/**
* 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.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.net.InetSocketAddress;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.hdfs.net.Peer;
import org.apache.hadoop.hdfs.protocol.DatanodeID;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
import org.apache.hadoop.hdfs.protocol.datatransfer.Sender;
import org.apache.hadoop.hdfs.protocol.proto.DataTransferProtos.BlockOpResponseProto;
import org.apache.hadoop.hdfs.protocolPB.PBHelper;
import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
import org.apache.hadoop.hdfs.security.token.block.InvalidBlockTokenException;
import org.apache.hadoop.hdfs.server.common.HdfsServerConstants;
import org.apache.hadoop.hdfs.server.datanode.CachingStrategy;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.ipc.RemoteException;
import org.apache.hadoop.net.unix.DomainSocket;
import org.apache.hadoop.security.AccessControlException;
import org.apache.hadoop.security.token.SecretManager.InvalidToken;
import org.apache.hadoop.security.token.Token;
/**
* Utility class to create BlockReader implementations.
*/
@InterfaceAudience.Private
public class BlockReaderFactory {
/**
* Create a new BlockReader specifically to satisfy a read.
* This method also sends the OP_READ_BLOCK request.
*
* @param conf the DFSClient configuration
* @param file File location
* @param block The block object
* @param blockToken The block token for security
* @param startOffset The read offset, relative to block head
* @param len The number of bytes to read, or -1 to read as many as
* possible.
* @param bufferSize The IO buffer size (not the client buffer size)
* Ignored except on the legacy BlockReader.
* @param verifyChecksum Whether to verify checksum
* @param clientName Client name. Used for log messages.
* @param peer The peer
* @param datanodeID The datanode that the Peer is connected to
* @param domainSocketFactory The DomainSocketFactory to notify if the Peer
* is a DomainPeer which turns out to be faulty.
* If null, no factory will be notified in this
* case.
* @param allowShortCircuitLocalReads True if short-circuit local reads
* should be allowed.
* @return New BlockReader instance
*/
public static BlockReader newBlockReader(DFSClient.Conf conf,
String file,
ExtendedBlock block,
Token<BlockTokenIdentifier> blockToken,
long startOffset, long len,
boolean verifyChecksum,
String clientName,
Peer peer,
DatanodeID datanodeID,
DomainSocketFactory domSockFactory,
PeerCache peerCache,
FileInputStreamCache fisCache,
boolean allowShortCircuitLocalReads,
CachingStrategy cachingStrategy)
throws IOException {
peer.setReadTimeout(conf.socketTimeout);
peer.setWriteTimeout(HdfsServerConstants.WRITE_TIMEOUT);
if (peer.getDomainSocket() != null) {
if (allowShortCircuitLocalReads && !conf.useLegacyBlockReaderLocal) {
// If this is a domain socket, and short-circuit local reads are
// enabled, try to set up a BlockReaderLocal.
BlockReader reader = newShortCircuitBlockReader(conf, file,
block, blockToken, startOffset, len, peer, datanodeID,
domSockFactory, verifyChecksum, fisCache);
if (reader != null) {
// One we've constructed the short-circuit block reader, we don't
// need the socket any more. So let's return it to the cache.
if (peerCache != null) {
peerCache.put(datanodeID, peer);
} else {
IOUtils.cleanup(null, peer);
}
return reader;
}
}
// If this is a domain socket and we couldn't (or didn't want to) set
// up a BlockReaderLocal, check that we are allowed to pass data traffic
// over the socket before proceeding.
if (!conf.domainSocketDataTraffic) {
throw new IOException("Because we can't do short-circuit access, " +
"and data traffic over domain sockets is disabled, " +
"we cannot use this socket to talk to " + datanodeID);
}
}
if (conf.useLegacyBlockReader) {
@SuppressWarnings("deprecation")
RemoteBlockReader reader = RemoteBlockReader.newBlockReader(file,
block, blockToken, startOffset, len, conf.ioBufferSize,
verifyChecksum, clientName, peer, datanodeID, peerCache,
cachingStrategy);
return reader;
} else {
return RemoteBlockReader2.newBlockReader(
file, block, blockToken, startOffset, len,
verifyChecksum, clientName, peer, datanodeID, peerCache,
cachingStrategy);
}
}
/**
* Create a new short-circuit BlockReader.
*
* Here, we ask the DataNode to pass us file descriptors over our
* DomainSocket. If the DataNode declines to do so, we'll return null here;
* otherwise, we'll return the BlockReaderLocal. If the DataNode declines,
* this function will inform the DomainSocketFactory that short-circuit local
* reads are disabled for this DataNode, so that we don't ask again.
*
* @param conf the configuration.
* @param file the file name. Used in log messages.
* @param block The block object.
* @param blockToken The block token for security.
* @param startOffset The read offset, relative to block head.
* @param len The number of bytes to read, or -1 to read
* as many as possible.
* @param peer The peer to use.
* @param datanodeID The datanode that the Peer is connected to.
* @param domSockFactory The DomainSocketFactory to notify if the Peer
* is a DomainPeer which turns out to be faulty.
* If null, no factory will be notified in this
* case.
* @param verifyChecksum True if we should verify the checksums.
* Note: even if this is true, when
* DFS_CLIENT_READ_CHECKSUM_SKIP_CHECKSUM_KEY is
* set, we will skip checksums.
*
* @return The BlockReaderLocal, or null if the
* DataNode declined to provide short-circuit
* access.
* @throws IOException If there was a communication error.
*/
private static BlockReaderLocal newShortCircuitBlockReader(
DFSClient.Conf conf, String file, ExtendedBlock block,
Token<BlockTokenIdentifier> blockToken, long startOffset,
long len, Peer peer, DatanodeID datanodeID,
DomainSocketFactory domSockFactory, boolean verifyChecksum,
FileInputStreamCache fisCache) throws IOException {
final DataOutputStream out =
new DataOutputStream(new BufferedOutputStream(
peer.getOutputStream()));
new Sender(out).requestShortCircuitFds(block, blockToken, 1);
DataInputStream in =
new DataInputStream(peer.getInputStream());
BlockOpResponseProto resp = BlockOpResponseProto.parseFrom(
PBHelper.vintPrefixed(in));
DomainSocket sock = peer.getDomainSocket();
switch (resp.getStatus()) {
case SUCCESS:
BlockReaderLocal reader = null;
byte buf[] = new byte[1];
FileInputStream fis[] = new FileInputStream[2];
sock.recvFileInputStreams(fis, buf, 0, buf.length);
try {
reader = new BlockReaderLocal(conf, file, block,
startOffset, len, fis[0], fis[1], datanodeID, verifyChecksum,
fisCache);
} finally {
if (reader == null) {
IOUtils.cleanup(DFSClient.LOG, fis[0], fis[1]);
}
}
return reader;
case ERROR_UNSUPPORTED:
if (!resp.hasShortCircuitAccessVersion()) {
DFSClient.LOG.warn("short-circuit read access is disabled for " +
"DataNode " + datanodeID + ". reason: " + resp.getMessage());
domSockFactory.disableShortCircuitForPath(sock.getPath());
} else {
DFSClient.LOG.warn("short-circuit read access for the file " +
file + " is disabled for DataNode " + datanodeID +
". reason: " + resp.getMessage());
}
return null;
case ERROR_ACCESS_TOKEN:
String msg = "access control error while " +
"attempting to set up short-circuit access to " +
file + resp.getMessage();
DFSClient.LOG.debug(msg);
throw new InvalidBlockTokenException(msg);
default:
DFSClient.LOG.warn("error while attempting to set up short-circuit " +
"access to " + file + ": " + resp.getMessage());
domSockFactory.disableShortCircuitForPath(sock.getPath());
return null;
}
}
/**
* File name to print when accessing a block directly (from servlets)
* @param s Address of the block location
* @param poolId Block pool ID of the block
* @param blockId Block ID of the block
* @return string that has a file name for debug purposes
*/
public static String getFileName(final InetSocketAddress s,
final String poolId, final long blockId) {
return s.toString() + ":" + poolId + ":" + blockId;
}
/**
* Get {@link BlockReaderLocalLegacy} for short circuited local reads.
* This block reader implements the path-based style of local reads
* first introduced in HDFS-2246.
*/
static BlockReader getLegacyBlockReaderLocal(DFSClient dfsClient,
String src, ExtendedBlock blk,
Token<BlockTokenIdentifier> accessToken, DatanodeInfo chosenNode,
long offsetIntoBlock) throws InvalidToken, IOException {
try {
final long length = blk.getNumBytes() - offsetIntoBlock;
return BlockReaderLocalLegacy.newBlockReader(dfsClient, src, blk,
accessToken, chosenNode, offsetIntoBlock, length);
} catch (RemoteException re) {
throw re.unwrapRemoteException(InvalidToken.class,
AccessControlException.class);
}
}
}