Data Locality pattern #559

data-locality/README.md

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+---
+layout: pattern
+title: Data Locality
+folder: data-locality
+permalink: /patterns/data-locality/
+categories: Other
+tags:
+ - Java
+ - Difficulty-Intermediate
+ - Performance
+---
+
+## Intent
+Accelerate memory access by arranging data to take advantage of CPU caching.
+
+Modern CPUs have caches to speed up memory access. These can access memory adjacent to recently accessed memory much quicker. Take advantage of that to improve performance by increasing data locality keeping data in contiguous memory in the order that you process it.
+
+
+## Applicability
+
+* Like most optimizations, the first guideline for using the Data Locality pattern is when you have a performance problem.
+* With this pattern specifically, you’ll also want to be sure your performance problems are caused by cache misses.
+
+## Real world example
+
+* The [Artemis](http://gamadu.com/artemis/) game engine is one of the first and better-known frameworks that uses simple IDs for game entities.
+
+## Credits
+
+* [Game Programming Patterns Optimization Patterns: Data Locality](http://gameprogrammingpatterns.com/data-locality.html)

data-locality/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+    The MIT License
+    Copyright (c) 2014 Ilkka Seppälä
+
+    Permission is hereby granted, free of charge, to any person obtaining a copy
+    of this software and associated documentation files (the "Software"), to deal
+    in the Software without restriction, including without limitation the rights
+    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+    copies of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included in
+    all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+    THE SOFTWARE.
+
+-->
+<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>
+    <parent>
+        <groupId>com.iluwatar</groupId>
+        <artifactId>java-design-patterns</artifactId>
+        <version>1.22.0-SNAPSHOT</version>
+    </parent>
+    <artifactId>data-locality</artifactId>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+</project>

data-locality/src/main/java/com/iluwatar/data/locality/Application.java

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+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.data.locality;
+
+import com.iluwatar.data.locality.game.GameEntity;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Use the Data Locality pattern is when you have a performance problem.
+ * Take advantage of that to improve performance by increasing data locality — keeping data in
+ * contiguous memory in the order that you process it.
+ *
+ * Example:  Game loop that processes a bunch of game entities.
+ * Those entities are decomposed into different domains 
+ * — AI, physics, and rendering — using the Component pattern.
+ *
+ */
+public class Application {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(Application.class);
+
+  private static final int NUM_ENTITIES = 5;
+  /**
+   * Start game loop with each component have NUM_ENTITIES instance
+   */
+  public static void main(String[] args) {
+    LOGGER.info("Start Game Application using Data-Locality pattern");
+    GameEntity gameEntity = new GameEntity(NUM_ENTITIES);
+    gameEntity.start();
+    gameEntity.update();
+  }
+}

data-locality/src/main/java/com/iluwatar/data/locality/game/GameEntity.java

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+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.data.locality.game;
+
+import com.iluwatar.data.locality.game.component.manager.AiComponentManager;
+import com.iluwatar.data.locality.game.component.manager.PhysicsComponentManager;
+import com.iluwatar.data.locality.game.component.manager.RenderComponentManager;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * The game Entity maintains a big array of pointers .
+ * Each spin of the game loop, we need to run the following:
+ *
+ *     Update the AI components .
+ *
+ *     Update the physics components for them.
+ *
+ *     Render them using their render components.
+ */
+public class GameEntity {
+  private static final Logger LOGGER = LoggerFactory.getLogger(GameEntity.class);
+
+  private final AiComponentManager aiComponentManager;
+  private final PhysicsComponentManager physicsComponentManager;
+  private final RenderComponentManager renderComponentManager;
+
+  /**
+   * Init components
+   */
+  public GameEntity(int numEntities) {
+    LOGGER.info("Init Game with #Entity : {}", numEntities);
+    aiComponentManager = new AiComponentManager(numEntities);
+    physicsComponentManager = new PhysicsComponentManager(numEntities);
+    renderComponentManager = new RenderComponentManager(numEntities);
+  }
+
+  /**
+   * start all component
+   */
+  public void start() {
+    LOGGER.info("Start Game");
+    aiComponentManager.start();
+    physicsComponentManager.start();
+    renderComponentManager.start();
+  }
+
+  /**
+   * update all component
+   */
+  public void update() {
+    LOGGER.info("Update Game Component");
+    // Process AI.
+    aiComponentManager.update();
+
+    // update physics.
+    physicsComponentManager.update();
+
+    // Draw to screen.
+    renderComponentManager.render();
+  }
+
+}

data-locality/src/main/java/com/iluwatar/data/locality/game/component/AiComponent.java

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+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.data.locality.game.component;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Implementation of AI component for Game
+ */
+public class AiComponent implements Component {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(AiComponent.class);
+
+  /**
+   * Update ai component
+   */
+  @Override
+  public void update() {
+    LOGGER.info("update AI component");
+  }
+
+  @Override
+  public void render() {
+
+  }
+}

data-locality/src/main/java/com/iluwatar/data/locality/game/component/Component.java

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+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.data.locality.game.component;
+
+/**
+ * Implement different Game component update and render process
+ */
+public interface Component {
+
+  void update();
+
+  void render();
+}

data-locality/src/main/java/com/iluwatar/data/locality/game/component/PhysicsComponent.java

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+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.data.locality.game.component;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Implementation of Physics Component of Game
+ */
+public class PhysicsComponent implements Component {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(PhysicsComponent.class);
+  /**
+   * update physics component of game
+   */
+  @Override
+  public void update() {
+    LOGGER.info("Update physics component of game");
+  }
+
+  @Override
+  public void render() {
+    // do nothing
+  }
+}

data-locality/src/main/java/com/iluwatar/data/locality/game/component/RenderComponent.java

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+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.data.locality.game.component;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Implementation of Render Component of Game
+ */
+public class RenderComponent implements Component {
+
+  private static final Logger LOGGER = LoggerFactory.getLogger(RenderComponent.class);
+
+  @Override
+  public void update() {
+    // do nothing
+  }
+
+  /**
+   * render
+   */
+  @Override
+  public void render() {
+    LOGGER.info("Render Component");
+  }
+}