intkeygenerator/KeyGenerator.js

int secuential primarykey generator for SQL Server

var callbackRange;

var blockSize = 20;
var nextValue;
var startValue;
var queue = [];

function setRangeReservationCallback (callback)
{
	if (callbackRange && callbackRange != null) throw new Error('la funcion callback ya esta asignada.');
	callbackRange = callback;
}

function getBlock (size, callback){
	blockSize = size;
	callbackRange(size, function(err, value){
		if (err) {
			callback(err, null);
		} else {
			nextValue = value;	
			startValue = value;
			callback(err, value);
		}
	});
}

function next (callback){
	queue.push(callback);
	if (queue.length != 1) {
		return;
	}
	nextBody();
}

function nextBody(){
	if (isNaN(nextValue) || nextValue == null || startValue + blockSize == nextValue) {
		//console.log('start: ' + startValue + ', blockSize: ' + blockSize + ', nextValue: ' + nextValue);
		getBlock(blockSize, function(err, value){
			if (err) {
				endNext(err, null);
			} else {
				nextValue++;
				endNext(null, nextValue);
			}
		});
	} else {
		nextValue++;
		endNext(null, nextValue);
	}
}

function endNext(err, nextValue){
	var cb = queue[0];
	queue.splice(0, 1);
	cb(err, nextValue);
	if (queue.length != 0) nextBody();
}

function reset(){
	callbackRange = undefined;
	rangeSize = null;
	nextValue = null;
	rangeStart = null;
}

module.exports = {setRangeReservationCallback : setRangeReservationCallback, getBlock : getBlock, next : next, reset : reset, size : blockSize };