jechol / dist_limiter

Distributed rate limiter

DistLimiter

Distributed rate limiter.

Features

Distributed

Built on top of pg, nodes which are interested in the same resource automatically form a process group. They record local consume timestamps and exchange those records with other nodes when being asked to consume.

Garbage collection

Member processes automatically stop when window milliseconds elapsed after last consume on the node.

Sliding window algorithm

dist_limiter implemented sliding window algorithm.

Usage

Let's say we want to limit password challenge from IP "a.b.c.d" to at most 3 times a hour.

iex(1)> resource = {:ip, "a.b.c.d", :challenge_password}                             
{:ip, "a.b.c.d", :challenge_password}
iex(2)> limit = {3600 * 1000, 3}
{3600000, 3}
iex(3)> DistLimiter.get_remaining(resource, limit)                                        
3
iex(4)> DistLimiter.consume(resource, limit, 1)   
{:ok, 2}
iex(5)> DistLimiter.consume(resource, limit, 1)
{:ok, 1}
iex(6)> DistLimiter.consume(resource, limit, 1)
{:ok, 0}
iex(7)> DistLimiter.consume(resource, limit, 1)
{:error, :overflow}

Installation

Add dist_limiter to your list of dependencies in mix.exs:

def deps do
  [
    {:dist_limiter, "~> 0.1.1"}
  ]
end