First commit

.idea/.gitignore

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+# Default ignored files
+/shelf/
+/workspace.xml
+# Editor-based HTTP Client requests
+/httpRequests/
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml

.idea/encodings.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="Encoding">
+    <file url="file://$PROJECT_DIR$/src/main/java" charset="UTF-8" />
+    <file url="file://$PROJECT_DIR$/src/main/resources" charset="UTF-8" />
+  </component>
+</project>

.idea/misc.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ExternalStorageConfigurationManager" enabled="true" />
+  <component name="MavenProjectsManager">
+    <option name="originalFiles">
+      <list>
+        <option value="$PROJECT_DIR$/pom.xml" />
+      </list>
+    </option>
+  </component>
+  <component name="ProjectRootManager" version="2" languageLevel="JDK_22" default="true" project-jdk-name="22" project-jdk-type="JavaSDK">
+    <output url="file://$PROJECT_DIR$/out" />
+  </component>
+</project>

pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>org.example</groupId>
+    <artifactId>stream-examples</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <properties>
+        <maven.compiler.source>22</maven.compiler.source>
+        <maven.compiler.target>22</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-core</artifactId>
+            <version>1.37</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-generator-annprocess</artifactId>
+            <version>1.37</version>
+        </dependency>
+    </dependencies>
+
+</project>

src/main/java/com/alldressedprogramming/Main.java

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+package com.alldressedprogramming;
+
+import org.openjdk.jmh.annotations.*;
+import org.openjdk.jmh.infra.Blackhole;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
+import java.util.stream.IntStream;
+import java.util.stream.LongStream;
+import java.util.stream.Stream;
+
+
+@State(Scope.Benchmark)
+public class Main {
+
+    public record Song(List<String> composers) {
+    }
+
+    public record Album(List<Song> songs, int releaseYear) {
+    }
+
+    public static Song createFakeSong(Random random){
+        var composers = IntStream.range(1,10)
+                .map(i -> random.nextInt(0, 100))
+                .mapToObj(i -> i == 0 ? "taylor swift" : "not taylor swift #" + i )
+                .toList();
+        return new Song(composers);
+
+    }
+
+    public static Album createFakeAlbum(Random random) {
+        var seed = random.nextLong();
+        var songs = IntStream.range(2, 25)
+                .mapToObj(Random::new)
+                .map(Main::createFakeSong)
+                .toList();
+        return new Album(songs, random.nextInt(1990, 2024));
+    }
+
+    public static List<Album> createFakeAlbums(int n) {
+        return LongStream.range(0, n)
+                .mapToObj(Random::new)
+                .map(Main::createFakeAlbum)
+                .toList();
+
+    }
+
+    List<Album> albums;
+
+    @Setup(Level.Invocation)
+    public void setUp() {
+        albums = createFakeAlbums(1000);
+    }
+
+
+    @Benchmark
+    public void classical(Blackhole blackhole) {
+        List<Song> newTaylorSwift = new ArrayList<>();
+        for(Album album: albums){
+            if(album.releaseYear() > 2020){
+                for(Song song: album.songs()){
+                    if(song.composers().contains("taylor swift")){
+                        newTaylorSwift.add(song);
+                    }
+                }
+            }
+        }
+        blackhole.consume(newTaylorSwift);
+    }
+
+
+    public List<Album> getRecentAlbums(List<Album> albums){
+        List<Album> ret = new ArrayList<>();
+        for(Album album: albums){
+            if(album.releaseYear() > 2020){
+                ret.add(album);
+            }
+        }
+        return ret;
+    }
+
+    public List<Song> getTaylorSwiftSongs(List<Album> albums){
+        List<Song> ret = new ArrayList<>();
+        for(Album album: albums){
+            for(Song song: album.songs()){
+                if(song.composers().contains("taylor swift")){
+                    ret.add(song);
+                }
+            }
+        }
+        return ret;
+    }
+
+    @Benchmark
+    public void brokenDownWithMethods(Blackhole blackhole) {
+        List<Album> recentAlbums = getRecentAlbums(albums);
+        List<Song> newTaylorSwift = getTaylorSwiftSongs(recentAlbums);
+        blackhole.consume(newTaylorSwift);
+    }
+
+    public Stream<Album> getRecentAlbumsAsStream(Stream<Album> albums){
+        return albums.filter(album -> album.releaseYear() > 2020);
+    }
+
+    public Stream<Song> getTaylorSwiftSongsAsStream(Stream<Album> albums){
+        return albums
+                .flatMap(album ->  album.songs().stream())
+                .filter(song -> song.composers().contains("taylor swift"));
+    }
+
+    @Benchmark
+    public void brokenDownWithMethodsWithStreams(Blackhole blackhole) {
+        Stream<Album> recentAlbums = getRecentAlbumsAsStream(albums.stream());
+        Stream<Song> newTaylorSwift = getTaylorSwiftSongsAsStream(recentAlbums);
+        blackhole.consume(newTaylorSwift);
+    }
+
+    public static void main(String[] args) throws Exception {
+        org.openjdk.jmh.Main.main(args);
+    }
+}