org.apache.hadoop.hdfs.server.namenode.FSImageUtil Maven / Gradle / Ivy
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* 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.namenode;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.protocol.LayoutVersion.Feature;
import org.apache.hadoop.hdfs.server.namenode.FSImageFormatProtobuf.Loader;
import org.apache.hadoop.hdfs.server.namenode.FsImageProto.FileSummary;
import org.apache.hadoop.io.compress.CompressionCodec;
@InterfaceAudience.Private
public final class FSImageUtil {
public static final byte[] MAGIC_HEADER =
"HDFSIMG1".getBytes(StandardCharsets.UTF_8);
public static final int FILE_VERSION = 1;
public static boolean checkFileFormat(RandomAccessFile file)
throws IOException {
if (file.length() < Loader.MINIMUM_FILE_LENGTH)
return false;
byte[] magic = new byte[MAGIC_HEADER.length];
file.readFully(magic);
if (!Arrays.equals(MAGIC_HEADER, magic))
return false;
return true;
}
public static FileSummary loadSummary(RandomAccessFile file)
throws IOException {
final int FILE_LENGTH_FIELD_SIZE = 4;
long fileLength = file.length();
file.seek(fileLength - FILE_LENGTH_FIELD_SIZE);
int summaryLength = file.readInt();
if (summaryLength <= 0) {
throw new IOException("Negative length of the file");
}
file.seek(fileLength - FILE_LENGTH_FIELD_SIZE - summaryLength);
byte[] summaryBytes = new byte[summaryLength];
file.readFully(summaryBytes);
FileSummary summary = FileSummary
.parseDelimitedFrom(new ByteArrayInputStream(summaryBytes));
if (summary.getOndiskVersion() != FILE_VERSION) {
throw new IOException("Unsupported file version "
+ summary.getOndiskVersion());
}
if (!NameNodeLayoutVersion.supports(Feature.PROTOBUF_FORMAT,
summary.getLayoutVersion())) {
throw new IOException("Unsupported layout version "
+ summary.getLayoutVersion());
}
return summary;
}
public static InputStream wrapInputStreamForCompression(
Configuration conf, String codec, InputStream in) throws IOException {
if (codec.isEmpty())
return in;
FSImageCompression compression = FSImageCompression.createCompression(
conf, codec);
CompressionCodec imageCodec = compression.getImageCodec();
return imageCodec.createInputStream(in);
}
}