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@@ -0,0 +1,112 @@
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+package com.zfjg.manage.utils;
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+
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+import org.springframework.stereotype.Service;
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+
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+import java.net.NetworkInterface;
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+import java.security.SecureRandom;
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+import java.time.Instant;
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+import java.util.Enumeration;
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+
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+/**
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+ * Distributed Sequence Generator. Inspired by Twitter snowflake:
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+ * https://github.com/twitter/snowflake/tree/snowflake-2010
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+ *
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+ * <p>This class should be used as a Singleton. Make sure that you create and reuse a Single
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+ * instance of SequenceGenerator per node in your distributed system cluster.
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+ */
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+@Service
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+public class SequenceGenerator {
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+ private static final int TOTAL_BITS = 60;
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+ private static final int EPOCH_BITS = 42;
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+ private static final int NODE_ID_BITS = 10;
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+ private static final int SEQUENCE_BITS = 12;
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+
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+ private static final int maxNodeId = (int) (Math.pow(2, NODE_ID_BITS) - 1);
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+ private static final int maxSequence = (int) (Math.pow(2, SEQUENCE_BITS) - 1);
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+
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+ // Custom Epoch (January 1, 2015 Midnight UTC = 2015-01-01T00:00:00Z)
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+ private static final long CUSTOM_EPOCH = 1420070400000L;
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+
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+ private final int nodeId;
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+
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+ private volatile long lastTimestamp = -1L;
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+ private volatile long sequence = 0L;
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+
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+ // Create SequenceGenerator with a nodeId
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+ public SequenceGenerator(int nodeId) {
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+ if (nodeId < 0 || nodeId > maxNodeId) {
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+ throw new IllegalArgumentException(
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+ String.format("NodeId must be between %d and %d", 0, maxNodeId));
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+ }
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+ this.nodeId = nodeId;
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+ }
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+
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+ // Let SequenceGenerator generate a nodeId
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+ public SequenceGenerator() {
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+ this.nodeId = createNodeId();
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+ }
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+
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+ public synchronized long nextId() {
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+ long currentTimestamp = timestamp();
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+
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+ if (currentTimestamp < lastTimestamp) {
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+ throw new IllegalStateException("Invalid System Clock!");
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+ }
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+
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+ if (currentTimestamp == lastTimestamp) {
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+ sequence = (sequence + 1) & maxSequence;
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+ if (sequence == 0) {
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+ // Sequence Exhausted, wait till next millisecond.
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+ currentTimestamp = waitNextMillis(currentTimestamp);
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+ }
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+ } else {
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+ // reset sequence to start with zero for the next millisecond
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+ sequence = 0;
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+ }
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+
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+ lastTimestamp = currentTimestamp;
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+
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+ long id = currentTimestamp << (TOTAL_BITS - EPOCH_BITS);
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+ id |= (nodeId << (TOTAL_BITS - EPOCH_BITS - NODE_ID_BITS));
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+ id |= sequence;
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+ return id;
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+ }
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+
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+ // Get current timestamp in milliseconds, adjust for the custom epoch.
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+ private static long timestamp() {
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+ return Instant.now().toEpochMilli() - CUSTOM_EPOCH;
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+ }
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+
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+ // Block and wait till next millisecond
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+ private long waitNextMillis(long currentTimestamp) {
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+ while (currentTimestamp == lastTimestamp) {
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+ currentTimestamp = timestamp();
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+ }
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+ return currentTimestamp;
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+ }
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+
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+ private int createNodeId() {
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+ int nodeId;
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+ try {
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+ StringBuilder sb = new StringBuilder();
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+ Enumeration<NetworkInterface> networkInterfaces = NetworkInterface.getNetworkInterfaces();
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+ while (networkInterfaces.hasMoreElements()) {
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+ NetworkInterface networkInterface = networkInterfaces.nextElement();
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+ byte[] mac = networkInterface.getHardwareAddress();
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+ if (mac != null) {
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+ for (int i = 0; i < mac.length; i++) {
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+ sb.append(String.format("%02X", mac[i]));
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+ }
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+ }
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+ }
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+ nodeId = sb.toString().hashCode();
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+ } catch (Exception ex) {
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+ nodeId = (new SecureRandom().nextInt());
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+ }
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+ nodeId = nodeId & maxNodeId;
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+
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+ return nodeId;
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+ }
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+
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+
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+}
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huhu