Workers

This package lets you easily push jobs onto a mongo-backed queue and have them asynchronously picked up and ran by a separate 'headless' meteor process.

Dervived from differential:workers, resolved MongoDB Authentication Bug

Goals

• The code you write for you job handlers should look and behave just like the rest of your application code, and have access to the meteor API and packages you know and love.
• Self contained deployment. We wanted to be able to deploy our app just like we always have and not have a separate deployment for the application handling the jobs.
• Simple interface with minimal configuration and setup.

Simple Usage

Install package

meteor add differential:workers

Add a job

Job.push new LoadRetentionJob
  projectId: projectId
  cohortInterval: "day"

Handle a job

class @LoadRetentionJob extends Job
  handleJob: ->
    project = Project.findOne @params.projectId

    unless project
      throw new Error "Project not found, could not load retention!"

Docs

Currently all methods are only available on the server.

To add a job:

job = new LoadRetentionJob projectId: projectId
Job.push (job, [options], [callback])

Arguments

• job - (Object) The job parameters. Will be available to the job handler.
• options - (Object) - Optional. Monq parameters to be added to the job (delay, etc).
• callback (Function) - Optional. Callback to run after job has successfully been added to the queue.

To handle a job:

Extend the Job class and implement the handleJob method. The class name must end with Job and be globally available. Classes ending in Job are automatically registered to handle their corresponding jobs when they are dequeued. Inside your job handler this.params will be the hash that you passed in as the parameter to new Job(), and this.getMetadata(this.params._id) will return additional information about the job in the queue used by monq. You can also run jobs on a cron schedule, rather than pushing them into the queue. To do this, just implement a static method setupCron(parser) on your job class. We use percolate-studio's synced-cron package for scheduling. You will be passed a later.js parser object as the only argument.

class @CleanUpJob extends Job
  @setupCron: (parser) ->
    parser.recur().on(0).hour()

  handleJob: ->
    doCleanUpStuff()

You can also implement afterJob in your handler class. If an error is thrown in your handler, it will be passed in as the only argument to this function, otherwise it will be undefined.

Configuration

Uses Meteor.settings API.

{
  "cluster": {
    "count": 2
  },
  "workers": {
    "count": 10,
    "monq": {
      // default monq parameters overrides
    },
    "cron": {
      "log": false, // show SyncedCron logging
      "disable": false // disable cron scheduler (nice for debugging sometimes)
    }
  },
}

• This will set up 2 background worker processes. If you are deploying to multiple servers, or servos (modulus), this will fire up 2 workers on each. It will then start up 10 Monq workers on each process.