fail-safe-queue

Fail Safe Queue

It's a very simple Queue of functions. But also let's you define, for each one, a rollback in case something goes wrong later on the queue stack calling.

Heavily inspired by caolan/async.

Installation

npm install fail-safe-queue --save

Quick Examples

Success example:

var queue = require('fail-safe-queue')

queue([
  {
    up: function(next){
      console.log('+ up! 1')
      next(null, 1)
    },
    down: function(prev){
      console.log('- down! 1')
      prev()
    }
  },
  function(next){
    console.log('+ up! 2')
    next(null, 2)
  },
  {
    up: function(next){
      console.log('+ up! 3')
      next('3 con error', 3)
    },
    down: function(prev){
      console.log('- down! 3')
      prev()
    }
  }
], function(err, upResults, downResults){
  console.log('err', err)
  console.log('upResults', upResults)
})

Will echo:

  + up! 1
  + up! 2
  + up! 3
  err null
  results [ [ 1 ], [ 2 ], [ 3 ] ]

Fail example:

var queue = require('fail-safe-queue')

queue([
  {
    up: function(next){
      console.log('+ up! 1')
      next(null, 1)
    },
    down: function(prev){
      console.log('- down! 1')
      prev()
    }
  },
  {
    up: function(next){
      console.log('+ up! 2')
      next('This method triggered an error :S', 2)
    },
    down: function(prev){
      console.log('- down! 2')
      prev()
    }
  },
  {
    up: function(next){
      console.log('+ up! 3')
      next(null, 3)
    },
    down: function(prev){
      console.log('- down! 3')
      prev()
    }
  }
], function(err, upResults){
  console.log('err', err)
  console.log('upResults', upResults)
})

Will echo:

  + up! 1
  + up! 2
  - down! 1
  err This method triggered an error :S
  results [ [ 1 ] ]

API

queue(tasks, [callback])

Arguments

• tasks - It's an array of tasks. Each task could be a simple function to be called in order or an object with two functions, up: [Function(next)] and down: [Function(prev)].
• callback(err, results) - An optional callback to run once all the functions have completed. This function gets a results array containing all the result arguments passed to the task callbacks.