/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hdfs.server.namenode;
import java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.LinkedHashMap;
import java.util.ArrayList;
import java.util.Map;
import java.util.Comparator;
import java.util.Set;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hdfs.protocol.Block;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
import org.apache.hadoop.hdfs.protocol.LocatedBlock;
import org.apache.hadoop.net.NetworkTopology;
import org.apache.hadoop.net.Node;
import org.apache.hadoop.raid.RaidNode;
/**
* This BlockPlacementPolicy spreads out the group of blocks which used by RAID
* for recovering each other. This is important for the availability
* of the blocks. This class can be used by multiple threads. It has to be
* thread safe.
*/
public class BlockPlacementPolicyRaid extends BlockPlacementPolicy {
public static final Log LOG =
LogFactory.getLog(BlockPlacementPolicyRaid.class);
Configuration conf;
private int stripeLength;
private int xorParityLength;
private int rsParityLength;
private String xorPrefix = null;
private String rsPrefix = null;
private String raidTempPrefix = null;
private String raidrsTempPrefix = null;
private String raidHarTempPrefix = null;
private String raidrsHarTempPrefix = null;
private FSNamesystem namesystem = FSNamesystem.getFSNamesystem();
private BlockPlacementPolicyDefault defaultPolicy;
private CachedLocatedBlocks cachedLocatedBlocks;
private CachedFullPathNames cachedFullPathNames;
/** {@inheritDoc} */
@Override
public void initialize(Configuration conf, FSClusterStats stats,
NetworkTopology clusterMap) {
this.conf = conf;
this.stripeLength = RaidNode.getStripeLength(conf);
this.rsParityLength = RaidNode.rsParityLength(conf);
this.xorParityLength = 1;
this.cachedLocatedBlocks = new CachedLocatedBlocks();
this.cachedFullPathNames = new CachedFullPathNames();
try {
this.xorPrefix = RaidNode.xorDestinationPath(conf).toUri().getPath();
this.rsPrefix = RaidNode.rsDestinationPath(conf).toUri().getPath();
} catch (IOException e) {
}
if (this.xorPrefix == null) {
this.xorPrefix = RaidNode.DEFAULT_RAID_LOCATION;
}
if (this.rsPrefix == null) {
this.rsPrefix = RaidNode.DEFAULT_RAIDRS_LOCATION;
}
this.raidTempPrefix = RaidNode.xorTempPrefix(conf);
this.raidrsTempPrefix = RaidNode.rsTempPrefix(conf);
this.raidHarTempPrefix = RaidNode.xorHarTempPrefix(conf);
this.raidrsHarTempPrefix = RaidNode.rsHarTempPrefix(conf);
defaultPolicy = new BlockPlacementPolicyDefault(conf, stats, clusterMap);
}
@Override
DatanodeDescriptor[] chooseTarget(String srcPath, int numOfReplicas,
DatanodeDescriptor writer, List<DatanodeDescriptor> chosenNodes,
long blocksize) {
try {
List<Node> excludedNodes = getExcludedNodes(srcPath);
DatanodeDescriptor[] result =
defaultPolicy.chooseTarget(numOfReplicas, writer,
chosenNodes, excludedNodes, blocksize);
cachedLocatedBlocks.get(srcPath).
add(new LocatedBlock(new Block(), result));
return result;
} catch (Exception e) {
System.out.println(e);
FSNamesystem.LOG.debug(
"Error happend when choosing datanode to write.", e);
return defaultPolicy.chooseTarget(srcPath, numOfReplicas, writer,
chosenNodes, blocksize);
}
}
@Override
public int verifyBlockPlacement(String srcPath, LocatedBlock lBlk,
int minRacks) {
return defaultPolicy.verifyBlockPlacement(srcPath, lBlk, minRacks);
}
/** {@inheritDoc} */
@Override
public DatanodeDescriptor chooseReplicaToDelete(FSInodeInfo inode,
Block block, short replicationFactor,
Collection<DatanodeDescriptor> first,
Collection<DatanodeDescriptor> second) {
DatanodeDescriptor chosenNode = null;
try {
String path = cachedFullPathNames.get(inode);
List<LocatedBlock> companionBlocks = getCompanionBlocks(path, block);
if (companionBlocks == null || companionBlocks.size() == 0) {
// Use the default method if it is not a valid raided or parity file
return defaultPolicy.chooseReplicaToDelete(
inode, block, replicationFactor, first, second);
}
// Delete from the first collection first
// This ensures the number of unique rack of this block is not reduced
Collection<DatanodeDescriptor> all = new HashSet<DatanodeDescriptor>();
all.addAll(first);
all.addAll(second);
chosenNode = chooseReplicaToDelete(companionBlocks, all);
if (chosenNode != null) {
return chosenNode;
}
return defaultPolicy.chooseReplicaToDelete(
inode, block, replicationFactor, first, second);
} catch (Exception e) {
LOG.debug("Failed to choose the correct replica to delete", e);
return defaultPolicy.chooseReplicaToDelete(
inode, block, replicationFactor, first, second);
}
}
/**
* Obtain the excluded nodes for the current block that is being written
*/
List<Node> getExcludedNodes(String file) throws IOException {
Set<Node> excluded = new HashSet<Node>();
for (LocatedBlock b : getCompanionBlocks(file)) {
for (Node n : b.getLocations()) {
excluded.add(n);
}
}
return new ArrayList<Node>(excluded);
}
private DatanodeDescriptor chooseReplicaToDelete(
Collection<LocatedBlock> companionBlocks,
Collection<DatanodeDescriptor> dataNodes) throws IOException {
if (dataNodes.isEmpty()) {
return null;
}
// Count the number of replicas on each node and rack
final Map<String, Integer> nodeCompanionBlockCount =
countCompanionBlocks(companionBlocks, false);
final Map<String, Integer> rackCompanionBlockCount =
countCompanionBlocks(companionBlocks, true);
NodeComparator comparator =
new NodeComparator(nodeCompanionBlockCount, rackCompanionBlockCount);
return Collections.max(dataNodes, comparator);
}
/**
* Count how many companion blocks are on each datanode or the each rack
* @param companionBlocks a collection of all the companion blocks
* @param doRackCount count the companion blocks on the racks of datanodes
* @param result the map from node name to the number of companion blocks
*/
static Map<String, Integer> countCompanionBlocks(
Collection<LocatedBlock> companionBlocks, boolean doRackCount) {
Map<String, Integer> result = new HashMap<String, Integer>();
for (LocatedBlock block : companionBlocks) {
for (DatanodeInfo d : block.getLocations()) {
String name = doRackCount ? d.getParent().getName() : d.getName();
if (result.containsKey(name)) {
int count = result.get(name) + 1;
result.put(name, count);
} else {
result.put(name, 1);
}
}
}
return result;
}
/**
* Compares the datanodes based on the number of companion blocks on the same
* node and rack. If even, compare the remaining space on the datanodes.
*/
class NodeComparator implements Comparator<DatanodeDescriptor> {
private Map<String, Integer> nodeBlockCount;
private Map<String, Integer> rackBlockCount;
private NodeComparator(Map<String, Integer> nodeBlockCount,
Map<String, Integer> rackBlockCount) {
this.nodeBlockCount = nodeBlockCount;
this.rackBlockCount = rackBlockCount;
}
@Override
public int compare(DatanodeDescriptor d1, DatanodeDescriptor d2) {
int res = compareBlockCount(d1, d2, nodeBlockCount);
if (res != 0) {
return res;
}
res = compareBlockCount(d1.getParent(), d2.getParent(), rackBlockCount);
if (res != 0) {
return res;
}
if (d1.getRemaining() > d2.getRemaining()) {
return -1;
}
if (d1.getRemaining() < d2.getRemaining()) {
return 1;
}
return 0;
}
private int compareBlockCount(Node node1, Node node2,
Map<String, Integer> blockCount) {
Integer count1 = blockCount.get(node1.getName());
Integer count2 = blockCount.get(node2.getName());
count1 = count1 == null ? 0 : count1;
count2 = count2 == null ? 0 : count2;
if (count1 > count2) {
return 1;
}
if (count1 < count2) {
return -1;
}
return 0;
}
}
/**
* Obtain the companion blocks of the block that is currently being written.
* Companion blocks are defined as the blocks that can help recover each
* others by using raid decoder.
* @param path the path of the file contains the block
* @return the block locations of companion blocks
*/
List<LocatedBlock> getCompanionBlocks(String path)
throws IOException {
// This will be the index of the block which is currently being written
int blockIndex = cachedLocatedBlocks.get(path).size();
return getCompanionBlocks(path, blockIndex);
}
/**
* Obtain the companion blocks of the give block
* Companion blocks are defined as the blocks that can help recover each
* others by using raid decoder.
* @param path the path of the file contains the block
* @param block the given block
* @return the block locations of companion blocks
*/
List<LocatedBlock> getCompanionBlocks(String path, Block block)
throws IOException {
int blockIndex = getBlockIndex(path, block);
return getCompanionBlocks(path, blockIndex);
}
List<LocatedBlock> getCompanionBlocks(String path, int blockIndex)
throws IOException {
if (isXorHarTempParityFile(path)) {
// temp har xor parity file
return getCompanionBlocksForHarParityBlock(
path, xorParityLength, blockIndex);
}
if (isRsHarTempParityFile(path)) {
// temp har rs parity file
return getCompanionBlocksForHarParityBlock(
path, rsParityLength, blockIndex);
}
if (isXorTempParityFile(path)) {
// temp xor parity file
return getCompanionBlocksForParityBlock(
getSourceFile(path, raidTempPrefix), path,
xorParityLength, blockIndex);
}
if (isRsTempParityFile(path)) {
// temp rs parity file
return getCompanionBlocksForParityBlock(
getSourceFile(path, raidrsTempPrefix), path,
rsParityLength, blockIndex);
}
if (isXorParityFile(path)) {
// xor parity file
return getCompanionBlocksForParityBlock(getSourceFile(path, xorPrefix),
path, xorParityLength, blockIndex);
}
if (isRsParityFile(path)) {
// rs parity file
return getCompanionBlocksForParityBlock(getSourceFile(path, rsPrefix),
path, rsParityLength, blockIndex);
}
String parity = getParityFile(path);
if (parity == null) {
// corresponding parity file not found.
// return an empty list
return new ArrayList<LocatedBlock>();
}
if (isXorParityFile(parity)) {
// xor raided source file
return getCompanionBlocksForSourceBlock(
path, parity, xorParityLength, blockIndex);
}
if (isRsParityFile(parity)) {
// rs raided source file
return getCompanionBlocksForSourceBlock(
path, parity, rsParityLength, blockIndex);
}
// return an empty list
return new ArrayList<LocatedBlock>();
}
private List<LocatedBlock> getCompanionBlocksForHarParityBlock(
String parity, int parityLength, int blockIndex)
throws IOException {
// consider only parity file in this case because source file block
// location is not easy to obtain
List<LocatedBlock> parityBlocks = cachedLocatedBlocks.get(parity);
List<LocatedBlock> result = new ArrayList<LocatedBlock>();
synchronized (parityBlocks) {
int start = Math.max(0, blockIndex - parityLength + 1);
int end = Math.min(parityBlocks.size(), blockIndex + parityLength);
result = parityBlocks.subList(start, end);
}
return result;
}
private List<LocatedBlock> getCompanionBlocksForParityBlock(
String src, String parity, int parityLength, int blockIndex)
throws IOException {
List<LocatedBlock> result = new ArrayList<LocatedBlock>();
List<LocatedBlock> parityBlocks = cachedLocatedBlocks.get(parity);
int stripeIndex = blockIndex / parityLength;
synchronized (parityBlocks) {
int parityStart = stripeIndex * parityLength;
int parityEnd = Math.min(parityStart + parityLength,
parityBlocks.size());
// for parity, always consider the neighbor blocks as companion blocks
if (parityStart < parityBlocks.size()) {
result.addAll(parityBlocks.subList(parityStart, parityEnd));
}
}
if (src == null) {
return result;
}
List<LocatedBlock> sourceBlocks = cachedLocatedBlocks.get(src);
synchronized (sourceBlocks) {
int sourceStart = stripeIndex * stripeLength;
int sourceEnd = Math.min(sourceStart + stripeLength,
sourceBlocks.size());
if (sourceStart < sourceBlocks.size()) {
result.addAll(sourceBlocks.subList(sourceStart, sourceEnd));
}
}
return result;
}
private List<LocatedBlock> getCompanionBlocksForSourceBlock(
String src, String parity, int parityLength, int blockIndex)
throws IOException {
List<LocatedBlock> result = new ArrayList<LocatedBlock>();
List<LocatedBlock> sourceBlocks = cachedLocatedBlocks.get(src);
int stripeIndex = blockIndex / stripeLength;
synchronized (sourceBlocks) {
int sourceStart = stripeIndex * stripeLength;
int sourceEnd = Math.min(sourceStart + stripeLength,
sourceBlocks.size());
if (sourceStart < sourceBlocks.size()) {
result.addAll(sourceBlocks.subList(sourceStart, sourceEnd));
}
}
if (parity == null) {
return result;
}
List<LocatedBlock> parityBlocks = cachedLocatedBlocks.get(parity);
synchronized (parityBlocks) {
int parityStart = stripeIndex * parityLength;
int parityEnd = Math.min(parityStart + parityLength,
parityBlocks.size());
if (parityStart < parityBlocks.size()) {
result.addAll(parityBlocks.subList(parityStart, parityEnd));
}
}
return result;
}
private int getBlockIndex(String file, Block block) throws IOException {
List<LocatedBlock> blocks = cachedLocatedBlocks.get(file);
synchronized (blocks) {
for (int i = 0; i < blocks.size(); i++) {
if (blocks.get(i).getBlock().equals(block)) {
return i;
}
}
}
throw new IOException("Cannot locate " + block + " in file " + file);
}
/**
* Cache results for FSInodeInfo.getFullPathName()
*/
static class CachedFullPathNames {
private Cache<INodeWithHashCode, String> cacheInternal =
new Cache<INodeWithHashCode, String>() {
@Override
public String getDirectly(INodeWithHashCode inode) throws IOException {
FSNamesystem fs = FSNamesystem.getFSNamesystem();
fs.readLock();
try {
return inode.getFullPathName();
} finally {
fs.readUnlock();
}
}
};
private static class INodeWithHashCode {
FSInodeInfo inode;
INodeWithHashCode(FSInodeInfo inode) {
this.inode = inode;
}
@Override
public boolean equals(Object obj) {
return inode == obj;
}
@Override
public int hashCode() {
return System.identityHashCode(inode);
}
String getFullPathName() {
return inode.getFullPathName();
}
}
public String get(FSInodeInfo inode) throws IOException {
return cacheInternal.get(new INodeWithHashCode(inode));
}
}
/**
* Cache results for FSNamesystem.getBlockLocations()
*/
static class CachedLocatedBlocks extends Cache<String, List<LocatedBlock>> {
@Override
public List<LocatedBlock> getDirectly(String file) throws IOException {
FSNamesystem fs = FSNamesystem.getFSNamesystem();
long len = fs.dir.getFileInfo(file).getLen();
List<LocatedBlock> result =
fs.getBlockLocations(file, 0L, len).getLocatedBlocks();
if (result == null) {
result = new ArrayList<LocatedBlock>();
}
return Collections.synchronizedList(result);
}
}
static abstract class Cache<K, V> {
private Map<K, ValueWithTime> cache;
private static final long CACHE_TIMEOUT = 300000L; // 5 minutes
// The timeout is long but the consequence of stale value is not serious
Cache() {
Map<K, ValueWithTime> map = new LinkedHashMap<K, ValueWithTime>() {
private static final long serialVersionUID = 1L;
final private int MAX_ENTRIES = 50000;
@Override
protected boolean removeEldestEntry(
Map.Entry<K, ValueWithTime> eldest) {
return size() > MAX_ENTRIES;
}
};
this.cache = Collections.synchronizedMap(map);
}
// Note that this method may hold FSNamesystem.readLock() and it may
// be called inside FSNamesystem.writeLock(). If we make this method
// synchronized, it will deadlock.
abstract protected V getDirectly(K key) throws IOException;
public V get(K key) throws IOException {
// The method is not synchronized so we may get some stale value here but
// it's OK.
ValueWithTime result = cache.get(key);
long now = System.currentTimeMillis();
if (result != null &&
now - result.cachedTime < CACHE_TIMEOUT) {
return result.value;
}
result = new ValueWithTime();
result.value = getDirectly(key);
result.cachedTime = now;
cache.put(key, result);
return result.value;
}
private class ValueWithTime {
V value = null;
long cachedTime = 0L;
}
}
/**
* Get path for the corresponding source file for a valid parity
* file. Returns null if it does not exists
* @param parity the toUri path of the parity file
* @return the toUri path of the source file
*/
String getSourceFile(String parity, String prefix) throws IOException {
if (isHarFile(parity)) {
return null;
}
// remove the prefix
String src = parity.substring(prefix.length());
if (namesystem.dir.getFileInfo(src) == null) {
return null;
}
return src;
}
/**
* Get path for the corresponding parity file for a source file.
* Returns null if it does not exists
* @param src the toUri path of the source file
* @return the toUri path of the parity file
*/
String getParityFile(String src) throws IOException {
String xorParity = getParityFile(xorPrefix, src);
if (xorParity != null) {
return xorParity;
}
String rsParity = getParityFile(rsPrefix, src);
if (rsParity != null) {
return rsParity;
}
return null;
}
/**
* Get path for the parity file. Returns null if it does not exists
* @param parityPrefix usuall "/raid/" or "/raidrs/"
* @return the toUri path of the parity file
*/
private String getParityFile(String parityPrefix, String src)
throws IOException {
String parity = parityPrefix + src;
if (namesystem.dir.getFileInfo(parity) == null) {
return null;
}
return parity;
}
private boolean isHarFile(String path) {
return path.lastIndexOf(RaidNode.HAR_SUFFIX) != -1;
}
private boolean isXorHarTempParityFile(String path) {
return path.startsWith(raidHarTempPrefix + Path.SEPARATOR);
}
private boolean isRsHarTempParityFile(String path) {
return path.startsWith(raidrsHarTempPrefix + Path.SEPARATOR);
}
private boolean isXorTempParityFile(String path) {
return path.startsWith(raidTempPrefix + Path.SEPARATOR);
}
private boolean isRsTempParityFile(String path) {
return path.startsWith(raidrsTempPrefix + Path.SEPARATOR);
}
private boolean isXorParityFile(String path) {
return path.startsWith(xorPrefix + Path.SEPARATOR);
}
private boolean isRsParityFile(String path) {
return path.startsWith(rsPrefix + Path.SEPARATOR);
}
}