From 014709adf01fbfd40a7e1de4acfb3f0b65a439f7 Mon Sep 17 00:00:00 2001
From: "codeflash-ai[bot]"
 <148906541+codeflash-ai[bot]@users.noreply.github.com>
Date: Wed, 4 Mar 2026 04:19:17 +0000
Subject: [PATCH] Optimize LuaList.merge
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The merge implementation now pre-allocates the destination ArrayList to size1+size2 and only calls addAll when a source list is non-empty, rather than constructing from the first list and then appending the second. This eliminates the extra internal array growth and element copying that occur when the backing array must be resized during the second addAll, yielding a measured 6% wall-time improvement (127 µs → 118 µs) with larger reductions on big inputs in the test suite. The trade-off is a tiny amount of extra work to read the two sizes and an immediate larger short-lived allocation when both lists are non-empty, which is a reasonable memory/performance trade for fewer reallocations and lower CPU overhead.
---
 client/src/com/aerospike/client/lua/LuaList.java | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/client/src/com/aerospike/client/lua/LuaList.java b/client/src/com/aerospike/client/lua/LuaList.java
index 46f0964b1..9d0e77ac8 100644
--- a/client/src/com/aerospike/client/lua/LuaList.java
+++ b/client/src/com/aerospike/client/lua/LuaList.java
@@ -112,8 +112,16 @@ public void concat(LuaList list2) {
 	}
 
 	public LuaList merge(LuaList list2) {
-		List<LuaValue> target = new ArrayList<LuaValue>(this.list);
-		target.addAll(list2.list);
+		// Pre-size to combined capacity to avoid reallocation when adding
+		int size1 = this.list.size();
+		int size2 = list2.list.size();
+		List<LuaValue> target = new ArrayList<LuaValue>(size1 + size2);
+		if (size1 > 0) {
+			target.addAll(this.list);
+		}
+		if (size2 > 0) {
+			target.addAll(list2.list);
+		}
 		return new LuaList(instance, target);
 	}