hadoop MemoryMappedBlock 源码
haddop MemoryMappedBlock 代码
文件路径：/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/MemoryMappedBlock.java
/**
* 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.hdfs.server.datanode.fsdataset.impl;
import java.nio.MappedByteBuffer;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.hdfs.ExtendedBlockId;
import org.apache.hadoop.io.nativeio.NativeIO;
/**
* Represents an HDFS block that is mapped to memory by the DataNode.
*/
@InterfaceAudience.Private
@InterfaceStability.Unstable
public class MemoryMappedBlock implements MappableBlock {
private MappedByteBuffer mmap;
private final long length;
MemoryMappedBlock(MappedByteBuffer mmap, long length) {
this.mmap = mmap;
this.length = length;
assert length > 0;
}
@Override
public long getLength() {
return length;
}
@Override
public long getAddress() {
return -1L;
}
@Override
public ExtendedBlockId getKey() {
return null;
}
@Override
public void close() {
if (mmap != null) {
NativeIO.POSIX.munmap(mmap);
mmap = null;
}
}
}
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