org.apache.hadoop.hbase.regionserver.StoreUtils.java Source code

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Here is the source code for org.apache.hadoop.hbase.regionserver.StoreUtils.java

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/**
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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.apache.hadoop.hbase.regionserver;

import java.io.IOException;
import java.util.Collection;
import java.util.Optional;
import java.util.OptionalInt;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.CellComparator;
import org.apache.hadoop.hbase.CellUtil;
import org.apache.hadoop.hbase.classification.InterfaceAudience;

/**
 * Utility functions for region server storage layer.
 */
@InterfaceAudience.Private
public class StoreUtils {

    private static final Log LOG = LogFactory.getLog(StoreUtils.class);

    /**
     * Creates a deterministic hash code for store file collection.
     */
    public static OptionalInt getDeterministicRandomSeed(Collection<StoreFile> files) {
        return files.stream().mapToInt(f -> f.getPath().getName().hashCode()).findFirst();
    }

    /**
     * Determines whether any files in the collection are references.
     * @param files The files.
     */
    public static boolean hasReferences(final Collection<StoreFile> files) {
        if (files != null) {
            for (StoreFile hsf : files) {
                if (hsf.isReference()) {
                    return true;
                }
            }
        }
        return false;
    }

    /**
     * Gets lowest timestamp from candidate StoreFiles
     */
    public static long getLowestTimestamp(final Collection<StoreFile> candidates) throws IOException {
        long minTs = Long.MAX_VALUE;
        for (StoreFile storeFile : candidates) {
            minTs = Math.min(minTs, storeFile.getModificationTimeStamp());
        }
        return minTs;
    }

    /**
     * Gets the largest file (with reader) out of the list of files.
     * @param candidates The files to choose from.
     * @return The largest file; null if no file has a reader.
     */
    static Optional<StoreFile> getLargestFile(Collection<StoreFile> candidates) {
        return candidates.stream().filter(f -> f.getReader() != null)
                .max((f1, f2) -> Long.compare(f1.getReader().length(), f2.getReader().length()));
    }

    /**
     * Return the largest memstoreTS found across all storefiles in the given list. Store files that
     * were created by a mapreduce bulk load are ignored, as they do not correspond to any specific
     * put operation, and thus do not have a memstoreTS associated with them.
     * @return 0 if no non-bulk-load files are provided or, this is Store that does not yet have any
     *         store files.
     */
    public static long getMaxMemstoreTSInList(Collection<StoreFile> sfs) {
        long max = 0;
        for (StoreFile sf : sfs) {
            if (!sf.isBulkLoadResult()) {
                max = Math.max(max, sf.getMaxMemstoreTS());
            }
        }
        return max;
    }

    /**
     * Return the highest sequence ID found across all storefiles in
     * the given list.
     * @param sfs
     * @return 0 if no non-bulk-load files are provided or, this is Store that
     * does not yet have any store files.
     */
    public static long getMaxSequenceIdInList(Collection<StoreFile> sfs) {
        long max = 0;
        for (StoreFile sf : sfs) {
            max = Math.max(max, sf.getMaxSequenceId());
        }
        return max;
    }

    /**
     * Gets the approximate mid-point of the given file that is optimal for use in splitting it.
     * @param file the store file
     * @param comparator Comparator used to compare KVs.
     * @return The split point row, or null if splitting is not possible, or reader is null.
     */
    static Optional<byte[]> getFileSplitPoint(StoreFile file, CellComparator comparator) throws IOException {
        StoreFileReader reader = file.getReader();
        if (reader == null) {
            LOG.warn("Storefile " + file + " Reader is null; cannot get split point");
            return Optional.empty();
        }
        // Get first, last, and mid keys. Midkey is the key that starts block
        // in middle of hfile. Has column and timestamp. Need to return just
        // the row we want to split on as midkey.
        Cell midkey = reader.midkey();
        if (midkey != null) {
            Cell firstKey = reader.getFirstKey();
            Cell lastKey = reader.getLastKey();
            // if the midkey is the same as the first or last keys, we cannot (ever) split this region.
            if (comparator.compareRows(midkey, firstKey) == 0 || comparator.compareRows(midkey, lastKey) == 0) {
                if (LOG.isDebugEnabled()) {
                    LOG.debug("cannot split because midkey is the same as first or last row");
                }
                return Optional.empty();
            }
            return Optional.of(CellUtil.cloneRow(midkey));
        }
        return Optional.empty();
    }
}