(lucene) branch atomic_stringhelper_randomid updated (9dbebd9444c -> a946e65fd25)

[ms...@apache.org]

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msfroh pushed a change to branch atomic_stringhelper_randomid
in repository https://gitbox.apache.org/repos/asf/lucene.git


 discard 9dbebd9444c Remove lock in StringHelper, using atomic getAndUpdate instead
     new a946e65fd25 Remove lock in StringHelper, using atomic getAndUpdate instead

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Summary of changes:
 lucene/core/src/java/org/apache/lucene/util/StringHelper.java | 1 -
 1 file changed, 1 deletion(-)

(lucene) 01/01: Remove lock in StringHelper, using atomic getAndUpdate instead

[ms...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

msfroh pushed a commit to branch atomic_stringhelper_randomid
in repository https://gitbox.apache.org/repos/asf/lucene.git

commit a946e65fd25fc53d2c848015e80049dcf5ed0447
Author: Michael Froh <ms...@apache.org>
AuthorDate: Mon Feb 23 13:30:13 2026 -0800

    Remove lock in StringHelper, using atomic getAndUpdate instead
    
    Signed-off-by: Michael Froh <ms...@apache.org>
---
 .../src/java/org/apache/lucene/util/StringHelper.java     | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/lucene/core/src/java/org/apache/lucene/util/StringHelper.java b/lucene/core/src/java/org/apache/lucene/util/StringHelper.java
index 2b75e2dd662..14923bcca8b 100644
--- a/lucene/core/src/java/org/apache/lucene/util/StringHelper.java
+++ b/lucene/core/src/java/org/apache/lucene/util/StringHelper.java
@@ -22,6 +22,7 @@ import java.nio.file.Files;
 import java.nio.file.Paths;
 import java.util.Arrays;
 import java.util.Properties;
+import java.util.concurrent.atomic.AtomicReference;
 
 /**
  * Methods for manipulating strings.
@@ -360,11 +361,9 @@ public abstract class StringHelper {
   }
 
   // Holds 128 bit unsigned value:
-  @SuppressWarnings("NonFinalStaticField")
-  private static BigInteger nextId;
+  private static final AtomicReference<BigInteger> nextId;
 
   private static final BigInteger mask128;
-  private static final Object idLock = new Object();
 
   static {
     // 128 bit unsigned mask
@@ -435,7 +434,7 @@ public abstract class StringHelper {
     BigInteger unsignedX1 = BigInteger.valueOf(x1).and(mask64);
 
     // Concatentate bits of x0 and x1, as unsigned 128 bit integer:
-    nextId = unsignedX0.shiftLeft(64).or(unsignedX1);
+    nextId = new AtomicReference<>(unsignedX0.shiftLeft(64).or(unsignedX1));
   }
 
   /** length in bytes of an ID */
@@ -458,11 +457,9 @@ public abstract class StringHelper {
     //     what impact that has on the period, whereas the simple ++ (mod 2^128)
     //     we use here is guaranteed to have the full period.
 
-    byte[] bits;
-    synchronized (idLock) {
-      bits = nextId.toByteArray();
-      nextId = nextId.add(BigInteger.ONE).and(mask128);
-    }
+
+    BigInteger next = nextId.getAndUpdate(n -> n.add(BigInteger.ONE).and(mask128));
+    byte[] bits = next.toByteArray();
 
     // toByteArray() always returns a sign bit, so it may require an extra byte (always zero)
     if (bits.length > ID_LENGTH) {