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.util.Collections;
021import java.util.List;
022import org.apache.hadoop.hbase.CellComparator;
023import org.apache.hadoop.hbase.util.ClassSize;
024import org.apache.yetus.audience.InterfaceAudience;
025
026/**
027 * ImmutableSegment is an abstract class that extends the API supported by a {@link Segment}, and is
028 * not needed for a {@link MutableSegment}.
029 */
030@InterfaceAudience.Private
031public abstract class ImmutableSegment extends Segment {
032
033  public static final long DEEP_OVERHEAD =
034    Segment.DEEP_OVERHEAD + ClassSize.NON_SYNC_TIMERANGE_TRACKER;
035
036  // each sub-type of immutable segment knows whether it is flat or not
037  protected abstract boolean canBeFlattened();
038
039  public int getNumUniqueKeys() {
040    return getCellSet().getNumUniqueKeys();
041  }
042
043  ///////////////////// CONSTRUCTORS /////////////////////
044  /**
045   * ------------------------------------------------------------------------ Empty C-tor to be used
046   * only for CompositeImmutableSegment
047   */
048  protected ImmutableSegment(CellComparator comparator) {
049    super(comparator, TimeRangeTracker.create(TimeRangeTracker.Type.NON_SYNC));
050  }
051
052  protected ImmutableSegment(CellComparator comparator, List<ImmutableSegment> segments) {
053    super(comparator, segments, TimeRangeTracker.create(TimeRangeTracker.Type.NON_SYNC));
054  }
055
056  /**
057   * ------------------------------------------------------------------------ C-tor to be used to
058   * build the derived classes
059   */
060  protected ImmutableSegment(CellSet cs, CellComparator comparator, MemStoreLAB memStoreLAB) {
061    super(cs, comparator, memStoreLAB, TimeRangeTracker.create(TimeRangeTracker.Type.NON_SYNC));
062  }
063
064  /**
065   * ------------------------------------------------------------------------ Copy C-tor to be used
066   * when new CSLMImmutableSegment (derived) is being built from a Mutable one. This C-tor should be
067   * used when active MutableSegment is pushed into the compaction pipeline and becomes an
068   * ImmutableSegment.
069   */
070  protected ImmutableSegment(Segment segment) {
071    super(segment);
072  }
073
074  ///////////////////// PUBLIC METHODS /////////////////////
075
076  public int getNumOfSegments() {
077    return 1;
078  }
079
080  public List<Segment> getAllSegments() {
081    return Collections.singletonList(this);
082  }
083
084  @Override
085  public String toString() {
086    String res = super.toString();
087    res += "Num uniques " + getNumUniqueKeys() + "; ";
088    return res;
089  }
090
091  /**
092   * We create a new {@link SnapshotSegmentScanner} to increase the reference count of
093   * {@link MemStoreLABImpl} used by this segment.
094   */
095  List<KeyValueScanner> getSnapshotScanners() {
096    return Collections.singletonList(new SnapshotSegmentScanner(this));
097  }
098}