rateLimit

Easily rate-limit a function to run no more often than every X miliseconds, by queuing up calls. All calls will be eventually executed, unlike throttling or debouncing, which drop extra calls.

This is useful for API clients, web crawling, or other tasks that need to wait at least some amount of time between calls, but for which throttling per se (dropping calls) is unacceptable.

On the server, you can use futures to allow returning a value from the rate-limited function. On the client, this is not yet implemented, but possible.

A private queue is used internally, as suggested on StackOverflow.

Installation

$ meteor add rate-limit

Example:

Simply run var fooLimited = rateLimit(foo, delayInMilliseconds);.

function foo(param1, param2) {
  console.log(param1, (param2 || ''));
}

var bar = rateLimit(foo, 1000);  // wait at least 1000 milliseconds between calls
foo('Starting up');
bar(1);  // runs right away
bar(2);  // runs after 1 second
bar(3, 'optional parameter');  // parameters are passed along to the original function

Usage

rateLimit(function, delayInMilliseconds, context /* default this */, options)

Parameters

• function to call
• minimum delayInMilliseconds to wait before consecutive calls to function
• context to pass (defaults to this)
• options:
  • debug: boolean - default false. Logs to the console the number of items in the queue after each call to function
  • futures: boolean - default false. MUST be enabled if you need the return value of function. Will yield execution of next statement (not block) until function returns.

TODO

• client-side support for returning values
• Meteor.Collection backing for persistence

See also

• jobCollection - powerful native Meteor package for job queue processing
• limiter - A generic rate limiter for Node.js

Author, license and copyright

Author: Dan Dascalescu (@dandv)

Development initially sponsored by StockBase, LLC.

The MIT License (MIT)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.