package?utils;

public?class?Snowflake?{

????/**?開始時間截?(2015-01-01)?*/
????private?final?long?twepoch?=?1420041600000L;

????/**?機器id所占的位數(shù)?*/
????private?final?long?workerIdBits?=?5L;

????/**?數(shù)據(jù)標(biāo)識id所占的位數(shù)?*/
????private?final?long?datacenterIdBits?=?5L;

????/**?支持的最大機器id，結(jié)果是31?(這個移位算法可以很快的計算出幾位二進制數(shù)所能表示的最大十進制數(shù))?*/
????private?final?long?maxWorkerId?=?-1L?^?(-1L?<<?workerIdBits);

????/**?支持的最大數(shù)據(jù)標(biāo)識id，結(jié)果是31?*/
????private?final?long?maxDatacenterId?=?-1L?^?(-1L?<<?datacenterIdBits);

????/**?序列在id中占的位數(shù)?*/
????private?final?long?sequenceBits?=?12L;

????/**?機器ID向左移12位?*/
????private?final?long?workerIdShift?=?sequenceBits;

????/**?數(shù)據(jù)標(biāo)識id向左移17位(12+5)?*/
????private?final?long?datacenterIdShift?=?sequenceBits?+?workerIdBits;

????/**?時間截向左移22位(5+5+12)?*/
????private?final?long?timestampLeftShift?=?sequenceBits?+?workerIdBits?+?datacenterIdBits;

????/**?生成序列的掩碼，這里為4095?(0b111111111111=0xfff=4095)?*/
????private?final?long?sequenceMask?=?-1L?^?(-1L?<<?sequenceBits);

????/**?工作機器ID(0~31)?*/
????private?long?workerId;

????/**?數(shù)據(jù)中心ID(0~31)?*/
????private?long?datacenterId;

????/**?毫秒內(nèi)序列(0~4095)?*/
????private?long?sequence?=?0L;

????/**?上次生成ID的時間截?*/
????private?long?lastTimestamp?=?-1L;

????public?Snowflake(long?workerId,?long?datacenterId)?{
????????if?(workerId?>?maxWorkerId?||?workerId?<?0)?{
????????????throw?new?IllegalArgumentException(String.format("worker?Id?can't?be?greater?than?%d?or?less?than?0",?maxWorkerId));
????????}
????????if?(datacenterId?>?maxDatacenterId?||?datacenterId?<?0)?{
????????????throw?new?IllegalArgumentException(String.format("datacenter?Id?can't?be?greater?than?%d?or?less?than?0",?maxDatacenterId));
????????}
????????this.workerId?=?workerId;
????????this.datacenterId?=?datacenterId;
????}

????public?synchronized?long?nextId()?{
????????long?timestamp?=?timeGen();

????????//如果當(dāng)前時間小于上一次ID生成的時間戳，說明系統(tǒng)時鐘回退過這個時候應(yīng)當(dāng)拋出異常
????????if?(timestamp?<?lastTimestamp)?{
????????????throw?new?RuntimeException(
????????????????????String.format("Clock?moved?backwards.??Refusing?to?generate?id?for?%d?milliseconds",?lastTimestamp?-?timestamp));
????????}

????????//如果是同一時間生成的，則進行毫秒內(nèi)序列
????????if?(lastTimestamp?==?timestamp)?{
????????????sequence?=?(sequence?+?1)?&?sequenceMask;
????????????//毫秒內(nèi)序列溢出
????????????if?(sequence?==?0)?{
????????????????//阻塞到下一個毫秒,獲得新的時間戳
????????????????timestamp?=?tilNextMillis(lastTimestamp);
????????????}
????????}
????????//時間戳改變，毫秒內(nèi)序列重置
????????else?{
????????????sequence?=?0L;
????????}

????????//上次生成ID的時間截
????????lastTimestamp?=?timestamp;

????????//移位并通過或運算拼到一起組成64位的ID
????????return?((timestamp?-?twepoch)?<<?timestampLeftShift)?//
????????????????|?(datacenterId?<<?datacenterIdShift)?//
????????????????|?(workerId?<<?workerIdShift)?//
????????????????|?sequence;
????}

????protected?long?tilNextMillis(long?lastTimestamp)?{
????????long?timestamp?=?timeGen();
????????while?(timestamp?<=?lastTimestamp)?{
????????????timestamp?=?timeGen();
????????}
????????return?timestamp;
????}

????protected?long?timeGen()?{
????????return?System.currentTimeMillis();
????}

????public?static?void?main(String[]?args)?{
????????Snowflake?idWorker?=?new?Snowflake(0,?0);

????????for?(int?i?=?0;?i?<?100;?i++)?{
????????????long?id?=?idWorker.nextId();
????????????System.out.println(Long.toBinaryString(id));
????????????System.out.println(id);
????????}
????}


}

pip?install?pysnowflake?-i?https://pypi.tuna.tsinghua.edu.cn/simple/

#?Importing?the?`snowflake.client`?module.
import?snowflake.client

#?Calling?the?`get_guid()`?function?from?the?`snowflake.client`?module.
uuid?=?snowflake.client.get_guid()

#?Printing?the?value?of?the?`uuid`?variable.
print(uuid)

#?Printing?the?binary?representation?of?the?`uuid`?variable.
print(bin(uuid))

#?4674877370191056897
#?0b100000011100000100000000011001100011010110000000001000000000001