/*
*
* 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.hbase.replication;
import java.util.ArrayList;
import java.util.List;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.TreeMap;
import java.util.TreeSet;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.Abortable;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.exceptions.DeserializationException;
import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
import org.apache.hadoop.hbase.protobuf.generated.ZooKeeperProtos;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.zookeeper.ZKUtil;
import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
import org.apache.hadoop.hbase.zookeeper.ZKUtil.ZKUtilOp;
import org.apache.zookeeper.KeeperException;
/**
* This class provides an implementation of the ReplicationQueues interface using Zookeeper. The
* base znode that this class works at is the myQueuesZnode. The myQueuesZnode contains a list of
* all outstanding WAL files on this region server that need to be replicated. The myQueuesZnode is
* the regionserver name (a concatenation of the region server’s hostname, client port and start
* code). For example:
*
* /hbase/replication/rs/hostname.example.org,6020,1234
*
* Within this znode, the region server maintains a set of WAL replication queues. These queues are
* represented by child znodes named using there give queue id. For example:
*
* /hbase/replication/rs/hostname.example.org,6020,1234/1
* /hbase/replication/rs/hostname.example.org,6020,1234/2
*
* Each queue has one child znode for every WAL that still needs to be replicated. The value of
* these WAL child znodes is the latest position that has been replicated. This position is updated
* every time a WAL entry is replicated. For example:
*
* /hbase/replication/rs/hostname.example.org,6020,1234/1/23522342.23422 [VALUE: 254]
*/
@InterfaceAudience.Private
public class ReplicationQueuesZKImpl extends ReplicationStateZKBase implements ReplicationQueues {
/** Znode containing all replication queues for this region server. */
private String myQueuesZnode;
/** Name of znode we use to lock during failover */
private final static String RS_LOCK_ZNODE = "lock";
private static final Log LOG = LogFactory.getLog(ReplicationQueuesZKImpl.class);
public ReplicationQueuesZKImpl(final ZooKeeperWatcher zk, Configuration conf,
Abortable abortable) {
super(zk, conf, abortable);
}
@Override
public void init(String serverName) throws ReplicationException {
this.myQueuesZnode = ZKUtil.joinZNode(this.queuesZNode, serverName);
try {
ZKUtil.createWithParents(this.zookeeper, this.myQueuesZnode);
} catch (KeeperException e) {
throw new ReplicationException("Could not initialize replication queues.", e);
}
}
@Override
public void removeQueue(String queueId) {
try {
ZKUtil.deleteNodeRecursively(this.zookeeper, ZKUtil.joinZNode(this.myQueuesZnode, queueId));
} catch (KeeperException e) {
this.abortable.abort("Failed to delete queue (queueId=" + queueId + ")", e);
}
}
@Override
public void addLog(String queueId, String filename) throws ReplicationException {
String znode = ZKUtil.joinZNode(this.myQueuesZnode, queueId);
znode = ZKUtil.joinZNode(znode, filename);
try {
ZKUtil.createWithParents(this.zookeeper, znode);
} catch (KeeperException e) {
throw new ReplicationException(
"Could not add log because znode could not be created. queueId=" + queueId
+ ", filename=" + filename);
}
}
@Override
public void removeLog(String queueId, String filename) {
try {
String znode = ZKUtil.joinZNode(this.myQueuesZnode, queueId);
znode = ZKUtil.joinZNode(znode, filename);
ZKUtil.deleteNode(this.zookeeper, znode);
} catch (KeeperException e) {
this.abortable.abort("Failed to remove wal from queue (queueId=" + queueId + ", filename="
+ filename + ")", e);
}
}
@Override
public void setLogPosition(String queueId, String filename, long position) {
try {
String znode = ZKUtil.joinZNode(this.myQueuesZnode, queueId);
znode = ZKUtil.joinZNode(znode, filename);
// Why serialize String of Long and not Long as bytes?
ZKUtil.setData(this.zookeeper, znode, ZKUtil.positionToByteArray(position));
} catch (KeeperException e) {
this.abortable.abort("Failed to write replication wal position (filename=" + filename
+ ", position=" + position + ")", e);
}
}
@Override
public long getLogPosition(String queueId, String filename) throws ReplicationException {
String clusterZnode = ZKUtil.joinZNode(this.myQueuesZnode, queueId);
String znode = ZKUtil.joinZNode(clusterZnode, filename);
byte[] bytes = null;
try {
bytes = ZKUtil.getData(this.zookeeper, znode);
} catch (KeeperException e) {
throw new ReplicationException("Internal Error: could not get position in log for queueId="
+ queueId + ", filename=" + filename, e);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
return 0;
}
try {
return ZKUtil.parseWALPositionFrom(bytes);
} catch (DeserializationException de) {
LOG.warn("Failed to parse WALPosition for queueId=" + queueId + " and wal=" + filename
+ "znode content, continuing.");
}
// if we can not parse the position, start at the beginning of the wal file
// again
return 0;
}
@Override
public boolean isThisOurZnode(String znode) {
return ZKUtil.joinZNode(this.queuesZNode, znode).equals(this.myQueuesZnode);
}
@Override
public SortedMap<String, SortedSet<String>> claimQueues(String regionserverZnode) {
SortedMap<String, SortedSet<String>> newQueues = new TreeMap<String, SortedSet<String>>();
// check whether there is multi support. If yes, use it.
if (conf.getBoolean(HConstants.ZOOKEEPER_USEMULTI, true)) {
LOG.info("Atomically moving " + regionserverZnode + "'s wals to my queue");
newQueues = copyQueuesFromRSUsingMulti(regionserverZnode);
} else {
LOG.info("Moving " + regionserverZnode + "'s wals to my queue");
if (!lockOtherRS(regionserverZnode)) {
return newQueues;
}
newQueues = copyQueuesFromRS(regionserverZnode);
deleteAnotherRSQueues(regionserverZnode);
}
return newQueues;
}
@Override
public void removeAllQueues() {
try {
ZKUtil.deleteNodeRecursively(this.zookeeper, this.myQueuesZnode);
} catch (KeeperException e) {
// if the znode is already expired, don't bother going further
if (e instanceof KeeperException.SessionExpiredException) {
return;
}
this.abortable.abort("Failed to delete replication queues for region server: "
+ this.myQueuesZnode, e);
}
}
@Override
public List<String> getLogsInQueue(String queueId) {
String znode = ZKUtil.joinZNode(this.myQueuesZnode, queueId);
List<String> result = null;
try {
result = ZKUtil.listChildrenNoWatch(this.zookeeper, znode);
} catch (KeeperException e) {
this.abortable.abort("Failed to get list of wals for queueId=" + queueId, e);
}
return result;
}
@Override
public List<String> getAllQueues() {
List<String> listOfQueues = null;
try {
listOfQueues = ZKUtil.listChildrenNoWatch(this.zookeeper, this.myQueuesZnode);
} catch (KeeperException e) {
this.abortable.abort("Failed to get a list of queues for region server: "
+ this.myQueuesZnode, e);
}
return listOfQueues;
}
/**
* Try to set a lock in another region server's znode.
* @param znode the server names of the other server
* @return true if the lock was acquired, false in every other cases
*/
private boolean lockOtherRS(String znode) {
try {
String parent = ZKUtil.joinZNode(this.queuesZNode, znode);
if (parent.equals(this.myQueuesZnode)) {
LOG.warn("Won't lock because this is us, we're dead!");
return false;
}
String p = ZKUtil.joinZNode(parent, RS_LOCK_ZNODE);
ZKUtil.createAndWatch(this.zookeeper, p, lockToByteArray(this.myQueuesZnode));
} catch (KeeperException e) {
// This exception will pop up if the znode under which we're trying to
// create the lock is already deleted by another region server, meaning
// that the transfer already occurred.
// NoNode => transfer is done and znodes are already deleted
// NodeExists => lock znode already created by another RS
if (e instanceof KeeperException.NoNodeException
|| e instanceof KeeperException.NodeExistsException) {
LOG.info("Won't transfer the queue," + " another RS took care of it because of: "
+ e.getMessage());
} else {
LOG.info("Failed lock other rs", e);
}
return false;
}
return true;
}
/**
* Delete all the replication queues for a given region server.
* @param regionserverZnode The znode of the region server to delete.
*/
private void deleteAnotherRSQueues(String regionserverZnode) {
String fullpath = ZKUtil.joinZNode(this.queuesZNode, regionserverZnode);
try {
List<String> clusters = ZKUtil.listChildrenNoWatch(this.zookeeper, fullpath);
for (String cluster : clusters) {
// No need to delete, it will be deleted later.
if (cluster.equals(RS_LOCK_ZNODE)) {
continue;
}
String fullClusterPath = ZKUtil.joinZNode(fullpath, cluster);
ZKUtil.deleteNodeRecursively(this.zookeeper, fullClusterPath);
}
// Finish cleaning up
ZKUtil.deleteNodeRecursively(this.zookeeper, fullpath);
} catch (KeeperException e) {
if (e instanceof KeeperException.NoNodeException
|| e instanceof KeeperException.NotEmptyException) {
// Testing a special case where another region server was able to
// create a lock just after we deleted it, but then was also able to
// delete the RS znode before us or its lock znode is still there.
if (e.getPath().equals(fullpath)) {
return;
}
}
this.abortable.abort("Failed to delete replication queues for region server: "
+ regionserverZnode, e);
}
}
/**
* It "atomically" copies all the wals queues from another region server and returns them all
* sorted per peer cluster (appended with the dead server's znode).
* @param znode pertaining to the region server to copy the queues from
* @return WAL queues sorted per peer cluster
*/
private SortedMap<String, SortedSet<String>> copyQueuesFromRSUsingMulti(String znode) {
SortedMap<String, SortedSet<String>> queues = new TreeMap<String, SortedSet<String>>();
// hbase/replication/rs/deadrs
String deadRSZnodePath = ZKUtil.joinZNode(this.queuesZNode, znode);
List<String> peerIdsToProcess = null;
List<ZKUtilOp> listOfOps = new ArrayList<ZKUtil.ZKUtilOp>();
try {
peerIdsToProcess = ZKUtil.listChildrenNoWatch(this.zookeeper, deadRSZnodePath);
if (peerIdsToProcess == null) return queues; // node already processed
for (String peerId : peerIdsToProcess) {
ReplicationQueueInfo replicationQueueInfo = new ReplicationQueueInfo(peerId);
if (!peerExists(replicationQueueInfo.getPeerId())) {
LOG.warn("Peer " + peerId + " didn't exist, skipping the replay");
// Protection against moving orphaned queues
continue;
}
String newPeerId = peerId + "-" + znode;
String newPeerZnode = ZKUtil.joinZNode(this.myQueuesZnode, newPeerId);
// check the logs queue for the old peer cluster
String oldClusterZnode = ZKUtil.joinZNode(deadRSZnodePath, peerId);
List<String> wals = ZKUtil.listChildrenNoWatch(this.zookeeper, oldClusterZnode);
if (wals == null || wals.size() == 0) {
listOfOps.add(ZKUtilOp.deleteNodeFailSilent(oldClusterZnode));
continue; // empty log queue.
}
// create the new cluster znode
SortedSet<String> logQueue = new TreeSet<String>();
queues.put(newPeerId, logQueue);
ZKUtilOp op = ZKUtilOp.createAndFailSilent(newPeerZnode, HConstants.EMPTY_BYTE_ARRAY);
listOfOps.add(op);
// get the offset of the logs and set it to new znodes
for (String wal : wals) {
String oldWalZnode = ZKUtil.joinZNode(oldClusterZnode, wal);
byte[] logOffset = ZKUtil.getData(this.zookeeper, oldWalZnode);
LOG.debug("Creating " + wal + " with data " + Bytes.toString(logOffset));
String newLogZnode = ZKUtil.joinZNode(newPeerZnode, wal);
listOfOps.add(ZKUtilOp.createAndFailSilent(newLogZnode, logOffset));
// add ops for deleting
listOfOps.add(ZKUtilOp.deleteNodeFailSilent(oldWalZnode));
logQueue.add(wal);
}
// add delete op for peer
listOfOps.add(ZKUtilOp.deleteNodeFailSilent(oldClusterZnode));
}
// add delete op for dead rs
listOfOps.add(ZKUtilOp.deleteNodeFailSilent(deadRSZnodePath));
LOG.debug(" The multi list size is: " + listOfOps.size());
ZKUtil.multiOrSequential(this.zookeeper, listOfOps, false);
LOG.info("Atomically moved the dead regionserver logs. ");
} catch (KeeperException e) {
// Multi call failed; it looks like some other regionserver took away the logs.
LOG.warn("Got exception in copyQueuesFromRSUsingMulti: ", e);
queues.clear();
} catch (InterruptedException e) {
LOG.warn("Got exception in copyQueuesFromRSUsingMulti: ", e);
queues.clear();
Thread.currentThread().interrupt();
}
return queues;
}
/**
* This methods copies all the wals queues from another region server and returns them all sorted
* per peer cluster (appended with the dead server's znode)
* @param znode server names to copy
* @return all wals for all peers of that cluster, null if an error occurred
*/
private SortedMap<String, SortedSet<String>> copyQueuesFromRS(String znode) {
// TODO this method isn't atomic enough, we could start copying and then
// TODO fail for some reason and we would end up with znodes we don't want.
SortedMap<String, SortedSet<String>> queues = new TreeMap<String, SortedSet<String>>();
try {
String nodePath = ZKUtil.joinZNode(this.queuesZNode, znode);
List<String> clusters = ZKUtil.listChildrenNoWatch(this.zookeeper, nodePath);
// We have a lock znode in there, it will count as one.
if (clusters == null || clusters.size() <= 1) {
return queues;
}
// The lock isn't a peer cluster, remove it
clusters.remove(RS_LOCK_ZNODE);
for (String cluster : clusters) {
ReplicationQueueInfo replicationQueueInfo = new ReplicationQueueInfo(cluster);
if (!peerExists(replicationQueueInfo.getPeerId())) {
LOG.warn("Peer " + cluster + " didn't exist, skipping the replay");
// Protection against moving orphaned queues
continue;
}
// We add the name of the recovered RS to the new znode, we can even
// do that for queues that were recovered 10 times giving a znode like
// number-startcode-number-otherstartcode-number-anotherstartcode-etc
String newCluster = cluster + "-" + znode;
String newClusterZnode = ZKUtil.joinZNode(this.myQueuesZnode, newCluster);
String clusterPath = ZKUtil.joinZNode(nodePath, cluster);
List<String> wals = ZKUtil.listChildrenNoWatch(this.zookeeper, clusterPath);
// That region server didn't have anything to replicate for this cluster
if (wals == null || wals.size() == 0) {
continue;
}
ZKUtil.createNodeIfNotExistsAndWatch(this.zookeeper, newClusterZnode,
HConstants.EMPTY_BYTE_ARRAY);
SortedSet<String> logQueue = new TreeSet<String>();
queues.put(newCluster, logQueue);
for (String wal : wals) {
String z = ZKUtil.joinZNode(clusterPath, wal);
byte[] positionBytes = ZKUtil.getData(this.zookeeper, z);
long position = 0;
try {
position = ZKUtil.parseWALPositionFrom(positionBytes);
} catch (DeserializationException e) {
LOG.warn("Failed parse of wal position from the following znode: " + z
+ ", Exception: " + e);
}
LOG.debug("Creating " + wal + " with data " + position);
String child = ZKUtil.joinZNode(newClusterZnode, wal);
// Position doesn't actually change, we are just deserializing it for
// logging, so just use the already serialized version
ZKUtil.createAndWatch(this.zookeeper, child, positionBytes);
logQueue.add(wal);
}
}
} catch (KeeperException e) {
this.abortable.abort("Copy queues from rs", e);
} catch (InterruptedException e) {
LOG.warn(e);
Thread.currentThread().interrupt();
}
return queues;
}
/**
* @param lockOwner
* @return Serialized protobuf of <code>lockOwner</code> with pb magic prefix prepended suitable
* for use as content of an replication lock during region server fail over.
*/
static byte[] lockToByteArray(final String lockOwner) {
byte[] bytes =
ZooKeeperProtos.ReplicationLock.newBuilder().setLockOwner(lockOwner).build().toByteArray();
return ProtobufUtil.prependPBMagic(bytes);
}
}