TieredMergePolicyProvider.java

/*
 * Licensed to ElasticSearch and Shay Banon under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. ElasticSearch licenses this
 * file to you 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.elasticsearch.index.merge.policy;

import org.apache.lucene.index.*;
import org.elasticsearch.ElasticSearchException;
import org.elasticsearch.cluster.metadata.IndexMetaData;
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.unit.ByteSizeUnit;
import org.elasticsearch.common.unit.ByteSizeValue;
import org.elasticsearch.index.settings.IndexSettingsService;
import org.elasticsearch.index.shard.AbstractIndexShardComponent;
import org.elasticsearch.index.store.Store;

import java.io.IOException;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArraySet;

public class TieredMergePolicyProvider extends AbstractIndexShardComponent implements MergePolicyProvider<TieredMergePolicy> {

    private final IndexSettingsService indexSettingsService;

    private final Set<CustomTieredMergePolicyProvider> policies = new CopyOnWriteArraySet<CustomTieredMergePolicyProvider>();

    private volatile boolean compoundFormat;
    private volatile double forceMergeDeletesPctAllowed;
    private volatile ByteSizeValue floorSegment;
    private volatile int maxMergeAtOnce;
    private volatile int maxMergeAtOnceExplicit;
    private volatile ByteSizeValue maxMergedSegment;
    private volatile double segmentsPerTier;
    private volatile double reclaimDeletesWeight;
    private boolean asyncMerge;

    private final ApplySettings applySettings = new ApplySettings();

    @Inject
    public TieredMergePolicyProvider(Store store, IndexSettingsService indexSettingsService) {
        super(store.shardId(), store.indexSettings());
        this.indexSettingsService = indexSettingsService;

        this.compoundFormat = indexSettings.getAsBoolean("index.compound_format", store.suggestUseCompoundFile());
        this.asyncMerge = indexSettings.getAsBoolean("index.merge.async", true);
        this.forceMergeDeletesPctAllowed = componentSettings.getAsDouble("expunge_deletes_allowed", 10d); // percentage
        this.floorSegment = componentSettings.getAsBytesSize("floor_segment", new ByteSizeValue(2, ByteSizeUnit.MB));
        this.maxMergeAtOnce = componentSettings.getAsInt("max_merge_at_once", 10);
        this.maxMergeAtOnceExplicit = componentSettings.getAsInt("max_merge_at_once_explicit", 30);
        // TODO is this really a good default number for max_merge_segment, what happens for large indices, won't they end up with many segments?
        this.maxMergedSegment = componentSettings.getAsBytesSize("max_merged_segment", componentSettings.getAsBytesSize("max_merge_segment", new ByteSizeValue(5, ByteSizeUnit.GB)));
        this.segmentsPerTier = componentSettings.getAsDouble("segments_per_tier", 10.0d);
        this.reclaimDeletesWeight = componentSettings.getAsDouble("reclaim_deletes_weight", 2.0d);

        fixSettingsIfNeeded();

        logger.debug("using [tiered] merge policy with expunge_deletes_allowed[{}], floor_segment[{}], max_merge_at_once[{}], max_merge_at_once_explicit[{}], max_merged_segment[{}], segments_per_tier[{}], reclaim_deletes_weight[{}], async_merge[{}]",
                forceMergeDeletesPctAllowed, floorSegment, maxMergeAtOnce, maxMergeAtOnceExplicit, maxMergedSegment, segmentsPerTier, reclaimDeletesWeight, asyncMerge);

        indexSettingsService.addListener(applySettings);
    }

    private void fixSettingsIfNeeded() {
        // fixing maxMergeAtOnce, see TieredMergePolicy#setMaxMergeAtOnce
        if (!(segmentsPerTier >= maxMergeAtOnce)) {
            int newMaxMergeAtOnce = (int) segmentsPerTier;
            logger.debug("[tiered] merge policy changing max_merge_at_once from [{}] to [{}] because segments_per_tier [{}] has to be higher or equal to it", maxMergeAtOnce, newMaxMergeAtOnce, segmentsPerTier);
            this.maxMergeAtOnce = newMaxMergeAtOnce;
        }
    }


    @Override
    public TieredMergePolicy newMergePolicy() {
        CustomTieredMergePolicyProvider mergePolicy;
        if (asyncMerge) {
            mergePolicy = new EnableMergeTieredMergePolicyProvider(this);
        } else {
            mergePolicy = new CustomTieredMergePolicyProvider(this);
        }
        mergePolicy.setUseCompoundFile(compoundFormat);
        mergePolicy.setForceMergeDeletesPctAllowed(forceMergeDeletesPctAllowed);
        mergePolicy.setFloorSegmentMB(floorSegment.mbFrac());
        mergePolicy.setMaxMergeAtOnce(maxMergeAtOnce);
        mergePolicy.setMaxMergeAtOnceExplicit(maxMergeAtOnceExplicit);
        mergePolicy.setMaxMergedSegmentMB(maxMergedSegment.mbFrac());
        mergePolicy.setSegmentsPerTier(segmentsPerTier);
        mergePolicy.setReclaimDeletesWeight(reclaimDeletesWeight);
        return mergePolicy;
    }

    @Override
    public void close(boolean delete) throws ElasticSearchException {
        indexSettingsService.removeListener(applySettings);
    }

    static {
        IndexMetaData.addDynamicSettings(
                "index.merge.policy.expunge_deletes_allowed",
                "index.merge.policy.floor_segment",
                "index.merge.policy.max_merge_at_once",
                "index.merge.policy.max_merge_at_once_explicit",
                "index.merge.policy.max_merged_segment",
                "index.merge.policy.segments_per_tier",
                "index.merge.policy.reclaim_deletes_weight",
                "index.compound_format"
        );
    }

    class ApplySettings implements IndexSettingsService.Listener {
        @Override
        public void onRefreshSettings(Settings settings) {
            double expungeDeletesPctAllowed = settings.getAsDouble("index.merge.policy.expunge_deletes_allowed", TieredMergePolicyProvider.this.forceMergeDeletesPctAllowed);
            if (expungeDeletesPctAllowed != TieredMergePolicyProvider.this.forceMergeDeletesPctAllowed) {
                logger.info("updating [expunge_deletes_allowed] from [{}] to [{}]", TieredMergePolicyProvider.this.forceMergeDeletesPctAllowed, expungeDeletesPctAllowed);
                TieredMergePolicyProvider.this.forceMergeDeletesPctAllowed = expungeDeletesPctAllowed;
                for (CustomTieredMergePolicyProvider policy : policies) {
                    policy.setForceMergeDeletesPctAllowed(expungeDeletesPctAllowed);
                }
            }

            ByteSizeValue floorSegment = settings.getAsBytesSize("index.merge.policy.floor_segment", TieredMergePolicyProvider.this.floorSegment);
            if (!floorSegment.equals(TieredMergePolicyProvider.this.floorSegment)) {
                logger.info("updating [floor_segment] from [{}] to [{}]", TieredMergePolicyProvider.this.floorSegment, floorSegment);
                TieredMergePolicyProvider.this.floorSegment = floorSegment;
                for (CustomTieredMergePolicyProvider policy : policies) {
                    policy.setFloorSegmentMB(floorSegment.mbFrac());
                }
            }

            int maxMergeAtOnce = settings.getAsInt("index.merge.policy.max_merge_at_once", TieredMergePolicyProvider.this.maxMergeAtOnce);
            if (maxMergeAtOnce != TieredMergePolicyProvider.this.maxMergeAtOnce) {
                logger.info("updating [max_merge_at_once] from [{}] to [{}]", TieredMergePolicyProvider.this.maxMergeAtOnce, maxMergeAtOnce);
                TieredMergePolicyProvider.this.maxMergeAtOnce = maxMergeAtOnce;
                for (CustomTieredMergePolicyProvider policy : policies) {
                    policy.setMaxMergeAtOnce(maxMergeAtOnce);
                }
            }

            int maxMergeAtOnceExplicit = settings.getAsInt("index.merge.policy.max_merge_at_once_explicit", TieredMergePolicyProvider.this.maxMergeAtOnceExplicit);
            if (maxMergeAtOnceExplicit != TieredMergePolicyProvider.this.maxMergeAtOnceExplicit) {
                logger.info("updating [max_merge_at_once_explicit] from [{}] to [{}]", TieredMergePolicyProvider.this.maxMergeAtOnceExplicit, maxMergeAtOnceExplicit);
                TieredMergePolicyProvider.this.maxMergeAtOnceExplicit = maxMergeAtOnceExplicit;
                for (CustomTieredMergePolicyProvider policy : policies) {
                    policy.setMaxMergeAtOnceExplicit(maxMergeAtOnceExplicit);
                }
            }

            ByteSizeValue maxMergedSegment = settings.getAsBytesSize("index.merge.policy.max_merged_segment", TieredMergePolicyProvider.this.maxMergedSegment);
            if (!maxMergedSegment.equals(TieredMergePolicyProvider.this.maxMergedSegment)) {
                logger.info("updating [max_merged_segment] from [{}] to [{}]", TieredMergePolicyProvider.this.maxMergedSegment, maxMergedSegment);
                TieredMergePolicyProvider.this.maxMergedSegment = maxMergedSegment;
                for (CustomTieredMergePolicyProvider policy : policies) {
                    policy.setFloorSegmentMB(maxMergedSegment.mbFrac());
                }
            }

            double segmentsPerTier = settings.getAsDouble("index.merge.policy.segments_per_tier", TieredMergePolicyProvider.this.segmentsPerTier);
            if (segmentsPerTier != TieredMergePolicyProvider.this.segmentsPerTier) {
                logger.info("updating [segments_per_tier] from [{}] to [{}]", TieredMergePolicyProvider.this.segmentsPerTier, segmentsPerTier);
                TieredMergePolicyProvider.this.segmentsPerTier = segmentsPerTier;
                for (CustomTieredMergePolicyProvider policy : policies) {
                    policy.setSegmentsPerTier(segmentsPerTier);
                }
            }

            double reclaimDeletesWeight = settings.getAsDouble("index.merge.policy.reclaim_deletes_weight", TieredMergePolicyProvider.this.reclaimDeletesWeight);
            if (reclaimDeletesWeight != TieredMergePolicyProvider.this.reclaimDeletesWeight) {
                logger.info("updating [reclaim_deletes_weight] from [{}] to [{}]", TieredMergePolicyProvider.this.reclaimDeletesWeight, reclaimDeletesWeight);
                TieredMergePolicyProvider.this.reclaimDeletesWeight = reclaimDeletesWeight;
                for (CustomTieredMergePolicyProvider policy : policies) {
                    policy.setReclaimDeletesWeight(reclaimDeletesWeight);
                }
            }

            boolean compoundFormat = settings.getAsBoolean("index.compound_format", TieredMergePolicyProvider.this.compoundFormat);
            if (compoundFormat != TieredMergePolicyProvider.this.compoundFormat) {
                logger.info("updating index.compound_format from [{}] to [{}]", TieredMergePolicyProvider.this.compoundFormat, compoundFormat);
                TieredMergePolicyProvider.this.compoundFormat = compoundFormat;
                for (CustomTieredMergePolicyProvider policy : policies) {
                    policy.setUseCompoundFile(compoundFormat);
                }
            }

            fixSettingsIfNeeded();
        }
    }

    public static class CustomTieredMergePolicyProvider extends TieredMergePolicy {

        private final TieredMergePolicyProvider provider;

        public CustomTieredMergePolicyProvider(TieredMergePolicyProvider provider) {
            super();
            this.provider = provider;
        }

        @Override
        public void close() {
            super.close();
            provider.policies.remove(this);
        }
    }

    public static class EnableMergeTieredMergePolicyProvider extends CustomTieredMergePolicyProvider implements EnableMergePolicy {

        private final ThreadLocal<Boolean> enableMerge = new ThreadLocal<Boolean>() {
            @Override
            protected Boolean initialValue() {
                return Boolean.FALSE;
            }
        };

        public EnableMergeTieredMergePolicyProvider(TieredMergePolicyProvider provider) {
            super(provider);
        }

        @Override
        public void enableMerge() {
            enableMerge.set(Boolean.TRUE);
        }

        @Override
        public void disableMerge() {
            enableMerge.set(Boolean.FALSE);
        }

        @Override
        public boolean isMergeEnabled() {
            return enableMerge.get() == Boolean.TRUE;
        }

        @Override
        public void close() {
            enableMerge.remove();
            super.close();
        }

        @Override
        public MergePolicy.MergeSpecification findMerges(SegmentInfos infos) throws IOException {
            if (enableMerge.get() == Boolean.FALSE) {
                return null;
            }
            return super.findMerges(infos);
        }

        @Override
        public MergeSpecification findForcedMerges(SegmentInfos infos, int maxSegmentCount, Map<SegmentInfo, Boolean> segmentsToMerge) throws IOException {
            if (enableMerge.get() == Boolean.FALSE) {
                return null;
            }
            return super.findForcedMerges(infos, maxSegmentCount, segmentsToMerge);
        }

        @Override
        public MergeSpecification findForcedDeletesMerges(SegmentInfos infos) throws CorruptIndexException, IOException {
            if (enableMerge.get() == Boolean.FALSE) {
                return null;
            }
            return super.findForcedDeletesMerges(infos);
        }
    }
}