com.linkedin.pinot.routing.builder.BalancedRandomRoutingTableBuilder.java Source code

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Here is the source code for com.linkedin.pinot.routing.builder.BalancedRandomRoutingTableBuilder.java

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/**
 * Copyright (C) 2014-2016 LinkedIn Corp. (pinot-core@linkedin.com)
 *
 * 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 com.linkedin.pinot.routing.builder;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.commons.configuration.Configuration;
import org.apache.helix.model.ExternalView;
import org.apache.helix.model.InstanceConfig;

import com.linkedin.pinot.routing.ServerToSegmentSetMap;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Create a given number of routing tables based on random selections from ExternalView.
 */
public class BalancedRandomRoutingTableBuilder implements RoutingTableBuilder {
    private static final Logger LOGGER = LoggerFactory.getLogger(BalancedRandomRoutingTableBuilder.class);

    private int _numberOfRoutingTables;

    public BalancedRandomRoutingTableBuilder() {
        this._numberOfRoutingTables = 10;
    }

    public BalancedRandomRoutingTableBuilder(int numberOfRoutingTables) {
        this._numberOfRoutingTables = numberOfRoutingTables;
    }

    @Override
    public void init(Configuration configuration) {
        _numberOfRoutingTables = configuration.getInt("numOfRoutingTables", 10);
    }

    @Override
    public synchronized List<ServerToSegmentSetMap> computeRoutingTableFromExternalView(String tableName,
            ExternalView externalView, List<InstanceConfig> instanceConfigList) {

        RoutingTableInstancePruner pruner = new RoutingTableInstancePruner(instanceConfigList);

        List<Map<String, Set<String>>> routingTables = new ArrayList<Map<String, Set<String>>>();
        for (int i = 0; i < _numberOfRoutingTables; ++i) {
            routingTables.add(new HashMap<String, Set<String>>());
        }

        String[] segmentSet = externalView.getPartitionSet().toArray(new String[0]);
        for (String segment : segmentSet) {
            Map<String, String> instanceToStateMap = externalView.getStateMap(segment);
            for (String instance : instanceToStateMap.keySet().toArray(new String[0])) {
                if (!instanceToStateMap.get(instance).equals("ONLINE") || pruner.isInactive(instance)) {
                    LOGGER.info("Removing offline/inactive instance '{}' from routing table computation", instance);
                    instanceToStateMap.remove(instance);
                }
            }
            if (instanceToStateMap.size() > 0) {
                List<String> instanceList = new ArrayList<String>(instanceToStateMap.keySet());
                for (int i = 0; i < _numberOfRoutingTables; ++i) {
                    Collections.shuffle(instanceList);
                    String[] instances = instanceList.toArray(new String[instanceList.size()]);

                    int minInstances = Integer.MAX_VALUE;
                    int minIdx = -1;
                    int base = 2;
                    for (int k = 0; k < instances.length; ++k) {
                        int sizeOfCurrentInstance = 0;
                        if (routingTables.get(i).containsKey(instances[k])) {
                            sizeOfCurrentInstance = routingTables.get(i).get(instances[k]).size();
                        }
                        if (sizeOfCurrentInstance < minInstances) {
                            minInstances = sizeOfCurrentInstance;
                            minIdx = k;
                            base = 2;
                        }
                        if (sizeOfCurrentInstance == minInstances && (System.currentTimeMillis() % base == 0)) {
                            minIdx = k;
                            base = 2;
                        } else {
                            base++;
                        }
                    }
                    if (routingTables.get(i).containsKey(instances[minIdx])) {
                        routingTables.get(i).get(instances[minIdx]).add(segment);
                    } else {
                        Set<String> instanceSegmentSet = new HashSet<String>();
                        instanceSegmentSet.add(segment);
                        routingTables.get(i).put(instances[minIdx], instanceSegmentSet);
                    }
                }
            }
        }

        List<ServerToSegmentSetMap> resultRoutingTableList = new ArrayList<ServerToSegmentSetMap>();
        for (int i = 0; i < _numberOfRoutingTables; ++i) {
            resultRoutingTableList.add(new ServerToSegmentSetMap(routingTables.get(i)));
        }
        return resultRoutingTableList;

    }
}