org.opensourcebank.batch.partition.HazelcastMapPartitioner.java Source code

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Here is the source code for org.opensourcebank.batch.partition.HazelcastMapPartitioner.java

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/*
 * Copyright 2011 Anatoly Polinsky
 *
 *    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.opensourcebank.batch.partition;

import com.hazelcast.core.Hazelcast;
import org.springframework.batch.core.partition.support.Partitioner;
import org.springframework.batch.item.ExecutionContext;
import org.springframework.beans.factory.InitializingBean;

import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

/**
 * <p> Depending on a grid size and a number of items to process,creates a map of
 *     {@link org.springframework.batch.item.ExecutionContext}s so they will be evenly distributed over nodes in a grid.
 * </p>
 * <p> Since each individual partition will get two numbers to represent a [from, to] range, this partitioner assumes
 *     that a map has {@link Long} keys ( IDs ) that are sorted sequentially form min to max ( e.g. 0,1,2,3,4,5, etc.. )
 * </p>
 *
 * @author anatoly.polinsky
 */
public class HazelcastMapPartitioner implements Partitioner, InitializingBean {

    private String mapName;

    public Map<String, ExecutionContext> partition(int gridSize) {

        Map<Long, Object> itemsMap = Hazelcast.getMap(mapName);
        Set<Long> itemsIds = itemsMap.keySet();

        long min = 0;
        long max = 0;

        if (itemsIds.size() > 0) {
            min = Collections.min(itemsIds);
            max = Collections.max(itemsIds);
        }

        long targetSize = (max - min) / gridSize + 1;

        Map<String, ExecutionContext> result = new HashMap<String, ExecutionContext>();
        int number = 0;
        long start = min;
        long end = start + targetSize - 1;

        while (start <= max) {

            ExecutionContext value = new ExecutionContext();
            result.put("partition" + number, value);

            if (end >= max) {
                end = max;
            }
            value.putLong("fromId", start);
            value.putLong("toId", end);
            value.putString("mapName", mapName);
            start += targetSize;
            end += targetSize;
            number++;
        }

        return result;
    }

    public void afterPropertiesSet() throws Exception {
        if (("".equals(mapName)) || (mapName == null)) {
            throw new IllegalArgumentException(this.getClass().getSimpleName() + ": 'mapName' must be set");
        }
    }

    public String getMapName() {
        return mapName;
    }

    public void setMapName(String mapName) {
        this.mapName = mapName;
    }
}