From 5283e54dc8aab3ba2f116b5cbc37cc752689f1c9 Mon Sep 17 00:00:00 2001
From: OS <29528966+lenboo@users.noreply.github.com>
Date: Tue, 9 Nov 2021 11:54:12 +0800
Subject: [PATCH] [cherry-pick][6774] fix snowflake bug  (#6752)

* Use nanoTime replace currentTimemill to avoid clock backwards (#6740)

* [Bug][SnowFlakeUtils] fix snowFlake bug (#6744)

* fix snowFlake bug

* fix hash machine

Co-authored-by: Wenjun Ruan <wenjun@apache.org>
Co-authored-by: JinYong Li <42576980+JinyLeeChina@users.noreply.github.com>
---
 .../common/utils/SnowFlakeUtils.java              | 15 +++++++++------
 .../common/utils/SnowFlakeUtilsTest.java          |  3 ++-
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/dolphinscheduler-common/src/main/java/org/apache/dolphinscheduler/common/utils/SnowFlakeUtils.java b/dolphinscheduler-common/src/main/java/org/apache/dolphinscheduler/common/utils/SnowFlakeUtils.java
index 1fa14fd6cf..6393e19b8c 100644
--- a/dolphinscheduler-common/src/main/java/org/apache/dolphinscheduler/common/utils/SnowFlakeUtils.java
+++ b/dolphinscheduler-common/src/main/java/org/apache/dolphinscheduler/common/utils/SnowFlakeUtils.java
@@ -24,20 +24,23 @@ import java.util.Objects;
 public class SnowFlakeUtils {
     // start timestamp
     private static final long START_TIMESTAMP = 1609430400000L; //2021-01-01 00:00:00
-    // Number of digits
-    private static final long SEQUENCE_BIT = 13;
+    // Each machine generates 32 in the same millisecond
+    private static final long SEQUENCE_BIT = 5;
     private static final long MACHINE_BIT = 2;
     private static final long MAX_SEQUENCE = ~(-1L << SEQUENCE_BIT);
     // The displacement to the left
-    private static final long MACHINE_LEFT = SEQUENCE_BIT;
-    private static final long TIMESTAMP_LEFT = SEQUENCE_BIT + MACHINE_BIT;
+    private static final long MACHINE_LEFT = SEQUENCE_BIT + MACHINE_BIT;
+    private static final long TIMESTAMP_LEFT = SEQUENCE_BIT + MACHINE_BIT + MACHINE_LEFT;
     private final int machineId;
     private long sequence = 0L;
     private long lastTimestamp = -1L;
 
+    private static final long SYSTEM_TIMESTAMP = System.currentTimeMillis();
+    private static final long SYSTEM_NANOTIME  = System.nanoTime();
+
     private SnowFlakeUtils() throws SnowFlakeException {
         try {
-            this.machineId = Math.abs(Objects.hash(InetAddress.getLocalHost().getHostName())) % 32;
+            this.machineId = Math.abs(Objects.hash(InetAddress.getLocalHost().getHostName())) % 4;
         } catch (UnknownHostException e) {
             throw new SnowFlakeException(e.getMessage());
         }
@@ -80,7 +83,7 @@ public class SnowFlakeUtils {
     }
 
     private long nowTimestamp() {
-        return System.currentTimeMillis();
+        return SYSTEM_TIMESTAMP + (System.nanoTime() - SYSTEM_NANOTIME) / 1000000;
     }
 
     public static class SnowFlakeException extends Exception {
diff --git a/dolphinscheduler-common/src/test/java/org/apache/dolphinscheduler/common/utils/SnowFlakeUtilsTest.java b/dolphinscheduler-common/src/test/java/org/apache/dolphinscheduler/common/utils/SnowFlakeUtilsTest.java
index 4f4c6673ea..bdf7096ba6 100644
--- a/dolphinscheduler-common/src/test/java/org/apache/dolphinscheduler/common/utils/SnowFlakeUtilsTest.java
+++ b/dolphinscheduler-common/src/test/java/org/apache/dolphinscheduler/common/utils/SnowFlakeUtilsTest.java
@@ -23,7 +23,8 @@ public class SnowFlakeUtilsTest {
     @Test
     public void testNextId() {
         try {
-            for (int i = 0; i < 5; i++) {
+            for (int i = 0; i < 100; i++) {
+                Thread.sleep(1);
                 System.out.println(SnowFlakeUtils.getInstance().nextId());
             }
         } catch (Exception e) {