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fastq

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

Benchmarks (1 million tasks):

- setImmediate: 812ms
- fastq: 854ms
- async.queue: 1298ms
- neoAsync.queue: 1249ms

Obtained on node 12.16.1, on a dedicated server.

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

- Installation
- Usage
- API
- Licence & copyright

# 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()`
- `queue#push()`
- `queue#unshift()`
- `queue#pause()`
- `queue#resume()`
- `queue#idle()`
- `queue#length()`
- `queue#getQueue()`
- `queue#kill()`
- `queue#killAndDrain()`
- `queue#concurrency`
- `queue#drain`
- `queue#empty`
- `queue#saturated`

## 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.getQueue()

Returns all the tasks be processed (in the queue). Returns empty array when there are no tasks

## 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