Resolve write performance regression (fixes #268)

bp-alex · bp-alex · commit ab6a6a0462a2 · 2025-11-04T14:00:22.000+11:00
Bisection using the LmdbJava Benchmarks project identified a 40% write performance regression introduced in commit 68f0a44: Commit Date Score Change Message =============================================================================== be2a15b 2023-02-04 00:28:16 89.07 [maven-release-plugin] pr 1cc7e6c 2023-12-04 07:42:08 94.49 +6.09% Test on Java 21 f17b63f 2023-12-05 01:34:17 91.57 -3.09% [maven-release-plugin] pr b5dfb25 2025-02-16 23:37:16 91.38 -0.21% Uplift lmdb from 0.9.29 t * 68f0a44 2025-02-16 23:46:30 128.63 +40.76% Add DbiFlags#MDB_UNSIGNED 928cf7b 2025-02-20 01:26:13 129.12 +0.38% Add url element to pom.xm dc24f4b 2025-10-31 00:20:59 122.03 -5.49% Generalise benchmark link Root cause: MaskedFlag.mask() was changed from a simple for-loop to Stream API in commit 68f0a44. This method is invoked once per write operation (Cursor.put() line 255), causing significant overhead from stream creation, lambda allocation, and boxing/unboxing. Fix: Restore for-loop implementation while preserving the onlyPropagatedToLmdb filtering logic added in 68f0a44. Performance verified with 1M entry write benchmark: - Before fix: 122.03 ms/op - After fix: 90.43 ms/op (within 2% of baseline 89.07 ms/op)
diff --git a/src/main/java/org/lmdbjava/MaskedFlag.java b/src/main/java/org/lmdbjava/MaskedFlag.java
@@ -75,7 +75,20 @@ static <M extends MaskedFlag> int mask(final Stream<M> flags) {
    */
   @SafeVarargs
   static <M extends MaskedFlag> int mask(final boolean onlyPropagatedToLmdb, final M... flags) {
-    return flags == null ? 0 : mask(onlyPropagatedToLmdb, Arrays.stream(flags));
+    if (flags == null || flags.length == 0) {
+      return 0;
+    }
+
+    int result = 0;
+    for (final M flag : flags) {
+      if (flag == null) {
+        continue;
+      }
+      if (!onlyPropagatedToLmdb || flag.isPropagatedToLmdb()) {
+        result |= flag.getMask();
+      }
+    }
+    return result;
   }
 
   /**
