atomic-key-store.js

'use strict';

var fs = require('fs');
var path = require('path');
var safeObj = require('./safeObj');

module.exports = function JsonStore(name, filestoreDir) {
    var self = this;
    var sourceData = { };
    var loopPtr;
    var fileSource = path.join(filestoreDir, name);

    fs.readFile(fileSource, function(err, json) {
        if (err) throw new Error(err);
        sourceData = JSON.parse(json);
    });

    return {
        get: get.bind(this),
        set: set.bind(this),
        spin: spin.bind(this, loopPtr)
    };

    // Atomic Spinner - Updates dataSource Atommicly
    function spin(loopPtr) {
        if (loopPtr) return;
        loopPtr = setTimeout(function() {
            if (loopPtr) {
                clearTimeout(loopPtr);
                loopPtr = null;
            }

            var files = fs.readdirSync(filestoreDir)
            var latest = files.map(function(file) {
                if (file.match(/.json$/)) {
                    var token = parseInt(path.basename(file, '.json'));
                    if (token !== NaN) return token;
                }
                return 0;
            }).sort().pop() + '.json';

            fs.renameSync(fileSource, fileSource + '.old');
            fs.renameSync(path.join(filestoreDir, latest), fileSource);

            fs.readFile(filestoreDir, function(err, json) {
                if (err) throw new Error(err);
                sourceData = JSON.parse(json);

                files.push(name + '.old');
                files.forEach(function(file) {
                    try {
                        fs.unlink(path.join(filestoreDir, file));
                    } catch (e) {}
                });
            });
        }.bind(this), 100);
    }

    function set(args, value) {
        return (function __set(obj, args, value) {
            var key = args.shift();
            if(args.length === 0) {
                obj[key] = value;
                return obj;
            }
            obj[key] = obj[key] || { };
            return __set.call(this, obj[key], args, value);
        }).call(dataSource, dataSource, args, value);
    }

    function get() {
        var args = Array.prototype.slice.call(arguments);
        var result = safeObj(sourceData)(args);

        if (result === undefined ||
            (typeof result === 'object' && Object.keys(result).length === 0)) {
            return null;
        }
        return result;
    }
};