com.liferay.registry.ServiceRankingUtil Maven / Gradle / Ivy

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/**
 * Copyright (c) 2000-present Liferay, Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation; either version 2.1 of the License, or (at your option)
 * any later version.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
 * details.
 */

package com.liferay.registry;

import java.util.Map;
import java.util.Optional;
import java.util.Set;

/**
 * @author Shuyang Zhou
 */
public class ServiceRankingUtil {

	public static int compare(
		ServiceReference serviceReference1,
		ServiceReference serviceReference2) {

		int value = Integer.compare(
			_getServiceRanking(serviceReference1),
			_getServiceRanking(serviceReference2));

		if (value != 0) {
			return value;
		}

		return -Long.compare(
			(Long)serviceReference1.getProperty("service.id"),
			(Long)serviceReference2.getProperty("service.id"));
	}

	public static  Optional, T>>
		getHighestRankingEntry(Map, T> services) {

		Set, T>> entrySet = services.entrySet();

		if (entrySet.isEmpty()) {
			return Optional.empty();
		}

		Map.Entry, T> maxEntry = null;

		for (Map.Entry, T> entry : entrySet) {
			if (maxEntry == null) {
				maxEntry = entry;
			}
			else if (compare(entry.getKey(), maxEntry.getKey()) > 0) {
				maxEntry = entry;
			}
		}

		return Optional.of(maxEntry);
	}

	private static int _getServiceRanking(
		ServiceReference serviceReference) {

		Object serviceRanking = serviceReference.getProperty("service.ranking");

		if (serviceRanking instanceof Integer) {
			return (Integer)serviceRanking;
		}

		if (serviceRanking instanceof String) {
			try {
				return Integer.parseInt((String)serviceRanking);
			}
			catch (NumberFormatException nfe) {
			}
		}

		return 0;
	}

}