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fastq v1.6.0

Fast, in memory work queue

fastq  build status

Fast, in memory work queue. fastq is API compatible with async.queue

Benchmarks (1 million tasks):

  • setImmediate: 1359ms
  • fastq: 1492ms
  • async.queue: 4039ms
  • neoAsync.queue: 4476ms

Obtained on node 4.2.2, on a MacBook Pro 2014 (i7, 16GB of RAM).

If you need zero-overhead series function call, check out fastseries. For zero-overhead parallel function call, check out fastparallel.

js-standard-style

Install

npm i fastq --save

Usage

'use strict'

var queue = require('fastq')(worker, 1)

queue.push(42, function (err, result) {
  if (err) { throw err }
  console.log('the result is', result)
})

function worker (arg, cb) {
  cb(null, 42 * 2)
}

Setting this

'use strict'

var that = { hello: 'world' }
var queue = require('fastq')(that, worker, 1)

queue.push(42, function (err, result) {
  if (err) { throw err }
  console.log(this)
  console.log('the result is', result)
})

function worker (arg, cb) {
  console.log(this)
  cb(null, 42 * 2)
}

API


fastqueue([that], worker, concurrency)

Creates a new queue.

Arguments:

  • that, optional context of the worker function.
  • worker, worker function, it would be called with that as this, if that is specified.
  • concurrency, number of concurrent tasks that could be executed in parallel.

queue.push(task, done)

Add a task at the end of the queue. done(err, result) will be called when the task was processed.


queue.unshift(task, done)

Add a task at the beginning of the queue. done(err, result) will be called when the task was processed.


queue.pause()

Pause the processing of tasks. Currently worked tasks are not stopped.


queue.resume()

Resume the processing of tasks.


queue.idle()

Returns false if there are tasks being processed or waiting to be processed. true otherwise.


queue.length()

Returns the number of tasks waiting to be processed (in the queue).


queue.kill()

Removes all tasks waiting to be processed, and reset drain to an empty function.


queue.killAndDrain()

Same than kill but the drain function will be called before reset to empty.


queue.concurrency

Property that returns the number of concurrent tasks that could be executed in parallel. It can be altered at runtime.


queue.drain

Function that will be called when the last item from the queue has been processed by a worker. It can be altered at runtime.


queue.empty

Function that will be called when the last item from the queue has been assigned to a worker. It can be altered at runtime.


queue.saturated

Function that will be called when the queue hits the concurrency limit. It can be altered at runtime.

License

ISC

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