org.apache.inlong.common.util.SnowFlake Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.inlong.common.util;
public class SnowFlake {
// start timestamp
private static final long START_STMP = 1480166465631L;
private static final long SEQUENCE_BIT = 9;
private static final long MACHINE_BIT = 13;
public static final long MAX_MACHINE_NUM = ~(-1L << MACHINE_BIT);
private static final long MAX_SEQUENCE = ~(-1L << SEQUENCE_BIT);
private static final long MACHINE_LEFT = SEQUENCE_BIT;
private static final long TIMESTMP_LEFT = SEQUENCE_BIT + MACHINE_BIT;
private long machineId;
private long sequence = 0L;
private long lastStmp = -1L;
public SnowFlake(long machineId) {
if (machineId > MAX_MACHINE_NUM || machineId < 0) {
throw new IllegalArgumentException(
machineId + "machineId can't be greater than MAX_MACHINE_NUM or less than 0 MAX_MACHINE_NUM"
+ MAX_MACHINE_NUM);
}
this.machineId = machineId;
}
/**
* generate nextId
*/
public synchronized long nextId() {
long currStmp = getNewstmp();
if (currStmp < lastStmp) {
throw new RuntimeException("Clock moved backwards. Refusing to generate id");
}
if (currStmp == lastStmp) {
sequence = (sequence + 1) & MAX_SEQUENCE;
if (sequence == 0L) {
currStmp = getNextMill();
}
} else {
sequence = 0L;
}
lastStmp = currStmp;
return (currStmp - START_STMP) << TIMESTMP_LEFT
| machineId << MACHINE_LEFT
| sequence;
}
private long getNextMill() {
long mill = getNewstmp();
while (mill <= lastStmp) {
mill = getNewstmp();
}
return mill;
}
private long getNewstmp() {
return System.currentTimeMillis();
}
}