jobQ

Async and parallel execution of jobs, tasks and processes. This library is aimed to solve the problem of having to limit how many parallel tasks you want to perform. It accepts several kinds of sources including Arrays, Promises, Functions, etc.

Installation

npm install --save jobq

Usage

var jobQ = require('jobq')

var queue = new jobQ({
  process: function(x, callback){
    setTimeout(function() {
      callback(null, x)
    }, 3000)
  },
  source: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10],
  maxProceses: 2
})

queue.start()

Options

• source: required View source section.
• process: required View process section.
• maxProceses: <Number> indicates how many jobs will run in parallel. A value of 0 means 'no limit'. Default 1
• debug: <Boolean> enables or disables debug. Default false
• stopOnError: <Boolean> indicates if jobs will stop after first error or continue. If enabled, processFinish will be called with status error if an error occurs. Default false
• pooling: <Number> pooling timeout in milliseconds. When enabled, JobQ will continue to try and fetch data from the source (Function only). Default: No pooling

Events

var queue = new jobQ({
  process: myProcess,
  source: mySource,
  maxProceses: 2
})

queue.on('start', function(){})
queue.on('jobFetch', function(){})
queue.on('jobRun', function(){})
queue.on('jobFinish', function(){})
queue.on('processFinish', function(){})
queue.on('pooling', function(){})
queue.on('pause', function(){})
queue.on('resume', function(){})
queue.on('error', function(){})

queue.start()

start

Emited once after calling start() with an object containing:

• startTime: <Date> date when start was called
• processed: <Number> jobs processed so far
• errors: <Number> jobs errored so far
• maxProceses: <Number> maxProceses passed to constructor. Default 1
• stopOnError: <Boolean> stopOnError passed to constructor. Default false
• sourceType: <String> Detected source type (array, function, promise or stream).
• status: <String> queue status. will always be running at this point.

jobFetch

Emited once for each job before fetching it from the queue with an object containing:

• jobsRunning: <Number> current amount of processing jobs. It will not count the one that triggered the event.

jobRun

Emited once for each job when it starts running with:

• <number> job id (autoincrement)

jobFinish

Emited once after calling start() with an object containing:

• jobId: <Number> job id
• jobStartTime: <Date> date when job started to process
• jobEndTime: <Date> date when job finishes to process
• result: <any> job result received
• jobsRunning: <Number> current amount of processing jobs. It will count the one that triggered the event.

processFinish

Emited once after calling start() with an object containing:

• startTime: <Date> date when start was called
• endTime: <Date> date when queue was fully processed
• processed: <Number> total amount of jobs processed
• errors: <Number> total amount of errors
• maxProceses: <Number> maxProceses passed to constructor. Default 1
• stopOnError: <Boolean> stopOnError passed to constructor. Default false
• sourceType: <String> Detected source type (array, function, promise or stream).
• status: <String> queue status. will always be finished or error.

pooling

Emited every time the source function returns null as value and JobQ starts waiting to check again. Only emited if pooling is enabled, with an object containing:

• startTime: <Date> date when start was called
• processed: <Number> jobs processed so far
• errors: <Number> jobs errored so far
• maxProceses: <Number> maxProceses passed to constructor. Default 1
• stopOnError: <Boolean> stopOnError passed to constructor. Default false
• sourceType: <String> Detected source type (array, function, promise or stream).
• status: <String> queue status. will always be pooling at this point.

pause

Emited once after calling pause() with an object containing:

• startTime: <Date> date when start was called
• processed: <Number> jobs processed so far
• errors: <Number> jobs errored so far
• maxProceses: <Number> maxProceses passed to constructor. Default 1
• stopOnError: <Boolean> stopOnError passed to constructor. Default false
• sourceType: <String> Detected source type (array, function, promise or stream).
• status: <String> queue status. will always be paused at this point.

resume

Emited once after calling resume() with an object containing:

• startTime: <Date> date when start was called
• processed: <Number> jobs processed so far
• errors: <Number> jobs errored so far
• maxProceses: <Number> maxProceses passed to constructor. Default 1
• stopOnError: <Boolean> stopOnError passed to constructor. Default false
• sourceType: <String> Detected source type (array, function, promise or stream).
• status: <String> queue status. will always be running at this point.

error

Emited once for each job error:

• <Error> error received

Source

Source is where data will be fetched in order to be processed. It can be one of the following:

• <Array> like [1, 2, 3].
• <Array> of promise like [promise1, promise2, promise3].
• <Function> returning a value.
• <Function> returning a promise.
• <Function(callback)> returning nothing and passing data to callback with error as the first parameter and response as the second one.
• <ReadableStream> that supports on('readable') and read().
• <Promise> that resolves to any of the previous source types.

IMPORTANT: When using Function and Promise sources, you must pass null as value to stop execution.

Process

Process function receives a value from the queue and be anby of the following:

• <Function> that returns a value
• <Function> that returns a Promise wich resolves to a value
• <Function(callback)> that returns nothing and executes a callback with error as the first parameter and response as the second one.