Token Bucket Redis script

local name = KEYS[1];
local rate = tonumber(KEYS[2]);
local max = tonumber(KEYS[3]);
local interval = tonumber(KEYS[4]);
local now = tonumber(KEYS[5]);
local count = tonumber(redis.call('HGET', name, 'count'));
local mtime = tonumber(redis.call('HGET', name, 'mtime'));
if not mtime then
   count = max;
   mtime = now;
end
if now < mtime then
   mtime = now - interval;
end
if count < max then
   count = math.min(max, count + rate * ((now - mtime) / interval));
   redis.call('HSET', name, 'count', count);
end
redis.call('HSET', name, 'mtime', now);
if count < 1 then
   return 0;
else
   redis.call('HSET', name, 'count', count - 1);
   return 1;
end

Testing:

for d in 1 2 3 4 5; do redis-cli --eval rate.lua b 3 3 1000 $(node -e 'console.log(Date.now())'); done