flow.execution.RxJavaExecutionEngine Maven / Gradle / Ivy

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package flow.execution;

import static java.util.Collections.emptyList;

import java.util.LinkedList;
import java.util.List;

import flow.Dependency;
import flow.FlowException;
import flow.Product;
import flow.Provider;
import flow.planning.ExecutionPlanner.ExecutionStep;
import lombok.SneakyThrows;
import rx.Single;

/**
 * Execution engine that uses RxJava to execute providers.
 * Steps will be executed in parallel and RxJava handles necessary waiting for dependent steps.
 * 
 */
public class RxJavaExecutionEngine, P extends Provider> extends AbstractExecutionEngine, D, Prod, P> {
	
	@Override
	protected Single executeStep(ExecutionStep step, List> dependencies) throws FlowException {
		Single> deps;
		if (dependencies.isEmpty())
			deps = Single.just(emptyList());
		else
			deps = Single.zip(dependencies, this::convertArrayToTypedList);
		
		return deps.map(ds -> executeStepInternal(step, ds)).cache();
	}

	@SuppressWarnings("unchecked")
	private  List convertArrayToTypedList(Object[] results) {
		List castedObjects = new LinkedList();
		for(Object r : results)
			castedObjects.add((T)r);
		return castedObjects;
	}

	@SneakyThrows
	private Prod executeStepInternal(ExecutionStep step, List params) {
		return step.getProvider().invoke(params);
	}

	@Override
	protected Single wrapInputValue(Prod input) { 
		return Single.just(input);
	}

}