limiter
limiter
Rate limiter for Crystal. Memory and Redis based. Redis limiter is shared (unlike Memory limiter which is local for process), so it can be used across multiple processes.
Installation
Add this to your application's shard.yml
:
dependencies:
limiter:
github: kostya/limiter
Basic Limiter Usage
require "limiter"
limiter = Limiter::Memory.new
limiter.add_limit(2.seconds, 10) # allow 10 requests per 2.seconds
limiter.add_limit(1.hour, 1000) # allow 1000 requests per 1.hour
res = limiter.request? { some_high_cost_action } # => return value of block or nil
res = limiter.request! { some_high_cost_action } # => return value of block or raise Limiter::Error
Example Memory Limiter
require "limiter"
limiter = Limiter::Memory.new
limiter.add_limit(2.seconds, 10) # allow 10 requests per 2.seconds
limiter.add_limit(1.hour, 1000) # allow 1000 requests per 1.hour
record Result, val : Float64
def some_high_cost_action : Result
# ...
sleep 0.1
# ...
return Result.new(rand)
end
res = [] of Result
limited_count = 0
1000.times do
if val = limiter.request? { some_high_cost_action }
res << val
else
limited_count += 1
end
end
p res.size
p limited_count
Example Redis Limiter
require "redisoid" # https://github.com/kostya/redisoid
require "limiter"
redis_client = Redisoid.new
limiter = Limiter::Redis(Redisoid).new(redis_client, "my_limiter1")
limiter.add_limit(2.seconds, 10) # allow 10 requests per 2.seconds
limiter.add_limit(1.hour, 1000) # allow 1000 requests per 1.hour
record Result, val : Float64
def some_high_cost_action : Result
# ...
sleep 0.1
# ...
return Result.new(rand)
end
res = [] of Result
50.times do
if val = limiter.request? { some_high_cost_action }
res << val
else
x = limiter.next_usage_after
puts "processed: #{res.size}, next usage after #{x} seconds"
sleep(x)
end
end
puts "processed #{res.size}"