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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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+
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+package org.apache.dolphinscheduler.common.utils;
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+
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+import org.apache.dolphinscheduler.common.Constants;
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+
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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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+
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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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+
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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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+
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+ private static SnowFlakeUtils instance = null;
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+
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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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+
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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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+
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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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+
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+ private long nowTimestamp() {
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+ return System.currentTimeMillis();
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+ }
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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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+}
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