怎样才能让它像守护进程一样每 10 秒运行一次？

代码:

var spawn = require('child_process').spawn;
var mysql = require('mysql');
var JSFtp = require('jsftp');
var check = require('node-validator').check;
var sanitize = require('node-validator').sanitize;

//Setup the db connection
var db = mysql.createConnection({
  host : 'db',
  port : 3306,
  database: 'db',
  user : 'db',
  password : 'db'
});

//Make the connection
db.connect(function(err){
    if(err != null) {
        res.end('Error connecting to mysql:' + err+'\n');
    }
});

var die = function(msg){
    console.error(msg);
    process.exit(1);
}

function ip2long ( ip_address ) {
    var output = false;
    var parts = [];
    if (ip_address.match(/^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/)) {
        parts  = ip_address.split('.');
        output = ( parts[0] * 16777216 +
        ( parts[1] * 65536 ) +
        ( parts[2] * 256 ) +
        ( parts[3] * 1 ) );
    }
    return output;
}


db.query("SELECT * FROM queue WHERE cooldown > UNIX_TIMESTAMP(NOW()) AND simulated=0 ORDER BY cooldown DESC LIMIT 1", function(err, rows){
    if(err != null){
        die("Query error: " + err);
    }

    if(rows < 1){
        die("No rows");
    }

    //Set the vars from the query
    var name = rows[0]['name'];
    var ip = rows[0]['ip'];
    var iterations = rows[0]['runs'];

    var bin = "/home/hoar/sum/run"
    var args = ['arg='+name, 'arg2='+iterations, 'path=/var/www/upload/'+name+'.html', 'output=log.log'];
    var proc = spawn(bin, args);
    var time = "/.*/";
    var pct = "/^\d/";
    var name = rows[0]['name'];
    var ip = rows[0]['ip'];
    var iterations = rows[0]['runs'];

    proc.stdout.setEncoding('utf8');
    proc.stdout.on('data', function(data) {
        var str = data.toString();
        var s = str.split("|");
        var p = s[0].split("/");
        var t = (s[1] == null) ? "" : s[1];

        if(p != null && s[0] != "@"){ //Needed to check for @ because the program prints this as first line, which is good then we can do the query further done only once.
            //Check the return numbers from simc to see how many sims it has done
            if(parseInt(p[0]) < parseInt(p[1])){ 
                //Check if the 6th match is a number and the 7th only contains letters
                if(t != null){ 
                    var time = t.replace(/(\r\n|\n|\r)/gm,""); //Remove any line disturbers for db

                    //Update the database with the amount of time left on the simulation
                    db.query("UPDATE `queue` SET `status`=" + db.escape(time) + " WHERE (`name`=" + name + ")");
                    //console.log(p[0]+"/"+p[1] + " - " + t + " left");
                }
                //console.log(p[0]+"/"+p[1] + " iterations done");
            }
        }else{
            //If the stdout is null run this query since we don't want to run this more than once.
            db.query("UPDATE `queue` SET `simulated`='2' WHERE (`name`=" + name + " AND simulated!='2')");
            //console.log("Updated db to 2");
        }
    });

    proc.stderr.on('data', function (data) {
        var str = data.toString();
        //If the program returns stderr we want to make sure it stops and we update the database to let the user know.
        if(str.indexOf("ERROR! Setup failure...")){ 

            //Update the database with the amount of time left on the simulation
            db.query("UPDATE `queue` SET `simulated`='3' WHERE (`name`=" + name + ")");

            //Kill the DB connection
            db.destroy(); 
            die("There was an error: " + data);
        }
    });

    proc.on('exit', function (code) {
    //Setup the ftp connection
    var ftp = new JSFtp({
      host: "ftp",
      port: 21,
      user: "ftp",
      pass: "ftp"
    });

        //Simulation ended with success update the database and kill.
        db.query("UPDATE `queue` SET `simulated`='1' WHERE (`name`=" + name + " AND simulated='2')");

        ftp.put('/var/www/upload/'+rows[0]['name']+'.html', 'public_html/mysite/'+ip2long(rows[0]['ip'])+'/'+rows[0]['name']+'.html', function(hadError) {
          if (!hadError)
            console.log("FTP error");

            ftp.raw.quit();
        });
        db.destroy(); 
        //die("Simulation is done");
    });

});//end sql

最佳答案

将您的数据库查询放入一个带有回调的函数中，并让回调在 10 秒后再次触发该函数:

function mydbquery(callback) {
    db.query("SELECT * FROM queue WHERE cooldown > UNIX_TIMESTAMP(NOW()) AND simulated=0 ORDER BY cooldown DESC LIMIT 1", function(err, rows){
    if(err != null){
        die("Query error: " + err);
    }

    if(rows < 1){
        die("No rows");
    }

    //Set the vars from the query
    var name = rows[0]['name'];
    var ip = rows[0]['ip'];
    var iterations = rows[0]['runs'];

    var bin = "/home/hoar/sum/run"
    var args = ['arg='+name, 'arg2='+iterations, 'path=/var/www/upload/'+name+'.html', 'output=log.log'];
    var proc = spawn(bin, args);
    var time = "/.*/";
    var pct = "/^\d/";
    var name = rows[0]['name'];
    var ip = rows[0]['ip'];
    var iterations = rows[0]['runs'];

    proc.stdout.setEncoding('utf8');
    proc.stdout.on('data', function(data) {
        var str = data.toString();
        var s = str.split("|");
        var p = s[0].split("/");
        var t = (s[1] == null) ? "" : s[1];

        if(p != null && s[0] != "@"){ //Needed to check for @ because the program prints this as first line, which is good then we can do the query further done only once.
            //Check the return numbers from simc to see how many sims it has done
            if(parseInt(p[0]) < parseInt(p[1])){ 
                //Check if the 6th match is a number and the 7th only contains letters
                if(t != null){ 
                    var time = t.replace(/(\r\n|\n|\r)/gm,""); //Remove any line disturbers for db

                    //Update the database with the amount of time left on the simulation
                    db.query("UPDATE `queue` SET `status`=" + db.escape(time) + " WHERE (`name`=" + name + ")");
                    //console.log(p[0]+"/"+p[1] + " - " + t + " left");
                }
                //console.log(p[0]+"/"+p[1] + " iterations done");
            }
        }else{
            //If the stdout is null run this query since we don't want to run this more than once.
            db.query("UPDATE `queue` SET `simulated`='2' WHERE (`name`=" + name + " AND simulated!='2')");
            //console.log("Updated db to 2");
        }
    });

    proc.stderr.on('data', function (data) {
        var str = data.toString();
        //If the program returns stderr we want to make sure it stops and we update the database to let the user know.
        if(str.indexOf("ERROR! Setup failure...")){ 

            //Update the database with the amount of time left on the simulation
            db.query("UPDATE `queue` SET `simulated`='3' WHERE (`name`=" + name + ")");

            //Kill the DB connection
            db.destroy(); 
            die("There was an error: " + data);
        }
    });

    proc.on('exit', function (code) {
        //Setup the ftp connection
        var ftp = new JSFtp({
          host: "ftp",
          port: 21,
          user: "ftp",
          pass: "ftp"
        });

        //Simulation ended with success update the database and kill.
        db.query("UPDATE `queue` SET `simulated`='1' WHERE (`name`=" + name + " AND simulated='2')");

        ftp.put('/var/www/upload/'+rows[0]['name']+'.html', 'public_html/mysite/'+ip2long(rows[0]['ip'])+'/'+rows[0]['name']+'.html', function(hadError) {
          if (!hadError)
            console.log("FTP error");

            ftp.raw.quit();
        });
        db.destroy();

        //die("Simulation is done");
//NEW CODE!!! 
        callback();
//END OF NEW CODE
    });

});//end sql
}

//NEW CODE!!!
function wait10sec(){
    setTimeout(function(){
        mydbquery(wait10sec);
    }, 10000);
}

mydbquery(wait10sec);
//END OF NEW CODE

因此它将执行您的查询，然后等待 10 秒再触发另一个。

关于javascript - 每 10 秒运行一次 node.js 脚本，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/21461132/