001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.regionserver;
019
020import java.io.IOException;
021import java.util.ArrayList;
022import java.util.Collections;
023import java.util.HashSet;
024import java.util.List;
025import java.util.NavigableSet;
026import java.util.Set;
027import org.apache.hadoop.fs.Path;
028import org.apache.hadoop.hbase.ExtendedCell;
029import org.apache.hadoop.hbase.client.Scan;
030import org.apache.hadoop.hbase.mob.MobCell;
031import org.apache.hadoop.hbase.mob.MobUtils;
032import org.apache.yetus.audience.InterfaceAudience;
033import org.slf4j.Logger;
034import org.slf4j.LoggerFactory;
035
036/**
037 * Scanner scans both the memstore and the MOB Store. Coalesce KeyValue stream into
038 * {@code List<KeyValue>} for a single row.
039 */
040@InterfaceAudience.Private
041public class MobStoreScanner extends StoreScanner {
042
043  private static final Logger LOG = LoggerFactory.getLogger(MobStoreScanner.class);
044
045  private boolean cacheMobBlocks = false;
046  private boolean rawMobScan = false;
047  private boolean readEmptyValueOnMobCellMiss = false;
048  private final HMobStore mobStore;
049  private final List<MobCell> referencedMobCells;
050  private final Set<Path> mobFilesRead = new HashSet<>();
051
052  public MobStoreScanner(HStore store, ScanInfo scanInfo, Scan scan,
053    final NavigableSet<byte[]> columns, long readPt) throws IOException {
054    super(store, scanInfo, scan, columns, readPt);
055    cacheMobBlocks = MobUtils.isCacheMobBlocks(scan);
056    rawMobScan = MobUtils.isRawMobScan(scan);
057    readEmptyValueOnMobCellMiss = MobUtils.isReadEmptyValueOnMobCellMiss(scan);
058    if (!(store instanceof HMobStore)) {
059      throw new IllegalArgumentException("The store " + store + " is not a HMobStore");
060    }
061    mobStore = (HMobStore) store;
062    this.referencedMobCells = new ArrayList<>();
063  }
064
065  /**
066   * Firstly reads the cells from the HBase. If the cell are a reference cell (which has the
067   * reference tag), the scanner need seek this cell from the mob file, and use the cell found from
068   * the mob file as the result.
069   */
070  @Override
071  public boolean next(List<? super ExtendedCell> outResult, ScannerContext ctx) throws IOException {
072    boolean result = super.next(outResult, ctx);
073    if (!rawMobScan) {
074      // retrieve the mob data
075      if (outResult.isEmpty()) {
076        return result;
077      }
078      long mobKVCount = 0;
079      long mobKVSize = 0;
080      for (int i = 0; i < outResult.size(); i++) {
081        // At server side, we should only get ExtendedCell
082        ExtendedCell cell = (ExtendedCell) outResult.get(i);
083        if (MobUtils.isMobReferenceCell(cell)) {
084          MobCell mobCell =
085            mobStore.resolve(cell, cacheMobBlocks, readPt, readEmptyValueOnMobCellMiss);
086          mobKVCount++;
087          mobKVSize += mobCell.getCell().getValueLength();
088          outResult.set(i, mobCell.getCell());
089          // Keep the MobCell here unless we shipped the RPC or close the scanner.
090          referencedMobCells.add(mobCell);
091        }
092      }
093      mobStore.updateMobScanCellsCount(mobKVCount);
094      mobStore.updateMobScanCellsSize(mobKVSize);
095    }
096    return result;
097  }
098
099  private void freeAllReferencedMobCells() throws IOException {
100    for (MobCell cell : referencedMobCells) {
101      cell.close();
102      mobFilesRead.addAll(cell.getFilesRead());
103    }
104    referencedMobCells.clear();
105  }
106
107  /**
108   * Returns the set of store file paths and MOB file paths successfully read by this scanner.
109   * Combines paths from the underlying store scanner with paths from resolved MOB cells (populated
110   * when referenced mob cells are closed, e.g. in close() or shipped()).
111   */
112  @Override
113  public Set<Path> getFilesRead() {
114    Set<Path> allFiles = new HashSet<>(super.getFilesRead());
115    allFiles.addAll(mobFilesRead);
116    return Collections.unmodifiableSet(allFiles);
117  }
118
119  @Override
120  public void shipped() throws IOException {
121    super.shipped();
122    this.freeAllReferencedMobCells();
123  }
124
125  @Override
126  public void close() {
127    super.close();
128    try {
129      this.freeAllReferencedMobCells();
130    } catch (IOException e) {
131      LOG.warn("Failed to free referenced mob cells: ", e);
132    }
133  }
134}