JobSource

JobSource is an ancestor to factories producing Jobs bound to a given Application and all having some common nature, for instance:

• Queue
• WebService
• DbServicePg

Basically, this is a collection of event handers and other options that are set to a job at the moment of creation.

Constructor

This class is considered abstract parent, so the constructor should be only called through super:

super (app, options)

Parameters

Name	Description
app	an Application instance.
options	a bag of options (see below)

Options

Name	Type	Default	Description
name	String		The unique name with which this JobSource is registered in the hosting Application
globals	Object	{...app.globals, src: this, logger: this.logger}	an object of properties to be injected in each new job as is. For function valued properies, this works like using mixins.
generators	Object	{...app.generators}	an object of functions to calculate properties (called without any parameters) injected in each new job
pools	Object	{...app.pools}	an object of ResourcePools to inject proxies to necessary shared resources in each new job
on	Object	{...app.handlers}	a bag of event handlers
logger	app.logger	A winston Logger
request	Object	{}	request parameters, common to all jobs produced
lag	Number or Array or Lag	0	The minimum time between the constructor call and the finished event
maxLatency	Number	Infinity	the maximum time between since the job creation to the end or error event, in milliseconds
maxPending	Number	Infinity	the maximum number of jobs pending in parallel

Properties

Name	Type	Description	Notes
pending	Set	created jobs still in progress
capacity	Number	computed as maxPending - pending.size: the number of jobs allowed to be created at once
tracker	Tracker	listening to the job's events and registering it with logger	In the base class, without [Tracker.LOGGING_EVENTS] defined, does nothing
[Tracker.LOGGING_ID]	String	computed as name

Methods

Public

createJob (request = {}, options = {})

Returns a new Job instance with the request provided (with this.request prepended), parent set from options (if any) and globals, generators, pools, handlers applied.

If maxPending is exhausted by pending.size, throws a JobSource.OverflowError.

If the numeric value of lag is infinite (which normally means that the Lag instance observed the maximum consecutive errors allowed), throws a JobSource.LockedError.

onJobInit (job)

This asynchronous method is executed prior to init for every Job created.

onJobEnd (job)

This asynchronous method is executed just after handling the end event for every Job emitting it.

onJobError (job)

This asynchronous method is executed just after handling the error event for every failed Job.

reset ()

Emits the reset event. Makes sense to notify lag if it's a Lag instance.

Internal

addHandler (event, handler)

Adds an event handler to an internal collection.

Parameters

Name	Description
event	a String, one of Job's event names.
handler	a job => {...} function to be set as handler

getJobLoggingDetails (job)

Returns the [Tracker.LOGGING_DETAILS] property for the job. In the base implementation, it's {request: job.request, user: job.user}

Static members

Name	Description
JobSource.LockedError	the class of error thrown when lag is infinite
JobSource.OverflowError	the class of error thrown when maxPending is exhausted

Events

Name	When emitted	Payload
job-start	When a new job emits start	The job
job-end	When a job emits end	The job
job-error	When a job emits error	The job
job-finish	When a job emits finish	The job
job-next	When a job emits next	The job
reset	When reset () is called