/**
* 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;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.fs.FileUtil;
import org.apache.hadoop.fs.HardLink;
import org.apache.hadoop.hdfs.protocol.Block;
import org.apache.hadoop.hdfs.server.datanode.FSDatasetInterface.FSVolumeInterface;
import org.apache.hadoop.io.IOUtils;
/**
* This class is used by datanodes to maintain meta data of its replicas.
* It provides a general interface for meta information of a replica.
*/
@InterfaceAudience.Private
abstract public class ReplicaInfo extends Block implements Replica {
/** volume where the replica belongs */
private FSVolumeInterface volume;
/** directory where block & meta files belong */
private File dir;
/**
* Constructor for a zero length replica
* @param blockId block id
* @param genStamp replica generation stamp
* @param vol volume where replica is located
* @param dir directory path where block and meta files are located
*/
ReplicaInfo(long blockId, long genStamp, FSVolumeInterface vol, File dir) {
this( blockId, 0L, genStamp, vol, dir);
}
/**
* Constructor
* @param block a block
* @param vol volume where replica is located
* @param dir directory path where block and meta files are located
*/
ReplicaInfo(Block block, FSVolumeInterface vol, File dir) {
this(block.getBlockId(), block.getNumBytes(),
block.getGenerationStamp(), vol, dir);
}
/**
* Constructor
* @param blockId block id
* @param len replica length
* @param genStamp replica generation stamp
* @param vol volume where replica is located
* @param dir directory path where block and meta files are located
*/
ReplicaInfo(long blockId, long len, long genStamp,
FSVolumeInterface vol, File dir) {
super(blockId, len, genStamp);
this.volume = vol;
this.dir = dir;
}
/**
* Copy constructor.
* @param from
*/
ReplicaInfo(ReplicaInfo from) {
this(from, from.getVolume(), from.getDir());
}
/**
* Get this replica's meta file name
* @return this replica's meta file name
*/
private String getMetaFileName() {
return getBlockName() + "_" + getGenerationStamp() + METADATA_EXTENSION;
}
/**
* Get the full path of this replica's data file
* @return the full path of this replica's data file
*/
File getBlockFile() {
return new File(getDir(), getBlockName());
}
/**
* Get the full path of this replica's meta file
* @return the full path of this replica's meta file
*/
File getMetaFile() {
return new File(getDir(), getMetaFileName());
}
/**
* Get the volume where this replica is located on disk
* @return the volume where this replica is located on disk
*/
FSVolumeInterface getVolume() {
return volume;
}
/**
* Set the volume where this replica is located on disk
*/
void setVolume(FSVolumeInterface vol) {
this.volume = vol;
}
/**
* Return the parent directory path where this replica is located
* @return the parent directory path where this replica is located
*/
File getDir() {
return dir;
}
/**
* Set the parent directory where this replica is located
* @param dir the parent directory where the replica is located
*/
void setDir(File dir) {
this.dir = dir;
}
/**
* check if this replica has already been unlinked.
* @return true if the replica has already been unlinked
* or no need to be detached; false otherwise
*/
boolean isUnlinked() {
return true; // no need to be unlinked
}
/**
* set that this replica is unlinked
*/
void setUnlinked() {
// no need to be unlinked
}
/**
* Copy specified file into a temporary file. Then rename the
* temporary file to the original name. This will cause any
* hardlinks to the original file to be removed. The temporary
* files are created in the same directory. The temporary files will
* be recovered (especially on Windows) on datanode restart.
*/
private void unlinkFile(File file, Block b) throws IOException {
File tmpFile = DatanodeUtil.createTmpFile(b, DatanodeUtil.getUnlinkTmpFile(file));
try {
FileInputStream in = new FileInputStream(file);
try {
FileOutputStream out = new FileOutputStream(tmpFile);
try {
IOUtils.copyBytes(in, out, 16*1024);
} finally {
out.close();
}
} finally {
in.close();
}
if (file.length() != tmpFile.length()) {
throw new IOException("Copy of file " + file + " size " + file.length()+
" into file " + tmpFile +
" resulted in a size of " + tmpFile.length());
}
FileUtil.replaceFile(tmpFile, file);
} catch (IOException e) {
boolean done = tmpFile.delete();
if (!done) {
DataNode.LOG.info("detachFile failed to delete temporary file " +
tmpFile);
}
throw e;
}
}
/**
* Remove a hard link by copying the block to a temporary place and
* then moving it back
* @param numLinks number of hard links
* @return true if copy is successful;
* false if it is already detached or no need to be detached
* @throws IOException if there is any copy error
*/
boolean unlinkBlock(int numLinks) throws IOException {
if (isUnlinked()) {
return false;
}
File file = getBlockFile();
if (file == null || getVolume() == null) {
throw new IOException("detachBlock:Block not found. " + this);
}
File meta = getMetaFile();
if (meta == null) {
throw new IOException("Meta file not found for block " + this);
}
if (HardLink.getLinkCount(file) > numLinks) {
DataNode.LOG.info("CopyOnWrite for block " + this);
unlinkFile(file, this);
}
if (HardLink.getLinkCount(meta) > numLinks) {
unlinkFile(meta, this);
}
setUnlinked();
return true;
}
/**
* Set this replica's generation stamp to be a newer one
* @param newGS new generation stamp
* @throws IOException is the new generation stamp is not greater than the current one
*/
void setNewerGenerationStamp(long newGS) throws IOException {
long curGS = getGenerationStamp();
if (newGS <= curGS) {
throw new IOException("New generation stamp (" + newGS
+ ") must be greater than current one (" + curGS + ")");
}
setGenerationStamp(newGS);
}
@Override //Object
public String toString() {
return getClass().getSimpleName()
+ ", " + super.toString()
+ ", " + getState()
+ "\n getNumBytes() = " + getNumBytes()
+ "\n getBytesOnDisk() = " + getBytesOnDisk()
+ "\n getVisibleLength()= " + getVisibleLength()
+ "\n getVolume() = " + getVolume()
+ "\n getBlockFile() = " + getBlockFile();
}
}