@MomsFriendlyDevCo/Scheduler

Generic Cron-like scheduler for tasks that should execute periodically.

This module is intended as a low-level scheduler for @MomsFriendlyDevCo/Agents.

Scheduled times

The following scheduled times are supported:

• * * * * * (i.e. six cron-timings) - Parsed by cron-parser
• every * (reoccuring intervals) - Parsed by timestring
• * (everything else) - Parsed by fix-time

Debugging

This module uses the debug NPM module for debugging. To enable set the environment variable to DEBUG=scheduler or DEBUG=scheduler* for detail.

For example:

DEBUG=scheduler mocha

API

Scheduler.settings

Global settings for the scheduler.

Available settings:

Setting	Type	Default	Description
autoStart	boolean	true	Automatically call Scheduler.start() when initialized
tickTimeout	number	1000 (~1s)	The precision of when to check the scheduled task queue
timeBias	number	0	What offset (in milliseconds) to add to each timing
throwUnknown	boolean	true	Complain about unknown time sequences within timings, single unknown timings will always throw

Notes:

• timeBias is intended to be used on a server with multiple instance profiles (i.e. each server could potentially execute similar processes). Setting it to a random number generator would ensure that not all tasks are executed within the same tick

Scheduler.tick()

Function called on each "tick". When called this function cancels the timing of the next tick. This function returns a promise which resolves when all queued tasks have completed.

Scheduler.start()

Resume / execute the scheduler and begin checking for queued tasks on each Scheduler.settings.tickTimeout. Returns the chainable Scheduler instance.

Scheduler.stop() / Scheduler.pause()

Stops the scheduler, which will not check for future tick items. Returns the chainable Scheduler instance.

Scheduler.Task(timing, cb, scheduler)

Task instance created within a scheduler. timing is an array of timings or a CSV of timings. cb is an optional callback function which gets attached. scheduler is an optional binding to the parent scheduler.

Task.timing(newTiming)

Resets and reschedules the task based on the new timing. This overrides the timing provided in the constructor. Returns the chainable Task instance.

Task.task(cb)

Sets the task to execute as if used in the constructor. Returns the chainable Task instance.

Task.taskCatch(cb)

Set the catch handler when a task fails. Returns the chainable Task instance.

Task.start()

Reschedule a task. Returns the chainable Task instance.

Task.stop()

Unschedule a task from its parent Scheduler. Returns the chainable Task instance.

Task.attachTo(scheduler)

Reschedule a task to a new scheduler. Returns the chainable Task instance.