/**
* 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 static org.apache.hadoop.util.Time.monotonicNow;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.PriorityQueue;
import java.util.SortedMap;
import java.util.TreeMap;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.hdfs.server.blockmanagement.BlockInfo;
import org.apache.hadoop.hdfs.server.common.HdfsServerConstants;
import org.apache.hadoop.util.Daemon;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
/**
* 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 from the namenode
* 2.4) p gets 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
*/
@InterfaceAudience.Private
public class LeaseManager {
public static final Log LOG = LogFactory.getLog(LeaseManager.class);
private final FSNamesystem fsnamesystem;
private long softLimit = HdfsServerConstants.LEASE_SOFTLIMIT_PERIOD;
private long hardLimit = HdfsServerConstants.LEASE_HARDLIMIT_PERIOD;
//
// Used for handling lock-leases
// Mapping: leaseHolder -> Lease
//
private final SortedMap<String, Lease> leases = new TreeMap<>();
// Set of: Lease
private final PriorityQueue<Lease> sortedLeases = new PriorityQueue<>(512,
new Comparator<Lease>() {
@Override
public int compare(Lease o1, Lease o2) {
return Long.signum(o1.getLastUpdate() - o2.getLastUpdate());
}
});
// INodeID -> Lease
private final HashMap<Long, Lease> leasesById = new HashMap<>();
private Daemon lmthread;
private volatile boolean shouldRunMonitor;
LeaseManager(FSNamesystem fsnamesystem) {this.fsnamesystem = fsnamesystem;}
Lease getLease(String holder) {
return leases.get(holder);
}
/**
* This method iterates through all the leases and counts the number of blocks
* which are not COMPLETE. The FSNamesystem read lock MUST be held before
* calling this method.
*/
synchronized long getNumUnderConstructionBlocks() {
assert this.fsnamesystem.hasReadLock() : "The FSNamesystem read lock wasn't"
+ "acquired before counting under construction blocks";
long numUCBlocks = 0;
for (Long id : getINodeIdWithLeases()) {
final INodeFile cons = fsnamesystem.getFSDirectory().getInode(id).asFile();
Preconditions.checkState(cons.isUnderConstruction());
BlockInfo[] blocks = cons.getBlocks();
if(blocks == null) {
continue;
}
for(BlockInfo b : blocks) {
if(!b.isComplete())
numUCBlocks++;
}
}
LOG.info("Number of blocks under construction: " + numUCBlocks);
return numUCBlocks;
}
Collection<Long> getINodeIdWithLeases() {return leasesById.keySet();}
/** @return the lease containing src */
public synchronized Lease getLease(INodeFile src) {return leasesById.get(src.getId());}
/** @return the number of leases currently in the system */
@VisibleForTesting
public synchronized int countLease() {
return sortedLeases.size();
}
/** @return the number of paths contained in all leases */
synchronized long countPath() {
return leasesById.size();
}
/**
* Adds (or re-adds) the lease for the specified file.
*/
synchronized Lease addLease(String holder, long inodeId) {
Lease lease = getLease(holder);
if (lease == null) {
lease = new Lease(holder);
leases.put(holder, lease);
sortedLeases.add(lease);
} else {
renewLease(lease);
}
leasesById.put(inodeId, lease);
lease.files.add(inodeId);
return lease;
}
/**
* Remove the specified lease and src.
*/
private synchronized void removeLease(Lease lease, long inodeId) {
leasesById.remove(inodeId);
if (!lease.removeFile(inodeId)) {
if (LOG.isDebugEnabled()) {
LOG.debug("inode " + inodeId + " not found in lease.files (=" + lease
+ ")");
}
}
if (!lease.hasFiles()) {
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(String holder, INodeFile src) {
Lease lease = getLease(holder);
if (lease != null) {
removeLease(lease, src.getId());
} else {
LOG.warn("Removing non-existent lease! holder=" + holder +
" src=" + src.getFullPathName());
}
}
synchronized void removeAllLeases() {
sortedLeases.clear();
leasesById.clear();
leases.clear();
}
/**
* Reassign lease for file src to the new holder.
*/
synchronized Lease reassignLease(Lease lease, INodeFile src,
String newHolder) {
assert newHolder != null : "new lease holder is null";
if (lease != null) {
removeLease(lease, src.getId());
}
return addLease(newHolder, src.getId());
}
/**
* Renew the lease(s) held by the given client
*/
synchronized void renewLease(String holder) {
renewLease(getLease(holder));
}
synchronized void renewLease(Lease lease) {
if (lease != null) {
sortedLeases.remove(lease);
lease.renew();
sortedLeases.add(lease);
}
}
/**
* Renew all of the currently open leases.
*/
synchronized void renewAllLeases() {
for (Lease l : leases.values()) {
renewLease(l);
}
}
/************************************************************
* 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 {
private final String holder;
private long lastUpdate;
private final HashSet<Long> files = new HashSet<>();
/** Only LeaseManager object can create a lease */
private Lease(String holder) {
this.holder = holder;
renew();
}
/** Only LeaseManager object can renew a lease */
private void renew() {
this.lastUpdate = monotonicNow();
}
/** @return true if the Hard Limit Timer has expired */
public boolean expiredHardLimit() {
return monotonicNow() - lastUpdate > hardLimit;
}
/** @return true if the Soft Limit Timer has expired */
public boolean expiredSoftLimit() {
return monotonicNow() - lastUpdate > softLimit;
}
/** Does this lease contain any path? */
boolean hasFiles() {return !files.isEmpty();}
boolean removeFile(long inodeId) {
return files.remove(inodeId);
}
@Override
public String toString() {
return "[Lease. Holder: " + holder
+ ", pending creates: " + files.size() + "]";
}
@Override
public int hashCode() {
return holder.hashCode();
}
private Collection<Long> getFiles() {
return Collections.unmodifiableCollection(files);
}
String getHolder() {
return holder;
}
@VisibleForTesting
long getLastUpdate() {
return lastUpdate;
}
}
@VisibleForTesting
synchronized void removeLeases(Collection<Long> inodes) {
for (long inode : inodes) {
Lease lease = leasesById.get(inode);
if (lease != null) {
removeLease(lease, inode);
}
}
}
public 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. */
@Override
public void run() {
for(; shouldRunMonitor && fsnamesystem.isRunning(); ) {
boolean needSync = false;
try {
fsnamesystem.writeLockInterruptibly();
try {
if (!fsnamesystem.isInSafeMode()) {
needSync = checkLeases();
}
} finally {
fsnamesystem.writeUnlock();
// lease reassignments should to be sync'ed.
if (needSync) {
fsnamesystem.getEditLog().logSync();
}
}
Thread.sleep(HdfsServerConstants.NAMENODE_LEASE_RECHECK_INTERVAL);
} catch(InterruptedException ie) {
if (LOG.isDebugEnabled()) {
LOG.debug(name + " is interrupted", ie);
}
} catch(Throwable e) {
LOG.warn("Unexpected throwable: ", e);
}
}
}
}
/** Check the leases beginning from the oldest.
* @return true is sync is needed.
*/
@VisibleForTesting
synchronized boolean checkLeases() {
boolean needSync = false;
assert fsnamesystem.hasWriteLock();
while(!sortedLeases.isEmpty() && sortedLeases.peek().expiredHardLimit()) {
Lease leaseToCheck = sortedLeases.poll();
LOG.info(leaseToCheck + " has expired hard limit");
final List<Long> removing = new ArrayList<>();
// need to create a copy of the oldest lease files, because
// internalReleaseLease() removes files corresponding to empty files,
// i.e. it needs to modify the collection being iterated over
// causing ConcurrentModificationException
Collection<Long> files = leaseToCheck.getFiles();
Long[] leaseINodeIds = files.toArray(new Long[files.size()]);
FSDirectory fsd = fsnamesystem.getFSDirectory();
String p = null;
for(Long id : leaseINodeIds) {
try {
INodesInPath iip = INodesInPath.fromINode(fsd.getInode(id));
p = iip.getPath();
// Sanity check to make sure the path is correct
if (!p.startsWith("/")) {
throw new IOException("Invalid path in the lease " + p);
}
boolean completed = fsnamesystem.internalReleaseLease(
leaseToCheck, p, iip,
HdfsServerConstants.NAMENODE_LEASE_HOLDER);
if (LOG.isDebugEnabled()) {
if (completed) {
LOG.debug("Lease recovery for inode " + id + " is complete. " +
"File closed.");
} else {
LOG.debug("Started block recovery " + p + " lease " + leaseToCheck);
}
}
// If a lease recovery happened, we need to sync later.
if (!needSync && !completed) {
needSync = true;
}
} catch (IOException e) {
LOG.error("Cannot release the path " + p + " in the lease "
+ leaseToCheck, e);
removing.add(id);
}
}
for(Long id : removing) {
removeLease(leaseToCheck, id);
}
}
return needSync;
}
@Override
public synchronized String toString() {
return getClass().getSimpleName() + "= {"
+ "\n leases=" + leases
+ "\n sortedLeases=" + sortedLeases
+ "\n leasesById=" + leasesById
+ "\n}";
}
void startMonitor() {
Preconditions.checkState(lmthread == null,
"Lease Monitor already running");
shouldRunMonitor = true;
lmthread = new Daemon(new Monitor());
lmthread.start();
}
void stopMonitor() {
if (lmthread != null) {
shouldRunMonitor = false;
try {
lmthread.interrupt();
lmthread.join(3000);
} catch (InterruptedException ie) {
LOG.warn("Encountered exception ", ie);
}
lmthread = null;
}
}
/**
* Trigger the currently-running Lease monitor to re-check
* its leases immediately. This is for use by unit tests.
*/
@VisibleForTesting
public void triggerMonitorCheckNow() {
Preconditions.checkState(lmthread != null,
"Lease monitor is not running");
lmthread.interrupt();
}
@VisibleForTesting
public void runLeaseChecks() {
checkLeases();
}
}