SpeciesIdGenerator.java

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package net.bmahe.genetics4j.neat;
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import java.util.concurrent.atomic.AtomicInteger;
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/**
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 * Generates unique identifiers for NEAT (NeuroEvolution of Augmenting Topologies) species.
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 *
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 * <p>SpeciesIdGenerator provides thread-safe generation of unique species identifiers used
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 * to distinguish between different species in the NEAT population. Each species receives
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 * a unique ID that remains constant throughout its lifecycle, enabling species tracking
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 * across generations and proper species management.
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 *
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 * <p>Key characteristics:
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 * <ul>
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 * <li><strong>Thread safety</strong>: Concurrent ID generation for parallel species creation</li>
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 * <li><strong>Uniqueness guarantee</strong>: Each generated ID is unique across the generator's lifetime</li>
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 * <li><strong>Sequential ordering</strong>: IDs are generated in sequential order for consistent tracking</li>
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 * <li><strong>Configurable start</strong>: Initial ID value can be customized for different scenarios</li>
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 * </ul>
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 *
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 * <p>Species lifecycle integration:
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 * <ul>
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 * <li><strong>Species creation</strong>: New species receive unique IDs upon formation</li>
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 * <li><strong>Species tracking</strong>: IDs enable consistent species identification across generations</li>
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 * <li><strong>Population management</strong>: Species IDs facilitate population organization and statistics</li>
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 * <li><strong>Evolution monitoring</strong>: IDs enable tracking of species formation, growth, and extinction</li>
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 * </ul>
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 *
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 * <p>Common usage patterns:
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 * <pre>{@code
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 * // Default species ID generator (starts from 0)
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 * SpeciesIdGenerator generator = new SpeciesIdGenerator();
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 *
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 * // Custom starting ID
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 * SpeciesIdGenerator customGenerator = new SpeciesIdGenerator(1000);
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 *
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 * // Generate unique species IDs
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 * int speciesId1 = generator.computeNewId();  // Returns 0
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 * int speciesId2 = generator.computeNewId();  // Returns 1
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 * int speciesId3 = generator.computeNewId();  // Returns 2
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 *
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 * // Create species with generated IDs
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 * Species<Double> species1 = new Species<>(speciesId1, ancestors1);
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 * Species<Double> species2 = new Species<>(speciesId2, ancestors2);
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 *
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 * // Thread-safe concurrent generation
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 * CompletableFuture<Integer> future1 = CompletableFuture.supplyAsync(generator::computeNewId);
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 * CompletableFuture<Integer> future2 = CompletableFuture.supplyAsync(generator::computeNewId);
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 * // Both futures will receive unique IDs
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 * }</pre>
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 *
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 * <p>Integration with NEAT species management:
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 * <ul>
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 * <li><strong>Species formation</strong>: New species created during population organization get unique IDs</li>
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 * <li><strong>Selection handlers</strong>: Used by NeatSelectionPolicyHandler for species tracking</li>
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 * <li><strong>Population statistics</strong>: Enables species-based metrics and analysis</li>
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 * <li><strong>Evolution context</strong>: Integrated into NEAT execution contexts for species management</li>
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 * </ul>
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 *
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 * <p>Thread safety considerations:
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 * <ul>
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 * <li><strong>Atomic operations</strong>: Uses AtomicInteger for thread-safe ID generation</li>
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 * <li><strong>Concurrent access</strong>: Multiple threads can safely generate IDs simultaneously</li>
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 * <li><strong>Lock-free</strong>: No synchronization overhead for high-performance scenarios</li>
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 * <li><strong>Consistency</strong>: Guarantees unique IDs even under high concurrency</li>
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 * </ul>
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 *
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 * <p>Performance characteristics:
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 * <ul>
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 * <li><strong>O(1) generation</strong>: Constant time ID generation</li>
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 * <li><strong>Memory efficient</strong>: Minimal memory footprint with single atomic counter</li>
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 * <li><strong>High throughput</strong>: Suitable for high-frequency species creation</li>
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 * <li><strong>No contention</strong>: Lock-free implementation avoids thread contention</li>
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 * </ul>
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 *
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 * @see Species
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 * @see net.bmahe.genetics4j.neat.selection.NeatSelectionPolicyHandler
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 * @see NeatEAExecutionContexts
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 */
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public class SpeciesIdGenerator {
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	public static final int DEFAULT_INITIAL_ID = 0;
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	private final AtomicInteger currentId;
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	/**
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	 * Constructs a new species ID generator with the specified initial value.
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	 *
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	 * <p>The initial value determines the first ID that will be generated.
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	 * Subsequent IDs will be incremented sequentially from this starting point.
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	 *
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	 * @param initialValue the first ID value to generate
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	 */
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	public SpeciesIdGenerator(final int initialValue) {
95 2 1. <init> : Removed assignment to member variable currentId → KILLED
2. <init> : removed call to java/util/concurrent/atomic/AtomicInteger::<init> → KILLED
 
		currentId = new AtomicInteger(initialValue);
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	}
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	/**
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	 * Constructs a new species ID generator with the default initial value (0).
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	 */
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	public SpeciesIdGenerator() {
102 1 1. <init> : Substituted 0 with 1 → SURVIVED
 
		this(DEFAULT_INITIAL_ID);
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	}
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	/**
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	 * Generates and returns a new unique species ID.
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	 *
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	 * <p>This method atomically increments the internal counter and returns
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	 * the previous value, ensuring that each call produces a unique identifier.
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	 * The operation is thread-safe and can be called concurrently from multiple
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	 * threads without risk of duplicate IDs.
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	 *
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	 * @return a unique species identifier
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	 */
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	public int computeNewId() {
116 2 1. computeNewId : replaced int return with 0 for net/bmahe/genetics4j/neat/SpeciesIdGenerator::computeNewId → SURVIVED
2. computeNewId : removed call to java/util/concurrent/atomic/AtomicInteger::getAndIncrement → SURVIVED
 
		return currentId.getAndIncrement();
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	}
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}

Mutations

95

1.1
Location : <init>
Killed by : net.bmahe.genetics4j.neat.selection.NeatSelectorImplTest.[engine:junit-jupiter]/[class:net.bmahe.genetics4j.neat.selection.NeatSelectorImplTest]/[method:select()] Removed assignment to member variable currentId → KILLED

2.2
Location : <init>
Killed by : net.bmahe.genetics4j.neat.selection.NeatSelectorImplTest.[engine:junit-jupiter]/[class:net.bmahe.genetics4j.neat.selection.NeatSelectorImplTest]/[method:select()] removed call to java/util/concurrent/atomic/AtomicInteger::<init> → KILLED

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1.1
Location : <init>
Killed by : none Substituted 0 with 1 → SURVIVED Covering tests

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1.1
Location : computeNewId
Killed by : none replaced int return with 0 for net/bmahe/genetics4j/neat/SpeciesIdGenerator::computeNewId → SURVIVED Covering tests

2.2
Location : computeNewId
Killed by : none removed call to java/util/concurrent/atomic/AtomicInteger::getAndIncrement → SURVIVED Covering tests

Active mutators

Tests examined


Report generated by PIT 1.19.6