/**
* 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.fs;
import java.io.*;
import java.util.Arrays;
import java.util.zip.CRC32;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.util.Progressable;
import org.apache.hadoop.util.PureJavaCrc32;
import org.apache.hadoop.util.StringUtils;
/****************************************************************
* Abstract Checksumed FileSystem.
* It provide a basice implementation of a Checksumed FileSystem,
* which creates a checksum file for each raw file.
* It generates & verifies checksums at the client side.
*
*****************************************************************/
public abstract class ChecksumFileSystem extends FilterFileSystem {
private static final byte[] CHECKSUM_VERSION = new byte[] {'c', 'r', 'c', 0};
private int bytesPerChecksum = 512;
private boolean verifyChecksum = true;
public static double getApproxChkSumLength(long size) {
return ChecksumFSOutputSummer.CHKSUM_AS_FRACTION * size;
}
public ChecksumFileSystem(FileSystem fs) {
super(fs);
}
public void setConf(Configuration conf) {
super.setConf(conf);
if (conf != null) {
bytesPerChecksum = conf.getInt("io.bytes.per.checksum", 512);
}
}
/**
* Set whether to verify checksum.
*/
public void setVerifyChecksum(boolean verifyChecksum) {
this.verifyChecksum = verifyChecksum;
}
/** get the raw file system */
public FileSystem getRawFileSystem() {
return fs;
}
/** Return the name of the checksum file associated with a file.*/
public Path getChecksumFile(Path file) {
return new Path(file.getParent(), "." + file.getName() + ".crc");
}
/** Return true iff file is a checksum file name.*/
public static boolean isChecksumFile(Path file) {
String name = file.getName();
return name.startsWith(".") && name.endsWith(".crc");
}
/** Return the length of the checksum file given the size of the
* actual file.
**/
public long getChecksumFileLength(Path file, long fileSize) {
return getChecksumLength(fileSize, getBytesPerSum());
}
/** Return the bytes Per Checksum */
public int getBytesPerSum() {
return bytesPerChecksum;
}
private int getSumBufferSize(int bytesPerSum, int bufferSize) {
int defaultBufferSize = getConf().getInt("io.file.buffer.size", 4096);
int proportionalBufferSize = bufferSize / bytesPerSum;
return Math.max(bytesPerSum,
Math.max(proportionalBufferSize, defaultBufferSize));
}
/*******************************************************
* For open()'s FSInputStream
* It verifies that data matches checksums.
*******************************************************/
private static class ChecksumFSInputChecker extends FSInputChecker {
public static final Log LOG
= LogFactory.getLog(FSInputChecker.class);
private ChecksumFileSystem fs;
private FSDataInputStream datas;
private FSDataInputStream sums;
private static final int HEADER_LENGTH = 8;
private int bytesPerSum = 1;
private long fileLen = -1L;
public ChecksumFSInputChecker(ChecksumFileSystem fs, Path file)
throws IOException {
this(fs, file, fs.getConf().getInt("io.file.buffer.size", 4096));
}
public ChecksumFSInputChecker(ChecksumFileSystem fs, Path file, int bufferSize)
throws IOException {
super( file, fs.getFileStatus(file).getReplication() );
this.datas = fs.getRawFileSystem().open(file, bufferSize);
this.fs = fs;
Path sumFile = fs.getChecksumFile(file);
try {
int sumBufferSize = fs.getSumBufferSize(fs.getBytesPerSum(), bufferSize);
sums = fs.getRawFileSystem().open(sumFile, sumBufferSize);
byte[] version = new byte[CHECKSUM_VERSION.length];
sums.readFully(version);
if (!Arrays.equals(version, CHECKSUM_VERSION))
throw new IOException("Not a checksum file: "+sumFile);
this.bytesPerSum = sums.readInt();
set(fs.verifyChecksum, new PureJavaCrc32(), bytesPerSum, 4);
} catch (FileNotFoundException e) { // quietly ignore
set(fs.verifyChecksum, null, 1, 0);
} catch (IOException e) { // loudly ignore
LOG.warn("Problem opening checksum file: "+ file +
". Ignoring exception: " +
StringUtils.stringifyException(e));
set(fs.verifyChecksum, null, 1, 0);
}
}
private long getChecksumFilePos( long dataPos ) {
return HEADER_LENGTH + 4*(dataPos/bytesPerSum);
}
protected long getChunkPosition( long dataPos ) {
return dataPos/bytesPerSum*bytesPerSum;
}
public int available() throws IOException {
return datas.available() + super.available();
}
public int read(long position, byte[] b, int off, int len)
throws IOException {
// parameter check
if ((off | len | (off + len) | (b.length - (off + len))) < 0) {
throw new IndexOutOfBoundsException();
} else if (len == 0) {
return 0;
}
if( position<0 ) {
throw new IllegalArgumentException(
"Parameter position can not to be negative");
}
ChecksumFSInputChecker checker = new ChecksumFSInputChecker(fs, file);
checker.seek(position);
int nread = checker.read(b, off, len);
checker.close();
return nread;
}
public void close() throws IOException {
datas.close();
if( sums != null ) {
sums.close();
}
set(fs.verifyChecksum, null, 1, 0);
}
@Override
public boolean seekToNewSource(long targetPos) throws IOException {
long sumsPos = getChecksumFilePos(targetPos);
fs.reportChecksumFailure(file, datas, targetPos, sums, sumsPos);
boolean newDataSource = datas.seekToNewSource(targetPos);
return sums.seekToNewSource(sumsPos) || newDataSource;
}
@Override
protected int readChunk(long pos, byte[] buf, int offset, int len,
byte[] checksum) throws IOException {
boolean eof = false;
if(needChecksum()) {
try {
long checksumPos = getChecksumFilePos(pos);
if(checksumPos != sums.getPos()) {
sums.seek(checksumPos);
}
sums.readFully(checksum);
} catch (EOFException e) {
eof = true;
}
len = bytesPerSum;
}
if(pos != datas.getPos()) {
datas.seek(pos);
}
int nread = readFully(datas, buf, offset, len);
if( eof && nread > 0) {
throw new ChecksumException("Checksum error: "+file+" at "+pos, pos);
}
return nread;
}
/* Return the file length */
private long getFileLength() throws IOException {
if( fileLen==-1L ) {
fileLen = fs.getContentSummary(file).getLength();
}
return fileLen;
}
/**
* Skips over and discards <code>n</code> bytes of data from the
* input stream.
*
*The <code>skip</code> method skips over some smaller number of bytes
* when reaching end of file before <code>n</code> bytes have been skipped.
* The actual number of bytes skipped is returned. If <code>n</code> is
* negative, no bytes are skipped.
*
* @param n the number of bytes to be skipped.
* @return the actual number of bytes skipped.
* @exception IOException if an I/O error occurs.
* ChecksumException if the chunk to skip to is corrupted
*/
public synchronized long skip(long n) throws IOException {
long curPos = getPos();
long fileLength = getFileLength();
if( n+curPos > fileLength ) {
n = fileLength - curPos;
}
return super.skip(n);
}
/**
* Seek to the given position in the stream.
* The next read() will be from that position.
*
* <p>This method does not allow seek past the end of the file.
* This produces IOException.
*
* @param pos the postion to seek to.
* @exception IOException if an I/O error occurs or seeks after EOF
* ChecksumException if the chunk to seek to is corrupted
*/
public synchronized void seek(long pos) throws IOException {
if(pos>getFileLength()) {
throw new IOException("Cannot seek after EOF");
}
super.seek(pos);
}
}
/**
* Opens an FSDataInputStream at the indicated Path.
* @param f the file name to open
* @param bufferSize the size of the buffer to be used.
*/
@Override
public FSDataInputStream open(Path f, int bufferSize) throws IOException {
return new FSDataInputStream(
new ChecksumFSInputChecker(this, f, bufferSize));
}
/** {@inheritDoc} */
public FSDataOutputStream append(Path f, int bufferSize,
Progressable progress) throws IOException {
throw new IOException("Not supported");
}
/**
* Calculated the length of the checksum file in bytes.
* @param size the length of the data file in bytes
* @param bytesPerSum the number of bytes in a checksum block
* @return the number of bytes in the checksum file
*/
public static long getChecksumLength(long size, int bytesPerSum) {
//the checksum length is equal to size passed divided by bytesPerSum +
//bytes written in the beginning of the checksum file.
return ((size + bytesPerSum - 1) / bytesPerSum) * 4 +
CHECKSUM_VERSION.length + 4;
}
/** This class provides an output stream for a checksummed file.
* It generates checksums for data. */
private static class ChecksumFSOutputSummer extends FSOutputSummer {
private FSDataOutputStream datas;
private FSDataOutputStream sums;
private static final float CHKSUM_AS_FRACTION = 0.01f;
public ChecksumFSOutputSummer(ChecksumFileSystem fs,
Path file,
boolean overwrite,
short replication,
long blockSize,
Configuration conf)
throws IOException {
this(fs, file, overwrite,
conf.getInt("io.file.buffer.size", 4096),
replication, blockSize, null);
}
public ChecksumFSOutputSummer(ChecksumFileSystem fs,
Path file,
boolean overwrite,
int bufferSize,
short replication,
long blockSize,
Progressable progress)
throws IOException {
super(new PureJavaCrc32(), fs.getBytesPerSum(), 4);
int bytesPerSum = fs.getBytesPerSum();
this.datas = fs.getRawFileSystem().create(file, overwrite, bufferSize,
replication, blockSize, progress);
int sumBufferSize = fs.getSumBufferSize(bytesPerSum, bufferSize);
this.sums = fs.getRawFileSystem().create(fs.getChecksumFile(file), true,
sumBufferSize, replication,
blockSize);
sums.write(CHECKSUM_VERSION, 0, CHECKSUM_VERSION.length);
sums.writeInt(bytesPerSum);
}
public void close() throws IOException {
flushBuffer();
sums.close();
datas.close();
}
@Override
protected void writeChunk(byte[] b, int offset, int len, byte[] checksum)
throws IOException {
datas.write(b, offset, len);
sums.write(checksum);
}
}
/** {@inheritDoc} */
@Override
public FSDataOutputStream create(Path f, FsPermission permission,
boolean overwrite, int bufferSize, short replication, long blockSize,
Progressable progress) throws IOException {
Path parent = f.getParent();
if (parent != null && !mkdirs(parent)) {
throw new IOException("Mkdirs failed to create " + parent);
}
final FSDataOutputStream out = new FSDataOutputStream(
new ChecksumFSOutputSummer(this, f, overwrite, bufferSize, replication,
blockSize, progress), null);
if (permission != null) {
setPermission(f, permission);
}
return out;
}
/**
* Set replication for an existing file.
* Implement the abstract <tt>setReplication</tt> of <tt>FileSystem</tt>
* @param src file name
* @param replication new replication
* @throws IOException
* @return true if successful;
* false if file does not exist or is a directory
*/
public boolean setReplication(Path src, short replication) throws IOException {
boolean value = fs.setReplication(src, replication);
if (!value)
return false;
Path checkFile = getChecksumFile(src);
if (exists(checkFile))
fs.setReplication(checkFile, replication);
return true;
}
/**
* Rename files/dirs
*/
public boolean rename(Path src, Path dst) throws IOException {
if (fs.isDirectory(src)) {
return fs.rename(src, dst);
} else {
boolean value = fs.rename(src, dst);
if (!value)
return false;
Path checkFile = getChecksumFile(src);
if (fs.exists(checkFile)) { //try to rename checksum
if (fs.isDirectory(dst)) {
value = fs.rename(checkFile, dst);
} else {
value = fs.rename(checkFile, getChecksumFile(dst));
}
}
return value;
}
}
/**
* Implement the delete(Path, boolean) in checksum
* file system.
*/
public boolean delete(Path f, boolean recursive) throws IOException{
FileStatus fstatus = null;
try {
fstatus = fs.getFileStatus(f);
} catch(FileNotFoundException e) {
return false;
}
if(fstatus.isDir()) {
//this works since the crcs are in the same
//directories and the files. so we just delete
//everything in the underlying filesystem
return fs.delete(f, recursive);
} else {
Path checkFile = getChecksumFile(f);
if (fs.exists(checkFile)) {
fs.delete(checkFile, true);
}
return fs.delete(f, true);
}
}
final private static PathFilter DEFAULT_FILTER = new PathFilter() {
public boolean accept(Path file) {
return !isChecksumFile(file);
}
};
/**
* List the statuses of the files/directories in the given path if the path is
* a directory.
*
* @param f
* given path
* @return the statuses of the files/directories in the given patch
* @throws IOException
*/
@Override
public FileStatus[] listStatus(Path f) throws IOException {
return fs.listStatus(f, DEFAULT_FILTER);
}
@Override
public boolean mkdirs(Path f) throws IOException {
return fs.mkdirs(f);
}
@Override
public void copyFromLocalFile(boolean delSrc, Path src, Path dst)
throws IOException {
Configuration conf = getConf();
FileUtil.copy(getLocal(conf), src, this, dst, delSrc, conf);
}
/**
* The src file is under FS, and the dst is on the local disk.
* Copy it from FS control to the local dst name.
*/
@Override
public void copyToLocalFile(boolean delSrc, Path src, Path dst)
throws IOException {
Configuration conf = getConf();
FileUtil.copy(this, src, getLocal(conf), dst, delSrc, conf);
}
/**
* The src file is under FS, and the dst is on the local disk.
* Copy it from FS control to the local dst name.
* If src and dst are directories, the copyCrc parameter
* determines whether to copy CRC files.
*/
public void copyToLocalFile(Path src, Path dst, boolean copyCrc)
throws IOException {
if (!fs.isDirectory(src)) { // source is a file
fs.copyToLocalFile(src, dst);
FileSystem localFs = getLocal(getConf()).getRawFileSystem();
if (localFs.isDirectory(dst)) {
dst = new Path(dst, src.getName());
}
dst = getChecksumFile(dst);
if (localFs.exists(dst)) { //remove old local checksum file
localFs.delete(dst, true);
}
Path checksumFile = getChecksumFile(src);
if (copyCrc && fs.exists(checksumFile)) { //copy checksum file
fs.copyToLocalFile(checksumFile, dst);
}
} else {
FileStatus[] srcs = listStatus(src);
for (FileStatus srcFile : srcs) {
copyToLocalFile(srcFile.getPath(),
new Path(dst, srcFile.getPath().getName()), copyCrc);
}
}
}
@Override
public Path startLocalOutput(Path fsOutputFile, Path tmpLocalFile)
throws IOException {
return tmpLocalFile;
}
@Override
public void completeLocalOutput(Path fsOutputFile, Path tmpLocalFile)
throws IOException {
moveFromLocalFile(tmpLocalFile, fsOutputFile);
}
/**
* Report a checksum error to the file system.
* @param f the file name containing the error
* @param in the stream open on the file
* @param inPos the position of the beginning of the bad data in the file
* @param sums the stream open on the checksum file
* @param sumsPos the position of the beginning of the bad data in the checksum file
* @return if retry is neccessary
*/
public boolean reportChecksumFailure(Path f, FSDataInputStream in,
long inPos, FSDataInputStream sums, long sumsPos) {
return false;
}
}