@MomsFriendlyDevCo/throttle

Async throttling mechanism based on MongoDB locking.

var Throttle = require('@momsfriendlydevco/throttle');

var throttler = new Throttle();
throttler.init()
	.then(()=> throttler.throttle(() => {
			// Worker is complete when promise resolves
			return Promise.resolve();
		},
		{
			id: 'foo',
			hash: ({foo: 'bar'}),
		}
	))
	.catch(e => {
		// The queue full of workers already in progress.
	});

API

Throttle(settings)

Main constructor. Requires instance.init() to be called before the instance is functional.

Throttle.defaults

Default settings.

| Setting | Type | Default | Description | |----------------------|----------|------------------------------------|-------------------------------------------------| | leading | boolean | true | Bypasses use of the queue | | queue | number | 1 | Number of items for which to keep queued callbacks | | lock | object | See below | Lock package configuration options | | lock.expiry | number | 1 hour | The time in milliseconds until the lock expires | | lock.ttl | number | 1 min | The time in milliseconds until keep-alive expires | | lock.mongodb | object | See below | MongoDB connection options | | lock.mongodb.uri | string | "mongodb://localhost/mfdc-cache" | The MongoDB URI to connect to | | lock.mongodb.collection | string | "locks" | The name of the collection to use | | lock.mongodb.options | object | See code | Additional connection options to use | | lock.omitFields | array | ['_id', '__v'] | Which fields to autmatically skip when using get() | | lock.includeKeys | boolean | true | Also save the key field values, reduces overhead to disable this |

throttler.init(settings)

Check all settings and connect to the database.

throttler.throttle(worker, options)

Callback worker will be called immediately if a lock is available or otherwise throttled in a queue. When queue is full promise will be rejected with error "Throttle queue is full".

| Option | Type | Default | Description | |----------------------|----------|------------------------------------|-------------------------------------------------| | id | mixed | undefined | Key within lock collection | | hash | string | undefined | An object which uniquely identies the object being locked |