//Snowflake algorithm code implementation
public class IdWorker {
// The time start marking point is used as a reference. Generally, the nearest time of the system is taken (once it is determined that it cannot change)
private final static long twepoch = 1288834974657L;
// Number of bits of machine identification
private final static long workerIdBits = 5L;
// Number of digits of data center identification
private final static long datacenterIdBits = 5L;
// Maximum value of machine ID
private final static long maxWorkerId = -1L ^ (-1L << workerIdBits);
// Maximum data center ID value
private final static long maxDatacenterId = -1L ^ (-1L << datacenterIdBits);
// Self-increasing position within milliseconds
private final static long sequenceBits = 12L;
// The machine ID is shifted to the left by 12 bits
private final static long workerIdShift = sequenceBits;
// The data center ID is shifted left by 17 bits
private final static long datacenterIdShift = sequenceBits + workerIdBits;
// Milliseconds shift left by 22 bits
private final static long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;
private final static long sequenceMask = -1L ^ (-1L << sequenceBits);
/* Last production id timestamp */
private static long lastTimestamp = -1L;
// 0, concurrent control
private long sequence = 0L;
private final long workerId;
// Data ID part
private final long datacenterId;
public IdWorker(){
this.datacenterId = getDatacenterId(maxDatacenterId);
this.workerId = getMaxWorkerId(datacenterId, maxWorkerId);
}
/**
* @param workerId
* Working machine ID
* @param datacenterId
* Serial number
*/
public IdWorker(long workerId, long datacenterId) {
if (workerId > maxWorkerId || workerId < 0) {
throw new IllegalArgumentException(("worker Id can't be greater than %d or less than 0", maxWorkerId));
}
if (datacenterId > maxDatacenterId || datacenterId < 0) {
throw new IllegalArgumentException(("datacenter Id can't be greater than %d or less than 0", maxDatacenterId));
}
this.workerId = workerId;
this.datacenterId = datacenterId;
}
/**
* Get the next ID
*
* @return
*/
public synchronized long nextId() {
long timestamp = timeGen();
if (timestamp < lastTimestamp) {
throw new RuntimeException(("Clock moved backwards. Refusing to generate id for %d milliseconds", lastTimestamp - timestamp));
}
if (lastTimestamp == timestamp) {
// In the current millisecond, +1
sequence = (sequence + 1) & sequenceMask;
if (sequence == 0) {
// If the current millisecond count is full, wait for the next second
timestamp = tilNextMillis(lastTimestamp);
}
} else {
sequence = 0L;
}
lastTimestamp = timestamp;
// ID offset combination generates the final ID and returns the ID
long nextId = ((timestamp - twepoch) << timestampLeftShift)
| (datacenterId << datacenterIdShift)
| (workerId << workerIdShift) | sequence;
return nextId;
}
private long tilNextMillis(final long lastTimestamp) {
long timestamp = this.timeGen();
while (timestamp <= lastTimestamp) {
timestamp = this.timeGen();
}
return timestamp;
}
private long timeGen() {
return ();
}
/**
* <p>
* Get maxWorkerId
* </p>
*/
protected static long getMaxWorkerId(long datacenterId, long maxWorkerId) {
StringBuffer mpid = new StringBuffer();
(datacenterId);
String name = ().getName();
if (!()) {
/*
* GET jvmPid
*/
(("@")[0]);
}
/*
* MAC + PID hashcode gets 16 low digits
*/
return (().hashCode() & 0xffff) % (maxWorkerId + 1);
}
/**
* <p>
* Data ID part
* </p>
*/
protected static long getDatacenterId(long maxDatacenterId) {
long id = 0L;
try {
InetAddress ip = ();
NetworkInterface network = (ip);
if (network == null) {
id = 1L;
} else {
byte[] mac = ();
id = ((0x000000FF & (long) mac[ - 1])
| (0x0000FF00 & (((long) mac[ - 2]) << 8))) >> 6;
id = id % (maxDatacenterId + 1);
}
} catch (Exception e) {
(" getDatacenterId: " + ());
}
return id;
}
}