ffratelimiter v0.1.1

node-rate-limiter

Rate limit any APIs/functions by using this rate limiter.

This module has been used extensively in http://www.ecosystm.co .

How to use

1. Installation

   npm install ffratelimiter

2. Create an constructor.

   var RateLimiter = require('./node_modules/ffratelimiter');

3. Create a rate limited queue with the above constructor.

    var params = {
        limit: NUMBER,          // default: 0
        window: NUMBER,         // default: 0
        concurrency: NUMBER,    // default: 1
        attempts: NUMBER,       // default: 1
        runforever: BOOLEAN     // default: false
    };

    var ratelimiter = new RateLimiter(params);


Here is a description of arguments of the constructor.

1. limit = max. number of calls (ignored if window is 0)
2. window = time window for rate limiting (0 if there is no window)
3. concurrency = number of parallel
4. attempts = number of attempts to make before failing
5. runforever = forever keep running

NOTE: when using runforever, if there is a roll-over from last item
to first item, then any new items added to work_queue will have to
wait until all the earlier items are processed. (where items refer to
the arguments for rate-limited function).

This is simply bad algo and has been done to keep things simple. We
were observing issues with using shift and push in the work_queue inside

3. Start inserting functions to be called into the queue, using the below function.

   this.callWrapper (fn, params, callback, scope)

   1. fn = function to be called each time. It will be called with arguments in params, followed by an internal callback function
   2. params = arguments passed to function fn
   3. callback = Called after successfully or unsuccessfully executing fn (in case of unsuccessful execution, and if attempts (say to 'n') is set, we try calling the function again for n times)
   4. scope = a scope for the callback optional

Examples

Check under tests folder.