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/**
* 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;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.EnumSet;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.fs.FSInputChecker;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.ReadOption;
import org.apache.hadoop.hdfs.net.Peer;
import org.apache.hadoop.hdfs.protocol.Block;
import org.apache.hadoop.hdfs.protocol.DatanodeID;
import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
import org.apache.hadoop.hdfs.protocol.datatransfer.DataTransferProtoUtil;
import org.apache.hadoop.hdfs.protocol.datatransfer.PacketHeader;
import org.apache.hadoop.hdfs.protocol.datatransfer.Sender;
import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.BlockOpResponseProto;
import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.ReadOpChecksumInfoProto;
import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.Status;
import org.apache.hadoop.hdfs.protocolPB.PBHelper;
import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
import org.apache.hadoop.hdfs.server.datanode.CachingStrategy;
import org.apache.hadoop.hdfs.shortcircuit.ClientMmap;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.net.NetUtils;
import org.apache.hadoop.security.token.Token;
import org.apache.hadoop.util.DataChecksum;
import org.apache.htrace.Sampler;
import org.apache.htrace.Trace;
import org.apache.htrace.TraceScope;
/**
* @deprecated this is an old implementation that is being left around
* in case any issues spring up with the new {@link RemoteBlockReader2} implementation.
* It will be removed in the next release.
*/
@InterfaceAudience.Private
@Deprecated
public class RemoteBlockReader extends FSInputChecker implements BlockReader {
private final Peer peer;
private final DatanodeID datanodeID;
private final DataInputStream in;
private DataChecksum checksum;
/** offset in block of the last chunk received */
private long lastChunkOffset = -1;
private long lastChunkLen = -1;
private long lastSeqNo = -1;
/** offset in block where reader wants to actually read */
private long startOffset;
private final long blockId;
/** offset in block of of first chunk - may be less than startOffset
if startOffset is not chunk-aligned */
private final long firstChunkOffset;
private final int bytesPerChecksum;
private final int checksumSize;
/**
* The total number of bytes we need to transfer from the DN.
* This is the amount that the user has requested plus some padding
* at the beginning so that the read can begin on a chunk boundary.
*/
private final long bytesNeededToFinish;
/**
* True if we are reading from a local DataNode.
*/
private final boolean isLocal;
private boolean eos = false;
private boolean sentStatusCode = false;
byte[] skipBuf = null;
ByteBuffer checksumBytes = null;
/** Amount of unread data in the current received packet */
int dataLeft = 0;
private final PeerCache peerCache;
/* FSInputChecker interface */
/* same interface as inputStream java.io.InputStream#read()
* used by DFSInputStream#read()
* This violates one rule when there is a checksum error:
* "Read should not modify user buffer before successful read"
* because it first reads the data to user buffer and then checks
* the checksum.
*/
@Override
public synchronized int read(byte[] buf, int off, int len)
throws IOException {
// This has to be set here, *before* the skip, since we can
// hit EOS during the skip, in the case that our entire read
// is smaller than the checksum chunk.
boolean eosBefore = eos;
//for the first read, skip the extra bytes at the front.
if (lastChunkLen < 0 && startOffset > firstChunkOffset && len > 0) {
// Skip these bytes. But don't call this.skip()!
int toSkip = (int)(startOffset - firstChunkOffset);
if ( skipBuf == null ) {
skipBuf = new byte[bytesPerChecksum];
}
if ( super.read(skipBuf, 0, toSkip) != toSkip ) {
// should never happen
throw new IOException("Could not skip required number of bytes");
}
}
int nRead = super.read(buf, off, len);
// if eos was set in the previous read, send a status code to the DN
if (eos && !eosBefore && nRead >= 0) {
if (needChecksum()) {
sendReadResult(peer, Status.CHECKSUM_OK);
} else {
sendReadResult(peer, Status.SUCCESS);
}
}
return nRead;
}
@Override
public synchronized long skip(long n) throws IOException {
/* How can we make sure we don't throw a ChecksumException, at least
* in majority of the cases?. This one throws. */
if ( skipBuf == null ) {
skipBuf = new byte[bytesPerChecksum];
}
long nSkipped = 0;
while ( nSkipped < n ) {
int toSkip = (int)Math.min(n-nSkipped, skipBuf.length);
int ret = read(skipBuf, 0, toSkip);
if ( ret <= 0 ) {
return nSkipped;
}
nSkipped += ret;
}
return nSkipped;
}
@Override
public int read() throws IOException {
throw new IOException("read() is not expected to be invoked. " +
"Use read(buf, off, len) instead.");
}
@Override
public boolean seekToNewSource(long targetPos) throws IOException {
/* Checksum errors are handled outside the BlockReader.
* DFSInputStream does not always call 'seekToNewSource'. In the
* case of pread(), it just tries a different replica without seeking.
*/
return false;
}
@Override
public void seek(long pos) throws IOException {
throw new IOException("Seek() is not supported in BlockInputChecker");
}
@Override
protected long getChunkPosition(long pos) {
throw new RuntimeException("getChunkPosition() is not supported, " +
"since seek is not required");
}
/**
* Makes sure that checksumBytes has enough capacity
* and limit is set to the number of checksum bytes needed
* to be read.
*/
private void adjustChecksumBytes(int dataLen) {
int requiredSize =
((dataLen + bytesPerChecksum - 1)/bytesPerChecksum)*checksumSize;
if (checksumBytes == null || requiredSize > checksumBytes.capacity()) {
checksumBytes = ByteBuffer.wrap(new byte[requiredSize]);
} else {
checksumBytes.clear();
}
checksumBytes.limit(requiredSize);
}
@Override
protected synchronized int readChunk(long pos, byte[] buf, int offset,
int len, byte[] checksumBuf)
throws IOException {
TraceScope scope =
Trace.startSpan("RemoteBlockReader#readChunk(" + blockId + ")",
Sampler.NEVER);
try {
return readChunkImpl(pos, buf, offset, len, checksumBuf);
} finally {
scope.close();
}
}
private synchronized int readChunkImpl(long pos, byte[] buf, int offset,
int len, byte[] checksumBuf)
throws IOException {
// Read one chunk.
if (eos) {
// Already hit EOF
return -1;
}
// Read one DATA_CHUNK.
long chunkOffset = lastChunkOffset;
if ( lastChunkLen > 0 ) {
chunkOffset += lastChunkLen;
}
// pos is relative to the start of the first chunk of the read.
// chunkOffset is relative to the start of the block.
// This makes sure that the read passed from FSInputChecker is the
// for the same chunk we expect to be reading from the DN.
if ( (pos + firstChunkOffset) != chunkOffset ) {
throw new IOException("Mismatch in pos : " + pos + " + " +
firstChunkOffset + " != " + chunkOffset);
}
// Read next packet if the previous packet has been read completely.
if (dataLeft <= 0) {
//Read packet headers.
PacketHeader header = new PacketHeader();
header.readFields(in);
if (LOG.isDebugEnabled()) {
LOG.debug("DFSClient readChunk got header " + header);
}
// Sanity check the lengths
if (!header.sanityCheck(lastSeqNo)) {
throw new IOException("BlockReader: error in packet header " +
header);
}
lastSeqNo = header.getSeqno();
dataLeft = header.getDataLen();
adjustChecksumBytes(header.getDataLen());
if (header.getDataLen() > 0) {
IOUtils.readFully(in, checksumBytes.array(), 0,
checksumBytes.limit());
}
}
// Sanity checks
assert len >= bytesPerChecksum;
assert checksum != null;
assert checksumSize == 0 || (checksumBuf.length % checksumSize == 0);
int checksumsToRead, bytesToRead;
if (checksumSize > 0) {
// How many chunks left in our packet - this is a ceiling
// since we may have a partial chunk at the end of the file
int chunksLeft = (dataLeft - 1) / bytesPerChecksum + 1;
// How many chunks we can fit in databuffer
// - note this is a floor since we always read full chunks
int chunksCanFit = Math.min(len / bytesPerChecksum,
checksumBuf.length / checksumSize);
// How many chunks should we read
checksumsToRead = Math.min(chunksLeft, chunksCanFit);
// How many bytes should we actually read
bytesToRead = Math.min(
checksumsToRead * bytesPerChecksum, // full chunks
dataLeft); // in case we have a partial
} else {
// no checksum
bytesToRead = Math.min(dataLeft, len);
checksumsToRead = 0;
}
if ( bytesToRead > 0 ) {
// Assert we have enough space
assert bytesToRead <= len;
assert checksumBytes.remaining() >= checksumSize * checksumsToRead;
assert checksumBuf.length >= checksumSize * checksumsToRead;
IOUtils.readFully(in, buf, offset, bytesToRead);
checksumBytes.get(checksumBuf, 0, checksumSize * checksumsToRead);
}
dataLeft -= bytesToRead;
assert dataLeft >= 0;
lastChunkOffset = chunkOffset;
lastChunkLen = bytesToRead;
// If there's no data left in the current packet after satisfying
// this read, and we have satisfied the client read, we expect
// an empty packet header from the DN to signify this.
// Note that pos + bytesToRead may in fact be greater since the
// DN finishes off the entire last chunk.
if (dataLeft == 0 &&
pos + bytesToRead >= bytesNeededToFinish) {
// Read header
PacketHeader hdr = new PacketHeader();
hdr.readFields(in);
if (!hdr.isLastPacketInBlock() ||
hdr.getDataLen() != 0) {
throw new IOException("Expected empty end-of-read packet! Header: " +
hdr);
}
eos = true;
}
if ( bytesToRead == 0 ) {
return -1;
}
return bytesToRead;
}
private RemoteBlockReader(String file, String bpid, long blockId,
DataInputStream in, DataChecksum checksum, boolean verifyChecksum,
long startOffset, long firstChunkOffset, long bytesToRead, Peer peer,
DatanodeID datanodeID, PeerCache peerCache) {
// Path is used only for printing block and file information in debug
super(new Path("/" + Block.BLOCK_FILE_PREFIX + blockId +
":" + bpid + ":of:"+ file)/*too non path-like?*/,
1, verifyChecksum,
checksum.getChecksumSize() > 0? checksum : null,
checksum.getBytesPerChecksum(),
checksum.getChecksumSize());
this.isLocal = DFSClient.isLocalAddress(NetUtils.
createSocketAddr(datanodeID.getXferAddr()));
this.peer = peer;
this.datanodeID = datanodeID;
this.in = in;
this.checksum = checksum;
this.startOffset = Math.max( startOffset, 0 );
this.blockId = blockId;
// The total number of bytes that we need to transfer from the DN is
// the amount that the user wants (bytesToRead), plus the padding at
// the beginning in order to chunk-align. Note that the DN may elect
// to send more than this amount if the read starts/ends mid-chunk.
this.bytesNeededToFinish = bytesToRead + (startOffset - firstChunkOffset);
this.firstChunkOffset = firstChunkOffset;
lastChunkOffset = firstChunkOffset;
lastChunkLen = -1;
bytesPerChecksum = this.checksum.getBytesPerChecksum();
checksumSize = this.checksum.getChecksumSize();
this.peerCache = peerCache;
}
/**
* Create a new BlockReader specifically to satisfy a read.
* This method also sends the OP_READ_BLOCK request.
*
* @param file File location
* @param block The block object
* @param blockToken The block token for security
* @param startOffset The read offset, relative to block head
* @param len The number of bytes to read
* @param bufferSize The IO buffer size (not the client buffer size)
* @param verifyChecksum Whether to verify checksum
* @param clientName Client name
* @return New BlockReader instance, or null on error.
*/
public static RemoteBlockReader newBlockReader(String file,
ExtendedBlock block,
Token blockToken,
long startOffset, long len,
int bufferSize, boolean verifyChecksum,
String clientName, Peer peer,
DatanodeID datanodeID,
PeerCache peerCache,
CachingStrategy cachingStrategy)
throws IOException {
// in and out will be closed when sock is closed (by the caller)
final DataOutputStream out =
new DataOutputStream(new BufferedOutputStream(peer.getOutputStream()));
new Sender(out).readBlock(block, blockToken, clientName, startOffset, len,
verifyChecksum, cachingStrategy);
//
// Get bytes in block, set streams
//
DataInputStream in = new DataInputStream(
new BufferedInputStream(peer.getInputStream(), bufferSize));
BlockOpResponseProto status = BlockOpResponseProto.parseFrom(
PBHelper.vintPrefixed(in));
RemoteBlockReader2.checkSuccess(status, peer, block, file);
ReadOpChecksumInfoProto checksumInfo =
status.getReadOpChecksumInfo();
DataChecksum checksum = DataTransferProtoUtil.fromProto(
checksumInfo.getChecksum());
//Warning when we get CHECKSUM_NULL?
// Read the first chunk offset.
long firstChunkOffset = checksumInfo.getChunkOffset();
if ( firstChunkOffset < 0 || firstChunkOffset > startOffset ||
firstChunkOffset <= (startOffset - checksum.getBytesPerChecksum())) {
throw new IOException("BlockReader: error in first chunk offset (" +
firstChunkOffset + ") startOffset is " +
startOffset + " for file " + file);
}
return new RemoteBlockReader(file, block.getBlockPoolId(), block.getBlockId(),
in, checksum, verifyChecksum, startOffset, firstChunkOffset, len,
peer, datanodeID, peerCache);
}
@Override
public synchronized void close() throws IOException {
startOffset = -1;
checksum = null;
if (peerCache != null & sentStatusCode) {
peerCache.put(datanodeID, peer);
} else {
peer.close();
}
// in will be closed when its Socket is closed.
}
@Override
public void readFully(byte[] buf, int readOffset, int amtToRead)
throws IOException {
IOUtils.readFully(this, buf, readOffset, amtToRead);
}
@Override
public int readAll(byte[] buf, int offset, int len) throws IOException {
return readFully(this, buf, offset, len);
}
/**
* When the reader reaches end of the read, it sends a status response
* (e.g. CHECKSUM_OK) to the DN. Failure to do so could lead to the DN
* closing our connection (which we will re-open), but won't affect
* data correctness.
*/
void sendReadResult(Peer peer, Status statusCode) {
assert !sentStatusCode : "already sent status code to " + peer;
try {
RemoteBlockReader2.writeReadResult(peer.getOutputStream(), statusCode);
sentStatusCode = true;
} catch (IOException e) {
// It's ok not to be able to send this. But something is probably wrong.
LOG.info("Could not send read status (" + statusCode + ") to datanode " +
peer.getRemoteAddressString() + ": " + e.getMessage());
}
}
@Override
public int read(ByteBuffer buf) throws IOException {
throw new UnsupportedOperationException("readDirect unsupported in RemoteBlockReader");
}
@Override
public int available() throws IOException {
// An optimistic estimate of how much data is available
// to us without doing network I/O.
return DFSClient.TCP_WINDOW_SIZE;
}
@Override
public boolean isLocal() {
return isLocal;
}
@Override
public boolean isShortCircuit() {
return false;
}
@Override
public ClientMmap getClientMmap(EnumSet opts) {
return null;
}
}
