/**
*
* 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.regionserver;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.hbase.HRegionInfo;
import org.apache.hadoop.hbase.RegionTransition;
import org.apache.hadoop.hbase.Server;
import org.apache.hadoop.hbase.ServerName;
import org.apache.hadoop.hbase.catalog.MetaEditor;
import org.apache.hadoop.hbase.executor.EventType;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.CancelableProgressable;
import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
import org.apache.hadoop.hbase.util.HasThread;
import org.apache.hadoop.hbase.util.PairOfSameType;
import org.apache.hadoop.hbase.zookeeper.ZKAssign;
import org.apache.hadoop.hbase.zookeeper.ZKUtil;
import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.KeeperException.NodeExistsException;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
/**
* Executes region split as a "transaction". Call {@link #prepare()} to setup
* the transaction, {@link #execute(Server, RegionServerServices)} to run the
* transaction and {@link #rollback(Server, RegionServerServices)} to cleanup if execute fails.
*
* <p>Here is an example of how you would use this class:
* <pre>
* SplitTransaction st = new SplitTransaction(this.conf, parent, midKey)
* if (!st.prepare()) return;
* try {
* st.execute(server, services);
* } catch (IOException ioe) {
* try {
* st.rollback(server, services);
* return;
* } catch (RuntimeException e) {
* myAbortable.abort("Failed split, abort");
* }
* }
* </Pre>
* <p>This class is not thread safe. Caller needs ensure split is run by
* one thread only.
*/
@InterfaceAudience.Private
public class SplitTransaction {
private static final Log LOG = LogFactory.getLog(SplitTransaction.class);
/*
* Region to split
*/
private final HRegion parent;
private HRegionInfo hri_a;
private HRegionInfo hri_b;
private long fileSplitTimeout = 30000;
private int znodeVersion = -1;
/*
* Row to split around
*/
private final byte [] splitrow;
/**
* Types to add to the transaction journal.
* Each enum is a step in the split transaction. Used to figure how much
* we need to rollback.
*/
enum JournalEntry {
/**
* Set region as in transition, set it into SPLITTING state.
*/
SET_SPLITTING_IN_ZK,
/**
* We created the temporary split data directory.
*/
CREATE_SPLIT_DIR,
/**
* Closed the parent region.
*/
CLOSED_PARENT_REGION,
/**
* The parent has been taken out of the server's online regions list.
*/
OFFLINED_PARENT,
/**
* Started in on creation of the first daughter region.
*/
STARTED_REGION_A_CREATION,
/**
* Started in on the creation of the second daughter region.
*/
STARTED_REGION_B_CREATION,
/**
* Point of no return.
* If we got here, then transaction is not recoverable other than by
* crashing out the regionserver.
*/
PONR
}
/*
* Journal of how far the split transaction has progressed.
*/
private final List<JournalEntry> journal = new ArrayList<JournalEntry>();
/**
* Constructor
* @param r Region to split
* @param splitrow Row to split around
*/
public SplitTransaction(final HRegion r, final byte [] splitrow) {
this.parent = r;
this.splitrow = splitrow;
}
/**
* Does checks on split inputs.
* @return <code>true</code> if the region is splittable else
* <code>false</code> if it is not (e.g. its already closed, etc.).
*/
public boolean prepare() {
if (!this.parent.isSplittable()) return false;
// Split key can be null if this region is unsplittable; i.e. has refs.
if (this.splitrow == null) return false;
HRegionInfo hri = this.parent.getRegionInfo();
parent.prepareToSplit();
// Check splitrow.
byte [] startKey = hri.getStartKey();
byte [] endKey = hri.getEndKey();
if (Bytes.equals(startKey, splitrow) ||
!this.parent.getRegionInfo().containsRow(splitrow)) {
LOG.info("Split row is not inside region key range or is equal to " +
"startkey: " + Bytes.toStringBinary(this.splitrow));
return false;
}
long rid = getDaughterRegionIdTimestamp(hri);
this.hri_a = new HRegionInfo(hri.getTableName(), startKey, this.splitrow, false, rid);
this.hri_b = new HRegionInfo(hri.getTableName(), this.splitrow, endKey, false, rid);
return true;
}
/**
* Calculate daughter regionid to use.
* @param hri Parent {@link HRegionInfo}
* @return Daughter region id (timestamp) to use.
*/
private static long getDaughterRegionIdTimestamp(final HRegionInfo hri) {
long rid = EnvironmentEdgeManager.currentTimeMillis();
// Regionid is timestamp. Can't be less than that of parent else will insert
// at wrong location in .META. (See HBASE-710).
if (rid < hri.getRegionId()) {
LOG.warn("Clock skew; parent regions id is " + hri.getRegionId() +
" but current time here is " + rid);
rid = hri.getRegionId() + 1;
}
return rid;
}
private static IOException closedByOtherException = new IOException(
"Failed to close region: already closed by another thread");
/**
* Prepare the regions and region files.
* @param server Hosting server instance. Can be null when testing (won't try
* and update in zk if a null server)
* @param services Used to online/offline regions.
* @throws IOException If thrown, transaction failed.
* Call {@link #rollback(Server, RegionServerServices)}
* @return Regions created
*/
/* package */PairOfSameType<HRegion> createDaughters(final Server server,
final RegionServerServices services) throws IOException {
LOG.info("Starting split of region " + this.parent);
if ((server != null && server.isStopped()) ||
(services != null && services.isStopping())) {
throw new IOException("Server is stopped or stopping");
}
assert !this.parent.lock.writeLock().isHeldByCurrentThread():
"Unsafe to hold write lock while performing RPCs";
// Coprocessor callback
if (this.parent.getCoprocessorHost() != null) {
this.parent.getCoprocessorHost().preSplit();
}
// Coprocessor callback
if (this.parent.getCoprocessorHost() != null) {
this.parent.getCoprocessorHost().preSplit(this.splitrow);
}
// If true, no cluster to write meta edits to or to update znodes in.
boolean testing = server == null? true:
server.getConfiguration().getBoolean("hbase.testing.nocluster", false);
this.fileSplitTimeout = testing ? this.fileSplitTimeout :
server.getConfiguration().getLong("hbase.regionserver.fileSplitTimeout",
this.fileSplitTimeout);
// Set ephemeral SPLITTING znode up in zk. Mocked servers sometimes don't
// have zookeeper so don't do zk stuff if server or zookeeper is null
if (server != null && server.getZooKeeper() != null) {
try {
createNodeSplitting(server.getZooKeeper(),
this.parent.getRegionInfo(), server.getServerName());
} catch (KeeperException e) {
throw new IOException("Failed creating SPLITTING znode on " +
this.parent.getRegionNameAsString(), e);
}
}
this.journal.add(JournalEntry.SET_SPLITTING_IN_ZK);
if (server != null && server.getZooKeeper() != null) {
try {
// Transition node from SPLITTING to SPLITTING after creating the split node.
// Master will get the callback for node change only if the transition is successful.
// Note that if the transition fails then the rollback will delete the created znode
// as the journal entry SET_SPLITTING_IN_ZK is added.
// TODO : May be we can add some new state to znode and handle the new state incase
// of success/failure
this.znodeVersion = transitionNodeSplitting(server.getZooKeeper(),
this.parent.getRegionInfo(), server.getServerName(), -1);
} catch (KeeperException e) {
throw new IOException("Failed setting SPLITTING znode on "
+ this.parent.getRegionNameAsString(), e);
}
}
this.parent.getRegionFileSystem().createSplitsDir();
this.journal.add(JournalEntry.CREATE_SPLIT_DIR);
Map<byte[], List<StoreFile>> hstoreFilesToSplit = null;
Exception exceptionToThrow = null;
try{
hstoreFilesToSplit = this.parent.close(false);
} catch (Exception e) {
exceptionToThrow = e;
}
if (exceptionToThrow == null && hstoreFilesToSplit == null) {
// The region was closed by a concurrent thread. We can't continue
// with the split, instead we must just abandon the split. If we
// reopen or split this could cause problems because the region has
// probably already been moved to a different server, or is in the
// process of moving to a different server.
exceptionToThrow = closedByOtherException;
}
if (exceptionToThrow != closedByOtherException) {
this.journal.add(JournalEntry.CLOSED_PARENT_REGION);
}
if (exceptionToThrow != null) {
if (exceptionToThrow instanceof IOException) throw (IOException)exceptionToThrow;
throw new IOException(exceptionToThrow);
}
if (!testing) {
services.removeFromOnlineRegions(this.parent, null);
}
this.journal.add(JournalEntry.OFFLINED_PARENT);
// TODO: If splitStoreFiles were multithreaded would we complete steps in
// less elapsed time? St.Ack 20100920
//
// splitStoreFiles creates daughter region dirs under the parent splits dir
// Nothing to unroll here if failure -- clean up of CREATE_SPLIT_DIR will
// clean this up.
splitStoreFiles(hstoreFilesToSplit);
// Log to the journal that we are creating region A, the first daughter
// region. We could fail halfway through. If we do, we could have left
// stuff in fs that needs cleanup -- a storefile or two. Thats why we
// add entry to journal BEFORE rather than AFTER the change.
this.journal.add(JournalEntry.STARTED_REGION_A_CREATION);
HRegion a = this.parent.createDaughterRegionFromSplits(this.hri_a);
// Ditto
this.journal.add(JournalEntry.STARTED_REGION_B_CREATION);
HRegion b = this.parent.createDaughterRegionFromSplits(this.hri_b);
// This is the point of no return. Adding subsequent edits to .META. as we
// do below when we do the daughter opens adding each to .META. can fail in
// various interesting ways the most interesting of which is a timeout
// BUT the edits all go through (See HBASE-3872). IF we reach the PONR
// then subsequent failures need to crash out this regionserver; the
// server shutdown processing should be able to fix-up the incomplete split.
// The offlined parent will have the daughters as extra columns. If
// we leave the daughter regions in place and do not remove them when we
// crash out, then they will have their references to the parent in place
// still and the server shutdown fixup of .META. will point to these
// regions.
// We should add PONR JournalEntry before offlineParentInMeta,so even if
// OfflineParentInMeta timeout,this will cause regionserver exit,and then
// master ServerShutdownHandler will fix daughter & avoid data loss. (See
// HBase-4562).
this.journal.add(JournalEntry.PONR);
// Edit parent in meta. Offlines parent region and adds splita and splitb
// as an atomic update. See HBASE-7721. This update to META makes the region
// will determine whether the region is split or not in case of failures.
// If it is successful, master will roll-forward, if not, master will rollback
// and assign the parent region.
if (!testing) {
MetaEditor.splitRegion(server.getCatalogTracker(), parent.getRegionInfo(),
a.getRegionInfo(), b.getRegionInfo(), server.getServerName());
}
return new PairOfSameType<HRegion>(a, b);
}
/**
* Perform time consuming opening of the daughter regions.
* @param server Hosting server instance. Can be null when testing (won't try
* and update in zk if a null server)
* @param services Used to online/offline regions.
* @param a first daughter region
* @param a second daughter region
* @throws IOException If thrown, transaction failed.
* Call {@link #rollback(Server, RegionServerServices)}
*/
/* package */void openDaughters(final Server server,
final RegionServerServices services, HRegion a, HRegion b)
throws IOException {
boolean stopped = server != null && server.isStopped();
boolean stopping = services != null && services.isStopping();
// TODO: Is this check needed here?
if (stopped || stopping) {
LOG.info("Not opening daughters " +
b.getRegionInfo().getRegionNameAsString() +
" and " +
a.getRegionInfo().getRegionNameAsString() +
" because stopping=" + stopping + ", stopped=" + stopped);
} else {
// Open daughters in parallel.
DaughterOpener aOpener = new DaughterOpener(server, a);
DaughterOpener bOpener = new DaughterOpener(server, b);
aOpener.start();
bOpener.start();
try {
aOpener.join();
bOpener.join();
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new IOException("Interrupted " + e.getMessage());
}
if (aOpener.getException() != null) {
throw new IOException("Failed " +
aOpener.getName(), aOpener.getException());
}
if (bOpener.getException() != null) {
throw new IOException("Failed " +
bOpener.getName(), bOpener.getException());
}
if (services != null) {
try {
// add 2nd daughter first (see HBASE-4335)
services.postOpenDeployTasks(b, server.getCatalogTracker());
// Should add it to OnlineRegions
services.addToOnlineRegions(b);
services.postOpenDeployTasks(a, server.getCatalogTracker());
services.addToOnlineRegions(a);
} catch (KeeperException ke) {
throw new IOException(ke);
}
}
}
}
/**
* Finish off split transaction, transition the zknode
* @param server Hosting server instance. Can be null when testing (won't try
* and update in zk if a null server)
* @param services Used to online/offline regions.
* @param a first daughter region
* @param a second daughter region
* @throws IOException If thrown, transaction failed.
* Call {@link #rollback(Server, RegionServerServices)}
*/
/* package */void transitionZKNode(final Server server,
final RegionServerServices services, HRegion a, HRegion b)
throws IOException {
// Tell master about split by updating zk. If we fail, abort.
if (server != null && server.getZooKeeper() != null) {
try {
this.znodeVersion = transitionNodeSplit(server.getZooKeeper(),
parent.getRegionInfo(), a.getRegionInfo(), b.getRegionInfo(),
server.getServerName(), this.znodeVersion);
int spins = 0;
// Now wait for the master to process the split. We know it's done
// when the znode is deleted. The reason we keep tickling the znode is
// that it's possible for the master to miss an event.
do {
if (spins % 10 == 0) {
LOG.debug("Still waiting on the master to process the split for " +
this.parent.getRegionInfo().getEncodedName());
}
Thread.sleep(100);
// When this returns -1 it means the znode doesn't exist
this.znodeVersion = tickleNodeSplit(server.getZooKeeper(),
parent.getRegionInfo(), a.getRegionInfo(), b.getRegionInfo(),
server.getServerName(), this.znodeVersion);
spins++;
} while (this.znodeVersion != -1 && !server.isStopped()
&& !services.isStopping());
} catch (Exception e) {
if (e instanceof InterruptedException) {
Thread.currentThread().interrupt();
}
throw new IOException("Failed telling master about split", e);
}
}
// Coprocessor callback
if (this.parent.getCoprocessorHost() != null) {
this.parent.getCoprocessorHost().postSplit(a,b);
}
// Leaving here, the splitdir with its dross will be in place but since the
// split was successful, just leave it; it'll be cleaned when parent is
// deleted and cleaned up.
}
/**
* Run the transaction.
* @param server Hosting server instance. Can be null when testing (won't try
* and update in zk if a null server)
* @param services Used to online/offline regions.
* @throws IOException If thrown, transaction failed.
* Call {@link #rollback(Server, RegionServerServices)}
* @return Regions created
* @throws IOException
* @see #rollback(Server, RegionServerServices)
*/
public PairOfSameType<HRegion> execute(final Server server,
final RegionServerServices services)
throws IOException {
PairOfSameType<HRegion> regions = createDaughters(server, services);
openDaughters(server, services, regions.getFirst(), regions.getSecond());
transitionZKNode(server, services, regions.getFirst(), regions.getSecond());
return regions;
}
/*
* Open daughter region in its own thread.
* If we fail, abort this hosting server.
*/
class DaughterOpener extends HasThread {
private final Server server;
private final HRegion r;
private Throwable t = null;
DaughterOpener(final Server s, final HRegion r) {
super((s == null? "null-services": s.getServerName()) +
"-daughterOpener=" + r.getRegionInfo().getEncodedName());
setDaemon(true);
this.server = s;
this.r = r;
}
/**
* @return Null if open succeeded else exception that causes us fail open.
* Call it after this thread exits else you may get wrong view on result.
*/
Throwable getException() {
return this.t;
}
@Override
public void run() {
try {
openDaughterRegion(this.server, r);
} catch (Throwable t) {
this.t = t;
}
}
}
/**
* Open daughter regions, add them to online list and update meta.
* @param server
* @param daughter
* @throws IOException
* @throws KeeperException
*/
void openDaughterRegion(final Server server, final HRegion daughter)
throws IOException, KeeperException {
HRegionInfo hri = daughter.getRegionInfo();
LoggingProgressable reporter = server == null ? null
: new LoggingProgressable(hri, server.getConfiguration().getLong(
"hbase.regionserver.split.daughter.open.log.interval", 10000));
daughter.openHRegion(reporter);
}
static class LoggingProgressable implements CancelableProgressable {
private final HRegionInfo hri;
private long lastLog = -1;
private final long interval;
LoggingProgressable(final HRegionInfo hri, final long interval) {
this.hri = hri;
this.interval = interval;
}
@Override
public boolean progress() {
long now = System.currentTimeMillis();
if (now - lastLog > this.interval) {
LOG.info("Opening " + this.hri.getRegionNameAsString());
this.lastLog = now;
}
return true;
}
}
private void splitStoreFiles(final Map<byte[], List<StoreFile>> hstoreFilesToSplit)
throws IOException {
if (hstoreFilesToSplit == null) {
// Could be null because close didn't succeed -- for now consider it fatal
throw new IOException("Close returned empty list of StoreFiles");
}
// The following code sets up a thread pool executor with as many slots as
// there's files to split. It then fires up everything, waits for
// completion and finally checks for any exception
int nbFiles = hstoreFilesToSplit.size();
if (nbFiles == 0) {
// no file needs to be splitted.
return;
}
ThreadFactoryBuilder builder = new ThreadFactoryBuilder();
builder.setNameFormat("StoreFileSplitter-%1$d");
ThreadFactory factory = builder.build();
ThreadPoolExecutor threadPool =
(ThreadPoolExecutor) Executors.newFixedThreadPool(nbFiles, factory);
List<Future<Void>> futures = new ArrayList<Future<Void>>(nbFiles);
// Split each store file.
for (Map.Entry<byte[], List<StoreFile>> entry: hstoreFilesToSplit.entrySet()) {
for (StoreFile sf: entry.getValue()) {
StoreFileSplitter sfs = new StoreFileSplitter(entry.getKey(), sf);
futures.add(threadPool.submit(sfs));
}
}
// Shutdown the pool
threadPool.shutdown();
// Wait for all the tasks to finish
try {
boolean stillRunning = !threadPool.awaitTermination(
this.fileSplitTimeout, TimeUnit.MILLISECONDS);
if (stillRunning) {
threadPool.shutdownNow();
// wait for the thread to shutdown completely.
while (!threadPool.isTerminated()) {
Thread.sleep(50);
}
throw new IOException("Took too long to split the" +
" files and create the references, aborting split");
}
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new IOException("Interrupted while waiting for file splitters", e);
}
// Look for any exception
for (Future<Void> future: futures) {
try {
future.get();
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new IOException(
"Interrupted while trying to get the results of file splitters", e);
} catch (ExecutionException e) {
throw new IOException(e);
}
}
}
private void splitStoreFile(final byte[] family, final StoreFile sf) throws IOException {
HRegionFileSystem fs = this.parent.getRegionFileSystem();
String familyName = Bytes.toString(family);
fs.splitStoreFile(this.hri_a, familyName, sf, this.splitrow, false);
fs.splitStoreFile(this.hri_b, familyName, sf, this.splitrow, true);
}
/**
* Utility class used to do the file splitting / reference writing
* in parallel instead of sequentially.
*/
class StoreFileSplitter implements Callable<Void> {
private final byte[] family;
private final StoreFile sf;
/**
* Constructor that takes what it needs to split
* @param family Family that contains the store file
* @param sf which file
*/
public StoreFileSplitter(final byte[] family, final StoreFile sf) {
this.sf = sf;
this.family = family;
}
public Void call() throws IOException {
splitStoreFile(family, sf);
return null;
}
}
/**
* @param server Hosting server instance (May be null when testing).
* @param services
* @throws IOException If thrown, rollback failed. Take drastic action.
* @return True if we successfully rolled back, false if we got to the point
* of no return and so now need to abort the server to minimize damage.
*/
public boolean rollback(final Server server, final RegionServerServices services)
throws IOException {
// Coprocessor callback
if (this.parent.getCoprocessorHost() != null) {
this.parent.getCoprocessorHost().preRollBackSplit();
}
boolean result = true;
ListIterator<JournalEntry> iterator =
this.journal.listIterator(this.journal.size());
// Iterate in reverse.
while (iterator.hasPrevious()) {
JournalEntry je = iterator.previous();
switch(je) {
case SET_SPLITTING_IN_ZK:
if (server != null && server.getZooKeeper() != null) {
cleanZK(server, this.parent.getRegionInfo());
}
break;
case CREATE_SPLIT_DIR:
this.parent.writestate.writesEnabled = true;
this.parent.getRegionFileSystem().cleanupSplitsDir();
break;
case CLOSED_PARENT_REGION:
try {
// So, this returns a seqid but if we just closed and then reopened, we
// should be ok. On close, we flushed using sequenceid obtained from
// hosting regionserver so no need to propagate the sequenceid returned
// out of initialize below up into regionserver as we normally do.
// TODO: Verify.
this.parent.initialize();
} catch (IOException e) {
LOG.error("Failed rollbacking CLOSED_PARENT_REGION of region " +
this.parent.getRegionNameAsString(), e);
throw new RuntimeException(e);
}
break;
case STARTED_REGION_A_CREATION:
this.parent.getRegionFileSystem().cleanupDaughterRegion(this.hri_a);
break;
case STARTED_REGION_B_CREATION:
this.parent.getRegionFileSystem().cleanupDaughterRegion(this.hri_b);
break;
case OFFLINED_PARENT:
if (services != null) services.addToOnlineRegions(this.parent);
break;
case PONR:
// We got to the point-of-no-return so we need to just abort. Return
// immediately. Do not clean up created daughter regions. They need
// to be in place so we don't delete the parent region mistakenly.
// See HBASE-3872.
return false;
default:
throw new RuntimeException("Unhandled journal entry: " + je);
}
}
// Coprocessor callback
if (this.parent.getCoprocessorHost() != null) {
this.parent.getCoprocessorHost().postRollBackSplit();
}
return result;
}
HRegionInfo getFirstDaughter() {
return hri_a;
}
HRegionInfo getSecondDaughter() {
return hri_b;
}
private static void cleanZK(final Server server, final HRegionInfo hri) {
try {
// Only delete if its in expected state; could have been hijacked.
ZKAssign.deleteNode(server.getZooKeeper(), hri.getEncodedName(),
EventType.RS_ZK_REGION_SPLITTING);
} catch (KeeperException e) {
server.abort("Failed cleanup of " + hri.getRegionNameAsString(), e);
}
}
/**
* Creates a new ephemeral node in the SPLITTING state for the specified region.
* Create it ephemeral in case regionserver dies mid-split.
*
* <p>Does not transition nodes from other states. If a node already exists
* for this region, a {@link NodeExistsException} will be thrown.
*
* @param zkw zk reference
* @param region region to be created as offline
* @param serverName server event originates from
* @return Version of znode created.
* @throws KeeperException
* @throws IOException
*/
int createNodeSplitting(final ZooKeeperWatcher zkw, final HRegionInfo region,
final ServerName serverName) throws KeeperException, IOException {
LOG.debug(zkw.prefix("Creating ephemeral node for " +
region.getEncodedName() + " in SPLITTING state"));
RegionTransition rt = RegionTransition.createRegionTransition(EventType.RS_ZK_REGION_SPLITTING,
region.getRegionName(), serverName);
String node = ZKAssign.getNodeName(zkw, region.getEncodedName());
if (!ZKUtil.createEphemeralNodeAndWatch(zkw, node, rt.toByteArray())) {
throw new IOException("Failed create of ephemeral " + node);
}
// Transition node from SPLITTING to SPLITTING and pick up version so we
// can be sure this znode is ours; version is needed deleting.
return transitionNodeSplitting(zkw, region, serverName, -1);
}
/**
* Transitions an existing node for the specified region which is
* currently in the SPLITTING state to be in the SPLIT state. Converts the
* ephemeral SPLITTING znode to an ephemeral SPLIT node. Master cleans up
* SPLIT znode when it reads it (or if we crash, zk will clean it up).
*
* <p>Does not transition nodes from other states. If for some reason the
* node could not be transitioned, the method returns -1. If the transition
* is successful, the version of the node after transition is returned.
*
* <p>This method can fail and return false for three different reasons:
* <ul><li>Node for this region does not exist</li>
* <li>Node for this region is not in SPLITTING state</li>
* <li>After verifying SPLITTING state, update fails because of wrong version
* (this should never actually happen since an RS only does this transition
* following a transition to SPLITTING. if two RS are conflicting, one would
* fail the original transition to SPLITTING and not this transition)</li>
* </ul>
*
* <p>Does not set any watches.
*
* <p>This method should only be used by a RegionServer when completing the
* open of a region.
*
* @param zkw zk reference
* @param parent region to be transitioned to opened
* @param a Daughter a of split
* @param b Daughter b of split
* @param serverName server event originates from
* @return version of node after transition, -1 if unsuccessful transition
* @throws KeeperException if unexpected zookeeper exception
* @throws IOException
*/
private static int transitionNodeSplit(ZooKeeperWatcher zkw,
HRegionInfo parent, HRegionInfo a, HRegionInfo b, ServerName serverName,
final int znodeVersion)
throws KeeperException, IOException {
byte [] payload = HRegionInfo.toDelimitedByteArray(a, b);
return ZKAssign.transitionNode(zkw, parent, serverName,
EventType.RS_ZK_REGION_SPLITTING, EventType.RS_ZK_REGION_SPLIT,
znodeVersion, payload);
}
/**
*
* @param zkw zk reference
* @param parent region to be transitioned to splitting
* @param serverName server event originates from
* @param version znode version
* @return version of node after transition, -1 if unsuccessful transition
* @throws KeeperException
* @throws IOException
*/
int transitionNodeSplitting(final ZooKeeperWatcher zkw, final HRegionInfo parent,
final ServerName serverName, final int version) throws KeeperException, IOException {
return ZKAssign.transitionNode(zkw, parent, serverName,
EventType.RS_ZK_REGION_SPLITTING, EventType.RS_ZK_REGION_SPLITTING, version);
}
private static int tickleNodeSplit(ZooKeeperWatcher zkw,
HRegionInfo parent, HRegionInfo a, HRegionInfo b, ServerName serverName,
final int znodeVersion)
throws KeeperException, IOException {
byte [] payload = HRegionInfo.toDelimitedByteArray(a, b);
return ZKAssign.transitionNode(zkw, parent, serverName,
EventType.RS_ZK_REGION_SPLIT, EventType.RS_ZK_REGION_SPLIT,
znodeVersion, payload);
}
}