/**
    *
    * 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.io.InterruptedIOException;
  import java.security.PrivilegedExceptionAction;
  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.fs.Path;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.Server;
  import org.apache.hadoop.hbase.ServerName;
  import org.apache.hadoop.hbase.client.Mutation;
  import org.apache.hadoop.hbase.client.Put;
  import org.apache.hadoop.hbase.protobuf.generated.RegionServerStatusProtos.RegionStateTransition.TransitionCode;
  import org.apache.hadoop.hbase.security.User;
  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.FSUtils;
  import org.apache.hadoop.hbase.util.HasThread;
  import org.apache.hadoop.hbase.util.Pair;
  import org.apache.hadoop.hbase.util.PairOfSameType;
  import org.apache.zookeeper.KeeperException;
  
  import com.google.common.annotations.VisibleForTesting;
  import com.google.common.util.concurrent.ThreadFactoryBuilder;
  
  @InterfaceAudience.Private
  public class SplitTransactionImpl implements SplitTransaction {
    private static final Log LOG = LogFactory.getLog(SplitTransactionImpl.class);
  
    /*
     * Region to split
     */
    private final HRegion parent;
    private HRegionInfo hri_a;
    private HRegionInfo hri_b;
    private long fileSplitTimeout = 30000;
  
    /*
     * Row to split around
     */
    private final byte [] splitrow;
  
    /*
     * Transaction state for listener, only valid during execute and
     * rollback
     */
    private SplitTransactionPhase currentPhase = SplitTransactionPhase.STARTED;
    private Server server;
    private RegionServerServices rsServices;
  
    public static class JournalEntryImpl implements JournalEntry {
      private SplitTransactionPhase type;
      private long timestamp;
  
      public JournalEntryImpl(SplitTransactionPhase type) {
        this(type, EnvironmentEdgeManager.currentTime());
      }
  
      public JournalEntryImpl(SplitTransactionPhase type, long timestamp) {
        this.type = type;
        this.timestamp = timestamp;
      }
  
      @Override
      public String toString() {
       StringBuilder sb = new StringBuilder();
       sb.append(type);
       sb.append(" at ");
       sb.append(timestamp);
       return sb.toString();
     }
 
     @Override
     public SplitTransactionPhase getPhase() {
       return type;
     }
 
     @Override
     public long getTimeStamp() {
       return timestamp;
     }
   }
 
   /*
    * Journal of how far the split transaction has progressed.
    */
   private final ArrayList<JournalEntry> journal = new ArrayList<JournalEntry>();
 
   /**
    * Listeners
    */
   private final ArrayList<TransactionListener> listeners = new ArrayList<TransactionListener>();
 
   /**
    * Constructor
    * @param r Region to split
    * @param splitrow Row to split around
    */
   public SplitTransactionImpl(final Region r, final byte [] splitrow) {
     this.parent = (HRegion)r;
     this.splitrow = splitrow;
     this.journal.add(new JournalEntryImpl(SplitTransactionPhase.STARTED));
   }
 
   private void transition(SplitTransactionPhase nextPhase) throws IOException {
     transition(nextPhase, false);
   }
 
   private void transition(SplitTransactionPhase nextPhase, boolean isRollback)
       throws IOException {
     if (!isRollback) {
       // Add to the journal first, because if the listener throws an exception
       // we need to roll back starting at 'nextPhase'
       this.journal.add(new JournalEntryImpl(nextPhase));
     }
     for (int i = 0; i < listeners.size(); i++) {
       TransactionListener listener = listeners.get(i);
       if (!isRollback) {
         listener.transition(this, currentPhase, nextPhase);
       } else {
         listener.rollback(this, currentPhase, nextPhase);
       }
     }
     currentPhase = nextPhase;
   }
 
   @Override
   public boolean prepare() throws IOException {
     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.getTable(), startKey, this.splitrow, false, rid);
     this.hri_b = new HRegionInfo(hri.getTable(), this.splitrow, endKey, false, rid);
 
     transition(SplitTransactionPhase.PREPARED);
 
     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.currentTime();
     // Regionid is timestamp.  Can't be less than that of parent else will insert
     // at wrong location in hbase: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.
    * @param user
    * @throws IOException If thrown, transaction failed.
    *    Call {@link #rollback(Server, RegionServerServices)}
    * @return Regions created
    */
   @VisibleForTesting
   PairOfSameType<Region> createDaughters(final Server server,
       final RegionServerServices services, User user) 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";
 
     transition(SplitTransactionPhase.BEFORE_PRE_SPLIT_HOOK);
 
     // Coprocessor callback
     if (this.parent.getCoprocessorHost() != null) {
       if (user == null) {
         // TODO: Remove one of these
         parent.getCoprocessorHost().preSplit();
         parent.getCoprocessorHost().preSplit(splitrow);
       } else {
         try {
           user.getUGI().doAs(new PrivilegedExceptionAction<Void>() {
             @Override
             public Void run() throws Exception {
               parent.getCoprocessorHost().preSplit();
               parent.getCoprocessorHost().preSplit(splitrow);
               return null;
             }
           });
         } catch (InterruptedException ie) {
           InterruptedIOException iioe = new InterruptedIOException();
           iioe.initCause(ie);
           throw iioe;
         }
       }
     }
 
     transition(SplitTransactionPhase.AFTER_PRE_SPLIT_HOOK);
 
     // 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);
 
     PairOfSameType<Region> daughterRegions = stepsBeforePONR(server, services, testing);
 
     final List<Mutation> metaEntries = new ArrayList<Mutation>();
     boolean ret = false;
     if (this.parent.getCoprocessorHost() != null) {
       if (user == null) {
         ret = parent.getCoprocessorHost().preSplitBeforePONR(splitrow, metaEntries);
       } else {
         try {
           ret = user.getUGI().doAs(new PrivilegedExceptionAction<Boolean>() {
             @Override
             public Boolean run() throws Exception {
               return parent.getCoprocessorHost().preSplitBeforePONR(splitrow, metaEntries);
             }
           });
         } catch (InterruptedException ie) {
           InterruptedIOException iioe = new InterruptedIOException();
           iioe.initCause(ie);
           throw iioe;
         }
       }
       if (ret) {
           throw new IOException("Coprocessor bypassing region "
             + parent.getRegionInfo().getRegionNameAsString() + " split.");
       }
       try {
         for (Mutation p : metaEntries) {
           HRegionInfo.parseRegionName(p.getRow());
         }
       } catch (IOException e) {
         LOG.error("Row key of mutation from coprossor is not parsable as region name."
             + "Mutations from coprocessor should only for hbase:meta table.");
         throw e;
       }
     }
 
     // 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).
 
     transition(SplitTransactionPhase.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 (services != null && !services.reportRegionStateTransition(TransitionCode.SPLIT_PONR,
         parent.getRegionInfo(), hri_a, hri_b)) {
       // Passed PONR, let SSH clean it up
       throw new IOException("Failed to notify master that split passed PONR: "
         + parent.getRegionInfo().getRegionNameAsString());
     }
     return daughterRegions;
   }
 
   @VisibleForTesting
   Put addLocation(final Put p, final ServerName sn, long openSeqNum) {
     p.addColumn(HConstants.CATALOG_FAMILY, HConstants.SERVER_QUALIFIER, Bytes
             .toBytes(sn.getHostAndPort()));
     p.addColumn(HConstants.CATALOG_FAMILY, HConstants.STARTCODE_QUALIFIER, Bytes.toBytes(sn
             .getStartcode()));
     p.addColumn(HConstants.CATALOG_FAMILY, HConstants.SEQNUM_QUALIFIER, Bytes.toBytes(openSeqNum));
     return p;
   }
 
   @VisibleForTesting
   public PairOfSameType<Region> stepsBeforePONR(final Server server,
       final RegionServerServices services, boolean testing) throws IOException {
     if (services != null && !services.reportRegionStateTransition(TransitionCode.READY_TO_SPLIT,
         parent.getRegionInfo(), hri_a, hri_b)) {
       throw new IOException("Failed to get ok from master to split "
         + parent.getRegionInfo().getRegionNameAsString());
     }
 
     transition(SplitTransactionPhase.SET_SPLITTING);
 
     this.parent.getRegionFileSystem().createSplitsDir();
 
     transition(SplitTransactionPhase.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) {
       transition(SplitTransactionPhase.CLOSED_PARENT_REGION);
     }
     if (exceptionToThrow != null) {
       if (exceptionToThrow instanceof IOException) throw (IOException)exceptionToThrow;
       throw new IOException(exceptionToThrow);
     }
     if (!testing) {
       services.removeFromOnlineRegions(this.parent, null);
     }
 
     transition(SplitTransactionPhase.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.
     Pair<Integer, Integer> expectedReferences = 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.
 
     transition(SplitTransactionPhase.STARTED_REGION_A_CREATION);
 
     assertReferenceFileCount(expectedReferences.getFirst(),
         this.parent.getRegionFileSystem().getSplitsDir(this.hri_a));
     HRegion a = this.parent.createDaughterRegionFromSplits(this.hri_a);
     assertReferenceFileCount(expectedReferences.getFirst(),
         new Path(this.parent.getRegionFileSystem().getTableDir(), this.hri_a.getEncodedName()));
 
     // Ditto
 
     transition(SplitTransactionPhase.STARTED_REGION_B_CREATION);
 
     assertReferenceFileCount(expectedReferences.getSecond(),
         this.parent.getRegionFileSystem().getSplitsDir(this.hri_b));
     HRegion b = this.parent.createDaughterRegionFromSplits(this.hri_b);
     assertReferenceFileCount(expectedReferences.getSecond(),
         new Path(this.parent.getRegionFileSystem().getTableDir(), this.hri_b.getEncodedName()));
 
     return new PairOfSameType<Region>(a, b);
   }
 
   @VisibleForTesting
   void assertReferenceFileCount(int expectedReferenceFileCount, Path dir)
       throws IOException {
     if (expectedReferenceFileCount != 0 &&
         expectedReferenceFileCount != FSUtils.getRegionReferenceFileCount(parent.getFilesystem(),
           dir)) {
       throw new IOException("Failing split. Expected reference file count isn't equal.");
     }
   }
 
   /**
    * Perform time consuming opening of the daughter regions.
    * @param server Hosting server instance.  Can be null when testing
    * @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)}
    */
   @VisibleForTesting
   void openDaughters(final Server server, final RegionServerServices services, Region a,
       Region 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();
         if (aOpener.getException() == null) {
           transition(SplitTransactionPhase.OPENED_REGION_A);
         }
         bOpener.join();
         if (bOpener.getException() == null) {
           transition(SplitTransactionPhase.OPENED_REGION_B);
         }
       } catch (InterruptedException e) {
         throw (InterruptedIOException)new InterruptedIOException().initCause(e);
       }
       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) {
         if (!services.reportRegionStateTransition(TransitionCode.SPLIT,
             parent.getRegionInfo(), hri_a, hri_b)) {
           throw new IOException("Failed to report split region to master: "
             + parent.getRegionInfo().getShortNameToLog());
         }
         // Should add it to OnlineRegions
         services.addToOnlineRegions(b);
         services.addToOnlineRegions(a);
       }
     }
   }
 
   @Override
   public PairOfSameType<Region> execute(final Server server,
     final RegionServerServices services)
         throws IOException {
     if (User.isHBaseSecurityEnabled(parent.getBaseConf())) {
       LOG.warn("Should use execute(Server, RegionServerServices, User)");
     }
     return execute(server, services, null);
   }
 
   @Override
   public PairOfSameType<Region> execute(final Server server, final RegionServerServices services,
     User user) throws IOException {
     this.server = server;
     this.rsServices = services;
     PairOfSameType<Region> regions = createDaughters(server, services, user);
     stepsAfterPONR(server, services, regions, user);
     transition(SplitTransactionPhase.COMPLETED);
     return regions;
   }
 
   @VisibleForTesting
   void stepsAfterPONR(final Server server,
       final RegionServerServices services, final PairOfSameType<Region> regions, User user)
       throws IOException {
     if (this.parent.getCoprocessorHost() != null) {
       if (user == null) {
         parent.getCoprocessorHost().preSplitAfterPONR();
       } else {
         try {
           user.getUGI().doAs(new PrivilegedExceptionAction<Void>() {
             @Override
             public Void run() throws Exception {
               parent.getCoprocessorHost().preSplitAfterPONR();
               return null;
             }
           });
         } catch (InterruptedException ie) {
           InterruptedIOException iioe = new InterruptedIOException();
           iioe.initCause(ie);
           throw iioe;
         }
       }
     }
 
     openDaughters(server, services, regions.getFirst(), regions.getSecond());
 
     transition(SplitTransactionPhase.BEFORE_POST_SPLIT_HOOK);
 
     // Coprocessor callback
     if (parent.getCoprocessorHost() != null) {
       if (user == null) {
         this.parent.getCoprocessorHost().postSplit(regions.getFirst(), regions.getSecond());
       } else {
         try {
           user.getUGI().doAs(new PrivilegedExceptionAction<Void>() {
             @Override
             public Void run() throws Exception {
               parent.getCoprocessorHost().postSplit(regions.getFirst(), regions.getSecond());
               return null;
             }
           });
         } catch (InterruptedException ie) {
           InterruptedIOException iioe = new InterruptedIOException();
           iioe.initCause(ie);
           throw iioe;
         }
       }
     }
 
     transition(SplitTransactionPhase.AFTER_POST_SPLIT_HOOK);
   }
 
   /*
    * Open daughter region in its own thread.
    * If we fail, abort this hosting server.
    */
   private class DaughterOpener extends HasThread {
     private final Server server;
     private final Region r;
     private Throwable t = null;
 
     DaughterOpener(final Server s, final Region 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
    */
   @VisibleForTesting
   void openDaughterRegion(final Server server, final Region 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));
     ((HRegion)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 = EnvironmentEdgeManager.currentTime();
       if (now - lastLog > this.interval) {
         LOG.info("Opening " + this.hri.getRegionNameAsString());
         this.lastLog = now;
       }
       return true;
     }
   }
 
   /**
    * Creates reference files for top and bottom half of the
    * @param hstoreFilesToSplit map of store files to create half file references for.
    * @return the number of reference files that were created.
    * @throws IOException
    */
   private Pair<Integer, Integer> 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 = 0;
     for (Map.Entry<byte[], List<StoreFile>> entry: hstoreFilesToSplit.entrySet()) {
         nbFiles += entry.getValue().size();
     }
     if (nbFiles == 0) {
       // no file needs to be splitted.
       return new Pair<Integer, Integer>(0,0);
     }
     // Default max #threads to use is the smaller of table's configured number of blocking store
     // files or the available number of logical cores.
     int defMaxThreads = Math.min(parent.conf.getInt(HStore.BLOCKING_STOREFILES_KEY,
                 HStore.DEFAULT_BLOCKING_STOREFILE_COUNT),
             Runtime.getRuntime().availableProcessors());
     // Max #threads is the smaller of the number of storefiles or the default max determined above.
     int maxThreads = Math.min(parent.conf.getInt(HConstants.REGION_SPLIT_THREADS_MAX,
                 defMaxThreads), nbFiles);
     LOG.info("Preparing to split " + nbFiles + " storefiles for region " + this.parent +
             " using " + maxThreads + " threads");
     ThreadFactoryBuilder builder = new ThreadFactoryBuilder();
     builder.setNameFormat("StoreFileSplitter-%1$d");
     ThreadFactory factory = builder.build();
     ThreadPoolExecutor threadPool =
       (ThreadPoolExecutor) Executors.newFixedThreadPool(maxThreads, factory);
     List<Future<Pair<Path,Path>>> futures = new ArrayList<Future<Pair<Path,Path>>> (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) {
       throw (InterruptedIOException)new InterruptedIOException().initCause(e);
     }
 
     int created_a = 0;
     int created_b = 0;
     // Look for any exception
     for (Future<Pair<Path, Path>> future : futures) {
       try {
         Pair<Path, Path> p = future.get();
         created_a += p.getFirst() != null ? 1 : 0;
         created_b += p.getSecond() != null ? 1 : 0;
       } catch (InterruptedException e) {
         throw (InterruptedIOException) new InterruptedIOException().initCause(e);
       } catch (ExecutionException e) {
         throw new IOException(e);
       }
     }
 
     if (LOG.isDebugEnabled()) {
       LOG.debug("Split storefiles for region " + this.parent + " Daughter A: " + created_a
           + " storefiles, Daughter B: " + created_b + " storefiles.");
     }
     return new Pair<Integer, Integer>(created_a, created_b);
   }
 
   private Pair<Path, Path> splitStoreFile(final byte[] family, final StoreFile sf)
       throws IOException {
     if (LOG.isDebugEnabled()) {
         LOG.debug("Splitting started for store file: " + sf.getPath() + " for region: " +
                   this.parent);
     }
     HRegionFileSystem fs = this.parent.getRegionFileSystem();
     String familyName = Bytes.toString(family);
     Path path_a =
         fs.splitStoreFile(this.hri_a, familyName, sf, this.splitrow, false,
           this.parent.getSplitPolicy());
     Path path_b =
         fs.splitStoreFile(this.hri_b, familyName, sf, this.splitrow, true,
           this.parent.getSplitPolicy());
     if (LOG.isDebugEnabled()) {
         LOG.debug("Splitting complete for store file: " + sf.getPath() + " for region: " +
                   this.parent);
     }
     return new Pair<Path,Path>(path_a, path_b);
   }
 
   /**
    * Utility class used to do the file splitting / reference writing
    * in parallel instead of sequentially.
    */
   private class StoreFileSplitter implements Callable<Pair<Path,Path>> {
     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 Pair<Path,Path> call() throws IOException {
       return splitStoreFile(family, sf);
     }
   }
 
   @Override
   public boolean rollback(final Server server, final RegionServerServices services)
       throws IOException {
     if (User.isHBaseSecurityEnabled(parent.getBaseConf())) {
       LOG.warn("Should use rollback(Server, RegionServerServices, User)");
     }
     return rollback(server, services, null);
   }
 
   @Override
   public boolean rollback(final Server server, final RegionServerServices services, User user)
       throws IOException {
     this.server = server;
     this.rsServices = services;
     // Coprocessor callback
     if (this.parent.getCoprocessorHost() != null) {
       if (user == null) {
         this.parent.getCoprocessorHost().preRollBackSplit();
       } else {
         try {
           user.getUGI().doAs(new PrivilegedExceptionAction<Void>() {
             @Override
             public Void run() throws Exception {
               parent.getCoprocessorHost().preRollBackSplit();
               return null;
             }
           });
         } catch (InterruptedException ie) {
           InterruptedIOException iioe = new InterruptedIOException();
           iioe.initCause(ie);
           throw iioe;
         }
       }
     }
 
     boolean result = true;
     ListIterator<JournalEntry> iterator =
       this.journal.listIterator(this.journal.size());
     // Iterate in reverse.
     while (iterator.hasPrevious()) {
       JournalEntry je = iterator.previous();
 
       transition(je.getPhase(), true);
 
       switch (je.getPhase()) {
 
       case SET_SPLITTING:
         if (services != null
             && !services.reportRegionStateTransition(TransitionCode.SPLIT_REVERTED,
                 parent.getRegionInfo(), hri_a, hri_b)) {
           return false;
         }
         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 " +
             parent.getRegionInfo().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;
 
       // Informational only cases
       case STARTED:
       case PREPARED:
       case BEFORE_PRE_SPLIT_HOOK:
       case AFTER_PRE_SPLIT_HOOK:
       case BEFORE_POST_SPLIT_HOOK:
       case AFTER_POST_SPLIT_HOOK:
       case OPENED_REGION_A:
       case OPENED_REGION_B:
       case COMPLETED:
         break;
 
       default:
         throw new RuntimeException("Unhandled journal entry: " + je);
       }
     }
     // Coprocessor callback
     if (this.parent.getCoprocessorHost() != null) {
       if (user == null) {
         this.parent.getCoprocessorHost().postRollBackSplit();
       } else {
         try {
           user.getUGI().doAs(new PrivilegedExceptionAction<Void>() {
             @Override
             public Void run() throws Exception {
               parent.getCoprocessorHost().postRollBackSplit();
               return null;
             }
           });
         } catch (InterruptedException ie) {
           InterruptedIOException iioe = new InterruptedIOException();
           iioe.initCause(ie);
           throw iioe;
         }
       }
     }
     return result;
   }
 
   /* package */ HRegionInfo getFirstDaughter() {
     return hri_a;
   }
 
   /* package */ HRegionInfo getSecondDaughter() {
     return hri_b;
   }
 
   @Override
   public List<JournalEntry> getJournal() {
     return journal;
   }
 
   @Override
   public SplitTransaction registerTransactionListener(TransactionListener listener) {
     listeners.add(listener);
     return this;
   }
 
   @Override
   public Server getServer() {
     return server;
   }
 
   @Override
   public RegionServerServices getRegionServerServices() {
     return rsServices;
   }
 
 }