OortObjectMergers.java

/*
 * Copyright (c) 2008-2017 the original author or authors.
 *
 * 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
 *
 *     http://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.cometd.oort;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

public class OortObjectMergers {
    private OortObjectMergers() {
    }

    public static OortObject.Merger<Long, Long> longSum() {
        return new LongSumMerger();
    }

    public static <K, V> OortObject.Merger<Map<K, V>, Map<K, V>> mapUnion() {
        return new MapUnionMerger<>();
    }

    public static <K, V> OortObject.Merger<ConcurrentMap<K, V>, ConcurrentMap<K, V>> concurrentMapUnion() {
        return new ConcurrentMapUnionMerger<>();
    }

    public static <E> OortObject.Merger<List<E>, List<E>> listUnion() {
        return new ListUnionMerger<>();
    }

    private static class LongSumMerger implements OortObject.Merger<Long, Long> {
        @Override
        public Long merge(Collection<OortObject.Info<Long>> infos) {
            long sum = 0;
            for (OortObject.Info<Long> info : infos) {
                sum += info.getObject();
            }
            return sum;
        }
    }

    private static class MapUnionMerger<K, V> implements OortObject.Merger<Map<K, V>, Map<K, V>> {
        @Override
        public Map<K, V> merge(Collection<OortObject.Info<Map<K, V>>> infos) {
            Map<K, V> result = new HashMap<>();
            for (OortObject.Info<Map<K, V>> value : infos) {
                result.putAll(value.getObject());
            }
            return result;
        }
    }

    private static class ConcurrentMapUnionMerger<K, V> implements OortObject.Merger<ConcurrentMap<K, V>, ConcurrentMap<K, V>> {
        @Override
        public ConcurrentMap<K, V> merge(Collection<OortObject.Info<ConcurrentMap<K, V>>> infos) {
            ConcurrentMap<K, V> result = new ConcurrentHashMap<>();
            for (OortObject.Info<ConcurrentMap<K, V>> value : infos) {
                result.putAll(value.getObject());
            }
            return result;
        }
    }

    public static class ListUnionMerger<E> implements OortObject.Merger<List<E>, List<E>> {
        @Override
        public List<E> merge(Collection<OortObject.Info<List<E>>> infos) {
            List<E> result = new ArrayList<>();
            for (OortObject.Info<List<E>> value : infos) {
                result.addAll(value.getObject());
            }
            return result;
        }
    }
}