rubidium
Rubidium is a one-time task emitter, inspired by the unix at
utility. This
module is a minimal implementation. It exports a constructor. Instances of the
constructor are event emitters, with methods to add and remove job
specifications. A job consists of a due time and a message.
Rubidium is built upon the use of setTimeout
, so the usual warnings apply.
That said, Rubidium creates a fresh timeout after each job is emitted, so it is
self-correcting to within the resolution of a timer.
Rubidium is built on vetebrate-event-emitter, which makes it robust against memory leaks. It has been bundled for you with its dependencies, so Rubidium has no dependencies in production.
Usage
A brief example is given below. See the examples directory for some more interesting examples, including wrapping a rubidium instance in an HTTP server, and persisting a rubidium instance over app restarts.
import Rubidium from 'rubidium';
var rb = new Rubidium();
rb.on('job', job => console.log(job.message));
// Add a job to be emitted in 5 seconds time.
rb.add({ time: Date.now() + 5000, message: '5 seconds have passed.' });
// Add a job to be emitted in one day.
rb.add({ time: Date.now() + 1000 * 60 * 60 * 24, 'One day as passed.' });
You could of course do this with vanilla timeouts. A rubidium instance allows you to do it all with a single timeout. It also works around the maximum timeout length, so you can have a job more than about 25 days into the future.
API
Rubidium
extends
vertebrate-event-emitter
,
so please see the docs for that for the base API around events (methods like
on
, off
etc.)
var rb = new Rubidium()
Construct a new Rubidium instance.
var hasJobs = rb.hasPendingJobs
A boolean property. True when there are jobs remaining in the queue.
var job = rb.add({ time, message, [uuid] }, silent)
Add a job. The time
must be a Date
instance or a timestamp integer (like
Date.now()
) representing the time for the job to be emitted. This method
returns a job with a uuid property that may be used to find or remove the job
from the queue.
When uuid
is in the spec, it will be copied into the job. This is useful for
reviving a persisted queue (see the section on persistence below). In general,
you should not be setting this.
When silent
is true, this addJob
event will not be emitted. This is useful
for reviving a persisted queue.
var job = rb.remove(uuid, silent)
Remove a job from a Rubidium instance with the job uuid. This function returns a
job if the job existed and was removed, or undefined
if the job did not exist.
When silent
is true, the removeJob
event will not be emitted.
var job = rb.find(uuid)
Get a job from the Rubidium instance with the job uuid. Returns undefined
when
no matching job is found.
rb.clear(silent)
Clear all pending jobs. When silent is true, the clearJobs
event will not be
emitted.
'job'
Event: Listeners on the 'job'
event receive a job object containing time
and
message
fields, where time
is an integer.
'addJob'
Event: This event is emitted when a new job is added. The job object is passed as an argument to listeners on this event.
'removeJob'
Event: This event is emitted when when a job is removed. The job object is passed as an
argument to listeners on this event. When the clear
method is used, this event
is emitted for every job.
'clearJobs'
Event: This event is emitted when all jobs for a Rubidium instance are cleared.