thumbsup/src/components/listr-work-queue

listr-work-queue

Drop-in Listr subclass for tasks that need to be picked from a queue concurrently

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ℹ️ About this package

The main difference with the standard concurrent: <count> option is that tasks are only rendered as they get picked up, and disappear once processed.

This component will not be necessary anymore if the following Listr feature request is implemented: #53 Display only the task that is running. When it is, we can simply rely on the concurrent: <count> option and let Listr look after the scheduling / execution of the tasks.

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Usage

const Listr = require('listr')
const ListrWorkQueue = require('./listr-work-queue/index.js')

const tasks = new Listr([{
  title: 'Running jobs',
  task: () => new ListrWorkQueue(/* tasks */, {
    concurrent: WORKER_COUNT,
    exitOnError: false
  })
}])

tasks.run().then(() => console.log('Done'))

Jobs

Every job is an object with 2 properties, similar to the standard Listr tasks. The task property must be a Promise. Observables and streams are not supported.

{
  title: 'Job A',
  task: () => new Promise(resolve => setTimeout(resolve, 1000))
}

Options

• concurrent: the number of workers getting tasks from the queue.

{
	concurrent: os.cpus().length
}

• exitOnError: whether to stop processing new jobs when one of the jobs fails (default is true). Note that pending tasks will still complete before the process is stopped.

{
	exitOnError: false
}

• update(): a callback to report on the overall progress. This can be used for example to update the parent task title.

{
  title: 'Running jobs',
  task: (ctx, parent) => new ListrWorkQueue(/* tasks */, {
    update: (completed, total) => {
      parent.title = `Running jobs (${completed}/${total})`
    }
  })
}