org.apache.hadoop.hdfs.server.datanode.BlockSender Maven / Gradle / Ivy
The newest version!
/**
* 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.datanode;
import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.SocketException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.util.Arrays;
import org.apache.commons.logging.Log;
import org.apache.hadoop.fs.ChecksumException;
import org.apache.hadoop.hdfs.protocol.Block;
import org.apache.hadoop.hdfs.protocol.FSConstants;
import org.apache.hadoop.hdfs.protocol.DataTransferProtocol.PacketHeader;
import org.apache.hadoop.hdfs.util.DataTransferThrottler;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.net.SocketOutputStream;
import org.apache.hadoop.util.DataChecksum;
import org.apache.hadoop.util.StringUtils;
/**
* Reads a block from the disk and sends it to a recipient.
*/
class BlockSender implements java.io.Closeable, FSConstants {
public static final Log LOG = DataNode.LOG;
static final Log ClientTraceLog = DataNode.ClientTraceLog;
private Block block; // the block to read from
/** the replica to read from */
private final Replica replica;
/** The visible length of a replica. */
private final long replicaVisibleLength;
private static final boolean is32Bit = System.getProperty("sun.arch.data.model").equals("32");
private InputStream blockIn; // data stream
private long blockInPosition = -1; // updated while using transferTo().
private DataInputStream checksumIn; // checksum datastream
private DataChecksum checksum; // checksum stream
private long offset; // starting position to read
private long endOffset; // ending position
private int bytesPerChecksum; // chunk size
private int checksumSize; // checksum size
private boolean corruptChecksumOk; // if need to verify checksum
private boolean chunkOffsetOK; // if need to send chunk offset
private long seqno; // sequence number of packet
private boolean transferToAllowed = true;
// set once entire requested byte range has been sent to the client
private boolean blockReadFully; //set when the whole block is read
private boolean sentEntireByteRange;
private boolean verifyChecksum; //if true, check is verified while reading
private DataTransferThrottler throttler;
private final String clientTraceFmt; // format of client trace log message
/**
* Minimum buffer used while sending data to clients. Used only if
* transferTo() is enabled. 64KB is not that large. It could be larger, but
* not sure if there will be much more improvement.
*/
private static final int MIN_BUFFER_WITH_TRANSFERTO = 64*1024;
private volatile ChunkChecksum lastChunkChecksum = null;
BlockSender(Block block, long startOffset, long length,
boolean corruptChecksumOk, boolean chunkOffsetOK,
boolean verifyChecksum, DataNode datanode) throws IOException {
this(block, startOffset, length, corruptChecksumOk, chunkOffsetOK,
verifyChecksum, datanode, null);
}
BlockSender(Block block, long startOffset, long length,
boolean corruptChecksumOk, boolean chunkOffsetOK,
boolean verifyChecksum, DataNode datanode, String clientTraceFmt)
throws IOException {
try {
this.block = block;
synchronized(datanode.data) {
this.replica = datanode.data.getReplica(block.getBlockId());
if (replica == null) {
throw new ReplicaNotFoundException(block);
}
this.replicaVisibleLength = replica.getVisibleLength();
}
long minEndOffset = startOffset + length;
// if this is a write in progress
ChunkChecksum chunkChecksum = null;
if (replica instanceof ReplicaBeingWritten) {
for (int i = 0; i < 30 && replica.getBytesOnDisk() < minEndOffset; i++) {
try {
Thread.sleep(100);
} catch (InterruptedException ie) {
throw new IOException(ie);
}
}
long currentBytesOnDisk = replica.getBytesOnDisk();
if (currentBytesOnDisk < minEndOffset) {
throw new IOException(String.format(
"need %d bytes, but only %d bytes available",
minEndOffset,
currentBytesOnDisk
));
}
ReplicaInPipeline rip = (ReplicaInPipeline) replica;
chunkChecksum = rip.getLastChecksumAndDataLen();
}
if (replica.getGenerationStamp() < block.getGenerationStamp()) {
throw new IOException(
"replica.getGenerationStamp() < block.getGenerationStamp(), block="
+ block + ", replica=" + replica);
}
if (replicaVisibleLength < 0) {
throw new IOException("The replica is not readable, block="
+ block + ", replica=" + replica);
}
if (DataNode.LOG.isDebugEnabled()) {
DataNode.LOG.debug("block=" + block + ", replica=" + replica);
}
this.chunkOffsetOK = chunkOffsetOK;
this.corruptChecksumOk = corruptChecksumOk;
this.verifyChecksum = verifyChecksum;
// transferToFully() fails on 32 bit platforms for block sizes >= 2GB,
// use normal transfer in those cases
this.transferToAllowed = datanode.transferToAllowed &&
(!is32Bit || length < (long) Integer.MAX_VALUE);
this.clientTraceFmt = clientTraceFmt;
if ( !corruptChecksumOk || datanode.data.metaFileExists(block) ) {
checksumIn = new DataInputStream(
new BufferedInputStream(datanode.data.getMetaDataInputStream(block),
BUFFER_SIZE));
// read and handle the common header here. For now just a version
BlockMetadataHeader header = BlockMetadataHeader.readHeader(checksumIn);
short version = header.getVersion();
if (version != FSDataset.METADATA_VERSION) {
LOG.warn("Wrong version (" + version + ") for metadata file for "
+ block + " ignoring ...");
}
checksum = header.getChecksum();
} else {
LOG.warn("Could not find metadata file for " + block);
// This only decides the buffer size. Use BUFFER_SIZE?
checksum = DataChecksum.newDataChecksum(DataChecksum.CHECKSUM_NULL,
16 * 1024);
}
/* If bytesPerChecksum is very large, then the metadata file
* is mostly corrupted. For now just truncate bytesPerchecksum to
* blockLength.
*/
bytesPerChecksum = checksum.getBytesPerChecksum();
if (bytesPerChecksum > 10*1024*1024 && bytesPerChecksum > replicaVisibleLength) {
checksum = DataChecksum.newDataChecksum(checksum.getChecksumType(),
Math.max((int)replicaVisibleLength, 10*1024*1024));
bytesPerChecksum = checksum.getBytesPerChecksum();
}
checksumSize = checksum.getChecksumSize();
if (length < 0) {
length = replicaVisibleLength;
}
// end is either last byte on disk or the length for which we have a
// checksum
if (chunkChecksum != null) {
endOffset = chunkChecksum.getDataLength();
} else {
endOffset = replica.getBytesOnDisk();
}
if (startOffset < 0 || startOffset > endOffset
|| (length + startOffset) > endOffset) {
String msg = " Offset " + startOffset + " and length " + length
+ " don't match block " + block + " ( blockLen " + endOffset + " )";
LOG.warn(datanode.dnRegistration + ":sendBlock() : " + msg);
throw new IOException(msg);
}
offset = (startOffset - (startOffset % bytesPerChecksum));
if (length >= 0) {
// Make sure endOffset points to end of a checksumed chunk.
long tmpLen = startOffset + length;
if (tmpLen % bytesPerChecksum != 0) {
tmpLen += (bytesPerChecksum - tmpLen % bytesPerChecksum);
}
if (tmpLen < endOffset) {
// will use on-disk checksum here since the end is a stable chunk
endOffset = tmpLen;
} else if (chunkChecksum != null) {
//in last chunk which is changing. flag that we need to use in-memory
// checksum
this.lastChunkChecksum = chunkChecksum;
}
}
// seek to the right offsets
if (offset > 0) {
long checksumSkip = (offset / bytesPerChecksum) * checksumSize;
// note blockInStream is seeked when created below
if (checksumSkip > 0) {
// Should we use seek() for checksum file as well?
IOUtils.skipFully(checksumIn, checksumSkip);
}
}
seqno = 0;
if (DataNode.LOG.isDebugEnabled()) {
DataNode.LOG.debug("replica=" + replica);
}
blockIn = datanode.data.getBlockInputStream(block, offset); // seek to offset
} catch (IOException ioe) {
IOUtils.closeStream(this);
IOUtils.closeStream(blockIn);
throw ioe;
}
}
/**
* close opened files.
*/
public void close() throws IOException {
IOException ioe = null;
// close checksum file
if(checksumIn!=null) {
try {
checksumIn.close();
} catch (IOException e) {
ioe = e;
}
checksumIn = null;
}
// close data file
if(blockIn!=null) {
try {
blockIn.close();
} catch (IOException e) {
ioe = e;
}
blockIn = null;
}
// throw IOException if there is any
if(ioe!= null) {
throw ioe;
}
}
/**
* Converts an IOExcpetion (not subclasses) to SocketException.
* This is typically done to indicate to upper layers that the error
* was a socket error rather than often more serious exceptions like
* disk errors.
*/
private static IOException ioeToSocketException(IOException ioe) {
if (ioe.getClass().equals(IOException.class)) {
// "se" could be a new class in stead of SocketException.
IOException se = new SocketException("Original Exception : " + ioe);
se.initCause(ioe);
/* Change the stacktrace so that original trace is not truncated
* when printed.*/
se.setStackTrace(ioe.getStackTrace());
return se;
}
// otherwise just return the same exception.
return ioe;
}
/**
* Sends upto maxChunks chunks of data.
*
* 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= 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;
}
/**
* sendBlock() is used to read block and its metadata and stream the data to
* either a client or to another datanode.
*
* @param out stream to which the block is written to
* @param baseStream optional. if non-null, out is assumed to
* be a wrapper over this stream. This enables optimizations for
* sending the data, e.g.
* {@link SocketOutputStream#transferToFully(FileChannel,
* long, int)}.
* @param throttler for sending data.
* @return total bytes reads, including crc.
*/
long sendBlock(DataOutputStream out, OutputStream baseStream,
DataTransferThrottler throttler) throws IOException {
if( out == null ) {
throw new IOException( "out stream is null" );
}
this.throttler = throttler;
long initialOffset = offset;
long totalRead = 0;
OutputStream streamForSendChunks = out;
final long startTime = ClientTraceLog.isInfoEnabled() ? System.nanoTime() : 0;
try {
try {
checksum.writeHeader(out);
if ( chunkOffsetOK ) {
out.writeLong( offset );
}
out.flush();
} catch (IOException e) { //socket error
throw ioeToSocketException(e);
}
int maxChunksPerPacket;
int pktSize = PacketHeader.PKT_HEADER_LEN;
if (transferToAllowed && !verifyChecksum &&
baseStream instanceof SocketOutputStream &&
blockIn instanceof FileInputStream) {
FileChannel fileChannel = ((FileInputStream)blockIn).getChannel();
// blockInPosition also indicates sendChunks() uses transferTo.
blockInPosition = fileChannel.position();
streamForSendChunks = baseStream;
// assure a mininum buffer size.
maxChunksPerPacket = (Math.max(BUFFER_SIZE,
MIN_BUFFER_WITH_TRANSFERTO)
+ bytesPerChecksum - 1)/bytesPerChecksum;
// allocate smaller buffer while using transferTo().
pktSize += checksumSize * maxChunksPerPacket;
} else {
maxChunksPerPacket = Math.max(1,
(BUFFER_SIZE + bytesPerChecksum - 1)/bytesPerChecksum);
pktSize += (bytesPerChecksum + checksumSize) * maxChunksPerPacket;
}
ByteBuffer pktBuf = ByteBuffer.allocate(pktSize);
while (endOffset > offset) {
long len = sendChunks(pktBuf, maxChunksPerPacket,
streamForSendChunks);
offset += len;
totalRead += len + ((len + bytesPerChecksum - 1)/bytesPerChecksum*
checksumSize);
seqno++;
}
try {
// send an empty packet to mark the end of the block
sendChunks(pktBuf, maxChunksPerPacket, streamForSendChunks);
out.flush();
} catch (IOException e) { //socket error
throw ioeToSocketException(e);
}
sentEntireByteRange = true;
} finally {
if (clientTraceFmt != null) {
final long endTime = System.nanoTime();
ClientTraceLog.info(String.format(clientTraceFmt, totalRead, initialOffset, endTime - startTime));
}
close();
}
blockReadFully = initialOffset == 0 && offset >= replicaVisibleLength;
return totalRead;
}
boolean isBlockReadFully() {
return blockReadFully;
}
boolean didSendEntireByteRange() {
return sentEntireByteRange;
}
}