GPUEASystemFactory.java

package net.bmahe.genetics4j.gpu;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.ForkJoinPool;

import net.bmahe.genetics4j.core.EASystem;

import net.bmahe.genetics4j.core.EASystemFactory;

import net.bmahe.genetics4j.gpu.spec.GPUEAConfiguration;

import net.bmahe.genetics4j.gpu.spec.GPUEAExecutionContext;

/**

 * Factory class for creating GPU-accelerated evolutionary algorithm systems using OpenCL.

 * 

 * <p>GPUEASystemFactory provides convenient factory methods for creating {@link EASystem} instances that leverage GPU

 * acceleration through OpenCL for fitness evaluation. This factory extends the capabilities of the core EA framework to

 * support high-performance computing on graphics processors and other OpenCL-compatible devices.

 * 

 * <p>The factory handles the integration between GPU-specific configurations and the core EA framework:

 * <ul>

 * <li><strong>GPU Configuration</strong>: Uses {@link GPUEAConfiguration} with OpenCL program specifications</li>

 * <li><strong>Device Selection</strong>: Leverages {@link GPUEAExecutionContext} for platform and device filtering</li>

 * <li><strong>GPU Evaluator</strong>: Creates specialized {@link GPUFitnessEvaluator} for OpenCL fitness

 * computation</li>

 * <li><strong>Resource Management</strong>: Coordinates executor services with OpenCL resource lifecycle</li>

 * </ul>

 * 

 * <p>GPU acceleration benefits:

 * <ul>

 * <li><strong>Massive parallelism</strong>: Evaluate hundreds or thousands of individuals simultaneously</li>

 * <li><strong>Memory bandwidth</strong>: High-throughput data processing for population-based algorithms</li>

 * <li><strong>Specialized hardware</strong>: Leverage dedicated compute units optimized for parallel operations</li>

 * <li><strong>Energy efficiency</strong>: Often better performance-per-watt compared to CPU-only execution</li>

 * </ul>

 * 

 * <p>Common usage patterns:

 * 

 * <pre>{@code

 * // Define OpenCL kernel for fitness evaluation

 * Program fitnessProgram = Program.ofResource("/kernels/fitness.cl")

 * 		.withBuildOption("-DPROBLEM_SIZE=256");

 * 

 * // Configure GPU-specific EA settings

 * GPUEAConfiguration<Double> gpuConfig = GPUEAConfigurationBuilder.<Double>builder()

 * 		.chromosomeSpecs(chromosomeSpec)

 * 		.parentSelectionPolicy(Tournament.of(3))

 * 		.combinationPolicy(SinglePointCrossover.build())

 * 		.mutationPolicies(List.of(RandomMutation.of(0.1)))

 * 		.replacementStrategy(Elitism.builder()

 * 				.offspringRatio(0.8)

 * 				.build())

 * 		.program(fitnessProgram)

 * 		.fitness(myGPUFitness)

 * 		.build();

 * 

 * // Configure execution context with device preferences

 * GPUEAExecutionContext<Double> gpuContext = GPUEAExecutionContextBuilder.<Double>builder()

 * 		.populationSize(1000)

 * 		.termination(Generations.of(100))

 * 		.platformFilter(platform -> platform.profile() == PlatformProfile.FULL_PROFILE)

 * 		.deviceFilter(device -> device.type() == DeviceType.GPU)

 * 		.build();

 * 

 * // Create GPU-accelerated EA system

 * EASystem<Double> gpuSystem = GPUEASystemFactory.from(gpuConfig, gpuContext);

 * 

 * // Run evolution on GPU

 * EvolutionResult<Double> result = gpuSystem.evolve();

 * }</pre>

 * 

 * <p>OpenCL integration considerations:

 * <ul>

 * <li><strong>Device compatibility</strong>: Ensure target devices support required OpenCL features</li>

 * <li><strong>Memory management</strong>: GPU memory is typically limited compared to system RAM</li>

 * <li><strong>Kernel optimization</strong>: GPU performance depends heavily on kernel implementation</li>

 * <li><strong>Transfer overhead</strong>: Consider data transfer costs between CPU and GPU memory</li>

 * </ul>

 * 

 * <p>Performance optimization tips:

 * <ul>

 * <li><strong>Large populations</strong>: GPU acceleration benefits increase with population size</li>

 * <li><strong>Complex fitness functions</strong>: More computation per individual improves GPU utilization</li>

 * <li><strong>Minimize transfers</strong>: Keep data on GPU between generations when possible</li>

 * <li><strong>Coalesced memory access</strong>: Design kernels for optimal memory access patterns</li>

 * </ul>

 * 

 * @see GPUEAConfiguration

 * @see GPUEAExecutionContext

 * @see GPUFitnessEvaluator

 * @see net.bmahe.genetics4j.core.EASystemFactory

 * @see net.bmahe.genetics4j.gpu.opencl.model.Program

 */

public class GPUEASystemFactory {

	/**

	 * Creates a GPU-accelerated EA system with explicit thread pool management.

	 * 

	 * <p>This method provides full control over thread pool management while enabling GPU acceleration for fitness

	 * evaluation. The provided executor service is used for coordinating between CPU and GPU operations, managing

	 * asynchronous OpenCL operations, and handling concurrent access to OpenCL resources.

	 * 

	 * <p>The factory method performs the following operations:

	 * <ol>

	 * <li>Creates a specialized {@link GPUFitnessEvaluator} configured for OpenCL execution</li>

	 * <li>Integrates the GPU evaluator with the core EA framework</li>

	 * <li>Ensures proper resource management and cleanup for OpenCL contexts</li>

	 * </ol>

	 * 

	 * <p>Use this method when:

	 * <ul>

	 * <li>You need explicit control over thread pool configuration and lifecycle</li>

	 * <li>Integration with existing thread management systems is required</li>

	 * <li>Custom executor services are needed for performance tuning</li>

	 * <li>Resource-constrained environments require careful thread pool sizing</li>

	 * </ul>

	 * 

	 * @param <T>                   the type of fitness values, must be comparable for selection operations

	 * @param gpuEAConfiguration    the GPU-specific EA configuration with OpenCL program and fitness function

	 * @param gpuEAExecutionContext the GPU execution context with device selection and population parameters

	 * @param executorService       the thread pool for managing CPU-GPU coordination (caller responsible for shutdown)

	 * @return a fully configured {@link EASystem} with GPU acceleration capabilities

	 * @throws IllegalArgumentException if any parameter is null

	 * @throws RuntimeException         if OpenCL initialization fails or no compatible devices are found

	 */

	public static <T extends Comparable<T>> EASystem<T> from(final GPUEAConfiguration<T> gpuEAConfiguration,

			final GPUEAExecutionContext<T> gpuEAExecutionContext, final ExecutorService executorService) {

				gpuEAConfiguration,

				executorService);

	}

	/**

	 * Creates a GPU-accelerated EA system using the common thread pool.

	 * 

	 * <p>This convenience method provides GPU acceleration without requiring explicit thread pool management. It

	 * automatically uses {@link ForkJoinPool#commonPool()} for CPU-GPU coordination, making it ideal for applications

	 * where thread pool management is not critical.

	 * 

	 * <p>This method is recommended for:

	 * <ul>

	 * <li>Rapid prototyping and experimentation with GPU acceleration</li>

	 * <li>Applications where default thread pool behavior is sufficient</li>

	 * <li>Educational purposes and demonstration code</li>

	 * <li>Simple GPU-accelerated applications without complex threading requirements</li>

	 * </ul>

	 * 

	 * <p>The common thread pool provides automatic parallelization and reasonable default behavior for most GPU

	 * acceleration scenarios. However, for production systems with specific performance requirements, consider using

	 * {@link #from(GPUEAConfiguration, GPUEAExecutionContext, ExecutorService)} with a custom thread pool.

	 * 

	 * @param <T>                   the type of fitness values, must be comparable for selection operations

	 * @param gpuEAConfiguration    the GPU-specific EA configuration with OpenCL program and fitness function

	 * @param gpuEAExecutionContext the GPU execution context with device selection and population parameters

	 * @return a fully configured {@link EASystem} with GPU acceleration using the common thread pool

	 * @throws IllegalArgumentException if any parameter is null

	 * @throws RuntimeException         if OpenCL initialization fails or no compatible devices are found

	 */

	public static <T extends Comparable<T>> EASystem<T> from(final GPUEAConfiguration<T> gpuEAConfiguration,

			final GPUEAExecutionContext<T> gpuEAExecutionContext) {

	}

}

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