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.io.hfile;
019
020import org.apache.hadoop.hbase.io.ByteBuffAllocator;
021import org.apache.hadoop.hbase.nio.ByteBuff;
022import org.apache.yetus.audience.InterfaceAudience;
023
024/**
025 * The {@link ByteBuffAllocator} won't allocate pooled heap {@link ByteBuff} now; at the same time,
026 * if allocate an off-heap {@link ByteBuff} from allocator, then it must be a pooled one. That's to
027 * say, an exclusive memory HFileBlock would must be an heap block and a shared memory HFileBlock
028 * would must be an off-heap block.
029 * <p>
030 * The exclusive memory HFileBlock will do nothing when calling retain or release methods, because
031 * its memory will be garbage collected by JVM, even if its reference count decrease to zero, we can
032 * do nothing for the de-allocating.
033 * <p>
034 * @see org.apache.hadoop.hbase.io.hfile.SharedMemHFileBlock
035 */
036@InterfaceAudience.Private
037public class ExclusiveMemHFileBlock extends HFileBlock {
038
039  ExclusiveMemHFileBlock(BlockType blockType, int onDiskSizeWithoutHeader,
040    int uncompressedSizeWithoutHeader, long prevBlockOffset, ByteBuff buf, boolean fillHeader,
041    long offset, int nextBlockOnDiskSize, int onDiskDataSizeWithHeader, HFileContext fileContext,
042    ByteBuffAllocator alloc) {
043    super(blockType, onDiskSizeWithoutHeader, uncompressedSizeWithoutHeader, prevBlockOffset, buf,
044      fillHeader, offset, nextBlockOnDiskSize, onDiskDataSizeWithHeader, fileContext, alloc);
045  }
046
047  @Override
048  public int refCnt() {
049    return 0;
050  }
051
052  @Override
053  public ExclusiveMemHFileBlock retain() {
054    // do nothing
055    return this;
056  }
057
058  @Override
059  public boolean release() {
060    // do nothing
061    return false;
062  }
063
064  @Override
065  public boolean isSharedMem() {
066    return false;
067  }
068}