Resolve #1940: Refactor ThenKeyExpression#normalizeKeyForPositions fo…

…r performance (#1941)
FoundationDB · Dec 12, 2022 · b2bc403 · b2bc403
1 parent d7a2687
commit b2bc403
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diff --git a/docs/ReleaseNotes.md b/docs/ReleaseNotes.md
@@ -15,7 +15,7 @@ The Guava dependency version has been updated to 31.1. Projects may need to chec
 // begin next release
 ### NEXT_RELEASE
 
-* **Bug fix** Fix 1 [(Issue #NNN)](https://github.com/FoundationDB/fdb-record-layer/issues/NNN)
+* **Bug fix** Refactor ThenKeyExpression#normalizeKeyForPositions to reduce hotspot detected by removing stream() implementation to reduce new object creation [(Issue #1940)](https://github.com/FoundationDB/fdb-record-layer/issues/1940)
 * **Bug fix** Fix 2 [(Issue #NNN)](https://github.com/FoundationDB/fdb-record-layer/issues/NNN)
 * **Bug fix** Fix 3 [(Issue #NNN)](https://github.com/FoundationDB/fdb-record-layer/issues/NNN)
 * **Bug fix** Fix 4 [(Issue #NNN)](https://github.com/FoundationDB/fdb-record-layer/issues/NNN)

diff --git a/...e/src/main/java/com/apple/foundationdb/record/metadata/expressions/ThenKeyExpression.java b/...e/src/main/java/com/apple/foundationdb/record/metadata/expressions/ThenKeyExpression.java
@@ -194,9 +194,11 @@ public <S extends KeyExpressionVisitor.State, R> R expand(@Nonnull final KeyExpr
     @Nonnull
     @Override
     public List<KeyExpression> normalizeKeyForPositions() {
-        return getChildren()
-                .stream().flatMap(k -> k.normalizeKeyForPositions().stream())
-                .collect(Collectors.toList());
+        List<KeyExpression> list = new ArrayList<>();
+        for (KeyExpression k : getChildren()) {
+            list.addAll(k.normalizeKeyForPositions());
+        }
+        return list;
     }
 
     @Override