org.apache.hadoop.hdfs.server.datanode.DatanodeUtil Maven / Gradle / Ivy
/**
* 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.FileNotFoundException;
import java.io.IOException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.hdfs.protocol.Block;
import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
import org.apache.hadoop.hdfs.server.datanode.fsdataset.FsDatasetSpi;
import org.apache.hadoop.hdfs.server.datanode.fsdataset.FsVolumeSpi;
import org.apache.hadoop.hdfs.server.datanode.fsdataset.LengthInputStream;
/** Provide utility methods for Datanode. */
@InterfaceAudience.Private
public class DatanodeUtil {
public static final String UNLINK_BLOCK_SUFFIX = ".unlinked";
public static final String DISK_ERROR = "Possible disk error: ";
private static final String SEP = System.getProperty("file.separator");
/** Get the cause of an I/O exception if caused by a possible disk error
* @param ioe an I/O exception
* @return cause if the I/O exception is caused by a possible disk error;
* null otherwise.
*/
static IOException getCauseIfDiskError(IOException ioe) {
if (ioe.getMessage()!=null && ioe.getMessage().startsWith(DISK_ERROR)) {
return (IOException)ioe.getCause();
} else {
return null;
}
}
/**
* Create a new file.
* @throws IOException
* if the file already exists or if the file cannot be created.
*/
public static File createFileWithExistsCheck(
FsVolumeSpi volume, Block b, File f,
FileIoProvider fileIoProvider) throws IOException {
if (fileIoProvider.exists(volume, f)) {
throw new IOException("Failed to create temporary file for " + b
+ ". File " + f + " should not be present, but is.");
}
// Create the zero-length temp file
final boolean fileCreated;
try {
fileCreated = fileIoProvider.createFile(volume, f);
} catch (IOException ioe) {
throw new IOException(DISK_ERROR + "Failed to create " + f, ioe);
}
if (!fileCreated) {
throw new IOException("Failed to create temporary file for " + b
+ ". File " + f + " should be creatable, but is already present.");
}
return f;
}
/**
* @return the meta name given the block name and generation stamp.
*/
public static String getMetaName(String blockName, long generationStamp) {
return blockName + "_" + generationStamp + Block.METADATA_EXTENSION;
}
/** @return the unlink file. */
public static File getUnlinkTmpFile(File f) {
return new File(f.getParentFile(), f.getName()+UNLINK_BLOCK_SUFFIX);
}
/**
* Checks whether there are any files anywhere in the directory tree rooted
* at dir (directories don't count as files). dir must exist
* @return true if there are no files
* @throws IOException if unable to list subdirectories
*/
public static boolean dirNoFilesRecursive(
FsVolumeSpi volume, File dir,
FileIoProvider fileIoProvider) throws IOException {
File[] contents = fileIoProvider.listFiles(volume, dir);
if (contents == null) {
throw new IOException("Cannot list contents of " + dir);
}
for (File f : contents) {
if (!f.isDirectory() ||
(f.isDirectory() && !dirNoFilesRecursive(
volume, f, fileIoProvider))) {
return false;
}
}
return true;
}
/**
* Get the directory where a finalized block with this ID should be stored.
* Do not attempt to create the directory.
* @param root the root directory where finalized blocks are stored
* @param blockId
* @return
*/
public static File idToBlockDir(File root, long blockId) {
int d1 = (int) ((blockId >> 16) & 0x1F);
int d2 = (int) ((blockId >> 8) & 0x1F);
String path = DataStorage.BLOCK_SUBDIR_PREFIX + d1 + SEP +
DataStorage.BLOCK_SUBDIR_PREFIX + d2;
return new File(root, path);
}
/**
* @return the FileInputStream for the meta data of the given block.
* @throws FileNotFoundException
* if the file not found.
* @throws ClassCastException
* if the underlying input stream is not a FileInputStream.
*/
public static FileInputStream getMetaDataInputStream(
ExtendedBlock b, FsDatasetSpi data) throws IOException {
final LengthInputStream lin = data.getMetaDataInputStream(b);
if (lin == null) {
throw new FileNotFoundException("Meta file for " + b + " not found.");
}
return (FileInputStream)lin.getWrappedStream();
}
}