Gearman-coffee NPM

gearman-coffee

gearman-coffee is an implementation of the Gearman protocol in CoffeeScript. It exposes a conventional Node library for creating Gearman workers and clients, and listening for events related to both. It aims to be a very a lightweight wrapper around the protocol itself.

Installation

npm install gearman-coffee

Workers

Workers are created with the name and function that they perform:

worker = new Worker 'reverse', (payload, worker) ->
  return worker.error 'No payload' unless payload?
  reversed = payload.toString("utf-8").split('').reverse().join ''
  worker.complete reversed

The worker function itself is passed an object that contains the following convenience methods:

warning(warning): sends a 'WORK_WARNING' packet
status(num,den): sends a 'WORK_STATUS' packet
data(data): sends a 'WORK_DATA' packet
error([warning]): sends an optional 'WORK_WARNING' before 'WORK_FAIL'
complete([data]): sends an optional 'WORK_DATA' before 'WORK_COMPLETE'
done([warning]): calls error if warning passed, otherwise complete

The exact meaning of these is best documented on the Gearman website itself: http://gearman.org/index.php?id=protocol.

Workers optionally take a hash of options. These options control the Gearman server connection settings as well as debug output and retry behavior:

default_options =
  host: 'localhost'
  port: 4730
  debug: false
  max_retries: 0
worker = new Worker 'unstable', (payload, worker) ->
  return worker.error() if Math.random() < 0.5
  worker.done()
, default_options

Clients

Clients are used to submit work to Gearman. By default they connect to Gearman at localhost:4730:

default_options =
  host: 'localhost'
  port: 4730
  debug: false
client = new Client default_options

The submitJob method of the client takes in the name of the worker and the workload you'd like to send. It returns an EventEmitter that relays Gearman server notifications:

client.submitJob('reverse', 'kitteh')
  .on 'created', (handle) ->          # JOB_CREATED
  .on 'data', (handle, data) ->       # WORK_DATA
  .on 'warning', (handle, warning) -> # WORK_WARNING
  .on 'status', (handle, num, den) -> # WORK_STATUS
  .on 'complete', (handle, data) ->   # WORK_COMPLETE
  .on 'fail', (handle) ->             # WORK_FAIL