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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.EOFException;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.ClosedByInterruptException;
import java.util.AbstractMap;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.EnumSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.Callable;
import java.util.concurrent.CancellationException;
import java.util.concurrent.CompletionService;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorCompletionService;
import java.util.concurrent.Future;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.commons.io.IOUtils;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.fs.ByteBufferReadable;
import org.apache.hadoop.fs.ByteBufferUtil;
import org.apache.hadoop.fs.CanSetDropBehind;
import org.apache.hadoop.fs.CanSetReadahead;
import org.apache.hadoop.fs.CanUnbuffer;
import org.apache.hadoop.fs.ChecksumException;
import org.apache.hadoop.fs.FSInputStream;
import org.apache.hadoop.fs.FileEncryptionInfo;
import org.apache.hadoop.fs.HasEnhancedByteBufferAccess;
import org.apache.hadoop.fs.ReadOption;
import org.apache.hadoop.fs.StorageType;
import org.apache.hadoop.fs.StreamCapabilities;
import org.apache.hadoop.hdfs.DFSUtilClient.CorruptedBlocks;
import org.apache.hadoop.hdfs.client.impl.BlockReaderFactory;
import org.apache.hadoop.hdfs.client.impl.DfsClientConf;
import org.apache.hadoop.hdfs.protocol.BlockType;
import org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
import org.apache.hadoop.hdfs.protocol.LocatedBlock;
import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
import org.apache.hadoop.hdfs.protocol.datatransfer.InvalidEncryptionKeyException;
import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
import org.apache.hadoop.hdfs.security.token.block.InvalidBlockTokenException;
import org.apache.hadoop.hdfs.server.datanode.CachingStrategy;
import org.apache.hadoop.hdfs.server.datanode.ReplicaNotFoundException;
import org.apache.hadoop.hdfs.shortcircuit.ClientMmap;
import org.apache.hadoop.hdfs.util.IOUtilsClient;
import org.apache.hadoop.io.ByteBufferPool;
import org.apache.hadoop.ipc.RPC;
import org.apache.hadoop.ipc.RemoteException;
import org.apache.hadoop.ipc.RetriableException;
import org.apache.hadoop.net.NetUtils;
import org.apache.hadoop.security.token.SecretManager.InvalidToken;
import org.apache.hadoop.security.token.Token;
import org.apache.hadoop.util.IdentityHashStore;
import org.apache.hadoop.util.StopWatch;
import org.apache.hadoop.util.StringUtils;
import org.apache.htrace.core.SpanId;
import com.google.common.annotations.VisibleForTesting;
import javax.annotation.Nonnull;
import static org.apache.hadoop.hdfs.util.IOUtilsClient.updateReadStatistics;
/****************************************************************
* DFSInputStream provides bytes from a named file. It handles
* negotiation of the namenode and various datanodes as necessary.
****************************************************************/
@InterfaceAudience.Private
public class DFSInputStream extends FSInputStream
implements ByteBufferReadable, CanSetDropBehind, CanSetReadahead,
HasEnhancedByteBufferAccess, CanUnbuffer, StreamCapabilities {
@VisibleForTesting
public static boolean tcpReadsDisabledForTesting = false;
private long hedgedReadOpsLoopNumForTesting = 0;
protected final DFSClient dfsClient;
protected AtomicBoolean closed = new AtomicBoolean(false);
protected final String src;
protected final boolean verifyChecksum;
// state by stateful read only:
// (protected by lock on this)
/////
private DatanodeInfo currentNode = null;
protected LocatedBlock currentLocatedBlock = null;
protected long pos = 0;
protected long blockEnd = -1;
private BlockReader blockReader = null;
////
// state shared by stateful and positional read:
// (protected by lock on infoLock)
////
protected LocatedBlocks locatedBlocks = null;
private long lastBlockBeingWrittenLength = 0;
private FileEncryptionInfo fileEncryptionInfo = null;
protected CachingStrategy cachingStrategy;
////
protected final ReadStatistics readStatistics = new ReadStatistics();
// lock for state shared between read and pread
// Note: Never acquire a lock on with this lock held to avoid deadlocks
// (it's OK to acquire this lock when the lock on is held)
protected final Object infoLock = new Object();
/**
* Track the ByteBuffers that we have handed out to readers.
*
* The value type can be either ByteBufferPool or ClientMmap, depending on
* whether we this is a memory-mapped buffer or not.
*/
private IdentityHashStore extendedReadBuffers;
private synchronized IdentityHashStore
getExtendedReadBuffers() {
if (extendedReadBuffers == null) {
extendedReadBuffers = new IdentityHashStore<>(0);
}
return extendedReadBuffers;
}
/**
* This variable tracks the number of failures since the start of the
* most recent user-facing operation. That is to say, it should be reset
* whenever the user makes a call on this stream, and if at any point
* during the retry logic, the failure count exceeds a threshold,
* the errors will be thrown back to the operation.
*
* Specifically this counts the number of times the client has gone
* back to the namenode to get a new list of block locations, and is
* capped at maxBlockAcquireFailures
*/
protected int failures = 0;
/* XXX Use of CocurrentHashMap is temp fix. Need to fix
* parallel accesses to DFSInputStream (through ptreads) properly */
private final ConcurrentHashMap deadNodes =
new ConcurrentHashMap<>();
private byte[] oneByteBuf; // used for 'int read()'
void addToDeadNodes(DatanodeInfo dnInfo) {
deadNodes.put(dnInfo, dnInfo);
}
DFSInputStream(DFSClient dfsClient, String src, boolean verifyChecksum,
LocatedBlocks locatedBlocks) throws IOException {
this.dfsClient = dfsClient;
this.verifyChecksum = verifyChecksum;
this.src = src;
synchronized (infoLock) {
this.cachingStrategy = dfsClient.getDefaultReadCachingStrategy();
}
this.locatedBlocks = locatedBlocks;
openInfo(false);
}
@VisibleForTesting
public long getlastBlockBeingWrittenLengthForTesting() {
return lastBlockBeingWrittenLength;
}
/**
* Grab the open-file info from namenode
* @param refreshLocatedBlocks whether to re-fetch locatedblocks
*/
void openInfo(boolean refreshLocatedBlocks) throws IOException {
final DfsClientConf conf = dfsClient.getConf();
synchronized(infoLock) {
lastBlockBeingWrittenLength =
fetchLocatedBlocksAndGetLastBlockLength(refreshLocatedBlocks);
int retriesForLastBlockLength = conf.getRetryTimesForGetLastBlockLength();
while (retriesForLastBlockLength > 0) {
// Getting last block length as -1 is a special case. When cluster
// restarts, DNs may not report immediately. At this time partial block
// locations will not be available with NN for getting the length. Lets
// retry for 3 times to get the length.
if (lastBlockBeingWrittenLength == -1) {
DFSClient.LOG.warn("Last block locations not available. "
+ "Datanodes might not have reported blocks completely."
+ " Will retry for " + retriesForLastBlockLength + " times");
waitFor(conf.getRetryIntervalForGetLastBlockLength());
lastBlockBeingWrittenLength =
fetchLocatedBlocksAndGetLastBlockLength(true);
} else {
break;
}
retriesForLastBlockLength--;
}
if (lastBlockBeingWrittenLength == -1
&& retriesForLastBlockLength == 0) {
throw new IOException("Could not obtain the last block locations.");
}
}
}
private void waitFor(int waitTime) throws IOException {
try {
Thread.sleep(waitTime);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new InterruptedIOException(
"Interrupted while getting the last block length.");
}
}
private long fetchLocatedBlocksAndGetLastBlockLength(boolean refresh)
throws IOException {
LocatedBlocks newInfo = locatedBlocks;
if (locatedBlocks == null || refresh) {
newInfo = dfsClient.getLocatedBlocks(src, 0);
}
DFSClient.LOG.debug("newInfo = {}", newInfo);
if (newInfo == null) {
throw new IOException("Cannot open filename " + src);
}
if (locatedBlocks != null) {
Iterator oldIter = locatedBlocks.getLocatedBlocks().iterator();
Iterator newIter = newInfo.getLocatedBlocks().iterator();
while (oldIter.hasNext() && newIter.hasNext()) {
if (!oldIter.next().getBlock().equals(newIter.next().getBlock())) {
throw new IOException("Blocklist for " + src + " has changed!");
}
}
}
locatedBlocks = newInfo;
long lastBlockBeingWrittenLength = 0;
if (!locatedBlocks.isLastBlockComplete()) {
final LocatedBlock last = locatedBlocks.getLastLocatedBlock();
if (last != null) {
if (last.getLocations().length == 0) {
if (last.getBlockSize() == 0) {
// if the length is zero, then no data has been written to
// datanode. So no need to wait for the locations.
return 0;
}
return -1;
}
final long len = readBlockLength(last);
last.getBlock().setNumBytes(len);
lastBlockBeingWrittenLength = len;
}
}
fileEncryptionInfo = locatedBlocks.getFileEncryptionInfo();
return lastBlockBeingWrittenLength;
}
/** Read the block length from one of the datanodes. */
private long readBlockLength(LocatedBlock locatedblock) throws IOException {
assert locatedblock != null : "LocatedBlock cannot be null";
int replicaNotFoundCount = locatedblock.getLocations().length;
final DfsClientConf conf = dfsClient.getConf();
final int timeout = conf.getSocketTimeout();
LinkedList nodeList = new LinkedList(
Arrays.asList(locatedblock.getLocations()));
LinkedList retryList = new LinkedList();
boolean isRetry = false;
StopWatch sw = new StopWatch();
while (nodeList.size() > 0) {
DatanodeInfo datanode = nodeList.pop();
ClientDatanodeProtocol cdp = null;
try {
cdp = DFSUtilClient.createClientDatanodeProtocolProxy(datanode,
dfsClient.getConfiguration(), timeout,
conf.isConnectToDnViaHostname(), locatedblock);
final long n = cdp.getReplicaVisibleLength(locatedblock.getBlock());
if (n >= 0) {
return n;
}
} catch (IOException ioe) {
checkInterrupted(ioe);
if (ioe instanceof RemoteException) {
if (((RemoteException) ioe).unwrapRemoteException() instanceof
ReplicaNotFoundException) {
// replica is not on the DN. We will treat it as 0 length
// if no one actually has a replica.
replicaNotFoundCount--;
} else if (((RemoteException) ioe).unwrapRemoteException() instanceof
RetriableException) {
// add to the list to be retried if necessary.
retryList.add(datanode);
}
}
DFSClient.LOG.debug("Failed to getReplicaVisibleLength from datanode {}"
+ " for block {}", datanode, locatedblock.getBlock(), ioe);
} finally {
if (cdp != null) {
RPC.stopProxy(cdp);
}
}
// Ran out of nodes, but there are retriable nodes.
if (nodeList.size() == 0 && retryList.size() > 0) {
nodeList.addAll(retryList);
retryList.clear();
isRetry = true;
}
if (isRetry) {
// start the stop watch if not already running.
if (!sw.isRunning()) {
sw.start();
}
try {
Thread.sleep(500); // delay between retries.
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new InterruptedIOException(
"Interrupted while getting the length.");
}
}
// see if we ran out of retry time
if (sw.isRunning() && sw.now(TimeUnit.MILLISECONDS) > timeout) {
break;
}
}
// Namenode told us about these locations, but none know about the replica
// means that we hit the race between pipeline creation start and end.
// we require all 3 because some other exception could have happened
// on a DN that has it. we want to report that error
if (replicaNotFoundCount == 0) {
return 0;
}
throw new CannotObtainBlockLengthException(locatedblock);
}
public long getFileLength() {
synchronized(infoLock) {
return locatedBlocks == null? 0:
locatedBlocks.getFileLength() + lastBlockBeingWrittenLength;
}
}
// Short circuit local reads are forbidden for files that are
// under construction. See HDFS-2757.
boolean shortCircuitForbidden() {
synchronized(infoLock) {
return locatedBlocks.isUnderConstruction();
}
}
/**
* Returns the datanode from which the stream is currently reading.
*/
public synchronized DatanodeInfo getCurrentDatanode() {
return currentNode;
}
/**
* Returns the block containing the target position.
*/
synchronized public ExtendedBlock getCurrentBlock() {
if (currentLocatedBlock == null){
return null;
}
return currentLocatedBlock.getBlock();
}
/**
* Return collection of blocks that has already been located.
*/
public List getAllBlocks() throws IOException {
return getBlockRange(0, getFileLength());
}
/**
* Get block at the specified position.
* Fetch it from the namenode if not cached.
*
* @param offset block corresponding to this offset in file is returned
* @return located block
* @throws IOException
*/
protected LocatedBlock getBlockAt(long offset) throws IOException {
synchronized(infoLock) {
assert (locatedBlocks != null) : "locatedBlocks is null";
final LocatedBlock blk;
//check offset
if (offset < 0 || offset >= getFileLength()) {
throw new IOException("offset < 0 || offset >= getFileLength(), offset="
+ offset
+ ", locatedBlocks=" + locatedBlocks);
}
else if (offset >= locatedBlocks.getFileLength()) {
// offset to the portion of the last block,
// which is not known to the name-node yet;
// getting the last block
blk = locatedBlocks.getLastLocatedBlock();
}
else {
// search cached blocks first
blk = fetchBlockAt(offset, 0, true);
}
return blk;
}
}
/** Fetch a block from namenode and cache it */
protected LocatedBlock fetchBlockAt(long offset) throws IOException {
return fetchBlockAt(offset, 0, false); // don't use cache
}
/** Fetch a block from namenode and cache it */
private LocatedBlock fetchBlockAt(long offset, long length, boolean useCache)
throws IOException {
synchronized(infoLock) {
int targetBlockIdx = locatedBlocks.findBlock(offset);
if (targetBlockIdx < 0) { // block is not cached
targetBlockIdx = LocatedBlocks.getInsertIndex(targetBlockIdx);
useCache = false;
}
if (!useCache) { // fetch blocks
final LocatedBlocks newBlocks = (length == 0)
? dfsClient.getLocatedBlocks(src, offset)
: dfsClient.getLocatedBlocks(src, offset, length);
if (newBlocks == null || newBlocks.locatedBlockCount() == 0) {
throw new EOFException("Could not find target position " + offset);
}
locatedBlocks.insertRange(targetBlockIdx, newBlocks.getLocatedBlocks());
}
return locatedBlocks.get(targetBlockIdx);
}
}
/**
* Get blocks in the specified range.
* Fetch them from the namenode if not cached. This function
* will not get a read request beyond the EOF.
* @param offset starting offset in file
* @param length length of data
* @return consequent segment of located blocks
* @throws IOException
*/
private List getBlockRange(long offset,
long length) throws IOException {
// getFileLength(): returns total file length
// locatedBlocks.getFileLength(): returns length of completed blocks
if (offset >= getFileLength()) {
throw new IOException("Offset: " + offset +
" exceeds file length: " + getFileLength());
}
synchronized(infoLock) {
final List blocks;
final long lengthOfCompleteBlk = locatedBlocks.getFileLength();
final boolean readOffsetWithinCompleteBlk = offset < lengthOfCompleteBlk;
final boolean readLengthPastCompleteBlk = offset + length > lengthOfCompleteBlk;
if (readOffsetWithinCompleteBlk) {
//get the blocks of finalized (completed) block range
blocks = getFinalizedBlockRange(offset,
Math.min(length, lengthOfCompleteBlk - offset));
} else {
blocks = new ArrayList<>(1);
}
// get the blocks from incomplete block range
if (readLengthPastCompleteBlk) {
blocks.add(locatedBlocks.getLastLocatedBlock());
}
return blocks;
}
}
/**
* Get blocks in the specified range.
* Includes only the complete blocks.
* Fetch them from the namenode if not cached.
*/
private List getFinalizedBlockRange(
long offset, long length) throws IOException {
synchronized(infoLock) {
assert (locatedBlocks != null) : "locatedBlocks is null";
List blockRange = new ArrayList<>();
// search cached blocks first
long remaining = length;
long curOff = offset;
while(remaining > 0) {
LocatedBlock blk = fetchBlockAt(curOff, remaining, true);
assert curOff >= blk.getStartOffset() : "Block not found";
blockRange.add(blk);
long bytesRead = blk.getStartOffset() + blk.getBlockSize() - curOff;
remaining -= bytesRead;
curOff += bytesRead;
}
return blockRange;
}
}
/**
* Open a DataInputStream to a DataNode so that it can be read from.
* We get block ID and the IDs of the destinations at startup, from the namenode.
*/
private synchronized DatanodeInfo blockSeekTo(long target)
throws IOException {
if (target >= getFileLength()) {
throw new IOException("Attempted to read past end of file");
}
// Will be getting a new BlockReader.
closeCurrentBlockReaders();
//
// Connect to best DataNode for desired Block, with potential offset
//
DatanodeInfo chosenNode;
int refetchToken = 1; // only need to get a new access token once
int refetchEncryptionKey = 1; // only need to get a new encryption key once
boolean connectFailedOnce = false;
while (true) {
//
// Compute desired block
//
LocatedBlock targetBlock = getBlockAt(target);
// update current position
this.pos = target;
this.blockEnd = targetBlock.getStartOffset() +
targetBlock.getBlockSize() - 1;
this.currentLocatedBlock = targetBlock;
long offsetIntoBlock = target - targetBlock.getStartOffset();
DNAddrPair retval = chooseDataNode(targetBlock, null);
chosenNode = retval.info;
InetSocketAddress targetAddr = retval.addr;
StorageType storageType = retval.storageType;
// Latest block if refreshed by chooseDatanode()
targetBlock = retval.block;
try {
blockReader = getBlockReader(targetBlock, offsetIntoBlock,
targetBlock.getBlockSize() - offsetIntoBlock, targetAddr,
storageType, chosenNode);
if(connectFailedOnce) {
DFSClient.LOG.info("Successfully connected to " + targetAddr +
" for " + targetBlock.getBlock());
}
return chosenNode;
} catch (IOException ex) {
checkInterrupted(ex);
if (ex instanceof InvalidEncryptionKeyException && refetchEncryptionKey > 0) {
DFSClient.LOG.info("Will fetch a new encryption key and retry, "
+ "encryption key was invalid when connecting to " + targetAddr
+ " : " + ex);
// The encryption key used is invalid.
refetchEncryptionKey--;
dfsClient.clearDataEncryptionKey();
} else if (refetchToken > 0 && tokenRefetchNeeded(ex, targetAddr)) {
refetchToken--;
fetchBlockAt(target);
} else {
connectFailedOnce = true;
DFSClient.LOG.warn("Failed to connect to {} for file {} for block "
+ "{}, add to deadNodes and continue. ", targetAddr, src,
targetBlock.getBlock(), ex);
// Put chosen node into dead list, continue
addToDeadNodes(chosenNode);
}
}
}
}
private void checkInterrupted(IOException e) throws IOException {
if (Thread.currentThread().isInterrupted() &&
(e instanceof ClosedByInterruptException ||
e instanceof InterruptedIOException)) {
DFSClient.LOG.debug("The reading thread has been interrupted.", e);
throw e;
}
}
protected BlockReader getBlockReader(LocatedBlock targetBlock,
long offsetInBlock, long length, InetSocketAddress targetAddr,
StorageType storageType, DatanodeInfo datanode) throws IOException {
ExtendedBlock blk = targetBlock.getBlock();
Token accessToken = targetBlock.getBlockToken();
CachingStrategy curCachingStrategy;
boolean shortCircuitForbidden;
synchronized (infoLock) {
curCachingStrategy = cachingStrategy;
shortCircuitForbidden = shortCircuitForbidden();
}
return new BlockReaderFactory(dfsClient.getConf()).
setInetSocketAddress(targetAddr).
setRemotePeerFactory(dfsClient).
setDatanodeInfo(datanode).
setStorageType(storageType).
setFileName(src).
setBlock(blk).
setBlockToken(accessToken).
setStartOffset(offsetInBlock).
setVerifyChecksum(verifyChecksum).
setClientName(dfsClient.clientName).
setLength(length).
setCachingStrategy(curCachingStrategy).
setAllowShortCircuitLocalReads(!shortCircuitForbidden).
setClientCacheContext(dfsClient.getClientContext()).
setUserGroupInformation(dfsClient.ugi).
setConfiguration(dfsClient.getConfiguration()).
build();
}
/**
* Close it down!
*/
@Override
public synchronized void close() throws IOException {
if (!closed.compareAndSet(false, true)) {
DFSClient.LOG.debug("DFSInputStream has been closed already");
return;
}
dfsClient.checkOpen();
if ((extendedReadBuffers != null) && (!extendedReadBuffers.isEmpty())) {
final StringBuilder builder = new StringBuilder();
extendedReadBuffers.visitAll(new IdentityHashStore.Visitor() {
private String prefix = "";
@Override
public void accept(ByteBuffer k, Object v) {
builder.append(prefix).append(k);
prefix = ", ";
}
});
DFSClient.LOG.warn("closing file " + src + ", but there are still " +
"unreleased ByteBuffers allocated by read(). " +
"Please release " + builder.toString() + ".");
}
closeCurrentBlockReaders();
super.close();
}
@Override
public synchronized int read() throws IOException {
if (oneByteBuf == null) {
oneByteBuf = new byte[1];
}
int ret = read(oneByteBuf, 0, 1);
return (ret <= 0) ? -1 : (oneByteBuf[0] & 0xff);
}
/* This is a used by regular read() and handles ChecksumExceptions.
* name readBuffer() is chosen to imply similarity to readBuffer() in
* ChecksumFileSystem
*/
private synchronized int readBuffer(ReaderStrategy reader, int len,
CorruptedBlocks corruptedBlocks)
throws IOException {
IOException ioe;
/* we retry current node only once. So this is set to true only here.
* Intention is to handle one common case of an error that is not a
* failure on datanode or client : when DataNode closes the connection
* since client is idle. If there are other cases of "non-errors" then
* then a datanode might be retried by setting this to true again.
*/
boolean retryCurrentNode = true;
while (true) {
// retry as many times as seekToNewSource allows.
try {
return reader.readFromBlock(blockReader, len);
} catch (ChecksumException ce) {
DFSClient.LOG.warn("Found Checksum error for "
+ getCurrentBlock() + " from " + currentNode
+ " at " + ce.getPos());
ioe = ce;
retryCurrentNode = false;
// we want to remember which block replicas we have tried
corruptedBlocks.addCorruptedBlock(getCurrentBlock(), currentNode);
} catch (IOException e) {
if (!retryCurrentNode) {
DFSClient.LOG.warn("Exception while reading from "
+ getCurrentBlock() + " of " + src + " from "
+ currentNode, e);
}
ioe = e;
}
boolean sourceFound;
if (retryCurrentNode) {
/* possibly retry the same node so that transient errors don't
* result in application level failures (e.g. Datanode could have
* closed the connection because the client is idle for too long).
*/
sourceFound = seekToBlockSource(pos);
} else {
addToDeadNodes(currentNode);
sourceFound = seekToNewSource(pos);
}
if (!sourceFound) {
throw ioe;
}
retryCurrentNode = false;
}
}
protected synchronized int readWithStrategy(ReaderStrategy strategy)
throws IOException {
dfsClient.checkOpen();
if (closed.get()) {
throw new IOException("Stream closed");
}
int len = strategy.getTargetLength();
CorruptedBlocks corruptedBlocks = new CorruptedBlocks();
failures = 0;
if (pos < getFileLength()) {
int retries = 2;
while (retries > 0) {
try {
// currentNode can be left as null if previous read had a checksum
// error on the same block. See HDFS-3067
if (pos > blockEnd || currentNode == null) {
currentNode = blockSeekTo(pos);
}
int realLen = (int) Math.min(len, (blockEnd - pos + 1L));
synchronized(infoLock) {
if (locatedBlocks.isLastBlockComplete()) {
realLen = (int) Math.min(realLen,
locatedBlocks.getFileLength() - pos);
}
}
int result = readBuffer(strategy, realLen, corruptedBlocks);
if (result >= 0) {
pos += result;
} else {
// got a EOS from reader though we expect more data on it.
throw new IOException("Unexpected EOS from the reader");
}
updateReadStatistics(readStatistics, result, blockReader);
dfsClient.updateFileSystemReadStats(blockReader.getNetworkDistance(),
result);
if (readStatistics.getBlockType() == BlockType.STRIPED) {
dfsClient.updateFileSystemECReadStats(result);
}
return result;
} catch (ChecksumException ce) {
throw ce;
} catch (IOException e) {
checkInterrupted(e);
if (retries == 1) {
DFSClient.LOG.warn("DFS Read", e);
}
blockEnd = -1;
if (currentNode != null) {
addToDeadNodes(currentNode);
}
if (--retries == 0) {
throw e;
}
} finally {
// Check if need to report block replicas corruption either read
// was successful or ChecksumException occurred.
reportCheckSumFailure(corruptedBlocks,
getCurrentBlockLocationsLength(), false);
}
}
}
return -1;
}
protected int getCurrentBlockLocationsLength() {
int len = 0;
if (currentLocatedBlock == null) {
DFSClient.LOG.info("Found null currentLocatedBlock. pos={}, "
+ "blockEnd={}, fileLength={}", pos, blockEnd, getFileLength());
} else {
len = currentLocatedBlock.getLocations().length;
}
return len;
}
/**
* Read the entire buffer.
*/
@Override
public synchronized int read(@Nonnull final byte buf[], int off, int len)
throws IOException {
validatePositionedReadArgs(pos, buf, off, len);
if (len == 0) {
return 0;
}
ReaderStrategy byteArrayReader =
new ByteArrayStrategy(buf, off, len, readStatistics, dfsClient);
return readWithStrategy(byteArrayReader);
}
@Override
public synchronized int read(final ByteBuffer buf) throws IOException {
ReaderStrategy byteBufferReader =
new ByteBufferStrategy(buf, readStatistics, dfsClient);
return readWithStrategy(byteBufferReader);
}
private DNAddrPair chooseDataNode(LocatedBlock block,
Collection ignoredNodes) throws IOException {
return chooseDataNode(block, ignoredNodes, true);
}
/**
* Choose datanode to read from.
*
* @param block Block to choose datanode addr from
* @param ignoredNodes Ignored nodes inside.
* @param refetchIfRequired Whether to refetch if no nodes to chose
* from.
* @return Returns chosen DNAddrPair; Can be null if refetchIfRequired is
* false.
*/
private DNAddrPair chooseDataNode(LocatedBlock block,
Collection ignoredNodes, boolean refetchIfRequired)
throws IOException {
while (true) {
DNAddrPair result = getBestNodeDNAddrPair(block, ignoredNodes);
if (result != null) {
return result;
} else if (refetchIfRequired) {
block = refetchLocations(block, ignoredNodes);
} else {
return null;
}
}
}
private LocatedBlock refetchLocations(LocatedBlock block,
Collection ignoredNodes) throws IOException {
String errMsg = getBestNodeDNAddrPairErrorString(block.getLocations(),
deadNodes, ignoredNodes);
String blockInfo = block.getBlock() + " file=" + src;
if (failures >= dfsClient.getConf().getMaxBlockAcquireFailures()) {
String description = "Could not obtain block: " + blockInfo;
DFSClient.LOG.warn(description + errMsg
+ ". Throwing a BlockMissingException");
throw new BlockMissingException(src, description,
block.getStartOffset());
}
DatanodeInfo[] nodes = block.getLocations();
if (nodes == null || nodes.length == 0) {
DFSClient.LOG.info("No node available for " + blockInfo);
}
DFSClient.LOG.info("Could not obtain " + block.getBlock()
+ " from any node: " + errMsg
+ ". Will get new block locations from namenode and retry...");
try {
// Introducing a random factor to the wait time before another retry.
// The wait time is dependent on # of failures and a random factor.
// At the first time of getting a BlockMissingException, the wait time
// is a random number between 0..3000 ms. If the first retry
// still fails, we will wait 3000 ms grace period before the 2nd retry.
// Also at the second retry, the waiting window is expanded to 6000 ms
// alleviating the request rate from the server. Similarly the 3rd retry
// will wait 6000ms grace period before retry and the waiting window is
// expanded to 9000ms.
final int timeWindow = dfsClient.getConf().getTimeWindow();
// grace period for the last round of attempt
double waitTime = timeWindow * failures +
// expanding time window for each failure
timeWindow * (failures + 1) *
ThreadLocalRandom.current().nextDouble();
DFSClient.LOG.warn("DFS chooseDataNode: got # " + (failures + 1) +
" IOException, will wait for " + waitTime + " msec.");
Thread.sleep((long)waitTime);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new InterruptedIOException(
"Interrupted while choosing DataNode for read.");
}
deadNodes.clear(); //2nd option is to remove only nodes[blockId]
openInfo(true);
block = refreshLocatedBlock(block);
failures++;
return block;
}
/**
* Get the best node from which to stream the data.
* @param block LocatedBlock, containing nodes in priority order.
* @param ignoredNodes Do not choose nodes in this array (may be null)
* @return The DNAddrPair of the best node. Null if no node can be chosen.
*/
protected DNAddrPair getBestNodeDNAddrPair(LocatedBlock block,
Collection ignoredNodes) {
DatanodeInfo[] nodes = block.getLocations();
StorageType[] storageTypes = block.getStorageTypes();
DatanodeInfo chosenNode = null;
StorageType storageType = null;
if (nodes != null) {
for (int i = 0; i < nodes.length; i++) {
if (!deadNodes.containsKey(nodes[i])
&& (ignoredNodes == null || !ignoredNodes.contains(nodes[i]))) {
chosenNode = nodes[i];
// Storage types are ordered to correspond with nodes, so use the same
// index to get storage type.
if (storageTypes != null && i < storageTypes.length) {
storageType = storageTypes[i];
}
break;
}
}
}
if (chosenNode == null) {
reportLostBlock(block, ignoredNodes);
return null;
}
final String dnAddr =
chosenNode.getXferAddr(dfsClient.getConf().isConnectToDnViaHostname());
DFSClient.LOG.debug("Connecting to datanode {}", dnAddr);
InetSocketAddress targetAddr = NetUtils.createSocketAddr(dnAddr);
return new DNAddrPair(chosenNode, targetAddr, storageType, block);
}
/**
* Warn the user of a lost block
*/
protected void reportLostBlock(LocatedBlock lostBlock,
Collection ignoredNodes) {
DatanodeInfo[] nodes = lostBlock.getLocations();
DFSClient.LOG.warn("No live nodes contain block " + lostBlock.getBlock() +
" after checking nodes = " + Arrays.toString(nodes) +
", ignoredNodes = " + ignoredNodes);
}
private static String getBestNodeDNAddrPairErrorString(
DatanodeInfo nodes[], AbstractMap deadNodes, Collection ignoredNodes) {
StringBuilder errMsgr = new StringBuilder(
" No live nodes contain current block ");
errMsgr.append("Block locations:");
for (DatanodeInfo datanode : nodes) {
errMsgr.append(" ");
errMsgr.append(datanode.toString());
}
errMsgr.append(" Dead nodes: ");
for (DatanodeInfo datanode : deadNodes.keySet()) {
errMsgr.append(" ");
errMsgr.append(datanode.toString());
}
if (ignoredNodes != null) {
errMsgr.append(" Ignored nodes: ");
for (DatanodeInfo datanode : ignoredNodes) {
errMsgr.append(" ");
errMsgr.append(datanode.toString());
}
}
return errMsgr.toString();
}
protected void fetchBlockByteRange(LocatedBlock block, long start, long end,
ByteBuffer buf, CorruptedBlocks corruptedBlocks)
throws IOException {
while (true) {
DNAddrPair addressPair = chooseDataNode(block, null);
// Latest block, if refreshed internally
block = addressPair.block;
try {
actualGetFromOneDataNode(addressPair, start, end, buf,
corruptedBlocks);
return;
} catch (IOException e) {
checkInterrupted(e); // check if the read has been interrupted
// Ignore other IOException. Already processed inside the function.
// Loop through to try the next node.
}
}
}
private Callable getFromOneDataNode(final DNAddrPair datanode,
final LocatedBlock block, final long start, final long end,
final ByteBuffer bb,
final CorruptedBlocks corruptedBlocks,
final int hedgedReadId) {
return new Callable() {
@Override
public ByteBuffer call() throws Exception {
DFSClientFaultInjector.get().sleepBeforeHedgedGet();
actualGetFromOneDataNode(datanode, start, end, bb, corruptedBlocks);
return bb;
}
};
}
/**
* Read data from one DataNode.
*
* @param datanode the datanode from which to read data
* @param startInBlk the startInBlk offset of the block
* @param endInBlk the endInBlk offset of the block
* @param buf the given byte buffer into which the data is read
* @param corruptedBlocks map recording list of datanodes with corrupted
* block replica
*/
void actualGetFromOneDataNode(final DNAddrPair datanode, final long startInBlk,
final long endInBlk, ByteBuffer buf, CorruptedBlocks corruptedBlocks)
throws IOException {
DFSClientFaultInjector.get().startFetchFromDatanode();
int refetchToken = 1; // only need to get a new access token once
int refetchEncryptionKey = 1; // only need to get a new encryption key once
final int len = (int) (endInBlk - startInBlk + 1);
LocatedBlock block = datanode.block;
while (true) {
BlockReader reader = null;
try {
DFSClientFaultInjector.get().fetchFromDatanodeException();
reader = getBlockReader(block, startInBlk, len, datanode.addr,
datanode.storageType, datanode.info);
//Behave exactly as the readAll() call
ByteBuffer tmp = buf.duplicate();
tmp.limit(tmp.position() + len);
tmp = tmp.slice();
int nread = 0;
int ret;
while (true) {
ret = reader.read(tmp);
if (ret <= 0) {
break;
}
nread += ret;
}
buf.position(buf.position() + nread);
IOUtilsClient.updateReadStatistics(readStatistics, nread, reader);
dfsClient.updateFileSystemReadStats(
reader.getNetworkDistance(), nread);
if (readStatistics.getBlockType() == BlockType.STRIPED) {
dfsClient.updateFileSystemECReadStats(nread);
}
if (nread != len) {
throw new IOException("truncated return from reader.read(): " +
"excpected " + len + ", got " + nread);
}
DFSClientFaultInjector.get().readFromDatanodeDelay();
return;
} catch (ChecksumException e) {
String msg = "fetchBlockByteRange(). Got a checksum exception for "
+ src + " at " + block.getBlock() + ":" + e.getPos() + " from "
+ datanode.info;
DFSClient.LOG.warn(msg);
// we want to remember what we have tried
corruptedBlocks.addCorruptedBlock(block.getBlock(), datanode.info);
addToDeadNodes(datanode.info);
throw new IOException(msg);
} catch (IOException e) {
checkInterrupted(e);
if (e instanceof InvalidEncryptionKeyException && refetchEncryptionKey > 0) {
DFSClient.LOG.info("Will fetch a new encryption key and retry, "
+ "encryption key was invalid when connecting to " + datanode.addr
+ " : " + e);
// The encryption key used is invalid.
refetchEncryptionKey--;
dfsClient.clearDataEncryptionKey();
} else if (refetchToken > 0 && tokenRefetchNeeded(e, datanode.addr)) {
refetchToken--;
try {
fetchBlockAt(block.getStartOffset());
} catch (IOException fbae) {
// ignore IOE, since we can retry it later in a loop
}
} else {
String msg = "Failed to connect to " + datanode.addr + " for file "
+ src + " for block " + block.getBlock() + ":" + e;
DFSClient.LOG.warn("Connection failure: " + msg, e);
addToDeadNodes(datanode.info);
throw new IOException(msg);
}
// Refresh the block for updated tokens in case of token failures or
// encryption key failures.
block = refreshLocatedBlock(block);
} finally {
if (reader != null) {
reader.close();
}
}
}
}
/**
* Refresh cached block locations.
* @param block The currently cached block locations
* @return Refreshed block locations
* @throws IOException
*/
protected LocatedBlock refreshLocatedBlock(LocatedBlock block)
throws IOException {
return getBlockAt(block.getStartOffset());
}
/**
* Like {@link #fetchBlockByteRange}except we start up a second, parallel,
* 'hedged' read if the first read is taking longer than configured amount of
* time. We then wait on which ever read returns first.
*/
private void hedgedFetchBlockByteRange(LocatedBlock block, long start,
long end, ByteBuffer buf, CorruptedBlocks corruptedBlocks)
throws IOException {
final DfsClientConf conf = dfsClient.getConf();
ArrayList> futures = new ArrayList<>();
CompletionService hedgedService =
new ExecutorCompletionService<>(dfsClient.getHedgedReadsThreadPool());
ArrayList ignored = new ArrayList<>();
ByteBuffer bb;
int len = (int) (end - start + 1);
int hedgedReadId = 0;
while (true) {
// see HDFS-6591, this metric is used to verify/catch unnecessary loops
hedgedReadOpsLoopNumForTesting++;
DNAddrPair chosenNode = null;
// there is no request already executing.
if (futures.isEmpty()) {
// chooseDataNode is a commitment. If no node, we go to
// the NN to reget block locations. Only go here on first read.
chosenNode = chooseDataNode(block, ignored);
// Latest block, if refreshed internally
block = chosenNode.block;
bb = ByteBuffer.allocate(len);
Callable getFromDataNodeCallable = getFromOneDataNode(
chosenNode, block, start, end, bb,
corruptedBlocks, hedgedReadId++);
Future firstRequest = hedgedService
.submit(getFromDataNodeCallable);
futures.add(firstRequest);
Future future = null;
try {
future = hedgedService.poll(
conf.getHedgedReadThresholdMillis(), TimeUnit.MILLISECONDS);
if (future != null) {
ByteBuffer result = future.get();
result.flip();
buf.put(result);
return;
}
DFSClient.LOG.debug("Waited {}ms to read from {}; spawning hedged "
+ "read", conf.getHedgedReadThresholdMillis(), chosenNode.info);
dfsClient.getHedgedReadMetrics().incHedgedReadOps();
// continue; no need to refresh block locations
} catch (ExecutionException e) {
futures.remove(future);
} catch (InterruptedException e) {
throw new InterruptedIOException(
"Interrupted while waiting for reading task");
}
// Ignore this node on next go around.
// If poll timeout and the request still ongoing, don't consider it
// again. If read data failed, don't consider it either.
ignored.add(chosenNode.info);
} else {
// We are starting up a 'hedged' read. We have a read already
// ongoing. Call getBestNodeDNAddrPair instead of chooseDataNode.
// If no nodes to do hedged reads against, pass.
boolean refetch = false;
try {
chosenNode = chooseDataNode(block, ignored, false);
if (chosenNode != null) {
// Latest block, if refreshed internally
block = chosenNode.block;
bb = ByteBuffer.allocate(len);
Callable getFromDataNodeCallable =
getFromOneDataNode(chosenNode, block, start, end, bb,
corruptedBlocks, hedgedReadId++);
Future oneMoreRequest =
hedgedService.submit(getFromDataNodeCallable);
futures.add(oneMoreRequest);
} else {
refetch = true;
}
} catch (IOException ioe) {
DFSClient.LOG.debug("Failed getting node for hedged read: {}",
ioe.getMessage());
}
// if not succeeded. Submit callables for each datanode in a loop, wait
// for a fixed interval and get the result from the fastest one.
try {
ByteBuffer result = getFirstToComplete(hedgedService, futures);
// cancel the rest.
cancelAll(futures);
dfsClient.getHedgedReadMetrics().incHedgedReadWins();
result.flip();
buf.put(result);
return;
} catch (InterruptedException ie) {
// Ignore and retry
}
if (refetch) {
refetchLocations(block, ignored);
}
// We got here if exception. Ignore this node on next go around IFF
// we found a chosenNode to hedge read against.
if (chosenNode != null && chosenNode.info != null) {
ignored.add(chosenNode.info);
}
}
}
}
@VisibleForTesting
public long getHedgedReadOpsLoopNumForTesting() {
return hedgedReadOpsLoopNumForTesting;
}
private ByteBuffer getFirstToComplete(
CompletionService hedgedService,
ArrayList> futures) throws InterruptedException {
if (futures.isEmpty()) {
throw new InterruptedException("let's retry");
}
Future future = null;
try {
future = hedgedService.take();
ByteBuffer bb = future.get();
futures.remove(future);
return bb;
} catch (ExecutionException | CancellationException e) {
// already logged in the Callable
futures.remove(future);
}
throw new InterruptedException("let's retry");
}
private void cancelAll(List> futures) {
for (Future future : futures) {
// Unfortunately, hdfs reads do not take kindly to interruption.
// Threads return a variety of interrupted-type exceptions but
// also complaints about invalid pbs -- likely because read
// is interrupted before gets whole pb. Also verbose WARN
// logging. So, for now, do not interrupt running read.
future.cancel(false);
}
}
/**
* Should the block access token be refetched on an exception
*
* @param ex Exception received
* @param targetAddr Target datanode address from where exception was received
* @return true if block access token has expired or invalid and it should be
* refetched
*/
protected static boolean tokenRefetchNeeded(IOException ex,
InetSocketAddress targetAddr) {
/*
* Get a new access token and retry. Retry is needed in 2 cases. 1)
* When both NN and DN re-started while DFSClient holding a cached
* access token. 2) In the case that NN fails to update its
* access key at pre-set interval (by a wide margin) and
* subsequently restarts. In this case, DN re-registers itself with
* NN and receives a new access key, but DN will delete the old
* access key from its memory since it's considered expired based on
* the estimated expiration date.
*/
if (ex instanceof InvalidBlockTokenException ||
ex instanceof InvalidToken) {
DFSClient.LOG.debug(
"Access token was invalid when connecting to {}: {}",
targetAddr, ex);
return true;
}
return false;
}
/**
* Read bytes starting from the specified position.
*
* @param position start read from this position
* @param buffer read buffer
* @param offset offset into buffer
* @param length number of bytes to read
*
* @return actual number of bytes read
*/
@Override
public int read(long position, byte[] buffer, int offset, int length)
throws IOException {
validatePositionedReadArgs(position, buffer, offset, length);
if (length == 0) {
return 0;
}
ByteBuffer bb = ByteBuffer.wrap(buffer, offset, length);
return pread(position, bb);
}
private int pread(long position, ByteBuffer buffer)
throws IOException {
// sanity checks
dfsClient.checkOpen();
if (closed.get()) {
throw new IOException("Stream closed");
}
failures = 0;
long filelen = getFileLength();
if ((position < 0) || (position >= filelen)) {
return -1;
}
int length = buffer.remaining();
int realLen = length;
if ((position + length) > filelen) {
realLen = (int)(filelen - position);
}
// determine the block and byte range within the block
// corresponding to position and realLen
List blockRange = getBlockRange(position, realLen);
int remaining = realLen;
CorruptedBlocks corruptedBlocks = new CorruptedBlocks();
for (LocatedBlock blk : blockRange) {
long targetStart = position - blk.getStartOffset();
int bytesToRead = (int) Math.min(remaining,
blk.getBlockSize() - targetStart);
long targetEnd = targetStart + bytesToRead - 1;
try {
if (dfsClient.isHedgedReadsEnabled() && !blk.isStriped()) {
hedgedFetchBlockByteRange(blk, targetStart,
targetEnd, buffer, corruptedBlocks);
} else {
fetchBlockByteRange(blk, targetStart, targetEnd,
buffer, corruptedBlocks);
}
} finally {
// Check and report if any block replicas are corrupted.
// BlockMissingException may be caught if all block replicas are
// corrupted.
reportCheckSumFailure(corruptedBlocks, blk.getLocations().length,
false);
}
remaining -= bytesToRead;
position += bytesToRead;
}
assert remaining == 0 : "Wrong number of bytes read.";
return realLen;
}
/**
* DFSInputStream reports checksum failure.
* For replicated blocks, we have the following logic:
* Case I : client has tried multiple data nodes and at least one of the
* attempts has succeeded. We report the other failures as corrupted block to
* namenode.
* Case II: client has tried out all data nodes, but all failed. We
* only report if the total number of replica is 1. We do not
* report otherwise since this maybe due to the client is a handicapped client
* (who can not read).
*
* For erasure-coded blocks, each block in corruptedBlockMap is an internal
* block in a block group, and there is usually only one DataNode
* corresponding to each internal block. For this case we simply report the
* corrupted blocks to NameNode and ignore the above logic.
*
* @param corruptedBlocks map of corrupted blocks
* @param dataNodeCount number of data nodes who contains the block replicas
*/
protected void reportCheckSumFailure(CorruptedBlocks corruptedBlocks,
int dataNodeCount, boolean isStriped) {
Map> corruptedBlockMap =
corruptedBlocks.getCorruptionMap();
if (corruptedBlockMap == null) {
return;
}
List reportList = new ArrayList<>(corruptedBlockMap.size());
for (Map.Entry> entry :
corruptedBlockMap.entrySet()) {
ExtendedBlock blk = entry.getKey();
Set dnSet = entry.getValue();
if (isStriped || ((dnSet.size() < dataNodeCount) && (dnSet.size() > 0))
|| ((dataNodeCount == 1) && (dnSet.size() == dataNodeCount))) {
DatanodeInfo[] locs = new DatanodeInfo[dnSet.size()];
int i = 0;
for (DatanodeInfo dn:dnSet) {
locs[i++] = dn;
}
reportList.add(new LocatedBlock(blk, locs));
}
}
if (reportList.size() > 0) {
dfsClient.reportChecksumFailure(src,
reportList.toArray(new LocatedBlock[reportList.size()]));
}
corruptedBlockMap.clear();
}
@Override
public long skip(long n) throws IOException {
if (n > 0) {
long curPos = getPos();
long fileLen = getFileLength();
if (n+curPos > fileLen) {
n = fileLen - curPos;
}
seek(curPos+n);
return n;
}
return n < 0 ? -1 : 0;
}
/**
* Seek to a new arbitrary location
*/
@Override
public synchronized void seek(long targetPos) throws IOException {
if (targetPos > getFileLength()) {
throw new EOFException("Cannot seek after EOF");
}
if (targetPos < 0) {
throw new EOFException("Cannot seek to negative offset");
}
if (closed.get()) {
throw new IOException("Stream is closed!");
}
boolean done = false;
if (pos <= targetPos && targetPos <= blockEnd) {
//
// If this seek is to a positive position in the current
// block, and this piece of data might already be lying in
// the TCP buffer, then just eat up the intervening data.
//
int diff = (int)(targetPos - pos);
if (diff <= blockReader.available()) {
try {
pos += blockReader.skip(diff);
if (pos == targetPos) {
done = true;
} else {
// The range was already checked. If the block reader returns
// something unexpected instead of throwing an exception, it is
// most likely a bug.
String errMsg = "BlockReader failed to seek to " +
targetPos + ". Instead, it seeked to " + pos + ".";
DFSClient.LOG.warn(errMsg);
throw new IOException(errMsg);
}
} catch (IOException e) {//make following read to retry
DFSClient.LOG.debug("Exception while seek to {} from {} of {} from "
+ "{}", targetPos, getCurrentBlock(), src, currentNode, e);
checkInterrupted(e);
}
}
}
if (!done) {
pos = targetPos;
blockEnd = -1;
}
}
/**
* Same as {@link #seekToNewSource(long)} except that it does not exclude
* the current datanode and might connect to the same node.
*/
private boolean seekToBlockSource(long targetPos)
throws IOException {
currentNode = blockSeekTo(targetPos);
return true;
}
/**
* Seek to given position on a node other than the current node. If
* a node other than the current node is found, then returns true.
* If another node could not be found, then returns false.
*/
@Override
public synchronized boolean seekToNewSource(long targetPos)
throws IOException {
if (currentNode == null) {
return seekToBlockSource(targetPos);
}
boolean markedDead = deadNodes.containsKey(currentNode);
addToDeadNodes(currentNode);
DatanodeInfo oldNode = currentNode;
DatanodeInfo newNode = blockSeekTo(targetPos);
if (!markedDead) {
/* remove it from deadNodes. blockSeekTo could have cleared
* deadNodes and added currentNode again. Thats ok. */
deadNodes.remove(oldNode);
}
if (!oldNode.getDatanodeUuid().equals(newNode.getDatanodeUuid())) {
currentNode = newNode;
return true;
} else {
return false;
}
}
/**
*/
@Override
public synchronized long getPos() {
return pos;
}
/** Return the size of the remaining available bytes
* if the size is less than or equal to {@link Integer#MAX_VALUE},
* otherwise, return {@link Integer#MAX_VALUE}.
*/
@Override
public synchronized int available() throws IOException {
if (closed.get()) {
throw new IOException("Stream closed");
}
final long remaining = getFileLength() - pos;
return remaining <= Integer.MAX_VALUE? (int)remaining: Integer.MAX_VALUE;
}
/**
* We definitely don't support marks
*/
@Override
public boolean markSupported() {
return false;
}
@Override
public void mark(int readLimit) {
}
@Override
public void reset() throws IOException {
throw new IOException("Mark/reset not supported");
}
/** Utility class to encapsulate data node info and its address. */
static final class DNAddrPair {
final DatanodeInfo info;
final InetSocketAddress addr;
final StorageType storageType;
final LocatedBlock block;
DNAddrPair(DatanodeInfo info, InetSocketAddress addr,
StorageType storageType, LocatedBlock block) {
this.info = info;
this.addr = addr;
this.storageType = storageType;
this.block = block;
}
}
/**
* Get statistics about the reads which this DFSInputStream has done.
*/
public ReadStatistics getReadStatistics() {
return readStatistics;
}
/**
* Clear statistics about the reads which this DFSInputStream has done.
*/
public void clearReadStatistics() {
readStatistics.clear();
}
public FileEncryptionInfo getFileEncryptionInfo() {
synchronized(infoLock) {
return fileEncryptionInfo;
}
}
protected void closeCurrentBlockReaders() {
if (blockReader == null) return;
// Close the current block reader so that the new caching settings can
// take effect immediately.
try {
blockReader.close();
} catch (IOException e) {
DFSClient.LOG.error("error closing blockReader", e);
}
blockReader = null;
blockEnd = -1;
}
@Override
public synchronized void setReadahead(Long readahead)
throws IOException {
synchronized (infoLock) {
this.cachingStrategy =
new CachingStrategy.Builder(this.cachingStrategy).
setReadahead(readahead).build();
}
closeCurrentBlockReaders();
}
@Override
public synchronized void setDropBehind(Boolean dropBehind)
throws IOException {
synchronized (infoLock) {
this.cachingStrategy =
new CachingStrategy.Builder(this.cachingStrategy).
setDropBehind(dropBehind).build();
}
closeCurrentBlockReaders();
}
/**
* The immutable empty buffer we return when we reach EOF when doing a
* zero-copy read.
*/
private static final ByteBuffer EMPTY_BUFFER =
ByteBuffer.allocateDirect(0).asReadOnlyBuffer();
@Override
public synchronized ByteBuffer read(ByteBufferPool bufferPool,
int maxLength, EnumSet opts)
throws IOException, UnsupportedOperationException {
if (maxLength == 0) {
return EMPTY_BUFFER;
} else if (maxLength < 0) {
throw new IllegalArgumentException("can't read a negative " +
"number of bytes.");
}
if ((blockReader == null) || (blockEnd == -1)) {
if (pos >= getFileLength()) {
return null;
}
/*
* If we don't have a blockReader, or the one we have has no more bytes
* left to read, we call seekToBlockSource to get a new blockReader and
* recalculate blockEnd. Note that we assume we're not at EOF here
* (we check this above).
*/
if ((!seekToBlockSource(pos)) || (blockReader == null)) {
throw new IOException("failed to allocate new BlockReader " +
"at position " + pos);
}
}
ByteBuffer buffer = null;
if (dfsClient.getConf().getShortCircuitConf().isShortCircuitMmapEnabled()) {
buffer = tryReadZeroCopy(maxLength, opts);
}
if (buffer != null) {
return buffer;
}
buffer = ByteBufferUtil.fallbackRead(this, bufferPool, maxLength);
if (buffer != null) {
getExtendedReadBuffers().put(buffer, bufferPool);
}
return buffer;
}
private synchronized ByteBuffer tryReadZeroCopy(int maxLength,
EnumSet opts) throws IOException {
// Copy 'pos' and 'blockEnd' to local variables to make it easier for the
// JVM to optimize this function.
final long curPos = pos;
final long curEnd = blockEnd;
final long blockStartInFile = currentLocatedBlock.getStartOffset();
final long blockPos = curPos - blockStartInFile;
// Shorten this read if the end of the block is nearby.
long length63;
if ((curPos + maxLength) <= (curEnd + 1)) {
length63 = maxLength;
} else {
length63 = 1 + curEnd - curPos;
if (length63 <= 0) {
DFSClient.LOG.debug("Unable to perform a zero-copy read from offset {}"
+ " of {}; {} bytes left in block. blockPos={}; curPos={};"
+ "curEnd={}",
curPos, src, length63, blockPos, curPos, curEnd);
return null;
}
DFSClient.LOG.debug("Reducing read length from {} to {} to avoid going "
+ "more than one byte past the end of the block. blockPos={}; "
+" curPos={}; curEnd={}",
maxLength, length63, blockPos, curPos, curEnd);
}
// Make sure that don't go beyond 31-bit offsets in the MappedByteBuffer.
int length;
if (blockPos + length63 <= Integer.MAX_VALUE) {
length = (int)length63;
} else {
long length31 = Integer.MAX_VALUE - blockPos;
if (length31 <= 0) {
// Java ByteBuffers can't be longer than 2 GB, because they use
// 4-byte signed integers to represent capacity, etc.
// So we can't mmap the parts of the block higher than the 2 GB offset.
// FIXME: we could work around this with multiple memory maps.
// See HDFS-5101.
DFSClient.LOG.debug("Unable to perform a zero-copy read from offset {} "
+ " of {}; 31-bit MappedByteBuffer limit exceeded. blockPos={}, "
+ "curEnd={}", curPos, src, blockPos, curEnd);
return null;
}
length = (int)length31;
DFSClient.LOG.debug("Reducing read length from {} to {} to avoid 31-bit "
+ "limit. blockPos={}; curPos={}; curEnd={}",
maxLength, length, blockPos, curPos, curEnd);
}
final ClientMmap clientMmap = blockReader.getClientMmap(opts);
if (clientMmap == null) {
DFSClient.LOG.debug("unable to perform a zero-copy read from offset {} of"
+ " {}; BlockReader#getClientMmap returned null.", curPos, src);
return null;
}
boolean success = false;
ByteBuffer buffer;
try {
seek(curPos + length);
buffer = clientMmap.getMappedByteBuffer().asReadOnlyBuffer();
buffer.position((int)blockPos);
buffer.limit((int)(blockPos + length));
getExtendedReadBuffers().put(buffer, clientMmap);
readStatistics.addZeroCopyBytes(length);
DFSClient.LOG.debug("readZeroCopy read {} bytes from offset {} via the "
+ "zero-copy read path. blockEnd = {}", length, curPos, blockEnd);
success = true;
} finally {
if (!success) {
IOUtils.closeQuietly(clientMmap);
}
}
return buffer;
}
@Override
public synchronized void releaseBuffer(ByteBuffer buffer) {
if (buffer == EMPTY_BUFFER) return;
Object val = getExtendedReadBuffers().remove(buffer);
if (val == null) {
throw new IllegalArgumentException("tried to release a buffer " +
"that was not created by this stream, " + buffer);
}
if (val instanceof ClientMmap) {
IOUtils.closeQuietly((ClientMmap)val);
} else if (val instanceof ByteBufferPool) {
((ByteBufferPool)val).putBuffer(buffer);
}
}
@Override
public synchronized void unbuffer() {
closeCurrentBlockReaders();
}
@Override
public boolean hasCapability(String capability) {
switch (StringUtils.toLowerCase(capability)) {
case StreamCapabilities.READAHEAD:
case StreamCapabilities.DROPBEHIND:
case StreamCapabilities.UNBUFFER:
return true;
default:
return false;
}
}
}
