MultiThreadedListenerObjectExecutor.java

/*
 * Copyright (C) 2012-2024 RRiBbit.org
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.rribbit.execution;

import java.util.Collection;
import java.util.Collections;
import java.util.stream.Collectors;

import org.rribbit.ListenerObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This {@link AbstractListenerObjectExecutor} executes the {@link ListenerObject}s in parallel {@link Thread}s. If there is only one {@link ListenerObject} to be executed, then
 * it will be executed in the calling {@link Thread} and no new {@link Thread} will be created.
 *
 * Please note that spawning new {@link Thread}s to execute the {@link ListenerObject}s will result in the loss of the transaction context. If the transaction context must be preserved,
 * either make sure that only a single {@link ListenerObject} is executed or consider using the {@link SequentialListenerObjectExecutor}.
 *
 * @author G.J. Schouten
 *
 */
public class MultiThreadedListenerObjectExecutor extends AbstractListenerObjectExecutor {

	private static final Logger log = LoggerFactory.getLogger(MultiThreadedListenerObjectExecutor.class);

	@Override
	protected Collection<ExecutionResult> doExecuteListeners(Collection<ListenerObject> listenerObjects, Object... parameters) {

		if(listenerObjects.isEmpty()) {
			log.debug("No ListenerObjects to process");
			return Collections.emptyList();
		} else if(listenerObjects.size() == 1) { //There is only one, don't spawn a new Thread, but do it in this Thread
			log.debug("There is only one ListenerObject, not creating new Thread, executing it in this Thread");
			return Collections.singletonList(this.executeSingleListenerObject(listenerObjects.iterator().next(), parameters));
		}

		log.debug("Creating Threads for each ListenerObject and executing");
		return listenerObjects
			.stream()
			.parallel()
			.map(listenerObject -> this.executeSingleListenerObject(listenerObject, parameters))
			.collect(Collectors.toList());
	}
}