/**
* 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.dfs;
import java.io.IOException;
import java.util.*;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
/**
* LeaseManager does the lease housekeeping for writing on files.
* This class also provides useful static methods for lease recovery.
*
* Lease Recovery Algorithm
* 1) Namenode retrieves lease information
* 2) For each file f in the lease, consider the last block b of f
* 2.1) Get the datanodes which contains b
* 2.2) Assign one of the datanodes as the primary datanode p
* 2.3) p obtains a new generation stamp form the namenode
* 2.4) p get the block info from each datanode
* 2.5) p computes the minimum block length
* 2.6) p updates the datanodes, which have a valid generation stamp,
* with the new generation stamp and the minimum block length
* 2.7) p acknowledges the namenode the update results
* 2.8) Namenode updates the BlockInfo
* 2.9) Namenode removes f from the lease
* and removes the lease once all files have been removed
* 2.10) Namenode commit changes to edit log
*/
class LeaseManager {
static final Log LOG = LogFactory.getLog(LeaseManager.class);
private final FSNamesystem fsnamesystem;
private long softLimit = FSConstants.LEASE_SOFTLIMIT_PERIOD;
private long hardLimit = FSConstants.LEASE_HARDLIMIT_PERIOD;
//
// Used for handling lock-leases
// Mapping: leaseHolder -> Lease
//
private SortedMap<StringBytesWritable, Lease> leases = new TreeMap<StringBytesWritable, Lease>();
// Set of: Lease
private SortedSet<Lease> sortedLeases = new TreeSet<Lease>();
//
// Map path names to leases. It is protected by the sortedLeases lock.
// The map stores pathnames in lexicographical order.
//
private SortedMap<String, Lease> sortedLeasesByPath = new TreeMap<String, Lease>();
LeaseManager(FSNamesystem fsnamesystem) {this.fsnamesystem = fsnamesystem;}
Lease getLease(StringBytesWritable holder) throws IOException {
return leases.get(holder);
}
SortedSet<Lease> getSortedLeases() {return sortedLeases;}
/** @return the lease containing src */
Lease getLeaseByPath(String src) {return sortedLeasesByPath.get(src);}
/** list of blocks being recovered */
private static Map<Block, Block> ongoingRecovery = new HashMap<Block, Block>();
/** @return the number of leases currently in the system */
synchronized int countLease() {return sortedLeases.size();}
/** @return the number of paths contained in all leases */
synchronized int countPath() {
int count = 0;
for(Lease lease : sortedLeases) {
count += lease.getPaths().size();
}
return count;
}
/**
* Adds (or re-adds) the lease for the specified file.
*/
synchronized void addLease(StringBytesWritable holder, String src
) throws IOException {
Lease lease = getLease(holder);
if (lease == null) {
lease = new Lease(holder);
leases.put(holder, lease);
sortedLeases.add(lease);
} else {
renewLease(lease);
}
sortedLeasesByPath.put(src, lease);
lease.paths.add(new StringBytesWritable(src));
}
/**
* Remove the specified lease and src.
*/
synchronized void removeLease(Lease lease, String src) throws IOException {
sortedLeasesByPath.remove(src);
if (!lease.removePath(src)) {
LOG.error(src + " not found in lease.paths (=" + lease.paths + ")");
}
if (!lease.hasPath()) {
leases.remove(lease.holder);
if (!sortedLeases.remove(lease)) {
LOG.error(lease + " not found in sortedLeases");
}
}
}
/**
* Remove the lease for the specified holder and src
*/
synchronized void removeLease(StringBytesWritable holder, String src
) throws IOException {
Lease lease = getLease(holder);
if (lease != null) {
removeLease(lease, src);
}
}
/**
* Finds the pathname for the specified pendingFile
*/
synchronized String findPath(INodeFileUnderConstruction pendingFile
) throws IOException {
Lease lease = getLease(pendingFile.clientName);
if (lease != null) {
String src = lease.findPath(pendingFile);
if (src != null) {
return src;
}
}
throw new IOException("pendingFile (=" + pendingFile + ") not found."
+ "(lease=" + lease + ")");
}
/**
* Renew the lease(s) held by the given client
*/
synchronized void renewLease(String holder) throws IOException {
renewLease(getLease(new StringBytesWritable(holder)));
}
synchronized void renewLease(Lease lease) {
if (lease != null) {
sortedLeases.remove(lease);
lease.renew();
sortedLeases.add(lease);
}
}
/************************************************************
* A Lease governs all the locks held by a single client.
* For each client there's a corresponding lease, whose
* timestamp is updated when the client periodically
* checks in. If the client dies and allows its lease to
* expire, all the corresponding locks can be released.
*************************************************************/
class Lease implements Comparable<Lease> {
private StringBytesWritable holder;
private long lastUpdate;
private Collection<StringBytesWritable> paths = new TreeSet<StringBytesWritable>();
/** Only LeaseManager object can create a lease */
private Lease(StringBytesWritable holder) throws IOException {
this.holder = holder;
renew();
}
/** Only LeaseManager object can renew a lease */
private void renew() {
this.lastUpdate = FSNamesystem.now();
}
/** @return true if the Hard Limit Timer has expired */
public boolean expiredHardLimit() {
return FSNamesystem.now() - lastUpdate > hardLimit;
}
/** @return true if the Soft Limit Timer has expired */
public boolean expiredSoftLimit() {
return FSNamesystem.now() - lastUpdate > softLimit;
}
/**
* @return the path associated with the pendingFile and null if not found.
*/
private String findPath(INodeFileUnderConstruction pendingFile) {
for(Iterator<StringBytesWritable> i = paths.iterator(); i.hasNext(); ) {
String src = i.next().toString();
if (fsnamesystem.dir.getFileINode(src) == pendingFile) {
return src;
}
}
return null;
}
/** Does this lease contain any path? */
boolean hasPath() {return !paths.isEmpty();}
boolean removePath(String src) throws IOException {
return paths.remove(new StringBytesWritable(src));
}
/** {@inheritDoc} */
public String toString() {
return "[Lease. Holder: " + holder
+ ", pendingcreates: " + paths.size() + "]";
}
/** {@inheritDoc} */
public int compareTo(Lease o) {
Lease l1 = this;
Lease l2 = o;
long lu1 = l1.lastUpdate;
long lu2 = l2.lastUpdate;
if (lu1 < lu2) {
return -1;
} else if (lu1 > lu2) {
return 1;
} else {
return l1.holder.compareTo(l2.holder);
}
}
/** {@inheritDoc} */
public boolean equals(Object o) {
if (!(o instanceof Lease)) {
return false;
}
Lease obj = (Lease) o;
if (lastUpdate == obj.lastUpdate &&
holder.equals(obj.holder)) {
return true;
}
return false;
}
/** {@inheritDoc} */
public int hashCode() {
return holder.hashCode();
}
Collection<StringBytesWritable> getPaths() {
return paths;
}
void replacePath(String oldpath, String newpath) throws IOException {
paths.remove(new StringBytesWritable(oldpath));
paths.add(new StringBytesWritable(newpath));
}
}
synchronized void changeLease(String src, String dst,
String overwrite, String replaceBy) throws IOException {
if (LOG.isDebugEnabled()) {
LOG.debug(getClass().getSimpleName() + ".changelease: " +
" src=" + src + ", dest=" + dst +
", overwrite=" + overwrite +
", replaceBy=" + replaceBy);
}
for(Map.Entry<String, Lease> entry : findLeaseWithPrefixPath(src, sortedLeasesByPath)) {
final String oldpath = entry.getKey();
final Lease lease = entry.getValue();
final String newpath = oldpath.replaceFirst(
java.util.regex.Pattern.quote(overwrite), replaceBy);
if (LOG.isDebugEnabled()) {
LOG.debug("changeLease: replacing " + oldpath + " with " + newpath);
}
lease.replacePath(oldpath, newpath);
sortedLeasesByPath.remove(oldpath);
sortedLeasesByPath.put(newpath, lease);
}
}
synchronized void removeLeaseWithPrefixPath(String prefix) throws IOException {
for(Map.Entry<String, Lease> entry : findLeaseWithPrefixPath(prefix, sortedLeasesByPath)) {
if (LOG.isDebugEnabled()) {
LOG.debug(LeaseManager.class.getSimpleName()
+ ".removeLeaseWithPrefixPath: entry=" + entry);
}
removeLease(entry.getValue(), entry.getKey());
}
}
static private List<Map.Entry<String, Lease>> findLeaseWithPrefixPath(
String prefix, SortedMap<String, Lease> path2lease) {
if (LOG.isDebugEnabled()) {
LOG.debug(LeaseManager.class.getSimpleName() + ".findLease: prefix=" + prefix);
}
List<Map.Entry<String, Lease>> entries = new ArrayList<Map.Entry<String, Lease>>();
final int srclen = prefix.length();
for(Map.Entry<String, Lease> entry : path2lease.tailMap(prefix).entrySet()) {
final String p = entry.getKey();
if (!p.startsWith(prefix)) {
return entries;
}
if (p.length() == srclen || p.charAt(srclen) == Path.SEPARATOR_CHAR) {
entries.add(entry);
}
}
return entries;
}
void setLeasePeriod(long softLimit, long hardLimit) {
this.softLimit = softLimit;
this.hardLimit = hardLimit;
}
/******************************************************
* Monitor checks for leases that have expired,
* and disposes of them.
******************************************************/
class Monitor implements Runnable {
final String name = getClass().getSimpleName();
/** Check leases periodically. */
public void run() {
for(; fsnamesystem.isRunning(); ) {
synchronized(fsnamesystem) {
checkLeases();
}
try {
Thread.sleep(2000);
} catch(InterruptedException ie) {
if (LOG.isDebugEnabled()) {
LOG.debug(name + " is interrupted", ie);
}
}
}
}
}
/** Check the leases beginning from the oldest. */
private synchronized void checkLeases() {
for(; sortedLeases.size() > 0; ) {
final Lease oldest = sortedLeases.first();
if (!oldest.expiredHardLimit()) {
return;
}
LOG.info("Lease " + oldest + " has expired hard limit");
final List<StringBytesWritable> removing = new ArrayList<StringBytesWritable>();
// need to create a copy of the oldest lease paths, becuase
// internalReleaseLease() removes paths corresponding to empty files,
// i.e. it needs to modify the collection being iterated over
// causing ConcurrentModificationException
StringBytesWritable[] leasePaths = new StringBytesWritable[oldest.getPaths().size()];
oldest.getPaths().toArray(leasePaths);
for(StringBytesWritable p : leasePaths) {
try {
fsnamesystem.internalReleaseLease(oldest, p.getString());
} catch (IOException e) {
LOG.error("Cannot release the path "+p+" in the lease "+oldest, e);
removing.add(p);
}
}
for(StringBytesWritable p : removing) {
try {
removeLease(oldest, p.getString());
} catch (IOException e) {
LOG.error("Cannot removeLease: oldest=" + oldest + ", p=" + p, e);
}
}
}
}
/** {@inheritDoc} */
public synchronized String toString() {
return getClass().getSimpleName() + "= {"
+ "\n leases=" + leases
+ "\n sortedLeases=" + sortedLeases
+ "\n sortedLeasesByPath=" + sortedLeasesByPath
+ "\n}";
}
/*
* The following codes provides useful static methods for lease recovery.
*/
/** A convenient class used in lease recovery */
private static class BlockRecord {
final DatanodeID id;
final InterDatanodeProtocol datanode;
final Block block;
BlockRecord(DatanodeID id, InterDatanodeProtocol datanode, Block block) {
this.id = id;
this.datanode = datanode;
this.block = block;
}
public String toString() {
return "block:" + block + " node:" + id;
}
}
/**
* Recover a list of blocks.
* This method is invoked by the primary datanode.
*/
static void recoverBlocks(Block[] blocks, DatanodeID[][] targets,
DataNode primary, DatanodeProtocol namenode, Configuration conf) {
for(int i = 0; i < blocks.length; i++) {
try {
DataNode.logRecoverBlock("NameNode", blocks[i], targets[i]);
recoverBlock(blocks[i], targets[i], primary, namenode, conf, true);
} catch (IOException e) {
LOG.warn("recoverBlocks FAILED, blocks[" + i + "]=" + blocks[i], e);
}
}
}
/** Recover a block */
static Block recoverBlock(Block block, DatanodeID[] datanodeids,
DataNode primary, DatanodeProtocol namenode, Configuration conf,
boolean closeFile) throws IOException {
// If the block is already being recovered, then skip recovering it.
// This can happen if the namenode and client start recovering the same
// file at the same time.
synchronized (ongoingRecovery) {
Block tmp = new Block();
tmp.set(block.blkid, block.len, GenerationStamp.WILDCARD_STAMP);
if (ongoingRecovery.get(tmp) != null) {
String msg = "Block " + block + " is already being recovered, " +
" ignoring this request to recover it.";
LOG.info(msg);
throw new IOException(msg);
}
ongoingRecovery.put(block, block);
}
try {
List<BlockRecord> syncList = new ArrayList<BlockRecord>();
long minlength = Long.MAX_VALUE;
int errorCount = 0;
//check generation stamps
for(DatanodeID id : datanodeids) {
try {
InterDatanodeProtocol datanode = primary.dnRegistration.equals(id)?
primary: DataNode.createInterDataNodeProtocolProxy(id, conf);
BlockMetaDataInfo info = datanode.getBlockMetaDataInfo(block);
if (info != null && info.getGenerationStamp() >= block.generationStamp) {
syncList.add(new BlockRecord(id, datanode, new Block(info)));
if (info.len < minlength) {
minlength = info.len;
}
}
} catch (IOException e) {
++errorCount;
InterDatanodeProtocol.LOG.warn(
"Failed to getBlockMetaDataInfo for block (=" + block
+ ") from datanode (=" + id + ")", e);
}
}
if (syncList.isEmpty() && errorCount > 0) {
throw new IOException("All datanodes failed: block=" + block
+ ", datanodeids=" + Arrays.asList(datanodeids));
}
return syncBlock(block, minlength, syncList, namenode, closeFile);
} finally {
synchronized (ongoingRecovery) {
ongoingRecovery.remove(block);
}
}
}
/** Block synchronization */
private static Block syncBlock(Block block, long minlength,
List<BlockRecord> syncList, DatanodeProtocol namenode,
boolean closeFile) throws IOException {
if (LOG.isDebugEnabled()) {
LOG.debug("block=" + block + ", minlength=" + minlength
+ ", syncList=" + syncList + ", closeFile=" + closeFile);
}
//syncList.isEmpty() that all datanodes do not have the block
//so the block can be deleted.
if (syncList.isEmpty()) {
namenode.commitBlockSynchronization(block, 0, 0, closeFile, true,
DatanodeID.EMPTY_ARRAY);
return null;
}
List<DatanodeID> successList = new ArrayList<DatanodeID>();
long generationstamp = namenode.nextGenerationStamp(block);
Block newblock = new Block(block.blkid, minlength, generationstamp);
for(BlockRecord r : syncList) {
try {
r.datanode.updateBlock(r.block, newblock, closeFile);
successList.add(r.id);
} catch (IOException e) {
InterDatanodeProtocol.LOG.warn("Failed to updateBlock (newblock="
+ newblock + ", datanode=" + r.id + ")", e);
}
}
if (!successList.isEmpty()) {
namenode.commitBlockSynchronization(block,
newblock.generationStamp, newblock.len, closeFile, false,
successList.toArray(new DatanodeID[successList.size()]));
return newblock; // success
}
//failed
StringBuilder b = new StringBuilder();
for(BlockRecord r : syncList) {
b.append("\n " + r.id);
}
throw new IOException("Cannot recover " + block + ", none of these "
+ syncList.size() + " datanodes success {" + b + "\n}"); }
}