redis_rate_limit.lua

redis.replicate_commands()

local key=KEYS[1]
local size=tonumber(ARGV[1]) or 10
local count=tonumber(ARGV[2]) or 10
local duration=tonumber(ARGV[3]) or 1

local qps = count / duration
local ttl = math.ceil(size / qps)

local ta=redis.call('time')
local new_t=tonumber(ta[1])*1000000 + tonumber(ta[2])

local old_v=redis.call('get', key) or '0:0'
local p=string.find(old_v, ':', 1, true)

local old_t=string.sub(old_v,1,p-1)
local old_n=string.sub(old_v,p+1)

local new_n=old_n+(new_t-old_t) * qps / 1000000

if new_n > size then
  new_n = size
end
local ret
if new_n >= 1 then
  new_n = new_n - 1
  ret=1
else
  ret=0
end
local new_v=new_t .. ':' .. new_n
redis.call('setex', key, ttl, new_v)
return ret