org.apache.hadoop.fs.ChecksumFs 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.fs;
import java.io.*;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.EnumSet;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
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 Fs.
* It provide a basic implementation of a Checksumed Fs,
* which creates a checksum file for each raw file.
* It generates & verifies checksums at the client side.
*/
@InterfaceAudience.Private
@InterfaceStability.Evolving /*Evolving for a release,to be changed to Stable */
public abstract class ChecksumFs extends FilterFs {
private static final byte[] CHECKSUM_VERSION = new byte[] {'c', 'r', 'c', 0};
private int defaultBytesPerChecksum = 512;
private boolean verifyChecksum = true;
public static double getApproxChkSumLength(long size) {
return ChecksumFSOutputSummer.CHKSUM_AS_FRACTION * size;
}
public ChecksumFs(AbstractFileSystem theFs)
throws IOException, URISyntaxException {
super(theFs);
defaultBytesPerChecksum =
getMyFs().getServerDefaults().getBytesPerChecksum();
}
/**
* Set whether to verify checksum.
*/
public void setVerifyChecksum(boolean inVerifyChecksum) {
this.verifyChecksum = inVerifyChecksum;
}
/** get the raw file system. */
public AbstractFileSystem getRawFs() {
return getMyFs();
}
/** 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 defaultBytesPerChecksum;
}
private int getSumBufferSize(int bytesPerSum, int bufferSize)
throws IOException {
int defaultBufferSize = getMyFs().getServerDefaults().getFileBufferSize();
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 static final int HEADER_LENGTH = 8;
private ChecksumFs fs;
private FSDataInputStream datas;
private FSDataInputStream sums;
private int bytesPerSum = 1;
private long fileLen = -1L;
public ChecksumFSInputChecker(ChecksumFs fs, Path file)
throws IOException, UnresolvedLinkException {
this(fs, file, fs.getServerDefaults().getFileBufferSize());
}
public ChecksumFSInputChecker(ChecksumFs fs, Path file, int bufferSize)
throws IOException, UnresolvedLinkException {
super(file, fs.getFileStatus(file).getReplication());
this.datas = fs.getRawFs().open(file, bufferSize);
this.fs = fs;
Path sumFile = fs.getChecksumFile(file);
try {
int sumBufferSize = fs.getSumBufferSize(fs.getBytesPerSum(),
bufferSize);
sums = fs.getRawFs().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, UnresolvedLinkException {
// 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 {
final long sumsPos = getChecksumFilePos(targetPos);
fs.reportChecksumFailure(file, datas, targetPos, sums, sumsPos);
final 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()) {
assert checksum != null; // we have a checksum buffer
assert checksum.length % CHECKSUM_SIZE == 0; // it is sane length
assert len >= bytesPerSum; // we must read at least one chunk
final int checksumsToRead = Math.min(
len/bytesPerSum, // number of checksums based on len to read
checksum.length / CHECKSUM_SIZE); // size of checksum buffer
long checksumPos = getChecksumFilePos(pos);
if(checksumPos != sums.getPos()) {
sums.seek(checksumPos);
}
int sumLenRead = sums.read(checksum, 0, CHECKSUM_SIZE * checksumsToRead);
if (sumLenRead >= 0 && sumLenRead % CHECKSUM_SIZE != 0) {
throw new EOFException("Checksum file not a length multiple of checksum size " +
"in " + file + " at " + pos + " checksumpos: " + checksumPos +
" sumLenread: " + sumLenRead );
}
if (sumLenRead <= 0) { // we're at the end of the file
eof = true;
} else {
// Adjust amount of data to read based on how many checksum chunks we read
len = Math.min(len, bytesPerSum * (sumLenRead / CHECKSUM_SIZE));
}
}
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, UnresolvedLinkException {
if (fileLen==-1L) {
fileLen = fs.getFileStatus(file).getLen();
}
return fileLen;
}
/**
* Skips over and discards n bytes of data from the
* input stream.
*
* The skip method skips over some smaller number of bytes
* when reaching end of file before n bytes have been skipped.
* The actual number of bytes skipped is returned. If n 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 {
final long curPos = getPos();
final 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.
*
* 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, UnresolvedLinkException {
return new FSDataInputStream(
new ChecksumFSInputChecker(this, f, bufferSize));
}
/**
* 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(final ChecksumFs fs, final Path file,
final EnumSet createFlag,
final FsPermission absolutePermission, final int bufferSize,
final short replication, final long blockSize,
final Progressable progress, final int bytesPerChecksum,
final boolean createParent) throws IOException {
super(new PureJavaCrc32(), fs.getBytesPerSum(), 4);
this.datas = fs.getRawFs().createInternal(file, createFlag,
absolutePermission, bufferSize, replication, blockSize, progress,
bytesPerChecksum, createParent);
// Now create the chekcsumfile; adjust the buffsize
int bytesPerSum = fs.getBytesPerSum();
int sumBufferSize = fs.getSumBufferSize(bytesPerSum, bufferSize);
this.sums = fs.getRawFs().createInternal(fs.getChecksumFile(file),
EnumSet.of(CreateFlag.OVERWRITE), absolutePermission, sumBufferSize,
replication, blockSize, progress, bytesPerChecksum, createParent);
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);
}
}
@Override
public FSDataOutputStream createInternal(Path f,
EnumSet createFlag, FsPermission absolutePermission,
int bufferSize, short replication, long blockSize, Progressable progress,
int bytesPerChecksum, boolean createParent) throws IOException {
final FSDataOutputStream out = new FSDataOutputStream(
new ChecksumFSOutputSummer(this, f, createFlag, absolutePermission,
bufferSize, replication, blockSize, progress,
bytesPerChecksum, createParent), null);
return out;
}
/** Check if exists.
* @param f source file
*/
private boolean exists(Path f)
throws IOException, UnresolvedLinkException {
try {
return getMyFs().getFileStatus(f) != null;
} catch (FileNotFoundException e) {
return false;
}
}
/** True iff the named path is a directory.
* Note: Avoid using this method. Instead reuse the FileStatus
* returned by getFileStatus() or listStatus() methods.
*/
private boolean isDirectory(Path f)
throws IOException, UnresolvedLinkException {
try {
return getMyFs().getFileStatus(f).isDirectory();
} catch (FileNotFoundException e) {
return false; // f does not exist
}
}
/**
* Set replication for an existing file.
* Implement the abstract setReplication of FileSystem
* @param src file name
* @param replication new replication
* @throws IOException
* @return true if successful;
* false if file does not exist or is a directory
*/
@Override
public boolean setReplication(Path src, short replication)
throws IOException, UnresolvedLinkException {
boolean value = getMyFs().setReplication(src, replication);
if (!value) {
return false;
}
Path checkFile = getChecksumFile(src);
if (exists(checkFile)) {
getMyFs().setReplication(checkFile, replication);
}
return true;
}
/**
* Rename files/dirs.
*/
@Override
public void renameInternal(Path src, Path dst)
throws IOException, UnresolvedLinkException {
if (isDirectory(src)) {
getMyFs().rename(src, dst);
} else {
getMyFs().rename(src, dst);
Path checkFile = getChecksumFile(src);
if (exists(checkFile)) { //try to rename checksum
if (isDirectory(dst)) {
getMyFs().rename(checkFile, dst);
} else {
getMyFs().rename(checkFile, getChecksumFile(dst));
}
}
}
}
/**
* Implement the delete(Path, boolean) in checksum
* file system.
*/
public boolean delete(Path f, boolean recursive)
throws IOException, UnresolvedLinkException {
FileStatus fstatus = null;
try {
fstatus = getMyFs().getFileStatus(f);
} catch(FileNotFoundException e) {
return false;
}
if (fstatus.isDirectory()) {
//this works since the crcs are in the same
//directories and the files. so we just delete
//everything in the underlying filesystem
return getMyFs().delete(f, recursive);
} else {
Path checkFile = getChecksumFile(f);
if (exists(checkFile)) {
getMyFs().delete(checkFile, true);
}
return getMyFs().delete(f, true);
}
}
/**
* 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;
}
@Override
public FileStatus[] listStatus(Path f) throws IOException,
UnresolvedLinkException {
ArrayList results = new ArrayList();
FileStatus[] listing = getMyFs().listStatus(f);
if (listing != null) {
for (int i = 0; i < listing.length; i++) {
if (!isChecksumFile(listing[i].getPath())) {
results.add(listing[i]);
}
}
}
return results.toArray(new FileStatus[results.size()]);
}
}