garyvv / node-sharp

    let timebase = new Date(new Date().setHours(0, 0, 0, 0)).getTime()

    let time = Date.now() + Math.random()  // 没有锁，增加随机因子

    let elapse = (time - timebase) * MULTIPLY_BASE            // 阿里云执行保证不重复

    let elapseBin = (parseInt(Math.pow(2, 37) - 1) + parseInt(elapse)).toString(2) // 38bit

    let serverIdBin = (Math.pow(2, 4) - 1 + serverId).toString(2)     // 5bit // 1 to 2^4-1 ，即最大支持15台服务器

    let random = parseInt(Math.random() * (Math.pow(2, 6) - 1 - 1 + 1) + 1, 10)               //

    let randomBin = (Math.pow(2, 6) - 1 + random).toString(2)     // 7bit

    let resultBin = elapseBin + serverIdBin + randomBin   // 50bit

    let result = parseInt(resultBin, 2)

    return result

  },

}