private static void truncateBlock(File blockFile, File metaFile, long oldlen, long newlen)
throws IOException {
if (newlen == oldlen) {
return;
}
if (newlen > oldlen) {
throw new IOException(
"Cannout truncate block to from oldlen (=" + oldlen + ") to newlen (=" + newlen + ")");
}
DataChecksum dcs = BlockMetadataHeader.readHeader(metaFile).getChecksum();
int checksumsize = dcs.getChecksumSize();
int bpc = dcs.getBytesPerChecksum();
long n = (newlen - 1) / bpc + 1;
long newmetalen = BlockMetadataHeader.getHeaderSize() + n * checksumsize;
long lastchunkoffset = (n - 1) * bpc;
int lastchunksize = (int) (newlen - lastchunkoffset);
byte[] b = new byte[Math.max(lastchunksize, checksumsize)];
RandomAccessFile blockRAF = new RandomAccessFile(blockFile, "rw");
try {
// truncate blockFile
blockRAF.setLength(newlen);
// read last chunk
blockRAF.seek(lastchunkoffset);
blockRAF.readFully(b, 0, lastchunksize);
} finally {
blockRAF.close();
}
// compute checksum
dcs.update(b, 0, lastchunksize);
dcs.writeValue(b, 0, false);
// update metaFile
RandomAccessFile metaRAF = new RandomAccessFile(metaFile, "rw");
try {
metaRAF.setLength(newmetalen);
metaRAF.seek(newmetalen - checksumsize);
metaRAF.write(b, 0, checksumsize);
} finally {
metaRAF.close();
}
}
/**
* Find out the number of bytes in the block that match its crc.
*
* <p>This algorithm assumes that data corruption caused by unexpected datanode shutdown occurs
* only in the last crc chunk. So it checks only the last chunk.
*
* @param blockFile the block file
* @param genStamp generation stamp of the block
* @return the number of valid bytes
*/
private long validateIntegrityAndSetLength(File blockFile, long genStamp) {
DataInputStream checksumIn = null;
InputStream blockIn = null;
try {
final File metaFile = FsDatasetUtil.getMetaFile(blockFile, genStamp);
long blockFileLen = blockFile.length();
long metaFileLen = metaFile.length();
int crcHeaderLen = DataChecksum.getChecksumHeaderSize();
if (!blockFile.exists()
|| blockFileLen == 0
|| !metaFile.exists()
|| metaFileLen < crcHeaderLen) {
return 0;
}
checksumIn =
new DataInputStream(
new BufferedInputStream(
new FileInputStream(metaFile), HdfsConstants.IO_FILE_BUFFER_SIZE));
// read and handle the common header here. For now just a version
final DataChecksum checksum = BlockMetadataHeader.readDataChecksum(checksumIn, metaFile);
int bytesPerChecksum = checksum.getBytesPerChecksum();
int checksumSize = checksum.getChecksumSize();
long numChunks =
Math.min(
(blockFileLen + bytesPerChecksum - 1) / bytesPerChecksum,
(metaFileLen - crcHeaderLen) / checksumSize);
if (numChunks == 0) {
return 0;
}
IOUtils.skipFully(checksumIn, (numChunks - 1) * checksumSize);
blockIn = new FileInputStream(blockFile);
long lastChunkStartPos = (numChunks - 1) * bytesPerChecksum;
IOUtils.skipFully(blockIn, lastChunkStartPos);
int lastChunkSize = (int) Math.min(bytesPerChecksum, blockFileLen - lastChunkStartPos);
byte[] buf = new byte[lastChunkSize + checksumSize];
checksumIn.readFully(buf, lastChunkSize, checksumSize);
IOUtils.readFully(blockIn, buf, 0, lastChunkSize);
checksum.update(buf, 0, lastChunkSize);
long validFileLength;
if (checksum.compare(buf, lastChunkSize)) { // last chunk matches crc
validFileLength = lastChunkStartPos + lastChunkSize;
} else { // last chunck is corrupt
validFileLength = lastChunkStartPos;
}
// truncate if extra bytes are present without CRC
if (blockFile.length() > validFileLength) {
RandomAccessFile blockRAF = new RandomAccessFile(blockFile, "rw");
try {
// truncate blockFile
blockRAF.setLength(validFileLength);
} finally {
blockRAF.close();
}
}
return validFileLength;
} catch (IOException e) {
FsDatasetImpl.LOG.warn(e);
return 0;
} finally {
IOUtils.closeStream(checksumIn);
IOUtils.closeStream(blockIn);
}
}
/**
* Sends upto maxChunks chunks of data.
*
* <p>When blockInPosition is >= 0, assumes 'out' is a {@link SocketOutputStream} and tries {@link
* SocketOutputStream#transferToFully(FileChannel, long, int)} to send data (and updates
* blockInPosition).
*/
private int sendChunks(ByteBuffer pkt, int maxChunks, OutputStream out) throws IOException {
// Sends multiple chunks in one packet with a single write().
int len = (int) Math.min(endOffset - offset, (((long) bytesPerChecksum) * ((long) maxChunks)));
int numChunks = (len + bytesPerChecksum - 1) / bytesPerChecksum;
int packetLen = len + numChunks * checksumSize + 4;
boolean lastDataPacket = offset + len == endOffset && len > 0;
pkt.clear();
PacketHeader header = new PacketHeader(packetLen, offset, seqno, (len == 0), len);
header.putInBuffer(pkt);
int checksumOff = pkt.position();
int checksumLen = numChunks * checksumSize;
byte[] buf = pkt.array();
if (checksumSize > 0 && checksumIn != null) {
try {
checksumIn.readFully(buf, checksumOff, checksumLen);
} catch (IOException e) {
LOG.warn(
" Could not read or failed to veirfy checksum for data"
+ " at offset "
+ offset
+ " for block "
+ block
+ " got : "
+ StringUtils.stringifyException(e));
IOUtils.closeStream(checksumIn);
checksumIn = null;
if (corruptChecksumOk) {
if (checksumOff < checksumLen) {
// Just fill the array with zeros.
Arrays.fill(buf, checksumOff, checksumLen, (byte) 0);
}
} else {
throw e;
}
}
// write in progress that we need to use to get last checksum
if (lastDataPacket && lastChunkChecksum != null) {
int start = checksumOff + checksumLen - checksumSize;
byte[] updatedChecksum = lastChunkChecksum.getChecksum();
if (updatedChecksum != null) {
System.arraycopy(updatedChecksum, 0, buf, start, checksumSize);
}
}
}
int dataOff = checksumOff + checksumLen;
if (blockInPosition < 0) {
// normal transfer
IOUtils.readFully(blockIn, buf, dataOff, len);
if (verifyChecksum) {
int dOff = dataOff;
int cOff = checksumOff;
int dLeft = len;
for (int i = 0; i < numChunks; i++) {
checksum.reset();
int dLen = Math.min(dLeft, bytesPerChecksum);
checksum.update(buf, dOff, dLen);
if (!checksum.compare(buf, cOff)) {
long failedPos = offset + len - dLeft;
throw new ChecksumException("Checksum failed at " + failedPos, failedPos);
}
dLeft -= dLen;
dOff += dLen;
cOff += checksumSize;
}
}
// writing is done below (mainly to handle IOException)
}
try {
if (blockInPosition >= 0) {
// use transferTo(). Checks on out and blockIn are already done.
SocketOutputStream sockOut = (SocketOutputStream) out;
// first write the packet
sockOut.write(buf, 0, dataOff);
// no need to flush. since we know out is not a buffered stream.
sockOut.transferToFully(((FileInputStream) blockIn).getChannel(), blockInPosition, len);
blockInPosition += len;
} else {
// normal transfer
out.write(buf, 0, dataOff + len);
}
} catch (IOException e) {
/* Exception while writing to the client. Connection closure from
* the other end is mostly the case and we do not care much about
* it. But other things can go wrong, especially in transferTo(),
* which we do not want to ignore.
*
* The message parsing below should not be considered as a good
* coding example. NEVER do it to drive a program logic. NEVER.
* It was done here because the NIO throws an IOException for EPIPE.
*/
String ioem = e.getMessage();
if (!ioem.startsWith("Broken pipe") && !ioem.startsWith("Connection reset")) {
LOG.error("BlockSender.sendChunks() exception: ", e);
}
throw ioeToSocketException(e);
}
if (throttler != null) { // rebalancing so throttle
throttler.throttle(packetLen);
}
return len;
}