From 5c691960a2129612b905f9dcc0452014a06d14ad Mon Sep 17 00:00:00 2001
From: Stephane Nicoll <snicoll@vmware.com>
Date: Sat, 26 Aug 2023 17:45:25 +0200
Subject: [PATCH] Polish "Improve performance of
 CompositePropertySource#getPropertyNames"

See gh-27236
---
 .../env/CompositePropertySourceBenchmark.java  | 18 ++++++++++++------
 .../core/env/CompositePropertySource.java      |  6 ++----
 .../core/env/CompositePropertySourceTests.java | 10 ++++++++++
 3 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/spring-core/src/jmh/java/org/springframework/core/env/CompositePropertySourceBenchmark.java b/spring-core/src/jmh/java/org/springframework/core/env/CompositePropertySourceBenchmark.java
index 73d3d18f52..3d5eae2bdf 100644
--- a/spring-core/src/jmh/java/org/springframework/core/env/CompositePropertySourceBenchmark.java
+++ b/spring-core/src/jmh/java/org/springframework/core/env/CompositePropertySourceBenchmark.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,7 +20,6 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.TimeUnit;
 
-import org.apache.commons.lang3.RandomStringUtils;
 import org.openjdk.jmh.annotations.Benchmark;
 import org.openjdk.jmh.annotations.BenchmarkMode;
 import org.openjdk.jmh.annotations.Level;
@@ -34,6 +33,9 @@ import org.openjdk.jmh.annotations.State;
 import org.openjdk.jmh.annotations.Warmup;
 import org.openjdk.jmh.infra.Blackhole;
 
+import org.springframework.util.AlternativeJdkIdGenerator;
+import org.springframework.util.IdGenerator;
+
 /**
  * Benchmarks for {@link CompositePropertySource}.
  *
@@ -53,14 +55,16 @@ public class CompositePropertySourceBenchmark {
 	@State(Scope.Benchmark)
 	public static class BenchmarkState {
 
-		static final Object VALUE = new Object();
+		private static final IdGenerator ID_GENERATOR = new AlternativeJdkIdGenerator();
+
+		private static final Object VALUE = new Object();
 
 		CompositePropertySource composite;
 
-		@Param({"2", "5", "10"})
+		@Param({ "2", "5", "10" })
 		int numberOfPropertySource;
 
-		@Param({"10", "100", "1000"})
+		@Param({ "10", "100", "1000" })
 		int numberOfPropertyNamesPerSource;
 
 		@Setup(Level.Trial)
@@ -69,11 +73,13 @@ public class CompositePropertySourceBenchmark {
 			for (int i = 0; i < this.numberOfPropertySource; i++) {
 				Map<String, Object> map = new HashMap<>(this.numberOfPropertyNamesPerSource);
 				for (int j = 0; j < this.numberOfPropertyNamesPerSource; j++) {
-					map.put(RandomStringUtils.randomAlphanumeric(5, 50), VALUE);
+					map.put(ID_GENERATOR.generateId().toString(), VALUE);
 				}
 				PropertySource<?> propertySource = new MapPropertySource("propertySource" + i, map);
 				this.composite.addPropertySource(propertySource);
 			}
 		}
+
 	}
+
 }
diff --git a/spring-core/src/main/java/org/springframework/core/env/CompositePropertySource.java b/spring-core/src/main/java/org/springframework/core/env/CompositePropertySource.java
index efc59f67a9..7345ff4dff 100644
--- a/spring-core/src/main/java/org/springframework/core/env/CompositePropertySource.java
+++ b/spring-core/src/main/java/org/springframework/core/env/CompositePropertySource.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -90,9 +90,7 @@ public class CompositePropertySource extends EnumerablePropertySource<Object> {
 			total += names.length;
 		}
 		Set<String> allNames = new LinkedHashSet<>(total);
-		for (String[] names : namesList) {
-			allNames.addAll(Arrays.asList(names));
-		}
+		namesList.forEach(names -> allNames.addAll(Arrays.asList(names)));
 		return StringUtils.toStringArray(allNames);
 	}
 
diff --git a/spring-core/src/test/java/org/springframework/core/env/CompositePropertySourceTests.java b/spring-core/src/test/java/org/springframework/core/env/CompositePropertySourceTests.java
index d7bafe3764..fba8bd2aa5 100644
--- a/spring-core/src/test/java/org/springframework/core/env/CompositePropertySourceTests.java
+++ b/spring-core/src/test/java/org/springframework/core/env/CompositePropertySourceTests.java
@@ -17,6 +17,7 @@
 package org.springframework.core.env;
 
 import java.util.Collections;
+import java.util.Map;
 
 import org.junit.jupiter.api.Test;
 
@@ -46,4 +47,13 @@ class CompositePropertySourceTests {
 		assertThat(((i1 < i2) && (i2 < i3))).as("Bad order: " + s).isTrue();
 	}
 
+	@Test
+	void getPropertyNamesRemovesDuplicates() {
+		CompositePropertySource composite = new CompositePropertySource("c");
+		composite.addPropertySource(new MapPropertySource("p1", Map.of("p1.property", "value")));
+		composite.addPropertySource(new MapPropertySource("p2",
+				Map.of("p2.property1", "value", "p1.property", "value", "p2.property2", "value")));
+		assertThat(composite.getPropertyNames()).containsOnly("p1.property", "p2.property1", "p2.property2");
+	}
+
 }