流水号工具

key.js

var db = require('../config.js').db;
db.bind('sequence');
var defaultName = 'common';
var defaultOffset = 1;
var sequenceMap = {};
var sequenceLockMap = {};
exports.next = function(callback){
    exports.nextKey(defaultName, callback);
};

exports.nextKey = function(name,callback){
    if(name == undefined){
        name = defaultName;
    }
    if(sequenceLockMap[name]!=undefined) {
        setTimeout(exports.next, 5,name,callback);
        return;
    }
    if(sequenceMap[name] == undefined){
        sequenceLockMap[name] = true;
        db.sequence.findOne({_id:name}, function (err, result) {
            if(!err ){
                if(result!=undefined){
                    seq = result;
                    seq['current'] = seq['index'];
                    sequenceMap[name] = seq;
                    getKey(seq, callback);
                }else{
                    seq = {_id: name, index: 0, offset: defaultOffset};
                    sequenceMap[name] = seq;
                    seq.current = 0;
                    db.sequence.save(seq,null,function(err,result){
                        getKey(seq, callback);
                    });
                }
            }
        });
    }else{
        getKey(sequenceMap[name], callback);
    }
};

function getKey(seq,callback){
    if(seq['current']<seq['index']){
        seq['current'] = seq['current']+1;
        callback(null, seq['current']);
    }else{
        seq['index'] = seq['index'] + seq['offset'];
        db.sequence.save(seq,function(err,result) {
            seq['current'] = seq['current']+1;
            callback(null, seq['current']);
            sequenceLockMap[seq._id] = undefined;
        });
    }
}
if(!module.parent){
    console.log('key.next()', exports.next(function (err,num){console.log(num)}));
    console.log('key.next("test")', exports.nextKey('test',function (err,num){console.log(num)}));
}