/*

MIT License http://www.opensource.org/licenses/mit-license.php

Author Tobias Koppers @sokra

*/

var child_process = require("child_process");

function disconnectWorker(worker) {

if(worker.disconnect)

worker.disconnect();

else if(worker.kill)

worker.kill();

else

worker.process.kill();

}

function Workers(moduleToFork, count) {

this.nextId = 1;

this.workers = [];

this.workersRegister = [];

this.forkedWorkers = [];

this.workersJobs = [];

this.callbacks = {};

for(var i = 0; i < count; i++) {

var worker = child_process.fork(moduleToFork);

this.bindWorker(worker, i);

}

}

module.exports = Workers;

Workers.prototype.run = function() {

var args = Array.prototype.slice.call(arguments, 0);

var worker = -1;

var minJobs = -1;

this.workersJobs.forEach(function(jobs, idx) {

if(jobs < minJobs || minJobs == -1) {

minJobs = jobs;

worker = idx;

}

});

if(worker < 0) throw new Error("Not ready! Check workers.ready().");

args.unshift(worker);

this.pushJob.apply(this, args);

}

Workers.prototype.bindWorker = function(worker, idx) {

worker.send(null);

worker.once("message", function(msg) {

if(msg == "ready") {

idx = this.workers.length;

this.workers.push(worker);

this.workersJobs.push(0);

this.workersRegister.push({});

worker.on("message", function(result) {

this.workersJobs[idx]--;

var id = result.shift();

var callback = this.callbacks[id];

delete this.callbacks[id];

callback.apply(null, result);

}.bind(this));

} else {

disconnectWorker(worker);

this.forkedWorkers.splice(idx, 1);

}

}.bind(this));

}

Workers.prototype.ready = function() {

return this.workers.length > 0;

}

Workers.prototype.pushJob = function(worker) {

var args = Array.prototype.slice.call(arguments, 0);

var callback = args.pop();

var id = this.nextId++;

this.callbacks[id] = callback;

args[0] = id;

this.workersJobs[worker]++;

for(var i = 2; i < args.length; i++)

args[i] = JSON.stringify(args[i]);

var reg = this.workersRegister[worker][args[1]];

var regMapping = null;

var newValues = args.slice(2);

this.workersRegister[worker][args[1]] = newValues;

if(reg && newValues.length == reg.length) {

regMapping = [];

for(var i = 0; i < reg.length; i++) {

var match = reg[i] == newValues[i];

regMapping.push(match);

if(match) args[i+2] = null;

}

}

args.splice(2, 0, regMapping);

this.workers[worker].send(args);

}

Workers.prototype.close = function() {

this.workers.forEach(disconnectWorker);

this.workers.length = 0;

this.workersJobs.length = 0;

this.workersRegister.length = 0;

}

Workers.prototype.toJSON = function() {

return {};

}