This package helps with organizing of tasks between few instances of same app, It can identify processes and track them activity.

Installation

npm install process-custodian --save

How it works

This package gives collision-resistant fingerprint for each process. Process fingerprint has 6 char length with structure: (hostname - pid - random). So, It is optimized for horizontal scaling and binary search lookup performance.

After create new instance of ProcessCustodian, this package saves a heartbeat of process to the passed raw mongodb collection with frequency about tickTimeInSeconds (which default is 60s)

First of processes, which will be able to reserve self as a master, will be the master process to the moment of dead or lose master role if will be too busy to save in database a heartbeat at the time.

Example of use - with pure mongodb collection

import ProcessCustodian from  'process-custodian';
import {MongoClient}  from 'mongodb'

MongoClient.connect('mongodb://localhost:27017/test', function(err, db) {

  // Create a collection we want to drop later
  const collection = db.collection('process_custodian');

  const handle = new ProcessCustodian({rawCollection: collection, tickTimeInSeconds: 45});

  const stopOnTick = handle.onTick(() => {
    console.log('tick', handle.isMaster() ? 'master': 'slave')
  });
  
  handle.onIAmNewMaster(() => {
    console.log('I am master');
  });
  
  handle.onIAmSlave(() => {
    console.log('I am slave');
  });

Example of use - with meteor collection

import ProcessCustodian from  'process-custodian';
// for meteor:
const collection = new Mongo.Collection('process_custodian');

const handle = new ProcessCustodian({
    rawCollection: collection.rawCollection(),
    tickTimeInSeconds: 60
    marginTimeForRenew = 10
});

handle.onceTick(() => {
    console.log('tick', handle.isMaster() ? 'master': 'slave')
});
  
handle.onIAmNewMaster(() => {
    console.log('I am master');
});
  
handle.onIAmSlave(() => {
    console.log('I am slave');
});

// if no necessery any more 
handle.stop();

Help tools

import {getFingerprint, humanize} from  'process-custodian';

//Getting fingerprint
console.log('id:', getFingerprint()); // e.g. output: id: ji4fmf
console.log('human:', humanize(getFingerprint())); // e.g. output: human: ji-4f-mf

License

Like every package maintained by Vazco, Process Custodian is MIT licensed.