cn.ponfee.scheduler.common.base

类 Snowflake

java.lang.Object

cn.ponfee.scheduler.common.base.Snowflake

所有已实现的接口:

IdGenerator

public final class Snowflake
extends Object
implements IdGenerator

 基于snowflake算法的ID生成器

 BINARY(Long.MAX_VALUE         )=0111111111111111111111111111111111111111111111111111111111111111
 BINARY(2039-09-07 23:47:35.551)=0000000000000000000000011111111111111111111111111111111111111111
 
 0 | 0000000000 0000000000 0000000000 0000000000 0 | 00000 | 00000 | 0000000000 00
 - | ------------------timestamp------------------ | -did- | -wid- | -----seq-----
 
 00 ~ 00：1位未使用（实际上也是作为long的符号位）
 01 ~ 41：41位为毫秒级时间（能到“2039-09-07 23:47:35.551”，41位bit的最大Long值，超过会溢出）
 42 ~ 46：5位datacenterId
 47 ~ 51：5位workerId（并不算标识符，实际是为线程标识），
 52 ~ 63：12位该毫秒内的当前毫秒内的计数

 毫秒内序列 （由datacenter和机器ID作区分），并且效率较高。经测试，
 snowflake每秒能够产生26万ID左右，完全满足需要。

 计算掩码的三种方式：
   a：(1 << bits) - 1
   b：-1L ^ (-1L << bits)
   c：Long.MAX_VALUE >>> (63 - bits)
 

作者:

Ponfee

构造器概要

构造器

构造器和说明
Snowflake()
Snowflake(int workerId) no datacenterId max sequence count: 16384 max work count : 32 max time at : 2527-06-23 14:20:44.415
Snowflake(int workerId, int datacenterId) sequenceBits: 12 bit, value range of 0 ~ 4095(111111111111) workerIdBits: 5 bit, value range of 0 ~ 31(11111) datacenterIdBits: 5 bit, value range of 0 ~ 31(11111) workerIdShift: sequenceBits，左移12位(seq12位) datacenterIdShift: sequenceBits+workerIdBits，即左移17位(wid5位+seq12位) timestampShift: sequenceBits+workerIdBits+datacenterIdBits， 即左移22位(did5位+wid5位+seq12位) timestampMask: (1L<<(MAX_SIZE-timestampShift))-1 = (1L<<41)-1
Snowflake(int workerId, int datacenterId, int sequenceBits, int workerIdBits, int datacenterIdBits)

方法概要

限定符和类型	方法和说明
long	generateId() Returns id.
long	nextId()

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

构造器详细资料

Snowflake

public Snowflake(int workerId,
                 int datacenterId,
                 int sequenceBits,
                 int workerIdBits,
                 int datacenterIdBits)

Snowflake

public Snowflake(int workerId,
                 int datacenterId)

sequenceBits: 12 bit, value range of 0 ~ 4095(111111111111) workerIdBits: 5 bit, value range of 0 ~ 31(11111) datacenterIdBits: 5 bit, value range of 0 ~ 31(11111) workerIdShift: sequenceBits，左移12位(seq12位) datacenterIdShift: sequenceBits+workerIdBits，即左移17位(wid5位+seq12位) timestampShift: sequenceBits+workerIdBits+datacenterIdBits， 即左移22位(did5位+wid5位+seq12位) timestampMask: (1L<<(MAX_SIZE-timestampShift))-1 = (1L<<41)-1

参数:

workerId -

datacenterId -

Snowflake

public Snowflake()

Snowflake

public Snowflake(int workerId)

no datacenterId max sequence count: 16384 max work count : 32 max time at : 2527-06-23 14:20:44.415

参数:

workerId -

方法详细资料

generateId

public long generateId()

从接口复制的说明: IdGenerator

Returns id.

指定者:

generateId 在接口中 IdGenerator

返回:

id long value

nextId

public long nextId()