@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