/**
* 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.FileNotFoundException;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import org.apache.hadoop.fs.BlockMissingException;
import org.apache.hadoop.fs.ChecksumException;
import org.apache.hadoop.fs.FSInputStream;
import org.apache.hadoop.hdfs.BlockReader;
import org.apache.hadoop.hdfs.DFSClient.DataNodeSlowException;
import org.apache.hadoop.hdfs.protocol.Block;
import org.apache.hadoop.hdfs.protocol.ClientDatanodeProtocol;
import org.apache.hadoop.hdfs.protocol.DataTransferProtocol;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
import org.apache.hadoop.hdfs.protocol.LocatedBlock;
import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
import org.apache.hadoop.hdfs.protocol.LocatedBlocksWithMetaInfo;
import org.apache.hadoop.hdfs.protocol.VersionedLocatedBlocks;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.ipc.ProtocolProxy;
import org.apache.hadoop.ipc.RPC;
import org.apache.hadoop.ipc.RemoteException;
import org.apache.hadoop.net.NetUtils;
import org.apache.hadoop.security.AccessControlException;
import org.apache.hadoop.util.StringUtils;
/****************************************************************
* DFSInputStream provides bytes from a named file. It handles
* negotiation of the namenode and various datanodes as necessary.
****************************************************************/
public class DFSInputStream extends FSInputStream {
private Socket s = null;
private boolean closed = false;
private final DFSClient dfsClient;
private String src = null;
private long prefetchSize;
private BlockReader blockReader = null;
private boolean verifyChecksum;
private boolean clearOsBuffer;
private DFSLocatedBlocks locatedBlocks = null;
private DatanodeInfo currentNode = null;
private Block currentBlock = null;
private boolean isCurrentBlockUnderConstruction;
private long pos = 0;
private long blockEnd = -1;
private LocatedBlocks blocks = null;
private int namespaceId; // the namespace that this file belongs to
private int timeWindow = 3000; // wait time window (in msec) if BlockMissingException is caught
/* XXX Use of CocurrentHashMap is temp fix. Need to fix
* parallel accesses to DFSInputStream (through ptreads) properly */
private ConcurrentHashMap<DatanodeInfo, DatanodeInfo> deadNodes =
new ConcurrentHashMap<DatanodeInfo, DatanodeInfo>();
private int buffersize = 1;
private byte[] oneByteBuf = new byte[1]; // used for 'int read()'
void addToDeadNodes(DatanodeInfo dnInfo) {
deadNodes.put(dnInfo, dnInfo);
}
DFSInputStream(DFSClient dfsClient, String src, int buffersize, boolean verifyChecksum,
boolean clearOsBuffer) throws IOException {
this.src = src;
this.dfsClient = dfsClient;
init(buffersize, verifyChecksum, clearOsBuffer);
}
/**
* Used for snapshot
*/
DFSInputStream(DFSClient dfsClient, LocatedBlocksWithMetaInfo blocks, int buffersize,
boolean verifyChecksum) throws IOException {
this.blocks = blocks;
this.namespaceId = blocks.getNamespaceID();
this.dfsClient = dfsClient;
dfsClient.updateDataTransferProtocolVersionIfNeeded(blocks.getDataProtocolVersion());
dfsClient.getNewNameNodeIfNeeded(blocks.getMethodFingerPrint());
init(buffersize, verifyChecksum, false);
}
private void init(int buffersize, boolean verifyChecksum,
boolean clearOsBuffer) throws IOException {
this.verifyChecksum = verifyChecksum;
this.buffersize = buffersize;
this.clearOsBuffer = clearOsBuffer;
prefetchSize = dfsClient.conf.getLong("dfs.read.prefetch.size",
10 * dfsClient.defaultBlockSize);
timeWindow = dfsClient.conf.getInt(
"dfs.client.baseTimeWindow.waitOn.BlockMissingException",
timeWindow);
try {
openInfo();
} catch (IOException e) {
dfsClient.incReadExpCntToStats();
throw e;
}
}
/**
* Grab the open-file info from namenode
*/
synchronized void openInfo() throws IOException {
if (src == null && blocks == null) {
throw new IOException("No fine provided to open");
}
LocatedBlocks newInfo = src != null ?
getLocatedBlocks(src, 0, prefetchSize) : blocks;
if (newInfo == null) {
throw new IOException("Cannot open filename " + src);
}
// I think this check is not correct. A file could have been appended to
// between two calls to openInfo().
if (locatedBlocks != null && !locatedBlocks.isUnderConstruction() &&
!newInfo.isUnderConstruction()) {
Iterator<LocatedBlock> oldIter = locatedBlocks.getLocatedBlocks().iterator();
Iterator<LocatedBlock> 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!");
}
}
}
// if the file is under construction, then fetch size of last block
// from datanode.
if (newInfo.isUnderConstruction() && newInfo.locatedBlockCount() > 0) {
LocatedBlock last = newInfo.get(newInfo.locatedBlockCount()-1);
if (last.getLocations().length > 0) {
try {
Block newBlock = getBlockInfo(last);
// only if the block has data (not null)
if (newBlock != null) {
long newBlockSize = newBlock.getNumBytes();
newInfo.setLastBlockSize(newBlock.getBlockId(), newBlockSize);
}
} catch (IOException e) {
DFSClient.LOG.debug("DFSClient file " + src +
" is being concurrently append to" +
" but datanodes probably does not have block " +
last.getBlock(), e);
}
}
}
this.locatedBlocks = new DFSLocatedBlocks(newInfo);
this.currentNode = null;
}
private void checkLocatedBlocks(LocatedBlocks locatedBlocks)
throws IOException {
if (null == locatedBlocks) {
return;
}
if(!locatedBlocks.isUnderConstruction()) {
return;
}
List<LocatedBlock> lbs = locatedBlocks.getLocatedBlocks();
if (lbs == null) {
return;
}
for (int i = 0; i < lbs.size() - 1; i++) {
if (lbs.get(i).getBlockSize() <= 1) {
throw new IOException(
"File is under construction and namenode hasn't received the second last block yet.");
}
}
}
private LocatedBlocks getLocatedBlocks(String src, long start, long length)
throws IOException {
try {
if (dfsClient.namenodeProtocolProxy != null &&
dfsClient.namenodeProtocolProxy.isMethodSupported("openAndFetchMetaInfo",
String.class, long.class, long.class)) {
LocatedBlocksWithMetaInfo locs =
dfsClient.namenode.openAndFetchMetaInfo(src, start, length);
if (locs != null) {
this.namespaceId = locs.getNamespaceID();
dfsClient.updateDataTransferProtocolVersionIfNeeded(locs.getDataProtocolVersion());
dfsClient.getNewNameNodeIfNeeded(locs.getMethodFingerPrint());
}
checkLocatedBlocks(locs);
return locs;
} else if (dfsClient.namenodeProtocolProxy != null &&
dfsClient.namenodeProtocolProxy.isMethodSupported("open", String.class,
long.class, long.class)) {
VersionedLocatedBlocks locs = dfsClient.namenode.open(src, start, length);
if (locs != null) {
dfsClient.updateDataTransferProtocolVersionIfNeeded(locs.getDataProtocolVersion());
}
checkLocatedBlocks(locs);
return locs;
} else {
LocatedBlocks locs = dfsClient.namenode.getBlockLocations(src, start, length);
checkLocatedBlocks(locs);
return locs;
}
} catch(RemoteException re) {
throw re.unwrapRemoteException(AccessControlException.class,
FileNotFoundException.class);
}
}
/** Get block info from a datanode */
private Block getBlockInfo(LocatedBlock locatedblock) throws IOException {
if (locatedblock == null || locatedblock.getLocations().length == 0) {
return null;
}
int replicaNotFoundCount = locatedblock.getLocations().length;
for(DatanodeInfo datanode : locatedblock.getLocations()) {
ProtocolProxy<ClientDatanodeProtocol> cdp = null;
try {
cdp = DFSClient.createClientDNProtocolProxy(datanode,
dfsClient.conf, dfsClient.socketTimeout);
final Block newBlock;
if (cdp.isMethodSupported("getBlockInfo", int.class, Block.class)) {
newBlock = cdp.getProxy().getBlockInfo(
namespaceId, locatedblock.getBlock());
} else {
newBlock = cdp.getProxy().getBlockInfo(locatedblock.getBlock());
}
if (newBlock == null) {
// special case : replica might not be on the DN, treat as 0 length
replicaNotFoundCount--;
} else {
return newBlock;
}
}
catch(IOException ioe) {
if (DFSClient.LOG.isDebugEnabled()) {
DFSClient.LOG.debug("Failed to getBlockInfo from datanode "
+ datanode + " for block " + locatedblock.getBlock(), ioe);
}
} finally {
if (cdp != null) {
RPC.stopProxy(cdp.getProxy());
}
}
}
// 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 because some other exception could have happened
// on a DN that has it. we want to report that error
if (replicaNotFoundCount == 0) {
return null;
}
throw new IOException("Cannot obtain block info for " + locatedblock);
}
/**
* Returns whether the file opened is under construction.
*/
public synchronized boolean isUnderConstruction() {
return locatedBlocks.isUnderConstruction();
}
public long getFileLength() {
return locatedBlocks.getFileLength();
}
public DFSLocatedBlocks fetchLocatedBlocks() {
return locatedBlocks;
}
/**
* Returns the datanode from which the stream is currently reading.
*/
public DatanodeInfo getCurrentDatanode() {
return currentNode;
}
/**
* Returns the block containing the target position.
*/
public Block getCurrentBlock() {
return currentBlock;
}
/**
* Return collection of blocks that has already been located.
*/
synchronized List<LocatedBlock> getAllBlocks() throws IOException {
return getBlockRange(0, this.getFileLength());
}
/**
* Get block at the specified position. Fetch it from the namenode if not
* cached.
*
* @param offset
* @param updatePosition
* @param throwWhenNoFound
* when no block found for the offset return null instead of
* throwing an exception
* @return located block
* @throws IOException
*/
private LocatedBlock getBlockAt(long offset, boolean updatePosition,
boolean throwWhenNotFound) throws IOException {
assert (locatedBlocks != null) : "locatedBlocks is null";
// search cached blocks first
LocatedBlock blk = locatedBlocks.getBlockContainingOffset(offset);
if (blk == null) { // block is not cached
// fetch more blocks
LocatedBlocks newBlocks;
newBlocks = getLocatedBlocks(src, offset, prefetchSize);
if (newBlocks == null) {
if (!throwWhenNotFound) {
return null;
}
throw new IOException("Could not find target position " + offset);
}
locatedBlocks.insertRange(newBlocks.getLocatedBlocks());
locatedBlocks.setFileLength(newBlocks.getFileLength());
}
blk = locatedBlocks.getBlockContainingOffset(offset);
if (blk == null) {
if (!throwWhenNotFound) {
return null;
}
throw new IOException("Failed to determine location for block at "
+ "offset=" + offset);
}
if (updatePosition) {
// update current position
this.pos = offset;
this.blockEnd = blk.getStartOffset() + blk.getBlockSize() - 1;
this.currentBlock = blk.getBlock();
isCurrentBlockUnderConstruction = locatedBlocks
.isUnderConstructionBlock(this.currentBlock);
}
return blk;
}
/**
* Get blocks in the specified range. The locations of all blocks
* overlapping with the given segment of the file are retrieved. Fetch them
* from the namenode if not cached.
*
* @param offset the offset of the segment to read
* @param length the length of the segment to read
* @return consequent segment of located blocks
* @throws IOException
*/
private List<LocatedBlock> getBlockRange(final long offset,
final long length) throws IOException {
List<LocatedBlock> blockRange = new ArrayList<LocatedBlock>();
// Zero length. Not sure this ever happens in practice.
if (length == 0)
return blockRange;
// A defensive measure to ensure that we never loop here eternally.
// With a 256 M block size, 10000 blocks will correspond to 2.5 TB.
// No one should read this much data at once in practice.
int maxLoops = 10000;
// Copy locatedBlocks to a local data structure. This ensures that
// a concurrent invocation of openInfo() works OK, the reason being
// that openInfo may completely replace locatedBlocks.
DFSLocatedBlocks locatedBlocks = this.locatedBlocks;
if (locatedBlocks == null) {
// Make this an IO exception because this is input/output code error.
throw new IOException("locatedBlocks is null");
}
long remaining = length;
long curOff = offset;
while (remaining > 0) {
// a defensive check to bail out of this loop at all costs
if (--maxLoops < 0) {
String msg = "Failed to getBlockRange at offset " + offset +
", length=" + length +
", curOff=" + curOff +
", remaining=" + remaining +
". Aborting...";
DFSClient.LOG.warn(msg);
throw new IOException(msg);
}
LocatedBlock blk = locatedBlocks.getBlockContainingOffset(curOff);
if (blk == null) {
LocatedBlocks newBlocks;
newBlocks = getLocatedBlocks(src, curOff, remaining);
if (newBlocks == null) {
throw new IOException("Could not get block locations for curOff=" +
curOff + ", remaining=" + remaining + " (offset=" + offset +
")");
}
locatedBlocks.insertRange(newBlocks.getLocatedBlocks());
continue;
}
blockRange.add(blk);
long bytesRead = blk.getStartOffset() + blk.getBlockSize() - curOff;
remaining -= bytesRead;
curOff += bytesRead;
}
DFSClient.checkBlockRange(blockRange, offset, length);
return blockRange;
}
protected synchronized DatanodeInfo blockSeekTo(long target) throws IOException {
return blockSeekTo(target, true);
}
/**
* 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,
boolean throwWhenNotFound) throws IOException {
// We only allow to seek before the end of the file, or the end of the file
// and allowSeedtoEnd, which is the case called by available().
//
if (target > getFileLength() || (target == getFileLength() && throwWhenNotFound)) {
throw new IOException("Attempted to read past end of file");
}
if ( blockReader != null ) {
blockReader.close();
blockReader = null;
}
if (s != null) {
s.close();
s = null;
}
//
// Compute desired block.
//
LocatedBlock targetBlock = getBlockAt(target, true, throwWhenNotFound);
// Given target<= fileLength, when and only whenallowSeektoEnd is true and
// there is no block for the file yet, getBlockAt() returns null, in this
// case we should simply return null.
//
if (targetBlock == null) {
assert target == 0;
return null;
}
assert (target==this.pos) : "Wrong postion " + pos + " expect " + target;
long offsetIntoBlock = target - targetBlock.getStartOffset();
//
// Connect to best DataNode for desired Block, with potential offset
//
DatanodeInfo chosenNode = null;
while (s == null) {
DNAddrPair retval = chooseDataNode(targetBlock);
chosenNode = retval.info;
InetSocketAddress targetAddr = retval.addr;
// try reading the block locally. if this fails, then go via
// the datanode
Block blk = targetBlock.getBlock();
try {
if (DFSClient.LOG.isDebugEnabled()) {
DFSClient.LOG.warn("blockSeekTo shortCircuitLocalReads "
+ dfsClient.shortCircuitLocalReads +
" localhost " + dfsClient.localHost +
" targetAddr " + targetAddr);
}
if (dfsClient.shortCircuitLocalReads && dfsClient.localHost != null &&
(targetAddr.equals(dfsClient.localHost) ||
targetAddr.getHostName().startsWith("localhost"))) {
blockReader = BlockReaderLocal.newBlockReader(dfsClient.conf, src,
namespaceId, blk,
chosenNode,
offsetIntoBlock,
blk.getNumBytes() - offsetIntoBlock,
dfsClient.metrics,
this.verifyChecksum,
this.clearOsBuffer);
blockReader.setReadLocal(true);
blockReader.setFsStats(dfsClient.stats);
return chosenNode;
}
} catch (IOException ex) {
DFSClient.LOG.info("Failed to read block " + targetBlock.getBlock() +
" on local machine " + dfsClient.localHost +
". Try via the datanode on " + targetAddr + ":"
+ StringUtils.stringifyException(ex));
}
try {
s = dfsClient.socketFactory.createSocket();
NetUtils.connect(s, targetAddr, dfsClient.socketTimeout,
dfsClient.ipTosValue);
s.setSoTimeout(dfsClient.socketTimeout);
long minReadSpeedBps = (dfsClient.numNodeLeft(targetBlock.getLocations(),
deadNodes) > 1) ? dfsClient.minReadSpeedBps : -1;
blockReader = BlockReader.newBlockReader(
dfsClient.getDataTransferProtocolVersion(), namespaceId,
s, src, blk.getBlockId(),
blk.getGenerationStamp(),
offsetIntoBlock, blk.getNumBytes() - offsetIntoBlock,
buffersize, verifyChecksum,
dfsClient.clientName, minReadSpeedBps);
boolean isLocalHost = NetUtils.isLocalAddressWithCaching(targetAddr
.getAddress());
blockReader.setReadLocal(isLocalHost);
if (!isLocalHost) {
blockReader
.setReadRackLocal(dfsClient.isInLocalRack(targetAddr.getAddress()));
}
blockReader.setFsStats(dfsClient.stats);
return chosenNode;
} catch (IOException ex) {
// Put chosen node into dead list, continue
DFSClient.LOG.warn("Failed to connect to " + targetAddr, ex);
addToDeadNodes(chosenNode);
if (s != null) {
try {
s.close();
} catch (IOException iex) {
}
}
s = null;
}
}
return chosenNode;
}
/**
* Close it down!
*/
@Override
public synchronized void close() throws IOException {
if (closed) {
return;
}
dfsClient.checkOpen();
if ( blockReader != null ) {
blockReader.close();
blockReader = null;
}
if (s != null) {
s.close();
s = null;
}
super.close();
closed = true;
}
@Override
public synchronized int read() throws IOException {
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
* ChecksuFileSystem
*/
private synchronized int readBuffer(byte buf[], int off, int len)
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 {
int bytesRead = blockReader.read(buf, off, len);
// update length of file under construction if needed
if (isCurrentBlockUnderConstruction
&& blockReader.isBlkLenInfoUpdated()) {
locatedBlocks.setLastBlockSize(currentBlock.getBlockId(),
blockReader.getUpdatedBlockLength());
this.blockEnd = locatedBlocks.getFileLength() - 1;
blockReader.resetBlockLenInfo();
// if the last block is finalized, get file info from name-node.
// It is necessary because there might be new blocks added to
// the file. The client needs to check with the name-node whether
// it is the case, or the file has been finalized.
if (blockReader.isBlockFinalized() && src != null) {
openInfo();
}
}
return bytesRead;
} catch (DataNodeSlowException dnse) {
DFSClient.LOG.warn("Node " + currentNode + " is too slow when reading blk "
+ this.currentBlock + ". Try another datanode.");
ioe = dnse;
retryCurrentNode = false;
} catch ( ChecksumException ce ) {
DFSClient.LOG.warn("Found Checksum error for " + currentBlock + " from " +
currentNode.getName() + " at " + ce.getPos());
dfsClient.reportChecksumFailure(src, currentBlock, currentNode);
ioe = ce;
retryCurrentNode = false;
} catch ( IOException e ) {
if (!retryCurrentNode) {
DFSClient.LOG.warn("Exception while reading from " + currentBlock +
" of " + src + " from " + currentNode + ": " +
StringUtils.stringifyException(e));
}
ioe = e;
}
boolean sourceFound = false;
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, len != 0);
} else {
addToDeadNodes(currentNode);
sourceFound = seekToNewSource(pos, len != 0);
}
if (!sourceFound) {
throw ioe;
} else {
dfsClient.incReadExpCntToStats();
}
retryCurrentNode = false;
}
}
/**
* Read the entire buffer.
*/
@Override
public synchronized int read(byte buf[], int off, int len) throws IOException {
dfsClient.checkOpen();
if (closed) {
dfsClient.incReadExpCntToStats();
throw new IOException("Stream closed");
}
DFSClient.dfsInputStreamfailures.set(0);
long start = System.currentTimeMillis();
if (pos < getFileLength() || (pos == getFileLength() && len == 0)) {
int retries = 2;
while (retries > 0) {
try {
// If position equals or is larger than the end position of the
// block, we try to seek to the next block, unless:
// 1. user tries to read 0 bytes (usually by available() call), AND
// 2. there is at least a known block for the file (blockEnd != -1), AND
// 3. pos is the end of the file, AND
// 4. the end of the block is the end of the file
// (the current block is the known last block of the file)
// For this case, we want to stay in the current block, as in the case
// that it is the last block (which is almost always true given
// len == 0), the current block is the under-construction block whose size
// you want to update.
//
if (len == 0) { // called by available()
if (blockEnd == -1 // No current block selected
|| pos == getFileLength()) { // at the end of the file
currentNode = blockSeekTo(pos, false);
if (currentNode == null) {
// In this case, user wants to know available information of
// the file, but the file doesn't have any block created yet (it
// is a 0 size file). Simply 0 should be returned.
return 0;
}
} else {
throw new IOException(
"Try to read 0 bytes while current position is not the end of the file");
}
} else if (pos > blockEnd) {
currentNode = blockSeekTo(pos, true);
}
int realLen = (int) Math.min((long) len, (blockEnd - pos + 1L));
int result = readBuffer(buf, off, realLen);
if (result >= 0) {
pos += result;
} else if (len != 0){
// got a EOS from reader though we expect more data on it.
throw new IOException("Unexpected EOS from the reader");
}
if (dfsClient.stats != null && result != -1) {
dfsClient.stats.incrementBytesRead(result);
}
long timeval = System.currentTimeMillis() - start;
dfsClient.metrics.incReadTime(timeval);
dfsClient.metrics.incReadSize(result);
dfsClient.metrics.incReadOps();
return (result >= 0) ? result : 0;
} catch (ChecksumException ce) {
dfsClient.incReadExpCntToStats();
throw ce;
} catch (IOException e) {
dfsClient.incReadExpCntToStats();
if (retries == 1) {
DFSClient.LOG.warn("DFS Read: " + StringUtils.stringifyException(e));
}
blockEnd = -1;
if (currentNode != null) { addToDeadNodes(currentNode); }
if (--retries == 0) {
throw e;
}
}
}
}
return -1;
}
private DNAddrPair chooseDataNode(LocatedBlock block)
throws IOException {
while (true) {
DatanodeInfo[] nodes = block.getLocations();
String blockInfo = block.getBlock() + " file=" + src;
if(block.isCorrupt())
throw new BlockMissingException(src, "Block: " +
blockInfo + " is corrupt ", block.getStartOffset());
/*if(nodes.length == 1) {
long lastContact = System.currentTimeMillis() - nodes[0].getLastUpdate();
if(lastContact > 9000)
throw new BlockMissingException(src, "Could not obtain block: " +
blockInfo, block.getStartOffset());
}*/
DatanodeInfo chosenNode = null;
try {
chosenNode = dfsClient.bestNode(nodes, deadNodes);
InetSocketAddress targetAddr =
NetUtils.createSocketAddr(chosenNode.getName());
return new DNAddrPair(chosenNode, targetAddr);
} catch (IOException ie) {
int failureTimes = DFSClient.dfsInputStreamfailures.get();
if (failureTimes >= dfsClient.maxBlockAcquireFailures
|| failureTimes >= block.getLocations().length) {
throw new BlockMissingException(src, "Could not obtain block: " +
blockInfo, block.getStartOffset());
}
if (nodes == null || nodes.length == 0) {
DFSClient.LOG.info("No node available for block: " + blockInfo);
}
DFSClient.LOG.info("Could not obtain block " + block.getBlock() +
" from node: " +
(chosenNode == null ? "" : chosenNode.getHostName()) + ie +
". 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.
// waitTime = grace period for the last round of attempt +
// expanding time window for each failure
double waitTime = timeWindow * failureTimes +
timeWindow * (failureTimes + 1) * DFSClient.r.nextDouble();
DFSClient.LOG.warn("DFS chooseDataNode: got # " + (failureTimes + 1) +
" IOException, will wait for " + waitTime + " msec.", ie);
Thread.sleep((long)waitTime);
} catch (InterruptedException iex) {
}
deadNodes.clear(); //2nd option is to remove only nodes[blockId]
openInfo();
block = getBlockAt(block.getStartOffset(), false, true);
DFSClient.dfsInputStreamfailures.set(failureTimes+1);
continue;
}
}
}
private void fetchBlockByteRange(LocatedBlock block, long start,
long end, byte[] buf, int offset) throws IOException {
//
// Connect to best DataNode for desired Block, with potential offset
//
Socket dn = null;
while (true) {
// cached block locations may have been updated by chooseDatNode()
// or fetchBlockAt(). Always get the latest list of locations at the
// start of the loop.
block = getBlockAt(block.getStartOffset(), false, true);
DNAddrPair retval = chooseDataNode(block);
DatanodeInfo chosenNode = retval.info;
InetSocketAddress targetAddr = retval.addr;
BlockReader reader = null;
int len = (int) (end - start + 1);
try {
if (DFSClient.LOG.isDebugEnabled()) {
DFSClient.LOG.debug("fetchBlockByteRange shortCircuitLocalReads " +
dfsClient.shortCircuitLocalReads +
" localhst " + dfsClient.localHost +
" targetAddr " + targetAddr);
}
// first try reading the block locally.
if (dfsClient.shortCircuitLocalReads &&
NetUtils.isLocalAddressWithCaching(targetAddr.getAddress())) {
reader = BlockReaderLocal.newBlockReader(dfsClient.conf, src,
namespaceId, block.getBlock(),
chosenNode,
start,
len,
dfsClient.metrics,
verifyChecksum,
this.clearOsBuffer);
reader.setReadLocal(true);
reader.setFsStats(dfsClient.stats);
} else {
// go to the datanode
dn = dfsClient.socketFactory.createSocket();
NetUtils.connect(dn, targetAddr, dfsClient.socketTimeout,
dfsClient.ipTosValue);
dn.setSoTimeout(dfsClient.socketTimeout);
reader = BlockReader.newBlockReader(dfsClient.getDataTransferProtocolVersion(),
namespaceId,
dn, src,
block.getBlock().getBlockId(),
block.getBlock().getGenerationStamp(),
start, len, buffersize,
verifyChecksum, dfsClient.clientName,
dfsClient.minReadSpeedBps);
boolean isLocalHost = NetUtils.isLocalAddress(targetAddr.getAddress());
reader.setReadLocal(isLocalHost);
if (!isLocalHost) {
reader.setReadRackLocal(
dfsClient.isInLocalRack(targetAddr.getAddress()));
}
reader.setFsStats(dfsClient.stats);
}
int nread = reader.readAll(buf, offset, len);
if (nread != len) {
throw new IOException("truncated return from reader.read(): " +
"excpected " + len + ", got " + nread);
}
return;
} catch (ChecksumException e) {
DFSClient.LOG.warn("fetchBlockByteRange(). Got a checksum exception for " +
src + " at " + block.getBlock() + ":" +
e.getPos() + " from " + chosenNode.getName());
dfsClient.reportChecksumFailure(src, block.getBlock(), chosenNode);
} catch (IOException e) {
DFSClient.LOG.warn("Failed to connect to " + targetAddr +
" for file " + src +
" for block " + block.getBlock().getBlockId() + ":" +
StringUtils.stringifyException(e));
} finally {
IOUtils.closeStream(reader);
IOUtils.closeSocket(dn);
}
// Put chosen node into dead list, continue
addToDeadNodes(chosenNode);
}
}
/**
* This is highly optimized for preads. Reduce number of buffercopies.
* Its is similar to doing a scatter/gather kind of io, all data to be
* returned in a ByteBuffer.
*/
private ByteBuffer fetchBlockByteRangeScatterGather(LocatedBlock block,
long start, long len) throws IOException {
//
// Connect to best DataNode for desired Block, with potential offset
//
Socket dn = null;
while (true) {
// cached block locations may have been updated by chooseDatNode()
// or fetchBlockAt(). Always get the latest list of locations at the
// start of the loop.
block = getBlockAt(block.getStartOffset(), false, true);
DNAddrPair retval = chooseDataNode(block);
DatanodeInfo chosenNode = retval.info;
InetSocketAddress targetAddr = retval.addr;
ByteBuffer result = null;
BlockReaderLocal localReader = null;
BlockReaderAccelerator remoteReader = null;
try {
if (DFSClient.LOG.isDebugEnabled()) {
DFSClient.LOG.debug("fetchBlockByteRangeScatterGather " +
" localhst " + dfsClient.localHost +
" targetAddr " + targetAddr);
}
// first try reading the block locally.
if (dfsClient.shortCircuitLocalReads &&
NetUtils.isLocalAddressWithCaching(targetAddr.getAddress())) {
localReader = BlockReaderLocal.newBlockReader(dfsClient.conf, src,
namespaceId, block.getBlock(),
chosenNode,
start,
len,
dfsClient.metrics,
verifyChecksum,
this.clearOsBuffer);
localReader.setReadLocal(true);
localReader.setFsStats(dfsClient.stats);
result = localReader.readAll();
} else {
// go to the datanode
dn = dfsClient.socketFactory.createSocket();
NetUtils.connect(dn, targetAddr, dfsClient.socketTimeout,
dfsClient.ipTosValue);
dn.setSoTimeout(dfsClient.socketTimeout);
remoteReader = new BlockReaderAccelerator(dfsClient.conf,
targetAddr,
chosenNode,
dfsClient.getDataTransferProtocolVersion(),
namespaceId, dfsClient.clientName,
dn, src,
block,
start, len,
verifyChecksum, dfsClient.metrics);
result = remoteReader.readAll();
}
if (result.remaining() != len) {
throw new IOException("truncated return from reader.read(): " +
"expected " + len + ", got " +
result.remaining());
}
if (NetUtils.isLocalAddress(targetAddr.getAddress())) {
dfsClient.stats.incrementLocalBytesRead(len);
dfsClient.stats.incrementRackLocalBytesRead(len);
} else if (dfsClient.isInLocalRack(targetAddr.getAddress())) {
dfsClient.stats.incrementRackLocalBytesRead(len);
}
return result;
} catch (ChecksumException e) {
DFSClient.LOG.warn("fetchBlockByteRangeScatterGather(). Got a checksum exception for " +
src + " at " + block.getBlock() + ":" +
e.getPos() + " from " + chosenNode.getName());
dfsClient.reportChecksumFailure(src, block.getBlock(), chosenNode);
} catch (IOException e) {
DFSClient.LOG.warn("Failed to connect to " + targetAddr +
" for file " + src +
" for block " + block.getBlock().getBlockId() + ":" +
StringUtils.stringifyException(e));
} finally {
IOUtils.closeStream(localReader);
IOUtils.closeStream(remoteReader);
IOUtils.closeSocket(dn);
}
dfsClient.incReadExpCntToStats();
// Put chosen node into dead list, continue
addToDeadNodes(chosenNode);
}
}
/**
* 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 {
// sanity checks
dfsClient.checkOpen();
if (closed) {
throw new IOException("Stream closed");
}
DFSClient.dfsInputStreamfailures.set(0);
long start = System.currentTimeMillis();
long filelen = getFileLength();
if ((position < 0) || (position >= filelen)) {
return -1;
}
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<LocatedBlock> blockRange = getBlockRange(position, realLen);
int remaining = realLen;
for (LocatedBlock blk : blockRange) {
long targetStart = position - blk.getStartOffset();
long bytesToRead = Math.min(remaining, blk.getBlockSize() - targetStart);
fetchBlockByteRange(blk, targetStart,
targetStart + bytesToRead - 1, buffer, offset);
remaining -= bytesToRead;
position += bytesToRead;
offset += bytesToRead;
}
assert remaining == 0 : "Wrong number of bytes read.";
if (dfsClient.stats != null) {
dfsClient.stats.incrementBytesRead(realLen);
}
long timeval = System.currentTimeMillis() - start;
dfsClient.metrics.incPreadTime(timeval);
dfsClient.metrics.incPreadSize(realLen);
dfsClient.metrics.incPreadOps();
return realLen;
}
/**
* Read bytes starting from the specified position. This is optimized
* for fast preads from an application with minimum of buffer copies.
*
* @param position start read from this position
* @param length number of bytes to read
*
* @return A list of Byte Buffers that represent all the data that was
* read from the underlying system.
*/
@Override
public List<ByteBuffer> readFullyScatterGather(long position, int length)
throws IOException {
// if the server does not support scatter-gather,
// then use default implementation from FSDataInputStream.
if (dfsClient.dataTransferVersion < DataTransferProtocol.SCATTERGATHER_VERSION) {
return super.readFullyScatterGather(position, length);
}
// sanity checks
dfsClient.checkOpen();
if (closed) {
throw new IOException("Stream closed");
}
DFSClient.dfsInputStreamfailures.set(0);
long start = System.currentTimeMillis();
long filelen = getFileLength();
if ((position < 0) || (position > filelen)) {
String msg = " Invalid position " + position +
". File " + src + " is of size " + filelen;
DFSClient.LOG.warn(msg);
throw new IOException(msg);
}
List<ByteBuffer> results = new LinkedList<ByteBuffer>();
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<LocatedBlock> blockRange = getBlockRange(position, realLen);
int remaining = realLen;
for (LocatedBlock blk : blockRange) {
long targetStart = position - blk.getStartOffset();
long bytesToRead = Math.min(remaining, blk.getBlockSize() - targetStart);
ByteBuffer bb = fetchBlockByteRangeScatterGather(blk, targetStart,
bytesToRead);
results.add(bb);
remaining -= bytesToRead;
position += bytesToRead;
}
assert remaining == 0 : "Wrong number of bytes read.";
if (dfsClient.stats != null) {
dfsClient.stats.incrementBytesRead(realLen);
}
long timeval = System.currentTimeMillis() - start;
dfsClient.metrics.incPreadTime(timeval);
dfsClient.metrics.incPreadSize(realLen);
dfsClient.metrics.incPreadOps();
return results;
}
@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 IOException("Cannot seek after EOF");
}
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 <= DFSClient.TCP_WINDOW_SIZE) {
try {
pos += blockReader.skip(diff);
if (pos == targetPos) {
done = true;
}
} catch (IOException e) {//make following read to retry
dfsClient.incReadExpCntToStats();
DFSClient.LOG.debug("Exception while seek to " + targetPos + " from "
+ currentBlock +" of " + src + " from " + currentNode +
": " + StringUtils.stringifyException(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 synchronized boolean seekToBlockSource(long targetPos,
boolean throwWhenNotFound) throws IOException {
currentNode = blockSeekTo(targetPos, throwWhenNotFound);
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 {
return seekToNewSource(targetPos, 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.
*/
public synchronized boolean seekToNewSource(long targetPos,
boolean throwWhenNotFound) throws IOException {
boolean markedDead = deadNodes.containsKey(currentNode);
addToDeadNodes(currentNode);
DatanodeInfo oldNode = currentNode;
DatanodeInfo newNode = blockSeekTo(targetPos, throwWhenNotFound);
if (!markedDead) {
/* remove it from deadNodes. blockSeekTo could have cleared
* deadNodes and added currentNode again. Thats ok. */
deadNodes.remove(oldNode);
}
if (!oldNode.getStorageID().equals(newNode.getStorageID())) {
currentNode = newNode;
return true;
} else {
return false;
}
}
/**
*/
@Override
public synchronized long getPos() throws IOException {
return pos;
}
/**
* WARNING: This method does not work with files larger than 2GB.
* Use getFileLength() - getPos() instead.
*/
@Override
public synchronized int available() throws IOException {
if (closed) {
throw new IOException("Stream closed");
}
long length = getFileLength() - pos;
if (!isUnderConstruction() || length > 0) {
return (int) length;
}
read(DFSClient.emptyByteArray);
return (int) (getFileLength() - pos);
}
/**
* 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 ip address. */
private static class DNAddrPair {
DatanodeInfo info;
InetSocketAddress addr;
DNAddrPair(DatanodeInfo info, InetSocketAddress addr) {
this.info = info;
this.addr = addr;
}
}
}