swarthy/redis-semaphore

import { createEval } from '../../utils/index'

export const acquireLua = createEval<
  [string, number, string, number, number],
  0 | 1
>(
  `
  local key = KEYS[1]
  local limit = tonumber(ARGV[1])
  local identifier = ARGV[2]
  local lockTimeout = tonumber(ARGV[3])
  local now = tonumber(ARGV[4])
  local expiredTimestamp = now - lockTimeout

  redis.call('zremrangebyscore', key, '-inf', expiredTimestamp)

  if redis.call('zcard', key) < limit then
    redis.call('zadd', key, now, identifier)
    redis.call('pexpire', key, lockTimeout)
    return 1
  else
    return 0
  end`,
  1
)