/**
* 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.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.EOFException;
import java.io.DataInputStream;
import java.io.RandomAccessFile;
import java.nio.channels.FileChannel;
import org.apache.hadoop.hdfs.protocol.FSConstants;
import org.apache.hadoop.hdfs.server.common.HdfsConstants;
import org.apache.hadoop.io.IOUtils;
/**
* An implementation of the abstract class {@link EditLogInputStream}, which
* reads edits from a local file.
*/
class EditLogFileInputStream extends EditLogInputStream {
private File file;
private final FileInputStream fStream;
private final FileChannel fc;
private final RandomAccessFile rp;
final private long firstTxId;
final private long lastTxId;
private final int logVersion;
private FSEditLogOp.Reader reader;
private FSEditLogLoader.PositionTrackingInputStream tracker;
/**
* Open an EditLogInputStream for the given file.
* The file is pretransactional, so has no txids
* @param name filename to open
* @throws LogHeaderCorruptException if the header is either missing or
* appears to be corrupt/truncated
* @throws IOException if an actual IO error occurs while reading the
* header
*/
EditLogFileInputStream(File name)
throws LogHeaderCorruptException, IOException {
this(name, HdfsConstants.INVALID_TXID, HdfsConstants.INVALID_TXID);
}
/**
* Open an EditLogInputStream for the given file.
* @param name filename to open
* @param firstTxId first transaction found in file
* @param lastTxId last transaction id found in file
* @throws LogHeaderCorruptException if the header is either missing or
* appears to be corrupt/truncated
* @throws IOException if an actual IO error occurs while reading the
* header
*/
EditLogFileInputStream(File name, long firstTxId, long lastTxId)
throws LogHeaderCorruptException, IOException {
file = name;
rp = new RandomAccessFile(file, "r");
fStream = new FileInputStream(rp.getFD());
fc = rp.getChannel();
BufferedInputStream bin = new BufferedInputStream(fStream);
tracker = new FSEditLogLoader.PositionTrackingInputStream(bin);
DataInputStream in = new DataInputStream(tracker);
try {
logVersion = readLogVersion(in);
} catch (EOFException eofe) {
throw new LogHeaderCorruptException("No header found in log");
}
reader = new FSEditLogOp.Reader(in, logVersion);
this.firstTxId = firstTxId;
this.lastTxId = lastTxId;
}
@Override
public long getFirstTxId() throws IOException {
return firstTxId;
}
@Override
public void refresh(long position) throws IOException {
fc.position(position);
BufferedInputStream bin = new BufferedInputStream(fStream);
tracker = new FSEditLogLoader.PositionTrackingInputStream(bin, position);
DataInputStream in = new DataInputStream(tracker);
reader = new FSEditLogOp.Reader(in, logVersion);
}
@Override
public void position(long position) throws IOException {
fc.position(position);
}
@Override
public long getLastTxId() throws IOException {
return lastTxId;
}
@Override
public String getName() {
return file.getPath();
}
@Override
public FSEditLogOp readOp() throws IOException {
return reader.readOp();
}
@Override
public int getVersion() throws IOException {
return logVersion;
}
@Override
public void close() throws IOException {
fStream.close();
}
@Override
public long length() throws IOException {
return file.length();
}
@Override
public String toString() {
return getName();
}
static FSEditLogLoader.EditLogValidation validateEditLog(File file) throws IOException {
EditLogFileInputStream in;
try {
in = new EditLogFileInputStream(file);
} catch (LogHeaderCorruptException corrupt) {
// If it's missing its header, this is equivalent to no transactions
FSImage.LOG.warn("Log at " + file + " has no valid header",
corrupt);
return new FSEditLogLoader.EditLogValidation(0, HdfsConstants.INVALID_TXID,
HdfsConstants.INVALID_TXID);
}
try {
return FSEditLogLoader.validateEditLog(in);
} finally {
IOUtils.closeStream(in);
}
}
/**
* Read the header of fsedit log
* @param in fsedit stream
* @return the edit log version number
* @throws IOException if error occurs
*/
static int readLogVersion(DataInputStream in) throws IOException,
LogHeaderCorruptException {
int logVersion = 0;
// Read log file version. Could be missing.
in.mark(4);
// If edits log is greater than 2G, available method will return negative
// numbers, so we avoid having to call available
boolean available = true;
try {
logVersion = in.readByte();
} catch (EOFException e) {
available = false;
}
if (available) {
in.reset();
logVersion = in.readInt();
if (logVersion < FSConstants.LAYOUT_VERSION) { // future version
throw new LogHeaderCorruptException(
"Unexpected version of the file system log file: " + logVersion
+ ". Current version = " + FSConstants.LAYOUT_VERSION + ".");
}
}
return logVersion;
}
/**
* Exception indicating that the header of an edits log file is
* corrupted. This can be because the header is not present,
* or because the header data is invalid (eg claims to be
* over a newer version than the running NameNode)
*/
static class LogHeaderCorruptException extends IOException {
private static final long serialVersionUID = 1L;
private LogHeaderCorruptException(String msg) {
super(msg);
}
}
@Override
public long getPosition() throws IOException{
return tracker.getPos();
}
@Override
public long getReadChecksum() {
return reader.getChecksum();
}
}