-- key

local key = KEYS[1]

-- 最大儲存的令牌數

local max_permits = tonumber(KEYS[2])

-- 每秒鐘產生的令牌數

local permits_per_second = tonumber(KEYS[3])

-- 請求的令牌數

local required_permits = tonumber(ARGV[1])

-- 下次請求可以獲取令牌的起始時間

local next_free_ticket_micros = tonumber(redis.call('hget', key, 'next_free_ticket_micros') or 0)

-- 當前時間

local time = redis.call('time')

local now_micros = tonumber(time[1]) * 1000000 + tonumber(time[2])

-- 查詢獲取令牌是否超時

if (ARGV[2] ~= nil) then

-- 獲取令牌的超時時間

local timeout_micros = tonumber(ARGV[2])

local micros_to_wait = next_free_ticket_micros - now_micros

if (micros_to_wait > timeout_micros) then

return micros_to_wait

end

end

-- 當前儲存的令牌數

local stored_permits = tonumber(redis.call('hget', key, 'stored_permits') or 0)

-- 新增令牌的時間間隔

local stable_interval_micros = 1000000 / permits_per_second

-- 補充令牌

if (now_micros > next_free_ticket_micros) then

local new_permits = (now_micros - next_free_ticket_micros) / stable_interval_micros

stored_permits = math.min(max_permits, stored_permits + new_permits)

next_free_ticket_micros = now_micros

end

-- 消耗令牌

local moment_available = next_free_ticket_micros

local stored_permits_to_spend = math.min(required_permits, stored_permits)

local fresh_permits = required_permits - stored_permits_to_spend;

local wait_micros = fresh_permits * stable_interval_micros

redis.replicate_commands()

redis.call('hset', key, 'stored_permits', stored_permits - stored_permits_to_spend)

redis.call('hset', key, 'next_free_ticket_micros', next_free_ticket_micros + wait_micros)

redis.call('expire', key, 10)

-- 返回需要等待的時間長度

return moment_available - now_micros