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* snowFlakeUtils * snowFlakeUtils * snowFlakeUtils * fix instance * 'codestyle' * 'codestyle' * 'codestyle' * 'codestyle' * 'codestyle' Co-authored-by: 文蛤 <wenge@myweimai.com>pull/3/MERGE
JinyLeeChina
4 years ago
committed by
GitHub
5 changed files with 148 additions and 0 deletions
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/* |
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* Licensed to the Apache Software Foundation (ASF) under one or more |
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* contributor license agreements. See the NOTICE file distributed with |
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* this work for additional information regarding copyright ownership. |
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* The ASF licenses this file to You under the Apache License, Version 2.0 |
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* (the "License"); you may not use this file except in compliance with |
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* the License. You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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*/ |
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package org.apache.dolphinscheduler.common.utils; |
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import org.apache.dolphinscheduler.common.Constants; |
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import java.net.InetAddress; |
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import java.net.UnknownHostException; |
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import java.util.Objects; |
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public class SnowFlakeUtils { |
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// start timestamp
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private static final long START_TIMESTAMP = 1609430400000L; //2021-01-01
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// Number of digits
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private static final long SEQUENCE_BIT = 12; |
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private static final long MACHINE_BIT = 5; |
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private static final long DATA_CENTER_BIT = 5; |
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// Maximum value
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private static final long MAX_DATA_CENTER_NUM = ~(-1L << DATA_CENTER_BIT); |
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private static final long MAX_SEQUENCE = ~(-1L << SEQUENCE_BIT); |
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// The displacement to the left
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private static final long MACHINE_LEFT = SEQUENCE_BIT; |
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private static final long DATA_CENTER_LEFT = SEQUENCE_BIT + MACHINE_BIT; |
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private static final long TIMESTAMP_LEFT = DATA_CENTER_LEFT + DATA_CENTER_BIT; |
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private final int dataCenterId; |
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private final int machineId; |
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private long sequence = 0L; |
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private long lastTimestamp = -1L; |
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private SnowFlakeUtils() throws SnowFlakeException { |
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this.dataCenterId = PropertyUtils.getInt(Constants.SNOW_FLAKE_DATA_CENTER_ID, 1); |
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if (dataCenterId > MAX_DATA_CENTER_NUM || dataCenterId < 0) { |
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throw new IllegalArgumentException(String.format("dataCenterId can't be greater than %d or less than 0", MAX_DATA_CENTER_NUM)); |
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} |
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try { |
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this.machineId = Math.abs(Objects.hash(InetAddress.getLocalHost().getHostName())) % 32; |
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} catch (UnknownHostException e) { |
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throw new SnowFlakeException(e.getMessage()); |
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} |
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} |
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private static SnowFlakeUtils instance = null; |
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public static synchronized SnowFlakeUtils getInstance() throws SnowFlakeException { |
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if (instance == null) { |
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instance = new SnowFlakeUtils(); |
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} |
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return instance; |
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} |
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public synchronized long nextId() throws SnowFlakeException { |
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long currStmp = nowTimestamp(); |
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if (currStmp < lastTimestamp) { |
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throw new SnowFlakeException("Clock moved backwards. Refusing to generate id"); |
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} |
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if (currStmp == lastTimestamp) { |
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sequence = (sequence + 1) & MAX_SEQUENCE; |
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if (sequence == 0L) { |
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currStmp = getNextMill(); |
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} |
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} else { |
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sequence = 0L; |
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} |
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lastTimestamp = currStmp; |
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return (currStmp - START_TIMESTAMP) << TIMESTAMP_LEFT |
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| dataCenterId << DATA_CENTER_LEFT |
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| machineId << MACHINE_LEFT |
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| sequence; |
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} |
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private long getNextMill() { |
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long mill = nowTimestamp(); |
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while (mill <= lastTimestamp) { |
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mill = nowTimestamp(); |
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} |
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return mill; |
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} |
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private long nowTimestamp() { |
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return System.currentTimeMillis(); |
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} |
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public static class SnowFlakeException extends Exception { |
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public SnowFlakeException(String message) { |
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super(message); |
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} |
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} |
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} |
@ -0,0 +1,33 @@ |
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/* |
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* Licensed to the Apache Software Foundation (ASF) under one or more |
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* contributor license agreements. See the NOTICE file distributed with |
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* this work for additional information regarding copyright ownership. |
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* The ASF licenses this file to You under the Apache License, Version 2.0 |
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* (the "License"); you may not use this file except in compliance with |
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* the License. You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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*/ |
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package org.apache.dolphinscheduler.common.utils; |
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import org.junit.Test; |
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public class SnowFlakeUtilsTest { |
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@Test |
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public void testNextId() { |
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try { |
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for (int i = 0; i < 5; i++) { |
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System.out.println(SnowFlakeUtils.getInstance().nextId()); |
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} |
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} catch (Exception e) { |
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e.printStackTrace(); |
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} |
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} |
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} |
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