hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/ImmutableSegment.java

   1 /**
   2  *
   3  * Licensed to the Apache Software Foundation (ASF) under one
   4  * or more contributor license agreements.  See the NOTICE file
   5  * distributed with this work for additional information
   6  * regarding copyright ownership.  The ASF licenses this file
   7  * to you under the Apache License, Version 2.0 (the
   8  * "License"); you may not use this file except in compliance
   9  * with the License.  You may obtain a copy of the License at
  10  *
  11  *     http://www.apache.org/licenses/LICENSE-2.0
  12  *
  13  * Unless required by applicable law or agreed to in writing, software
  14  * distributed under the License is distributed on an "AS IS" BASIS,
  15  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  16  * See the License for the specific language governing permissions and
  17  * limitations under the License.
  18  */
  19 package org.apache.hadoop.hbase.regionserver;
  20
  21 import java.util.Collections;
  22 import java.util.List;
  23 import org.apache.hadoop.hbase.CellComparator;
  24 import org.apache.hadoop.hbase.util.ClassSize;
  25 import org.apache.yetus.audience.InterfaceAudience;
  26
  27 /**
  28  * ImmutableSegment is an abstract class that extends the API supported by a {@link Segment},
  29  * and is not needed for a {@link MutableSegment}.
  30  */
  31 @InterfaceAudience.Private
  32 public abstract class ImmutableSegment extends Segment {
  33
  34   public static final long DEEP_OVERHEAD = Segment.DEEP_OVERHEAD + ClassSize.NON_SYNC_TIMERANGE_TRACKER;
  35
  36   // each sub-type of immutable segment knows whether it is flat or not
  37   protected abstract boolean canBeFlattened();
  38
  39   public int getNumUniqueKeys() {
  40     return getCellSet().getNumUniqueKeys();
  41   }
  42
  43   /////////////////////  CONSTRUCTORS  /////////////////////
  44   /**------------------------------------------------------------------------
  45    * Empty C-tor to be used only for CompositeImmutableSegment
  46    */
  47   protected ImmutableSegment(CellComparator comparator) {
  48     super(comparator, TimeRangeTracker.create(TimeRangeTracker.Type.NON_SYNC));
  49   }
  50
  51   protected ImmutableSegment(CellComparator comparator, List<ImmutableSegment> segments) {
  52     super(comparator, segments, TimeRangeTracker.create(TimeRangeTracker.Type.NON_SYNC));
  53   }
  54
  55   /**------------------------------------------------------------------------
  56    * C-tor to be used to build the derived classes
  57    */
  58   protected ImmutableSegment(CellSet cs, CellComparator comparator, MemStoreLAB memStoreLAB) {
  59     super(cs, comparator, memStoreLAB, TimeRangeTracker.create(TimeRangeTracker.Type.NON_SYNC));
  60   }
  61
  62   /**------------------------------------------------------------------------
  63    * Copy C-tor to be used when new CSLMImmutableSegment (derived) is being built from a Mutable one.
  64    * This C-tor should be used when active MutableSegment is pushed into the compaction
  65    * pipeline and becomes an ImmutableSegment.
  66    */
  67   protected ImmutableSegment(Segment segment) {
  68     super(segment);
  69   }
  70
  71   /////////////////////  PUBLIC METHODS  /////////////////////
  72
  73   public int getNumOfSegments() {
  74     return 1;
  75   }
  76
  77   public List<Segment> getAllSegments() {
  78     return Collections.singletonList(this);
  79   }
  80
  81   @Override
  82   public String toString() {
  83     String res = super.toString();
  84     res += "Num uniques "+getNumUniqueKeys()+"; ";
  85     return res;
  86   }
  87
  88   /**
  89    * We create a new {@link SnapshotSegmentScanner} to increase the reference count of
  90    * {@link MemStoreLABImpl} used by this segment.
  91    */
  92   List<KeyValueScanner> getSnapshotScanners() {
  93     return Collections.singletonList(new SnapshotSegmentScanner(this));
  94   }
  95 }