meteor.md

JoSk usage within Meteor.js

NPM josk package can be used in Meteor environment just perfectly fine since it's server-only Node.js package.

If Meteor.js packages are preferred in your project/environment follow this document to install JoSk as ostrio:cron-jobs Atmosphere or Packosphere package

Install

meteor add ostrio:cron-jobs

Usage

import { JoSk, RedisAdapter, MongoAdapter } from 'meteor/ostrio:cron-jobs';

Initialization

JoSk is storage-agnostic (since v4.0.0). It's shipped with Redis and MongoDb "adapters" out of the box. Documentation below related to working with MongoDB provided and managed by Meteor.js. If you wish to use Redis as a driver for JoSk follow Redis-related documentation from NPM version of the package. NPM section of the documentation is fully applicable to package installed from Atmosphere/Packosphere, the only difference is in how package imported

import { MongoInternals } from 'meteor/mongo';
import { JoSk, MongoAdapter } from 'meteor/ostrio:cron-jobs';

const jobs = new JoSk({
  adapter: new MongoAdapter({
    db: db: MongoInternals.defaultRemoteCollectionDriver().mongo.db,
    prefix: 'cluster-scheduler',
  }),
  onError(reason, details) {
    // Use onError hook to catch runtime exceptions
    // thrown inside scheduled tasks
    console.log(reason, details.error);
  }
});

jobs.setInterval(async () => {
  /* ...code here... */
}, 60000, 'task-1m');

// TO SUPPORT CALLBACK APIs
// CALL ready() ONCE RUN IS COMPLETE
jobs.setInterval((ready) => {
  /* ...code here... */
  asyncCall(() => {
    /* ...more code here...*/
    ready();
  });
}, 60000, 'task-1m');

Note: This library relies on job ID. Always use different uid, even for the same task:

const task = function (ready) {
  //... code here
  ready();
};

jobs.setInterval(task, 60000, 'task-1m'); // every minute
jobs.setInterval(task, 2 * 60000, 'task-2m'); // every two minutes

CRON scheduler

Use JoSk to invoke synchronized tasks by CRON schedule, and cron-parser package to parse CRON expressions. To simplify CRON scheduling — grab and use setCron function below:

import { MongoInternals } from 'meteor/mongo';
import JoSk from 'meteor/ostrio:cron-jobs';
import parser from 'cron-parser';

const jobsCron = new JoSk({
  adapter: new MongoAdapter({
    db: db: MongoInternals.defaultRemoteCollectionDriver().mongo.db,
    prefix: 'cron-scheduler',
  }),
  minRevolvingDelay: 512, // Adjust revolving delays to higher values
  maxRevolvingDelay: 1000, // as CRON schedule defined to seconds
});

// CREATE HELPER FUNCTION
const setCron = async (uniqueName, cronTask, task) => {
  const nextTimestamp = +parser.parseExpression(cronTask).next().toDate();

  return await jobsCron.setInterval(function (ready) {
    ready(parser.parseExpression(cronTask).next().toDate());
    task();
  }, nextTimestamp - Date.now(), uniqueName);
};

// SCHEDULE A TASK
setCron('Run every two seconds cron', '*/2 * * * * *', function () {
  console.log(new Date);
});

Running Tests

1. Clone this package
2. Make sure Redis Server is installed and running
3. In Terminal (Console) go to directory where package is cloned
4. Then run:

# Default
REDIS_URL="redis://127.0.0.1:6379" meteor test-packages ./ --driver-package=meteortesting:mocha

# With custom port
REDIS_URL="redis://127.0.0.1:6379" meteor test-packages ./ --driver-package=meteortesting:mocha --port 8888

# With local MongoDB, debug and custom port
DEBUG=true MONGO_URL="mongodb://127.0.0.1:27017/meteor-josk-test-001" REDIS_URL="redis://127.0.0.1:6379" meteor test-packages ./ --driver-package=meteortesting:mocha --port 8888

# Be patient, tests are taking around 4 mins

Known Meteor Issues:

meteor@1 and meteor@2 known to rely on fibers an may cause the next exception:

Error: Can't wait without a fiber

Can be easily solved via "bounding to Fiber":

const bound = Meteor.bindEnvironment((callback) => {
  callback();
});

const db  = Collection.rawDatabase();
const jobs = new JoSk({db: db});

const task = (ready) => {
  bound(() => { // <-- use "bound" inside of a task
    ready();
  });
};

jobs.setInterval(task, 60 * 60 * 1000, 'task');