Question

我正在使用sequelezer将值插入本地数据库。它是一种需要在服务器上第一次运行的安装脚本。

由于nodejs“异步”函数调用，我的sqlite db正在获取锁定，我收到以下错误 Unhandled rejection SequelizeTimeoutError: SQLITE_BUSY: database is locked

这是我的代码

    var country_json = {
      "AF": "Afghanistan",
      "AX": "\u00c5land Islands",
      "AL": "Albania",
      //........
      "ZW": "Zimbabwe"
    };

for (key in country_json) {

        console.log("ABUZAR");
        console.log(key.toString('utf8') + " " + country_json[key].toString('utf8'));

        db.country_name.findOrCreate({

                where: {
                    country_iso: key.toString('utf8')
                },
                defaults: {
                    country_name: country_json[key].toString('utf8')
                }
            })
            .spread(function(country, created) {
                console.log(country.get({
                plain: true
                }));
                console.log(created);
            });

    }

我尝试了很少的同步npm模块，但是每个模块似乎都在运行。只是想知道如何在节点js中处理这些场景。

Answer 1

您可以使用SynJS将异步函数与循环，逻辑，递归等混合在一起 - 它将以同步方式逐个执行所有步骤。以下是用于说明的脚本：

global.SynJS = global.SynJS || require('synjs');
var Sequelize = require('sequelize');

var db = new Sequelize('tracker', 'tracker', 'tracker123', {
      host: 'localhost',
      dialect: 'mysql',
      pool: {
        max: 5,
        min: 0,
        idle: 10000
      },
    });

function insertWrapper(db,context,key,value) { // <- wrapper function that returns initially incomplete result
    var res = {done: false};
    db.query("select CONCAT(?,'--->',?)", { replacements: [key,value], type: db.QueryTypes.SELECT })
    .spread(function(row) {
        console.log('done: row=',row);
        res.done = true;
        SynJS.resume(context); // once result is ready, it notifies context of caller function to continue
    });
    return res;
}

function myFunc(modules,db, country_json) { // <- function that is run via SynJS
    for (var key in country_json) {
        var res = modules.insertWrapper(db,_synjsContext,key,country_json[key]);
        SynJS.wait(res.done); // <-- wait for the callback to finish
    }
};

var modules = { // <-- convenience object to pass whatever myFunc may need, as it cannot access closures 
        insertWrapper:  insertWrapper,
};

var country_json = {
          "AF": "Afghanistan",
          "AX": "\u00c5land Islands",
          "AL": "Albania",
          //........
          "ZW": "Zimbabwe"
    };

// run myFunc via SynJS
SynJS.run(myFunc,null,modules,db,country_json,function () {
    db.close();
    console.log('done');
});

它会产生以下输出：

Executing (default): select CONCAT('AF','--->','Afghanistan')
done: row= { 'CONCAT(\'AF\',\'--->\',\'Afghanistan\')': 'AF--->Afghanistan' }
Executing (default): select CONCAT('AX','--->','Ã…land Islands')
done: row= { 'CONCAT(\'AX\',\'--->\',\'Ã…land Islands\')': 'AX--->Ã…land Islands' }
Executing (default): select CONCAT('AL','--->','Albania')
done: row= { 'CONCAT(\'AL\',\'--->\',\'Albania\')': 'AL--->Albania' }
Executing (default): select CONCAT('ZW','--->','Zimbabwe')
done: row= { 'CONCAT(\'ZW\',\'--->\',\'Zimbabwe\')': 'ZW--->Zimbabwe' }
done

用于在SQLite中插入datavalue的同步循环

1 个答案: