Simple async batch with concurrency control and progress reporting.

Installation

This is a Node.js module available through the npm registry. Installation is done using the npm install command:

Usage

var Batch = require('batch')

new Batch([options], [...fns])

Create a new Batch, optionally passing an options object and/or a list of functions (fns) to queue.

The options object may contain the following keys:

• concurrency: set the default concurrency for the Batch, which can be changed using batch.concurrency(n).
• throws: set the default throws for the Batch, which can be changed using batch.throws(throws).

batch.concurrency(n)

Set concurrency to n.

batch.end([cb])

Execute all queued functions in parallel, executing cb(err, results).

batch.push(fn)

Queue a function.

batch.throws(throws)

Set whether Batch will or will not throw up.

progress event

Contains the "job" index, response value, duration information, and completion data.

{ index: 1,
  value: 'bar',
  pending: 2,
  total: 3,
  complete: 2,
  percent: 66,
  start: Thu Oct 04 2012 12:25:53 GMT-0700 (PDT),
  end: Thu Oct 04 2012 12:25:53 GMT-0700 (PDT),
  duration: 0 }

Example

var Batch = require('batch')
  , batch = new Batch;

batch.concurrency(4);

ids.forEach(function(id){
  batch.push(function(done){
    User.get(id, done);
  });
});

batch.on('progress', function(e){

});

batch.end(function(err, users){

});

License

MIT