/**
    *
    * 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.wal;
  
  import java.io.EOFException;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.InterruptedIOException;
  import java.text.ParseException;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Map;
  import java.util.NavigableSet;
  import java.util.Set;
  import java.util.TreeMap;
  import java.util.TreeSet;
  import java.util.UUID;
  import java.util.concurrent.Callable;
  import java.util.concurrent.CompletionService;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ExecutionException;
  import java.util.concurrent.ExecutorCompletionService;
  import java.util.concurrent.Future;
  import java.util.concurrent.ThreadFactory;
  import java.util.concurrent.ThreadPoolExecutor;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicBoolean;
  import java.util.concurrent.atomic.AtomicLong;
  import java.util.concurrent.atomic.AtomicReference;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.FileAlreadyExistsException;
  import org.apache.hadoop.fs.FileStatus;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.fs.PathFilter;
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.CellScanner;
  import org.apache.hadoop.hbase.CellUtil;
  import org.apache.hadoop.hbase.CoordinatedStateException;
  import org.apache.hadoop.hbase.CoordinatedStateManager;
  import org.apache.hadoop.hbase.HBaseConfiguration;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.HRegionLocation;
  import org.apache.hadoop.hbase.RemoteExceptionHandler;
  import org.apache.hadoop.hbase.ServerName;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.TableNotFoundException;
  import org.apache.hadoop.hbase.TableStateManager;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.client.ConnectionUtils;
  import org.apache.hadoop.hbase.client.Delete;
  import org.apache.hadoop.hbase.client.Durability;
  import org.apache.hadoop.hbase.client.HConnection;
  import org.apache.hadoop.hbase.client.HConnectionManager;
  import org.apache.hadoop.hbase.client.Mutation;
  import org.apache.hadoop.hbase.client.Put;
  import org.apache.hadoop.hbase.coordination.BaseCoordinatedStateManager;
  import org.apache.hadoop.hbase.coordination.ZKSplitLogManagerCoordination;
  import org.apache.hadoop.hbase.exceptions.RegionOpeningException;
  import org.apache.hadoop.hbase.io.HeapSize;
  import org.apache.hadoop.hbase.master.SplitLogManager;
  import org.apache.hadoop.hbase.monitoring.MonitoredTask;
  import org.apache.hadoop.hbase.monitoring.TaskMonitor;
  import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
  import org.apache.hadoop.hbase.protobuf.RequestConverter;
  import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.AdminService.BlockingInterface;
  import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.GetRegionInfoRequest;
  import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.GetRegionInfoResponse;
  import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.WALEntry;
  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.MutationProto.MutationType;
  import org.apache.hadoop.hbase.protobuf.generated.ClusterStatusProtos.RegionStoreSequenceIds;
  import org.apache.hadoop.hbase.protobuf.generated.ClusterStatusProtos.StoreSequenceId;
  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos;
 import org.apache.hadoop.hbase.protobuf.generated.WALProtos.CompactionDescriptor;
 import org.apache.hadoop.hbase.protobuf.generated.ZooKeeperProtos;
 import org.apache.hadoop.hbase.protobuf.generated.ZooKeeperProtos.SplitLogTask.RecoveryMode;
 import org.apache.hadoop.hbase.regionserver.HRegion;
 import org.apache.hadoop.hbase.regionserver.LastSequenceId;
 // imports for things that haven't moved from regionserver.wal yet.
 import org.apache.hadoop.hbase.regionserver.wal.FSHLog;
 import org.apache.hadoop.hbase.regionserver.wal.HLogKey;
 import org.apache.hadoop.hbase.regionserver.wal.WALCellCodec;
 import org.apache.hadoop.hbase.regionserver.wal.WALEdit;
 import org.apache.hadoop.hbase.regionserver.wal.WALEditsReplaySink;
 import org.apache.hadoop.hbase.util.Bytes;
 import org.apache.hadoop.hbase.util.CancelableProgressable;
 import org.apache.hadoop.hbase.util.ClassSize;
 import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
 import org.apache.hadoop.hbase.util.FSUtils;
 import org.apache.hadoop.hbase.util.Pair;
 import org.apache.hadoop.hbase.util.Threads;
 import org.apache.hadoop.hbase.wal.WAL.Entry;
 import org.apache.hadoop.hbase.wal.WAL.Reader;
 import org.apache.hadoop.hbase.wal.WALProvider.Writer;
 import org.apache.hadoop.hbase.zookeeper.ZKSplitLog;
 import org.apache.hadoop.io.MultipleIOException;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;
 import com.google.protobuf.ServiceException;
 import com.google.protobuf.TextFormat;
 
 /**
  * This class is responsible for splitting up a bunch of regionserver commit log
  * files that are no longer being written to, into new files, one per region for
  * region to replay on startup. Delete the old log files when finished.
  */
 @InterfaceAudience.Private
 @edu.umd.cs.findbugs.annotations.SuppressWarnings(value="JLM_JSR166_UTILCONCURRENT_MONITORENTER",
   justification="Synchronization on concurrent map is intended")
 public class WALSplitter {
   private static final Log LOG = LogFactory.getLog(WALSplitter.class);
 
   /** By default we retry errors in splitting, rather than skipping. */
   public static final boolean SPLIT_SKIP_ERRORS_DEFAULT = false;
 
   // Parameters for split process
   protected final Path walDir;
   protected final FileSystem walFS;
   protected final Configuration conf;
 
   // Major subcomponents of the split process.
   // These are separated into inner classes to make testing easier.
   PipelineController controller;
   OutputSink outputSink;
   EntryBuffers entryBuffers;
 
   private Set<TableName> disablingOrDisabledTables =
       new HashSet<TableName>();
   private BaseCoordinatedStateManager csm;
   private final WALFactory walFactory;
 
   private MonitoredTask status;
 
   // For checking the latest flushed sequence id
   protected final LastSequenceId sequenceIdChecker;
 
   protected boolean distributedLogReplay;
 
   private final boolean splitWriterCreationBounded;
 
 
   // Map encodedRegionName -> lastFlushedSequenceId
   protected Map<String, Long> lastFlushedSequenceIds = new ConcurrentHashMap<String, Long>();
 
   // Map encodedRegionName -> maxSeqIdInStores
   protected Map<String, Map<byte[], Long>> regionMaxSeqIdInStores =
       new ConcurrentHashMap<String, Map<byte[], Long>>();
 
   // Failed region server that the wal file being split belongs to
   protected String failedServerName = "";
 
   // Number of writer threads
   private final int numWriterThreads;
 
   // Min batch size when replay WAL edits
   private final int minBatchSize;
 
   // the file being split currently
   private FileStatus fileBeingSplit;
 
   public final static String SPLIT_WRITER_CREATION_BOUNDED = "hbase.split.writer.creation.bounded";
 
   @VisibleForTesting
   WALSplitter(final WALFactory factory, Configuration conf, Path walDir,
       FileSystem walFS, LastSequenceId idChecker,
       CoordinatedStateManager csm, RecoveryMode mode) {
     this.conf = HBaseConfiguration.create(conf);
     String codecClassName = conf
         .get(WALCellCodec.WAL_CELL_CODEC_CLASS_KEY, WALCellCodec.class.getName());
     this.conf.set(HConstants.RPC_CODEC_CONF_KEY, codecClassName);
     this.walDir = walDir;
     this.walFS = walFS;
     this.sequenceIdChecker = idChecker;
     this.csm = (BaseCoordinatedStateManager)csm;
     this.walFactory = factory;
     this.controller = new PipelineController();
     this.splitWriterCreationBounded = conf.getBoolean(SPLIT_WRITER_CREATION_BOUNDED, false);
     entryBuffers = new EntryBuffers(controller,
         this.conf.getInt("hbase.regionserver.hlog.splitlog.buffersize",
             128*1024*1024), splitWriterCreationBounded);
 
     // a larger minBatchSize may slow down recovery because replay writer has to wait for
     // enough edits before replaying them
     this.minBatchSize = this.conf.getInt("hbase.regionserver.wal.logreplay.batch.size", 64);
     this.distributedLogReplay = (RecoveryMode.LOG_REPLAY == mode);
 
     this.numWriterThreads = this.conf.getInt("hbase.regionserver.hlog.splitlog.writer.threads", 3);
     if (csm != null && this.distributedLogReplay) {
       outputSink = new LogReplayOutputSink(controller, entryBuffers, numWriterThreads);
     } else {
       if (this.distributedLogReplay) {
         LOG.info("ZooKeeperWatcher is passed in as NULL so disable distrubitedLogRepaly.");
       }
       this.distributedLogReplay = false;
       if(splitWriterCreationBounded){
         outputSink = new BoundedLogWriterCreationOutputSink(controller,
             entryBuffers, numWriterThreads);
       }else {
         outputSink = new LogRecoveredEditsOutputSink(controller, entryBuffers, numWriterThreads);
       }
     }
 
   }
 
   /**
    * Splits a WAL file into region's recovered-edits directory.
    * This is the main entry point for distributed log splitting from SplitLogWorker.
    * <p>
    * If the log file has N regions then N recovered.edits files will be produced.
    * <p>
    * @param rootDir
    * @param logfile
    * @param walFS FileSystem to use for WAL reading and splitting
    * @param conf
    * @param reporter
    * @param idChecker
    * @param cp coordination state manager
    * @return false if it is interrupted by the progress-able.
    * @throws IOException
    */
   public static boolean splitLogFile(Path walDir, FileStatus logfile, FileSystem walFS,
       Configuration conf, CancelableProgressable reporter, LastSequenceId idChecker,
       CoordinatedStateManager cp, RecoveryMode mode, final WALFactory factory) throws IOException {
     WALSplitter s = new WALSplitter(factory, conf, walDir, walFS, idChecker, cp, mode);
     return s.splitLogFile(logfile, reporter);
   }
 
   // A wrapper to split one log folder using the method used by distributed
   // log splitting. Used by tools and unit tests. It should be package private.
   // It is public only because UpgradeTo96 and TestWALObserver are in different packages,
   // which uses this method to do log splitting.
   public static List<Path> split(Path walRootDir, Path logDir, Path oldLogDir,
       FileSystem walFs, Configuration conf, final WALFactory factory) throws IOException {
     final FileStatus[] logfiles = SplitLogManager.getFileList(conf,
         Collections.singletonList(logDir), null);
     List<Path> splits = new ArrayList<Path>();
     if (logfiles != null && logfiles.length > 0) {
       for (FileStatus logfile: logfiles) {
         WALSplitter s = new WALSplitter(factory, conf, walRootDir, walFs, null, null,
             RecoveryMode.LOG_SPLITTING);
         if (s.splitLogFile(logfile, null)) {
           finishSplitLogFile(walRootDir, oldLogDir, logfile.getPath(), conf);
           if (s.outputSink.splits != null) {
             splits.addAll(s.outputSink.splits);
           }
         }
       }
     }
     if (!walFs.delete(logDir, true)) {
       throw new IOException("Unable to delete src dir: " + logDir);
     }
     return splits;
   }
 
   /**
    * log splitting implementation, splits one log file.
    * @param logfile should be an actual log file.
    */
   @VisibleForTesting
   boolean splitLogFile(FileStatus logfile, CancelableProgressable reporter) throws IOException {
     Preconditions.checkState(status == null);
     Preconditions.checkArgument(logfile.isFile(),
         "passed in file status is for something other than a regular file.");
     boolean isCorrupted = false;
     boolean skipErrors = conf.getBoolean("hbase.hlog.split.skip.errors",
       SPLIT_SKIP_ERRORS_DEFAULT);
     int interval = conf.getInt("hbase.splitlog.report.interval.loglines", 1024);
     Path logPath = logfile.getPath();
     boolean outputSinkStarted = false;
     boolean progress_failed = false;
     int editsCount = 0;
     int editsSkipped = 0;
 
     status =
         TaskMonitor.get().createStatus(
           "Splitting log file " + logfile.getPath() + "into a temporary staging area.");
     Reader in = null;
     this.fileBeingSplit = logfile;
     try {
       long logLength = logfile.getLen();
       LOG.info("Splitting wal: " + logPath + ", length=" + logLength);
       LOG.info("DistributedLogReplay = " + this.distributedLogReplay);
       status.setStatus("Opening log file");
       if (reporter != null && !reporter.progress()) {
         progress_failed = true;
         return false;
       }
       try {
         in = getReader(logfile, skipErrors, reporter);
       } catch (CorruptedLogFileException e) {
         LOG.warn("Could not get reader, corrupted log file " + logPath, e);
         ZKSplitLog.markCorrupted(walDir, logfile.getPath().getName(), walFS);
         isCorrupted = true;
       }
       if (in == null) {
         LOG.warn("Nothing to split in log file " + logPath);
         return true;
       }
       if (csm != null) {
         try {
           TableStateManager tsm = csm.getTableStateManager();
           disablingOrDisabledTables = tsm.getTablesInStates(
           ZooKeeperProtos.Table.State.DISABLED, ZooKeeperProtos.Table.State.DISABLING);
         } catch (CoordinatedStateException e) {
           throw new IOException("Can't get disabling/disabled tables", e);
         }
       }
       int numOpenedFilesBeforeReporting = conf.getInt("hbase.splitlog.report.openedfiles", 3);
       int numOpenedFilesLastCheck = 0;
       outputSink.setReporter(reporter);
       outputSink.startWriterThreads();
       outputSinkStarted = true;
       Entry entry;
       Long lastFlushedSequenceId = -1L;
       ServerName serverName = DefaultWALProvider.getServerNameFromWALDirectoryName(logPath);
       failedServerName = (serverName == null) ? "" : serverName.getServerName();
       while ((entry = getNextLogLine(in, logPath, skipErrors)) != null) {
         byte[] region = entry.getKey().getEncodedRegionName();
         String encodedRegionNameAsStr = Bytes.toString(region);
         lastFlushedSequenceId = lastFlushedSequenceIds.get(encodedRegionNameAsStr);
         if (lastFlushedSequenceId == null) {
           if (this.distributedLogReplay) {
             RegionStoreSequenceIds ids =
                 csm.getSplitLogWorkerCoordination().getRegionFlushedSequenceId(failedServerName,
                   encodedRegionNameAsStr);
             if (ids != null) {
               lastFlushedSequenceId = ids.getLastFlushedSequenceId();
               if (LOG.isDebugEnabled()) {
                 LOG.debug("DLR Last flushed sequenceid for " + encodedRegionNameAsStr + ": " +
                   TextFormat.shortDebugString(ids));
               }
             }
           } else if (sequenceIdChecker != null) {
             RegionStoreSequenceIds ids = sequenceIdChecker.getLastSequenceId(region);
             Map<byte[], Long> maxSeqIdInStores = new TreeMap<byte[], Long>(Bytes.BYTES_COMPARATOR);
             for (StoreSequenceId storeSeqId : ids.getStoreSequenceIdList()) {
               maxSeqIdInStores.put(storeSeqId.getFamilyName().toByteArray(),
                 storeSeqId.getSequenceId());
             }
             regionMaxSeqIdInStores.put(encodedRegionNameAsStr, maxSeqIdInStores);
             lastFlushedSequenceId = ids.getLastFlushedSequenceId();
             if (LOG.isDebugEnabled()) {
               LOG.debug("DLS Last flushed sequenceid for " + encodedRegionNameAsStr + ": " +
                   TextFormat.shortDebugString(ids));
             }
           }
           if (lastFlushedSequenceId == null) {
             lastFlushedSequenceId = -1L;
           }
           lastFlushedSequenceIds.put(encodedRegionNameAsStr, lastFlushedSequenceId);
         }
         if (lastFlushedSequenceId >= entry.getKey().getLogSeqNum()) {
           editsSkipped++;
           continue;
         }
         // Don't send Compaction/Close/Open region events to recovered edit type sinks.
         if (entry.getEdit().isMetaEdit() && !outputSink.keepRegionEvent(entry)) {
           editsSkipped++;
           continue;
         }
         entryBuffers.appendEntry(entry);
         editsCount++;
         int moreWritersFromLastCheck = this.getNumOpenWriters() - numOpenedFilesLastCheck;
         // If sufficient edits have passed, check if we should report progress.
         if (editsCount % interval == 0
             || moreWritersFromLastCheck > numOpenedFilesBeforeReporting) {
           numOpenedFilesLastCheck = this.getNumOpenWriters();
           String countsStr = (editsCount - (editsSkipped + outputSink.getSkippedEdits()))
               + " edits, skipped " + editsSkipped + " edits.";
           status.setStatus("Split " + countsStr);
           if (reporter != null && !reporter.progress()) {
             progress_failed = true;
             return false;
           }
         }
       }
     } catch (InterruptedException ie) {
       IOException iie = new InterruptedIOException();
       iie.initCause(ie);
       throw iie;
     } catch (CorruptedLogFileException e) {
       LOG.warn("Could not parse, corrupted log file " + logPath, e);
       csm.getSplitLogWorkerCoordination().markCorrupted(walDir,
         logfile.getPath().getName(), walFS);
       isCorrupted = true;
     } catch (IOException e) {
       e = RemoteExceptionHandler.checkIOException(e);
       throw e;
     } finally {
       LOG.debug("Finishing writing output logs and closing down.");
       try {
         if (null != in) {
           in.close();
         }
       } catch (IOException exception) {
         LOG.warn("Could not close wal reader: " + exception.getMessage());
         LOG.debug("exception details", exception);
       }
       try {
         if (outputSinkStarted) {
           // Set progress_failed to true as the immediate following statement will reset its value
           // when finishWritingAndClose() throws exception, progress_failed has the right value
           progress_failed = true;
           progress_failed = outputSink.finishWritingAndClose() == null;
         }
       } finally {
         String msg =
             "Processed " + editsCount + " edits across " + outputSink.getNumberOfRecoveredRegions()
                 + " regions; edits skipped=" + editsSkipped + "; log file=" + logPath +
                 ", length=" + logfile.getLen() + // See if length got updated post lease recovery
                 ", corrupted=" + isCorrupted + ", progress failed=" + progress_failed;
         LOG.info(msg);
         status.markComplete(msg);
       }
     }
     return !progress_failed;
   }
 
   /**
    * Completes the work done by splitLogFile by archiving logs
    * <p>
    * It is invoked by SplitLogManager once it knows that one of the
    * SplitLogWorkers have completed the splitLogFile() part. If the master
    * crashes then this function might get called multiple times.
    * <p>
    * @param logfile
    * @param conf
    * @throws IOException
    */
   public static void finishSplitLogFile(String logfile,
       Configuration conf)  throws IOException {
     Path walDir = FSUtils.getWALRootDir(conf);
     Path oldLogDir = new Path(walDir, HConstants.HREGION_OLDLOGDIR_NAME);
     Path logPath;
     if (FSUtils.isStartingWithPath(walDir, logfile)) {
       logPath = new Path(logfile);
     } else {
       logPath = new Path(walDir, logfile);
     }
     finishSplitLogFile(walDir, oldLogDir, logPath, conf);
   }
 
   private static void finishSplitLogFile(Path walDir, Path oldLogDir,
       Path logPath, Configuration conf) throws IOException {
     List<Path> processedLogs = new ArrayList<Path>();
     List<Path> corruptedLogs = new ArrayList<Path>();
     FileSystem walFS = walDir.getFileSystem(conf);
     if (ZKSplitLog.isCorrupted(walDir, logPath.getName(), walFS)) {
       corruptedLogs.add(logPath);
     } else {
       processedLogs.add(logPath);
     }
     archiveLogs(corruptedLogs, processedLogs, oldLogDir, walFS, conf);
     Path stagingDir = ZKSplitLog.getSplitLogDir(walDir, logPath.getName());
     walFS.delete(stagingDir, true);
   }
 
   /**
    * Moves processed logs to a oldLogDir after successful processing Moves
    * corrupted logs (any log that couldn't be successfully parsed to corruptDir
    * (.corrupt) for later investigation
    *
    * @param corruptedLogs
    * @param processedLogs
    * @param oldLogDir
    * @param walFS FileSystem to use for WAL archival
    * @param conf
    * @throws IOException
    */
   private static void archiveLogs(
       final List<Path> corruptedLogs,
       final List<Path> processedLogs, final Path oldLogDir,
       final FileSystem walFS, final Configuration conf) throws IOException {
     final Path corruptDir = new Path(FSUtils.getWALRootDir(conf), conf.get(
         "hbase.regionserver.hlog.splitlog.corrupt.dir",  HConstants.CORRUPT_DIR_NAME));
 
     if (!walFS.mkdirs(corruptDir)) {
       LOG.info("Unable to mkdir " + corruptDir);
     }
     walFS.mkdirs(oldLogDir);
 
     // this method can get restarted or called multiple times for archiving
     // the same log files.
     for (Path corrupted : corruptedLogs) {
       Path p = new Path(corruptDir, corrupted.getName());
       if (walFS.exists(corrupted)) {
         if (!walFS.rename(corrupted, p)) {
           LOG.warn("Unable to move corrupted log " + corrupted + " to " + p);
         } else {
           LOG.warn("Moved corrupted log " + corrupted + " to " + p);
         }
       }
     }
 
     for (Path p : processedLogs) {
       Path newPath = FSHLog.getWALArchivePath(oldLogDir, p);
       if (walFS.exists(p)) {
         if (!FSUtils.renameAndSetModifyTime(walFS, p, newPath)) {
           LOG.warn("Unable to move  " + p + " to " + newPath);
         } else {
           LOG.info("Archived processed log " + p + " to " + newPath);
         }
       }
     }
   }
 
   /**
    * Path to a file under RECOVERED_EDITS_DIR directory of the region found in
    * <code>logEntry</code> named for the sequenceid in the passed
    * <code>logEntry</code>: e.g. /hbase/some_table/2323432434/recovered.edits/2332.
    * This method also ensures existence of RECOVERED_EDITS_DIR under the region
    * creating it if necessary.
    * @param logEntry
    * @param fileNameBeingSplit the file being split currently. Used to generate tmp file name.
    * @param tmpDirName of the directory used to sideline old recovered edits file
    * @param conf
    * @return Path to file into which to dump split log edits.
    * @throws IOException
    */
   @SuppressWarnings("deprecation")
   @VisibleForTesting
   static Path getRegionSplitEditsPath(final Entry logEntry, String fileNameBeingSplit,
       String tmpDirName, Configuration conf) throws IOException {
     FileSystem walFS = FSUtils.getWALFileSystem(conf);
     Path tableDir = FSUtils.getWALTableDir(conf, logEntry.getKey().getTablename());
     String encodedRegionName = Bytes.toString(logEntry.getKey().getEncodedRegionName());
     Path regionDir = HRegion.getRegionDir(tableDir, encodedRegionName);
     Path dir = getRegionDirRecoveredEditsDir(regionDir);
 
     if (walFS.exists(dir) && walFS.isFile(dir)) {
       Path tmp = new Path(tmpDirName);
       if (!walFS.exists(tmp)) {
         walFS.mkdirs(tmp);
       }
       tmp = new Path(tmp,
         HConstants.RECOVERED_EDITS_DIR + "_" + encodedRegionName);
       LOG.warn("Found existing old file: " + dir + ". It could be some "
         + "leftover of an old installation. It should be a folder instead. "
         + "So moving it to " + tmp);
       if (!walFS.rename(dir, tmp)) {
         LOG.warn("Failed to sideline old file " + dir);
       }
     }
 
     if (!walFS.exists(dir) && !walFS.mkdirs(dir)) {
       LOG.warn("mkdir failed on " + dir);
     }
     // Append fileBeingSplit to prevent name conflict since we may have duplicate wal entries now.
     // Append file name ends with RECOVERED_LOG_TMPFILE_SUFFIX to ensure
     // region's replayRecoveredEdits will not delete it
     String fileName = formatRecoveredEditsFileName(logEntry.getKey().getLogSeqNum());
     fileName = getTmpRecoveredEditsFileName(fileName + "-" + fileNameBeingSplit);
     return new Path(dir, fileName);
   }
 
   private static String getTmpRecoveredEditsFileName(String fileName) {
     return fileName + RECOVERED_LOG_TMPFILE_SUFFIX;
   }
 
   /**
    * Get the completed recovered edits file path, renaming it to be by last edit
    * in the file from its first edit. Then we could use the name to skip
    * recovered edits when doing {@link HRegion#replayRecoveredEditsIfAny}.
    * @param srcPath
    * @param maximumEditLogSeqNum
    * @return dstPath take file's last edit log seq num as the name
    */
   private static Path getCompletedRecoveredEditsFilePath(Path srcPath,
       long maximumEditLogSeqNum) {
     String fileName = formatRecoveredEditsFileName(maximumEditLogSeqNum);
     return new Path(srcPath.getParent(), fileName);
   }
 
   @VisibleForTesting
   static String formatRecoveredEditsFileName(final long seqid) {
     return String.format("%019d", seqid);
   }
 
   private static final Pattern EDITFILES_NAME_PATTERN = Pattern.compile("-?[0-9]+");
   private static final String RECOVERED_LOG_TMPFILE_SUFFIX = ".temp";
 
   /**
    * @param regionDir
    *          This regions directory in the filesystem.
    * @return The directory that holds recovered edits files for the region
    *         <code>regionDir</code>
    */
   public static Path getRegionDirRecoveredEditsDir(final Path regionDir) {
     return new Path(regionDir, HConstants.RECOVERED_EDITS_DIR);
   }
 
   /**
    * Returns sorted set of edit files made by splitter, excluding files
    * with '.temp' suffix.
    *
    * @param walFS FileSystem to use for reading Recovered edits files
    * @param regionDir Directory where Recovered edits should reside
    * @return Files in passed <code>regionDir</code> as a sorted set.
    * @throws IOException
    */
   public static NavigableSet<Path> getSplitEditFilesSorted(final FileSystem walFS,
       final Path regionDir) throws IOException {
     NavigableSet<Path> filesSorted = new TreeSet<Path>();
     Path editsdir = getRegionDirRecoveredEditsDir(regionDir);
     if (!walFS.exists(editsdir)) {
       return filesSorted;
     }
     FileStatus[] files = FSUtils.listStatus(walFS, editsdir, new PathFilter() {
       @Override
       public boolean accept(Path p) {
         boolean result = false;
         try {
           // Return files and only files that match the editfile names pattern.
           // There can be other files in this directory other than edit files.
           // In particular, on error, we'll move aside the bad edit file giving
           // it a timestamp suffix. See moveAsideBadEditsFile.
           Matcher m = EDITFILES_NAME_PATTERN.matcher(p.getName());
           result = walFS.isFile(p) && m.matches();
           // Skip the file whose name ends with RECOVERED_LOG_TMPFILE_SUFFIX,
           // because it means splitwal thread is writting this file.
           if (p.getName().endsWith(RECOVERED_LOG_TMPFILE_SUFFIX)) {
             result = false;
           }
           // Skip SeqId Files
           if (isSequenceIdFile(p)) {
             result = false;
           }
         } catch (IOException e) {
           LOG.warn("Failed isFile check on " + p);
         }
         return result;
       }
     });
     if (files == null) {
       return filesSorted;
     }
     for (FileStatus status : files) {
       filesSorted.add(status.getPath());
     }
     return filesSorted;
   }
 
   /**
    * Move aside a bad edits file.
    *
    * @param walFS FileSystem to use for WAL operations
    * @param edits
    *          Edits file to move aside.
    * @return The name of the moved aside file.
    * @throws IOException
    */
   public static Path moveAsideBadEditsFile(final FileSystem walFS, final Path edits)
       throws IOException {
     Path moveAsideName = new Path(edits.getParent(), edits.getName() + "."
         + System.currentTimeMillis());
     if (!walFS.rename(edits, moveAsideName)) {
       LOG.warn("Rename failed from " + edits + " to " + moveAsideName);
     }
     return moveAsideName;
   }
 
   private static final String SEQUENCE_ID_FILE_SUFFIX = ".seqid";
   private static final String OLD_SEQUENCE_ID_FILE_SUFFIX = "_seqid";
   private static final int SEQUENCE_ID_FILE_SUFFIX_LENGTH = SEQUENCE_ID_FILE_SUFFIX.length();
 
   /**
    * Is the given file a region open sequence id file.
    */
   @VisibleForTesting
   public static boolean isSequenceIdFile(final Path file) {
     return file.getName().endsWith(SEQUENCE_ID_FILE_SUFFIX)
         || file.getName().endsWith(OLD_SEQUENCE_ID_FILE_SUFFIX);
   }
 
   /**
    * Create a file with name as region open sequence id
    * @param walFS FileSystem to write Sequence file to
    * @param regionDir WALRegionDir used to determine where to write edits files
    * @param newSeqId
    * @param saftyBumper
    * @return long new sequence Id value
    * @throws IOException
    */
   public static long writeRegionSequenceIdFile(final FileSystem walFS, final Path regionDir,
       long newSeqId, long saftyBumper) throws IOException {
 
     Path editsdir = WALSplitter.getRegionDirRecoveredEditsDir(regionDir);
     long maxSeqId = 0;
     FileStatus[] files = null;
     if (walFS.exists(editsdir)) {
       files = FSUtils.listStatus(walFS, editsdir, new PathFilter() {
         @Override
         public boolean accept(Path p) {
           return isSequenceIdFile(p);
         }
       });
       if (files != null) {
         for (FileStatus status : files) {
           String fileName = status.getPath().getName();
           try {
             Long tmpSeqId = Long.parseLong(fileName.substring(0, fileName.length()
                 - SEQUENCE_ID_FILE_SUFFIX_LENGTH));
             maxSeqId = Math.max(tmpSeqId, maxSeqId);
           } catch (NumberFormatException ex) {
             LOG.warn("Invalid SeqId File Name=" + fileName);
           }
         }
       }
     }
     if (maxSeqId > newSeqId) {
       newSeqId = maxSeqId;
     }
     newSeqId += saftyBumper; // bump up SeqId
 
     // write a new seqId file
     Path newSeqIdFile = new Path(editsdir, newSeqId + SEQUENCE_ID_FILE_SUFFIX);
     if (newSeqId != maxSeqId) {
       try {
         if (!walFS.createNewFile(newSeqIdFile) && !walFS.exists(newSeqIdFile)) {
           throw new IOException("Failed to create SeqId file:" + newSeqIdFile);
         }
         if (LOG.isDebugEnabled()) {
           LOG.debug("Wrote region seqId=" + newSeqIdFile + " to file, newSeqId=" + newSeqId
               + ", maxSeqId=" + maxSeqId);
         }
       } catch (FileAlreadyExistsException ignored) {
         // latest hdfs throws this exception. it's all right if newSeqIdFile already exists
       }
     }
     // remove old ones
     if (files != null) {
       for (FileStatus status : files) {
         if (newSeqIdFile.equals(status.getPath())) {
           continue;
         }
         walFS.delete(status.getPath(), false);
       }
     }
     return newSeqId;
   }
 
   /**
    * Create a new {@link Reader} for reading logs to split.
    *
    * @param file
    * @return A new Reader instance, caller should close
    * @throws IOException
    * @throws CorruptedLogFileException
    */
   protected Reader getReader(FileStatus file, boolean skipErrors, CancelableProgressable reporter)
       throws IOException, CorruptedLogFileException {
     Path path = file.getPath();
     long length = file.getLen();
     Reader in;
 
     // Check for possibly empty file. With appends, currently Hadoop reports a
     // zero length even if the file has been sync'd. Revisit if HDFS-376 or
     // HDFS-878 is committed.
     if (length <= 0) {
       LOG.warn("File " + path + " might be still open, length is 0");
     }
 
     try {
       FSUtils.getInstance(walFS, conf).recoverFileLease(walFS, path, conf, reporter);
       try {
         in = getReader(path, reporter);
       } catch (EOFException e) {
         if (length <= 0) {
           // TODO should we ignore an empty, not-last log file if skip.errors
           // is false? Either way, the caller should decide what to do. E.g.
           // ignore if this is the last log in sequence.
           // TODO is this scenario still possible if the log has been
           // recovered (i.e. closed)
           LOG.warn("Could not open " + path + " for reading. File is empty", e);
           return null;
         } else {
           // EOFException being ignored
           return null;
         }
       }
     } catch (IOException e) {
       if (e instanceof FileNotFoundException) {
         // A wal file may not exist anymore. Nothing can be recovered so move on
         LOG.warn("File " + path + " doesn't exist anymore.", e);
         return null;
       }
       if (!skipErrors || e instanceof InterruptedIOException) {
         throw e; // Don't mark the file corrupted if interrupted, or not skipErrors
       }
       CorruptedLogFileException t =
         new CorruptedLogFileException("skipErrors=true Could not open wal " +
             path + " ignoring");
       t.initCause(e);
       throw t;
     }
     return in;
   }
 
   static private Entry getNextLogLine(Reader in, Path path, boolean skipErrors)
   throws CorruptedLogFileException, IOException {
     try {
       return in.next();
     } catch (EOFException eof) {
       // truncated files are expected if a RS crashes (see HBASE-2643)
       LOG.info("EOF from wal " + path + ".  continuing");
       return null;
     } catch (IOException e) {
       // If the IOE resulted from bad file format,
       // then this problem is idempotent and retrying won't help
       if (e.getCause() != null &&
           (e.getCause() instanceof ParseException ||
            e.getCause() instanceof org.apache.hadoop.fs.ChecksumException)) {
         LOG.warn("Parse exception " + e.getCause().toString() + " from wal "
            + path + ".  continuing");
         return null;
       }
       if (!skipErrors) {
         throw e;
       }
       CorruptedLogFileException t =
         new CorruptedLogFileException("skipErrors=true Ignoring exception" +
             " while parsing wal " + path + ". Marking as corrupted");
       t.initCause(e);
       throw t;
     }
   }
 
   /**
    * Create a new {@link Writer} for writing log splits.
    * @return a new Writer instance, caller should close
    */
   protected Writer createWriter(Path logfile)
       throws IOException {
     return walFactory.createRecoveredEditsWriter(walFS, logfile);
   }
 
   /**
    * Create a new {@link Reader} for reading logs to split.
    * @return new Reader instance, caller should close
    */
   protected Reader getReader(Path curLogFile, CancelableProgressable reporter) throws IOException {
     return walFactory.createReader(walFS, curLogFile, reporter);
   }
 
   /**
    * Get current open writers
    */
   private int getNumOpenWriters() {
     int result = 0;
     if (this.outputSink != null) {
       result += this.outputSink.getNumOpenWriters();
     }
     return result;
   }
 
   /**
    * Contains some methods to control WAL-entries producer / consumer interactions
    */
   public static class PipelineController {
     // If an exception is thrown by one of the other threads, it will be
     // stored here.
     AtomicReference<Throwable> thrown = new AtomicReference<Throwable>();
 
     // Wait/notify for when data has been produced by the writer thread,
     // consumed by the reader thread, or an exception occurred
     public final Object dataAvailable = new Object();
 
     void writerThreadError(Throwable t) {
       thrown.compareAndSet(null, t);
     }
 
     /**
      * Check for errors in the writer threads. If any is found, rethrow it.
      */
     void checkForErrors() throws IOException {
       Throwable thrown = this.thrown.get();
       if (thrown == null) return;
       if (thrown instanceof IOException) {
         throw new IOException(thrown);
       } else {
         throw new RuntimeException(thrown);
       }
     }
   }
 
   /**
    * Class which accumulates edits and separates them into a buffer per region
    * while simultaneously accounting RAM usage. Blocks if the RAM usage crosses
    * a predefined threshold.
    *
    * Writer threads then pull region-specific buffers from this class.
    */
   public static class EntryBuffers {
     PipelineController controller;
 
     Map<byte[], RegionEntryBuffer> buffers =
       new TreeMap<byte[], RegionEntryBuffer>(Bytes.BYTES_COMPARATOR);
 
     /* Track which regions are currently in the middle of writing. We don't allow
        an IO thread to pick up bytes from a region if we're already writing
        data for that region in a different IO thread. */
     Set<byte[]> currentlyWriting = new TreeSet<byte[]>(Bytes.BYTES_COMPARATOR);
 
     long totalBuffered = 0;
     final long maxHeapUsage;
     boolean splitWriterCreationBounded;
 
 
     public EntryBuffers(PipelineController controller, long maxHeapUsage) {
       this(controller, maxHeapUsage, false);
     }
 
     public EntryBuffers(PipelineController controller, long maxHeapUsage,
         boolean splitWriterCreationBounded) {
       this.controller = controller;
       this.maxHeapUsage = maxHeapUsage;
       this.splitWriterCreationBounded = splitWriterCreationBounded;
     }
 
     /**
      * Append a log entry into the corresponding region buffer.
      * Blocks if the total heap usage has crossed the specified threshold.
      *
      * @throws InterruptedException
      * @throws IOException
      */
     public void appendEntry(Entry entry) throws InterruptedException, IOException {
       WALKey key = entry.getKey();
 
       RegionEntryBuffer buffer;
       long incrHeap;
       synchronized (this) {
         buffer = buffers.get(key.getEncodedRegionName());
         if (buffer == null) {
           buffer = new RegionEntryBuffer(key.getTablename(), key.getEncodedRegionName());
           buffers.put(key.getEncodedRegionName(), buffer);
         }
         incrHeap= buffer.appendEntry(entry);
       }
 
       // If we crossed the chunk threshold, wait for more space to be available
       synchronized (controller.dataAvailable) {
         totalBuffered += incrHeap;
         while (totalBuffered > maxHeapUsage && controller.thrown.get() == null) {
           LOG.debug("Used " + totalBuffered + " bytes of buffered edits, waiting for IO threads...");
           controller.dataAvailable.wait(2000);
         }
         controller.dataAvailable.notifyAll();
       }
       controller.checkForErrors();
     }
 
     /**
      * @return RegionEntryBuffer a buffer of edits to be written or replayed.
      */
     synchronized RegionEntryBuffer getChunkToWrite() {
       // The core part of limiting opening writers is it doesn't return chunk only if the heap size
       // is over maxHeapUsage. Thus it doesn't need to create a writer for each region
       // during splitting. It will flush all the logs in the buffer after splitting through a
       // threadpool, which means the number of writers it created is under control
       if(splitWriterCreationBounded && totalBuffered < maxHeapUsage){
         return null;
       }
 
       long biggestSize = 0;
       byte[] biggestBufferKey = null;
 
       for (Map.Entry<byte[], RegionEntryBuffer> entry : buffers.entrySet()) {
         long size = entry.getValue().heapSize();
         if (size > biggestSize && (!currentlyWriting.contains(entry.getKey()))) {
           biggestSize = size;
           biggestBufferKey = entry.getKey();
         }
       }
       if (biggestBufferKey == null) {
         return null;
       }
 
       RegionEntryBuffer buffer = buffers.remove(biggestBufferKey);
       currentlyWriting.add(biggestBufferKey);
       return buffer;
     }
 
     void doneWriting(RegionEntryBuffer buffer) {
       synchronized (this) {
         boolean removed = currentlyWriting.remove(buffer.encodedRegionName);
         assert removed;
       }
       long size = buffer.heapSize();
 
       synchronized (controller.dataAvailable) {
         totalBuffered -= size;
         // We may unblock writers
         controller.dataAvailable.notifyAll();
       }
     }
 
     synchronized boolean isRegionCurrentlyWriting(byte[] region) {
       return currentlyWriting.contains(region);
     }
 
     public void waitUntilDrained() {
       synchronized (controller.dataAvailable) {
         while (totalBuffered > 0) {
           try {
             controller.dataAvailable.wait(2000);
           } catch (InterruptedException e) {
             LOG.warn("Got interrupted while waiting for EntryBuffers is drained");
             Thread.interrupted();
             break;
           }
         }
       }
     }
   }
 
   /**
    * A buffer of some number of edits for a given region.
    * This accumulates edits and also provides a memory optimization in order to
    * share a single byte array instance for the table and region name.
    * Also tracks memory usage of the accumulated edits.
    */
   public static class RegionEntryBuffer implements HeapSize {
     long heapInBuffer = 0;
     List<Entry> entryBuffer;
     TableName tableName;
     byte[] encodedRegionName;
 
     RegionEntryBuffer(TableName tableName, byte[] region) {
       this.tableName = tableName;
       this.encodedRegionName = region;
       this.entryBuffer = new LinkedList<Entry>();
     }
 
     long appendEntry(Entry entry) {
       internify(entry);
       entryBuffer.add(entry);
       long incrHeap = entry.getEdit().heapSize() +
         ClassSize.align(2 * ClassSize.REFERENCE) + // WALKey pointers
         0; // TODO linkedlist entry
       heapInBuffer += incrHeap;
       return incrHeap;
     }
 
     private void internify(Entry entry) {
       WALKey k = entry.getKey();
       k.internTableName(this.tableName);
       k.internEncodedRegionName(this.encodedRegionName);
     }
 
     @Override
     public long heapSize() {
       return heapInBuffer;
     }
 
     public byte[] getEncodedRegionName() {
       return encodedRegionName;
     }
 
     public List<Entry> getEntryBuffer() {
       return entryBuffer;
     }
 
     public TableName getTableName() {
       return tableName;
     }
   }
 
   public static class WriterThread extends Thread {
     private volatile boolean shouldStop = false;
     private PipelineController controller;
     private EntryBuffers entryBuffers;
     private OutputSink outputSink = null;
 
     WriterThread(PipelineController controller, EntryBuffers entryBuffers, OutputSink sink, int i){
       super(Thread.currentThread().getName() + "-Writer-" + i);
       this.controller = controller;
       this.entryBuffers = entryBuffers;
       outputSink = sink;
     }
 
     @Override
     public void run()  {
       try {
         doRun();
       } catch (Throwable t) {
         LOG.error("Exiting thread", t);
         controller.writerThreadError(t);
       }
     }
 
     private void doRun() throws IOException {
       if (LOG.isTraceEnabled()) LOG.trace("Writer thread starting");
       while (true) {
         RegionEntryBuffer buffer = entryBuffers.getChunkToWrite();
         if (buffer == null) {
           // No data currently available, wait on some more to show up
           synchronized (controller.dataAvailable) {
             if (shouldStop && !this.outputSink.flush()) {
               return;
             }
             try {
               controller.dataAvailable.wait(500);
             } catch (InterruptedException ie) {
               if (!shouldStop) {
                 throw new RuntimeException(ie);
               }
             }
           }
           continue;
         }
 
         assert buffer != null;
         try {
           writeBuffer(buffer);
         } finally {
           entryBuffers.doneWriting(buffer);
         }
       }
     }
 
     private void writeBuffer(RegionEntryBuffer buffer) throws IOException {
       outputSink.append(buffer);
     }
 
     void finish() {
       synchronized (controller.dataAvailable) {
         shouldStop = true;
         controller.dataAvailable.notifyAll();
       }
     }
   }
 
   /**
    * The following class is an abstraction class to provide a common interface to support both
    * existing recovered edits file sink and region server WAL edits replay sink
    */
   public static abstract class OutputSink {
 
     protected PipelineController controller;
     protected EntryBuffers entryBuffers;
 
     protected ConcurrentHashMap<String, SinkWriter> writers = new ConcurrentHashMap<>();
     protected ConcurrentHashMap<String, Long> regionMaximumEditLogSeqNum =
         new ConcurrentHashMap<>();
 
     protected final List<WriterThread> writerThreads = Lists.newArrayList();
 
     /* Set of regions which we've decided should not output edits */
     protected final Set<byte[]> blacklistedRegions = Collections
         .synchronizedSet(new TreeSet<byte[]>(Bytes.BYTES_COMPARATOR));
 
     protected boolean closeAndCleanCompleted = false;
 
     protected boolean writersClosed = false;
 
     protected final int numThreads;
 
     protected CancelableProgressable reporter = null;
 
     protected AtomicLong skippedEdits = new AtomicLong();
 
     protected List<Path> splits = null;
 
     public OutputSink(PipelineController controller, EntryBuffers entryBuffers, int numWriters) {
       numThreads = numWriters;
       this.controller = controller;
       this.entryBuffers = entryBuffers;
     }
 
     void setReporter(CancelableProgressable reporter) {
       this.reporter = reporter;
     }
 
     /**
      * Start the threads that will pump data from the entryBuffers to the output files.
      */
     public synchronized void startWriterThreads() {
       for (int i = 0; i < numThreads; i++) {
         WriterThread t = new WriterThread(controller, entryBuffers, this, i);
         t.start();
         writerThreads.add(t);
       }
     }
 
     /**
      *
      * Update region's maximum edit log SeqNum.
      */
     void updateRegionMaximumEditLogSeqNum(Entry entry) {
 
       synchronized (regionMaximumEditLogSeqNum) {
         String encodedRegionName = Bytes.toString(entry.getKey().getEncodedRegionName());
         Long currentMaxSeqNum = regionMaximumEditLogSeqNum.get(encodedRegionName);
         if (currentMaxSeqNum == null || entry.getKey().getLogSeqNum() > currentMaxSeqNum) {
           regionMaximumEditLogSeqNum.put(encodedRegionName, entry.getKey()
               .getLogSeqNum());
         }
       }
     }
 
     Long getRegionMaximumEditLogSeqNum(byte[] region) {
       return regionMaximumEditLogSeqNum.get(Bytes.toString(region));
     }
 
     /**
      * @return the number of currently opened writers
      */
     int getNumOpenWriters() {
       return this.writers.size();
     }
 
     long getSkippedEdits() {
       return this.skippedEdits.get();
     }
 
     /**
      * Wait for writer threads to dump all info to the sink
      * @return true when there is no error
      * @throws IOException
      */
     protected boolean finishWriting(boolean interrupt) throws IOException {
       LOG.debug("Waiting for split writer threads to finish");
       boolean progress_failed = false;
       for (WriterThread t : writerThreads) {
         t.finish();
       }
       if (interrupt) {
         for (WriterThread t : writerThreads) {
           t.interrupt(); // interrupt the writer threads. We are stopping now.
         }
       }
 
       for (WriterThread t : writerThreads) {
         if (!progress_failed && reporter != null && !reporter.progress()) {
           progress_failed = true;
         }
         try {
           t.join();
         } catch (InterruptedException ie) {
           IOException iie = new InterruptedIOException();
           iie.initCause(ie);
           throw iie;
         }
       }
       controller.checkForErrors();
       LOG.info(this.writerThreads.size() + " split writers finished; closing...");
       return (!progress_failed);
     }
 
     public abstract List<Path> finishWritingAndClose() throws IOException;
 
     /**
      * @return a map from encoded region ID to the number of edits written out for that region.
      */
     public abstract Map<byte[], Long> getOutputCounts();
 
     /**
      * @return number of regions we've recovered
      */
     public abstract int getNumberOfRecoveredRegions();
 
     /**
      * @param buffer A WAL Edit Entry
      * @throws IOException
      */
     public abstract void append(RegionEntryBuffer buffer) throws IOException;
 
     /**
      * WriterThread call this function to help flush internal remaining edits in buffer before close
      * @return true when underlying sink has something to flush
      */
     public boolean flush() throws IOException {
       return false;
     }
 
     /**
      * Some WALEdit's contain only KV's for account on what happened to a region.
      * Not all sinks will want to get all of those edits.
      *
      * @return Return true if this sink wants to accept this region-level WALEdit.
      */
     public abstract boolean keepRegionEvent(Entry entry);
   }
 
   /**
    * Class that manages the output streams from the log splitting process.
    */
   class LogRecoveredEditsOutputSink extends OutputSink {
 
     public LogRecoveredEditsOutputSink(PipelineController controller, EntryBuffers entryBuffers,
         int numWriters) {
       // More threads could potentially write faster at the expense
       // of causing more disk seeks as the logs are split.
       // 3. After a certain setting (probably around 3) the
       // process will be bound on the reader in the current
       // implementation anyway.
       super(controller, entryBuffers, numWriters);
     }
 
     /**
      * @return null if failed to report progress
      * @throws IOException
      */
     @Override
     public List<Path> finishWritingAndClose() throws IOException {
       boolean isSuccessful = false;
       List<Path> result = null;
       try {
         isSuccessful = finishWriting(false);
       } finally {
         result = close();
         List<IOException> thrown = closeLogWriters(null);
         if (thrown != null && !thrown.isEmpty()) {
           throw MultipleIOException.createIOException(thrown);
         }
       }
       if (isSuccessful) {
         splits = result;
       }
       return splits;
     }
 
     // delete the one with fewer wal entries
     void deleteOneWithFewerEntries(WriterAndPath wap, Path dst)
         throws IOException {
       long dstMinLogSeqNum = -1L;
       try (WAL.Reader reader = walFactory.createReader(walFS, dst)) {
         WAL.Entry entry = reader.next();
         if (entry != null) {
           dstMinLogSeqNum = entry.getKey().getLogSeqNum();
         }
       } catch (EOFException e) {
         if (LOG.isDebugEnabled()) {
           LOG.debug(
             "Got EOF when reading first WAL entry from " + dst + ", an empty or broken WAL file?",
             e);
         }
       }
       if (wap.minLogSeqNum < dstMinLogSeqNum) {
         LOG.warn("Found existing old edits file. It could be the result of a previous failed"
             + " split attempt or we have duplicated wal entries. Deleting " + dst + ", length="
             + walFS.getFileStatus(dst).getLen());
         if (!walFS.delete(dst, false)) {
           LOG.warn("Failed deleting of old " + dst);
           throw new IOException("Failed deleting of old " + dst);
         }
       } else {
         LOG.warn("Found existing old edits file and we have less entries. Deleting " + wap.p
             + ", length=" + walFS.getFileStatus(wap.p).getLen());
         if (!walFS.delete(wap.p, false)) {
           LOG.warn("Failed deleting of " + wap.p);
           throw new IOException("Failed deleting of " + wap.p);
         }
       }
     }
 
     /**
      * Close all of the output streams.
      * @return the list of paths written.
      */
     List<Path> close() throws IOException {
       Preconditions.checkState(!closeAndCleanCompleted);
 
       final List<Path> paths = new ArrayList<Path>();
       final List<IOException> thrown = Lists.newArrayList();
       ThreadPoolExecutor closeThreadPool = Threads.getBoundedCachedThreadPool(numThreads, 30L,
         TimeUnit.SECONDS, new ThreadFactory() {
           private int count = 1;
 
           @Override
           public Thread newThread(Runnable r) {
             Thread t = new Thread(r, "split-log-closeStream-" + count++);
             return t;
           }
         });
       CompletionService<Void> completionService =
         new ExecutorCompletionService<Void>(closeThreadPool);
       boolean progress_failed;
       try{
         progress_failed = executeCloseTask(completionService, thrown, paths);
       } catch (InterruptedException e) {
         IOException iie = new InterruptedIOException();
         iie.initCause(e);
         throw iie;
       } catch (ExecutionException e) {
         throw new IOException(e.getCause());
       } finally {
         closeThreadPool.shutdownNow();
       }
 
       if (!thrown.isEmpty()) {
         throw MultipleIOException.createIOException(thrown);
       }
       writersClosed = true;
       closeAndCleanCompleted = true;
       if (progress_failed) {
         return null;
       }
       return paths;
     }
 
     boolean executeCloseTask(CompletionService<Void> completionService,
         final List<IOException> thrown, final List<Path> paths)
         throws InterruptedException, ExecutionException {
       for (final Map.Entry<String, SinkWriter> writersEntry : writers.entrySet()) {
         if (LOG.isTraceEnabled()) {
           LOG.trace("Submitting close of " + ((WriterAndPath) writersEntry.getValue()).p);
         }
         completionService.submit(new Callable<Void>() {
           @Override public Void call() throws Exception {
             WriterAndPath wap = (WriterAndPath) writersEntry.getValue();
             Path dst = closeWriter(writersEntry.getKey(), wap, thrown);
             paths.add(dst);
             return null;
           }
         });
       }
       boolean progress_failed = false;
       for (int i = 0, n = this.writers.size(); i < n; i++) {
         Future<Void> future = completionService.take();
         future.get();
         if (!progress_failed && reporter != null && !reporter.progress()) {
           progress_failed = true;
         }
       }
       return progress_failed;
     }
 
     Path closeWriter(String encodedRegionName, WriterAndPath wap, List<IOException> thrown)
         throws IOException {
       if (LOG.isTraceEnabled()) {
         LOG.trace("Closing " + wap.p);
       }
 
       try {
         wap.w.close();
       } catch (IOException ioe) {
         LOG.error("Couldn't close log at " + wap.p, ioe);
         thrown.add(ioe);
         return null;
       }
       if (LOG.isDebugEnabled()) {
         LOG.debug("Closed wap " + wap.p + " (wrote " + wap.editsWritten
             + " edits, skipped " + wap.editsSkipped + " edits in "
             + (wap.nanosSpent / 1000 / 1000) + "ms");
       }
       if (wap.editsWritten == 0) {
         // just remove the empty recovered.edits file
         if (walFS.exists(wap.p) && !walFS.delete(wap.p, false)) {
           LOG.warn("Failed deleting empty " + wap.p);
           throw new IOException("Failed deleting empty  " + wap.p);
         }
         return null;
       }
 
       Path dst = getCompletedRecoveredEditsFilePath(wap.p,
           regionMaximumEditLogSeqNum.get(encodedRegionName));
       try {
         if (!dst.equals(wap.p) && walFS.exists(dst)) {
           deleteOneWithFewerEntries(wap, dst);
         }
         // Skip the unit tests which create a splitter that reads and
         // writes the data without touching disk.
         // TestHLogSplit#testThreading is an example.
         if (walFS.exists(wap.p)) {
           if (!walFS.rename(wap.p, dst)) {
             throw new IOException("Failed renaming " + wap.p + " to " + dst);
           }
           LOG.info("Rename " + wap.p + " to " + dst);
         }
       } catch (IOException ioe) {
         LOG.error("Couldn't rename " + wap.p + " to " + dst, ioe);
         thrown.add(ioe);
         return null;
       }
       return dst;
     }
 
 
     private List<IOException> closeLogWriters(List<IOException> thrown) throws IOException {
       if (writersClosed) {
         return thrown;
       }
 
       if (thrown == null) {
         thrown = Lists.newArrayList();
       }
       try {
         for (WriterThread t : writerThreads) {
           while (t.isAlive()) {
             t.shouldStop = true;
             t.interrupt();
             try {
               t.join(10);
             } catch (InterruptedException e) {
               IOException iie = new InterruptedIOException();
               iie.initCause(e);
               throw iie;
             }
           }
         }
       } finally {
         WriterAndPath wap = null;
         for (SinkWriter tmpWAP : writers.values()) {
           try {
             wap = (WriterAndPath) tmpWAP;
             wap.w.close();
           } catch (IOException ioe) {
             LOG.error("Couldn't close log at " + wap.p, ioe);
             thrown.add(ioe);
             continue;
           }
           LOG.info(
               "Closed log " + wap.p + " (wrote " + wap.editsWritten + " edits in " + (wap.nanosSpent
                   / 1000 / 1000) + "ms)");
         }
         writersClosed = true;
       }
 
       return thrown;
     }
 
     /**
      * Get a writer and path for a log starting at the given entry. This function is threadsafe so
      * long as multiple threads are always acting on different regions.
      * @return null if this region shouldn't output any logs
      */
     WriterAndPath getWriterAndPath(Entry entry, boolean reusable) throws IOException {
       byte region[] = entry.getKey().getEncodedRegionName();
       String regionName = Bytes.toString(region);
       WriterAndPath ret = (WriterAndPath) writers.get(regionName);
       if (ret != null) {
         return ret;
       }
       // If we already decided that this region doesn't get any output
       // we don't need to check again.
       if (blacklistedRegions.contains(region)) {
         return null;
       }
       ret = createWAP(region, entry);
       if (ret == null) {
         blacklistedRegions.add(region);
         return null;
       }
 
       if(reusable) {
         writers.put(regionName, ret);
       }
       return ret;
     }
 
     /**
      * @return a path with a write for that path. caller should close.
      */
     WriterAndPath createWAP(byte[] region, Entry entry) throws IOException {
       String tmpDirName = conf.get(HConstants.TEMPORARY_FS_DIRECTORY_KEY,
         HConstants.DEFAULT_TEMPORARY_HDFS_DIRECTORY);
       Path regionedits = getRegionSplitEditsPath(entry,
           fileBeingSplit.getPath().getName(), tmpDirName, conf);
       if (regionedits == null) {
         return null;
       }
       if (walFS.exists(regionedits)) {
         LOG.warn("Found old edits file. It could be the "
             + "result of a previous failed split attempt. Deleting " + regionedits + ", length="
             + walFS.getFileStatus(regionedits).getLen());
         if (!walFS.delete(regionedits, false)) {
           LOG.warn("Failed delete of old " + regionedits);
         }
       }
       Writer w = createWriter(regionedits);
       LOG.debug("Creating writer path=" + regionedits);
       return new WriterAndPath(regionedits, w, entry.getKey().getLogSeqNum());
     }
 
     void filterCellByStore(Entry logEntry) {
       Map<byte[], Long> maxSeqIdInStores =
           regionMaxSeqIdInStores.get(Bytes.toString(logEntry.getKey().getEncodedRegionName()));
       if (maxSeqIdInStores == null || maxSeqIdInStores.isEmpty()) {
         return;
       }
       // Create the array list for the cells that aren't filtered.
       // We make the assumption that most cells will be kept.
       ArrayList<Cell> keptCells = new ArrayList<Cell>(logEntry.getEdit().getCells().size());
       for (Cell cell : logEntry.getEdit().getCells()) {
         if (CellUtil.matchingFamily(cell, WALEdit.METAFAMILY)) {
           keptCells.add(cell);
         } else {
           byte[] family = CellUtil.cloneFamily(cell);
           Long maxSeqId = maxSeqIdInStores.get(family);
           // Do not skip cell even if maxSeqId is null. Maybe we are in a rolling upgrade,
           // or the master was crashed before and we can not get the information.
           if (maxSeqId == null || maxSeqId.longValue() < logEntry.getKey().getLogSeqNum()) {
             keptCells.add(cell);
           }
         }
       }
 
       // Anything in the keptCells array list is still live.
       // So rather than removing the cells from the array list
       // which would be an O(n^2) operation, we just replace the list
       logEntry.getEdit().setCells(keptCells);
     }
 
     @Override
     public void append(RegionEntryBuffer buffer) throws IOException {
       appendBuffer(buffer, true);
     }
 
 
     WriterAndPath appendBuffer(RegionEntryBuffer buffer, boolean reusable) throws IOException{
       List<Entry> entries = buffer.entryBuffer;
       if (entries.isEmpty()) {
         LOG.warn("got an empty buffer, skipping");
         return null;
       }
       WriterAndPath wap = null;
 
       long startTime = System.nanoTime();
       try {
         int editsCount = 0;
 
         for (Entry logEntry : entries) {
           if (wap == null) {
             wap = getWriterAndPath(logEntry, reusable);
             if (wap == null) {
               if (LOG.isDebugEnabled()) {
                 LOG.debug("getWriterAndPath decided we don't need to write edits for " + logEntry);
               }
               return null;
             }
           }
           filterCellByStore(logEntry);
           if (!logEntry.getEdit().isEmpty()) {
             wap.w.append(logEntry);
             this.updateRegionMaximumEditLogSeqNum(logEntry);
             editsCount++;
           } else {
             wap.incrementSkippedEdits(1);
           }
         }
         // Pass along summary statistics
         wap.incrementEdits(editsCount);
         wap.incrementNanoTime(System.nanoTime() - startTime);
       } catch (IOException e) {
         e = RemoteExceptionHandler.checkIOException(e);
         LOG.fatal(" Got while writing log entry to log", e);
         throw e;
       }
       return wap;
     }
 
     @Override
     public boolean keepRegionEvent(Entry entry) {
       ArrayList<Cell> cells = entry.getEdit().getCells();
       for (int i = 0; i < cells.size(); i++) {
         if (WALEdit.isCompactionMarker(cells.get(i))) {
           return true;
         }
       }
       return false;
     }
 
     /**
      * @return a map from encoded region ID to the number of edits written out for that region.
      */
     @Override
     public Map<byte[], Long> getOutputCounts() {
       TreeMap<byte[], Long> ret = new TreeMap<byte[], Long>(Bytes.BYTES_COMPARATOR);
       synchronized (writers) {
         for (Map.Entry<String, SinkWriter> entry : writers.entrySet()) {
           ret.put(Bytes.toBytes(entry.getKey()), entry.getValue().editsWritten);
         }
       }
       return ret;
     }
 
     @Override
     public int getNumberOfRecoveredRegions() {
       return writers.size();
     }
   }
 
   /**
    * Class that will limit the number of hdfs writers we create to split the logs
    */
   class BoundedLogWriterCreationOutputSink extends LogRecoveredEditsOutputSink{
 
     ConcurrentHashMap<String, Long> regionRecoverStatMap = new ConcurrentHashMap<>();
 
 
     public BoundedLogWriterCreationOutputSink(PipelineController controller,
         EntryBuffers entryBuffers, int numWriters){
       super(controller, entryBuffers, numWriters);
     }
 
     @Override
     public List<Path> finishWritingAndClose() throws IOException {
       boolean isSuccessful;
       List<Path> result;
       try {
         isSuccessful = finishWriting(false);
       } finally {
         result = close();
       }
       if (isSuccessful) {
         splits = result;
       }
       return splits;
     }
 
     @Override
     boolean executeCloseTask(CompletionService<Void> closeCompletionService,
         final List<IOException> thrown, final List<Path> paths)
         throws InterruptedException, ExecutionException {
       for (final Map.Entry<byte[], RegionEntryBuffer> buffer : entryBuffers.buffers.entrySet()) {
         LOG.info("Submitting write then close of " +
             Bytes.toString(buffer.getValue().encodedRegionName));
         closeCompletionService.submit(new Callable<Void>() {
           public Void call() throws Exception {
             Path dst = writeThenClose(buffer.getValue());
             paths.add(dst);
             return null;
           }
         });
       }
 
       boolean progress_failed = false;
       for (int i = 0, n = entryBuffers.buffers.size(); i < n; i++) {
         Future<Void> future = closeCompletionService.take();
         future.get();
         if (!progress_failed && reporter != null && !reporter.progress()) {
           progress_failed = true;
         }
       }
       return progress_failed;
     }
 
     @Override
     public Map<byte[], Long> getOutputCounts() {
       Map<byte[], Long> regionRecoverStatMapResult = new HashMap<>();
       for(Map.Entry<String, Long> entry: regionRecoverStatMap.entrySet()){
         regionRecoverStatMapResult.put(Bytes.toBytes(entry.getKey()), entry.getValue());
       }
       return regionRecoverStatMapResult;
     }
 
     @Override
     public int getNumberOfRecoveredRegions() {
       return regionRecoverStatMap.size();
     }
 
     @Override
     public void append(RegionEntryBuffer buffer) throws IOException {
       writeThenClose(buffer);
     }
 
     private Path writeThenClose(RegionEntryBuffer buffer) throws IOException {
       WriterAndPath wap = appendBuffer(buffer, false);
       Path dst = null;
       if(wap != null){
         String encodedRegionName = Bytes.toString(buffer.encodedRegionName);
         Long value = regionRecoverStatMap.putIfAbsent(encodedRegionName, wap.editsWritten);
         if(value != null){
           Long newValue = regionRecoverStatMap.get(encodedRegionName) + wap.editsWritten;
           regionRecoverStatMap.put(encodedRegionName, newValue);
         }
       }
 
       List<IOException> thrown = new ArrayList<>();
       if(wap != null) {
         dst = closeWriter(Bytes.toString(buffer.encodedRegionName), wap, thrown);
       }
 
       if(!thrown.isEmpty()){
         throw MultipleIOException.createIOException(thrown);
       }
       return dst;
     }
   }
 
 
   /**
    * Class wraps the actual writer which writes data out and related statistics
    */
   public abstract static class SinkWriter {
     /* Count of edits written to this path */
     long editsWritten = 0;
     /* Count of edits skipped to this path */
     long editsSkipped = 0;
     /* Number of nanos spent writing to this log */
     long nanosSpent = 0;
 
     void incrementEdits(int edits) {
       editsWritten += edits;
     }
 
     void incrementSkippedEdits(int skipped) {
       editsSkipped += skipped;
     }
 
     void incrementNanoTime(long nanos) {
       nanosSpent += nanos;
     }
   }
 
   /**
    * Private data structure that wraps a Writer and its Path, also collecting statistics about the
    * data written to this output.
    */
   private final static class WriterAndPath extends SinkWriter {
     final Path p;
     final Writer w;
     final long minLogSeqNum;
 
     WriterAndPath(final Path p, final Writer w, final long minLogSeqNum) {
       this.p = p;
       this.w = w;
       this.minLogSeqNum = minLogSeqNum;
     }
   }
 
   /**
    * Class that manages to replay edits from WAL files directly to assigned fail over region servers
    */
   class LogReplayOutputSink extends OutputSink {
     private static final double BUFFER_THRESHOLD = 0.35;
     private static final String KEY_DELIMITER = "#";
 
     private long waitRegionOnlineTimeOut;
     private final Set<String> recoveredRegions = Collections.synchronizedSet(new HashSet<String>());
     private final Map<String, RegionServerWriter> rsWriters =
         new ConcurrentHashMap<String, RegionServerWriter>();
     // online encoded region name -> region location map
     private final Map<String, HRegionLocation> onlineRegions =
         new ConcurrentHashMap<String, HRegionLocation>();
 
     private final Map<TableName, HConnection> tableNameToHConnectionMap = Collections
         .synchronizedMap(new TreeMap<TableName, HConnection>());
     /**
      * Map key -> value layout
      * servername:table name -> Queue(Row)
      */
     private final Map<String, List<Pair<HRegionLocation, Entry>>> serverToBufferQueueMap =
         new ConcurrentHashMap<String, List<Pair<HRegionLocation, Entry>>>();
     private final List<Throwable> thrown = new ArrayList<Throwable>();
 
     // The following sink is used in distrubitedLogReplay mode for entries of regions in a disabling
     // table. It's a limitation of distributedLogReplay. Because log replay needs a region is
     // assigned and online before it can replay wal edits while regions of disabling/disabled table
     // won't be assigned by AM. We can retire this code after HBASE-8234.
     private LogRecoveredEditsOutputSink logRecoveredEditsOutputSink;
     private boolean hasEditsInDisablingOrDisabledTables = false;
 
     public LogReplayOutputSink(PipelineController controller, EntryBuffers entryBuffers,
         int numWriters) {
       super(controller, entryBuffers, numWriters);
       this.waitRegionOnlineTimeOut = conf.getInt(HConstants.HBASE_SPLITLOG_MANAGER_TIMEOUT,
           ZKSplitLogManagerCoordination.DEFAULT_TIMEOUT);
       this.logRecoveredEditsOutputSink = new LogRecoveredEditsOutputSink(controller,
         entryBuffers, numWriters);
       this.logRecoveredEditsOutputSink.setReporter(reporter);
     }
 
     @Override
     public void append(RegionEntryBuffer buffer) throws IOException {
       List<Entry> entries = buffer.entryBuffer;
       if (entries.isEmpty()) {
         LOG.warn("got an empty buffer, skipping");
         return;
       }
 
       // check if current region in a disabling or disabled table
       if (disablingOrDisabledTables.contains(buffer.tableName)) {
         // need fall back to old way
         logRecoveredEditsOutputSink.append(buffer);
         hasEditsInDisablingOrDisabledTables = true;
         // store regions we have recovered so far
         addToRecoveredRegions(Bytes.toString(buffer.encodedRegionName));
         return;
       }
 
       // group entries by region servers
       groupEditsByServer(entries);
 
       // process workitems
       String maxLocKey = null;
       int maxSize = 0;
       List<Pair<HRegionLocation, Entry>> maxQueue = null;
       synchronized (this.serverToBufferQueueMap) {
         for (Map.Entry<String, List<Pair<HRegionLocation, Entry>>> entry:
               serverToBufferQueueMap.entrySet()) {
           List<Pair<HRegionLocation, Entry>> curQueue = entry.getValue();
           if (curQueue.size() > maxSize) {
             maxSize = curQueue.size();
             maxQueue = curQueue;
             maxLocKey = entry.getKey();
           }
         }
         if (maxSize < minBatchSize
             && entryBuffers.totalBuffered < BUFFER_THRESHOLD * entryBuffers.maxHeapUsage) {
           // buffer more to process
           return;
         } else if (maxSize > 0) {
           this.serverToBufferQueueMap.remove(maxLocKey);
         }
       }
 
       if (maxSize > 0) {
         processWorkItems(maxLocKey, maxQueue);
       }
     }
 
     private void addToRecoveredRegions(String encodedRegionName) {
       if (!recoveredRegions.contains(encodedRegionName)) {
         recoveredRegions.add(encodedRegionName);
       }
     }
 
     /**
      * Helper function to group WALEntries to individual region servers
      * @throws IOException
      */
     private void groupEditsByServer(List<Entry> entries) throws IOException {
       Set<TableName> nonExistentTables = null;
       Long cachedLastFlushedSequenceId = -1l;
       for (Entry entry : entries) {
         WALEdit edit = entry.getEdit();
         TableName table = entry.getKey().getTablename();
         // clear scopes which isn't needed for recovery
         entry.getKey().setScopes(null);
         String encodeRegionNameStr = Bytes.toString(entry.getKey().getEncodedRegionName());
         // skip edits of non-existent tables
         if (nonExistentTables != null && nonExistentTables.contains(table)) {
           this.skippedEdits.incrementAndGet();
           continue;
         }
 
         Map<byte[], Long> maxStoreSequenceIds = null;
         boolean needSkip = false;
         HRegionLocation loc = null;
         String locKey = null;
         List<Cell> cells = edit.getCells();
         List<Cell> skippedCells = new ArrayList<Cell>();
         HConnection hconn = this.getConnectionByTableName(table);
 
         for (Cell cell : cells) {
           byte[] row = CellUtil.cloneRow(cell);
           byte[] family = CellUtil.cloneFamily(cell);
           boolean isCompactionEntry = false;
           if (CellUtil.matchingFamily(cell, WALEdit.METAFAMILY)) {
             CompactionDescriptor compaction = WALEdit.getCompaction(cell);
             if (compaction != null && compaction.hasRegionName()) {
               try {
                 byte[][] regionName = HRegionInfo.parseRegionName(compaction.getRegionName()
                   .toByteArray());
                 row = regionName[1]; // startKey of the region
                 family = compaction.getFamilyName().toByteArray();
                 isCompactionEntry = true;
               } catch (Exception ex) {
                 LOG.warn("Unexpected exception received, ignoring " + ex);
                 skippedCells.add(cell);
                 continue;
               }
             } else {
               skippedCells.add(cell);
               continue;
             }
           }
 
           try {
             loc =
                 locateRegionAndRefreshLastFlushedSequenceId(hconn, table, row,
                   encodeRegionNameStr);
             // skip replaying the compaction if the region is gone
             if (isCompactionEntry && !encodeRegionNameStr.equalsIgnoreCase(
               loc.getRegionInfo().getEncodedName())) {
               LOG.info("Not replaying a compaction marker for an older region: "
                   + encodeRegionNameStr);
               needSkip = true;
             }
           } catch (TableNotFoundException ex) {
             // table has been deleted so skip edits of the table
             LOG.info("Table " + table + " doesn't exist. Skip log replay for region "
                 + encodeRegionNameStr);
             lastFlushedSequenceIds.put(encodeRegionNameStr, Long.MAX_VALUE);
             if (nonExistentTables == null) {
               nonExistentTables = new TreeSet<TableName>();
             }
             nonExistentTables.add(table);
             this.skippedEdits.incrementAndGet();
             needSkip = true;
             break;
           }
 
           cachedLastFlushedSequenceId =
               lastFlushedSequenceIds.get(loc.getRegionInfo().getEncodedName());
           if (cachedLastFlushedSequenceId != null
               && cachedLastFlushedSequenceId >= entry.getKey().getLogSeqNum()) {
             // skip the whole WAL entry
             this.skippedEdits.incrementAndGet();
             needSkip = true;
             break;
           } else {
             if (maxStoreSequenceIds == null) {
               maxStoreSequenceIds =
                   regionMaxSeqIdInStores.get(loc.getRegionInfo().getEncodedName());
             }
             if (maxStoreSequenceIds != null) {
               Long maxStoreSeqId = maxStoreSequenceIds.get(family);
               if (maxStoreSeqId == null || maxStoreSeqId >= entry.getKey().getLogSeqNum()) {
                 // skip current kv if column family doesn't exist anymore or already flushed
                 skippedCells.add(cell);
                 continue;
               }
             }
           }
         }
 
         // skip the edit
         if (loc == null || needSkip) continue;
 
         if (!skippedCells.isEmpty()) {
           cells.removeAll(skippedCells);
         }
 
         synchronized (serverToBufferQueueMap) {
           locKey = loc.getHostnamePort() + KEY_DELIMITER + table;
           List<Pair<HRegionLocation, Entry>> queue = serverToBufferQueueMap.get(locKey);
           if (queue == null) {
             queue =
                 Collections.synchronizedList(new ArrayList<Pair<HRegionLocation, Entry>>());
             serverToBufferQueueMap.put(locKey, queue);
           }
           queue.add(new Pair<HRegionLocation, Entry>(loc, entry));
         }
         // store regions we have recovered so far
         addToRecoveredRegions(loc.getRegionInfo().getEncodedName());
       }
     }
 
     /**
      * Locate destination region based on table name & row. This function also makes sure the
      * destination region is online for replay.
      * @throws IOException
      */
     private HRegionLocation locateRegionAndRefreshLastFlushedSequenceId(HConnection hconn,
         TableName table, byte[] row, String originalEncodedRegionName) throws IOException {
       // fetch location from cache
       HRegionLocation loc = onlineRegions.get(originalEncodedRegionName);
       if(loc != null) return loc;
       // fetch location from hbase:meta directly without using cache to avoid hit old dead server
       loc = hconn.getRegionLocation(table, row, true);
       if (loc == null) {
         throw new IOException("Can't locate location for row:" + Bytes.toString(row)
             + " of table:" + table);
       }
       // check if current row moves to a different region due to region merge/split
       if (!originalEncodedRegionName.equalsIgnoreCase(loc.getRegionInfo().getEncodedName())) {
         // originalEncodedRegionName should have already flushed
         lastFlushedSequenceIds.put(originalEncodedRegionName, Long.MAX_VALUE);
         HRegionLocation tmpLoc = onlineRegions.get(loc.getRegionInfo().getEncodedName());
         if (tmpLoc != null) return tmpLoc;
       }
 
       Long lastFlushedSequenceId = -1l;
       AtomicBoolean isRecovering = new AtomicBoolean(true);
       loc = waitUntilRegionOnline(loc, row, this.waitRegionOnlineTimeOut, isRecovering);
       if (!isRecovering.get()) {
         // region isn't in recovering at all because WAL file may contain a region that has
         // been moved to somewhere before hosting RS fails
         lastFlushedSequenceIds.put(loc.getRegionInfo().getEncodedName(), Long.MAX_VALUE);
         LOG.info("logReplay skip region: " + loc.getRegionInfo().getEncodedName()
             + " because it's not in recovering.");
       } else {
         Long cachedLastFlushedSequenceId =
             lastFlushedSequenceIds.get(loc.getRegionInfo().getEncodedName());
 
         // retrieve last flushed sequence Id from ZK. Because region postOpenDeployTasks will
         // update the value for the region
         RegionStoreSequenceIds ids =
             csm.getSplitLogWorkerCoordination().getRegionFlushedSequenceId(failedServerName,
               loc.getRegionInfo().getEncodedName());
         if (ids != null) {
           lastFlushedSequenceId = ids.getLastFlushedSequenceId();
           Map<byte[], Long> storeIds = new TreeMap<byte[], Long>(Bytes.BYTES_COMPARATOR);
           List<StoreSequenceId> maxSeqIdInStores = ids.getStoreSequenceIdList();
           for (StoreSequenceId id : maxSeqIdInStores) {
             storeIds.put(id.getFamilyName().toByteArray(), id.getSequenceId());
           }
           regionMaxSeqIdInStores.put(loc.getRegionInfo().getEncodedName(), storeIds);
         }
 
         if (cachedLastFlushedSequenceId == null
             || lastFlushedSequenceId > cachedLastFlushedSequenceId) {
           lastFlushedSequenceIds.put(loc.getRegionInfo().getEncodedName(), lastFlushedSequenceId);
         }
       }
 
       onlineRegions.put(loc.getRegionInfo().getEncodedName(), loc);
       return loc;
     }
 
     private void processWorkItems(String key, List<Pair<HRegionLocation, Entry>> actions)
         throws IOException {
       RegionServerWriter rsw = null;
 
       long startTime = System.nanoTime();
       try {
         rsw = getRegionServerWriter(key);
         rsw.sink.replayEntries(actions);
 
         // Pass along summary statistics
         rsw.incrementEdits(actions.size());
         rsw.incrementNanoTime(System.nanoTime() - startTime);
       } catch (IOException e) {
         e = RemoteExceptionHandler.checkIOException(e);
         LOG.fatal(" Got while writing log entry to log", e);
         throw e;
       }
     }
 
     /**
      * Wait until region is online on the destination region server
      * @param loc
      * @param row
      * @param timeout How long to wait
      * @param isRecovering Recovering state of the region interested on destination region server.
      * @return True when region is online on the destination region server
      * @throws InterruptedException
      */
     private HRegionLocation waitUntilRegionOnline(HRegionLocation loc, byte[] row,
         final long timeout, AtomicBoolean isRecovering)
         throws IOException {
       final long endTime = EnvironmentEdgeManager.currentTime() + timeout;
       final long pause = conf.getLong(HConstants.HBASE_CLIENT_PAUSE,
         HConstants.DEFAULT_HBASE_CLIENT_PAUSE);
       boolean reloadLocation = false;
       TableName tableName = loc.getRegionInfo().getTable();
       int tries = 0;
       Throwable cause = null;
       while (endTime > EnvironmentEdgeManager.currentTime()) {
         try {
           // Try and get regioninfo from the hosting server.
           HConnection hconn = getConnectionByTableName(tableName);
           if(reloadLocation) {
             loc = hconn.getRegionLocation(tableName, row, true);
           }
           BlockingInterface remoteSvr = hconn.getAdmin(loc.getServerName());
           HRegionInfo region = loc.getRegionInfo();
           try {
             GetRegionInfoRequest request =
                 RequestConverter.buildGetRegionInfoRequest(region.getRegionName());
             GetRegionInfoResponse response = remoteSvr.getRegionInfo(null, request);
             if (HRegionInfo.convert(response.getRegionInfo()) != null) {
               isRecovering.set((response.hasIsRecovering()) ? response.getIsRecovering() : true);
               return loc;
             }
           } catch (ServiceException se) {
             throw ProtobufUtil.getRemoteException(se);
           }
         } catch (IOException e) {
           cause = e.getCause();
           if(!(cause instanceof RegionOpeningException)) {
             reloadLocation = true;
           }
         }
         long expectedSleep = ConnectionUtils.getPauseTime(pause, tries);
         try {
           Thread.sleep(expectedSleep);
         } catch (InterruptedException e) {
           throw new IOException("Interrupted when waiting region " +
               loc.getRegionInfo().getEncodedName() + " online.", e);
         }
         tries++;
       }
 
       throw new IOException("Timeout when waiting region " + loc.getRegionInfo().getEncodedName() +
         " online for " + timeout + " milliseconds.", cause);
     }
 
     @Override
     public boolean flush() throws IOException {
       String curLoc = null;
       int curSize = 0;
       List<Pair<HRegionLocation, Entry>> curQueue = null;
       synchronized (this.serverToBufferQueueMap) {
         for (Map.Entry<String, List<Pair<HRegionLocation, Entry>>> entry :
                 serverToBufferQueueMap.entrySet()) {
           String locationKey = entry.getKey();
           curQueue = entry.getValue();
           if (!curQueue.isEmpty()) {
             curSize = curQueue.size();
             curLoc = locationKey;
             break;
           }
         }
         if (curSize > 0) {
           this.serverToBufferQueueMap.remove(curLoc);
         }
       }
 
       if (curSize > 0) {
         this.processWorkItems(curLoc, curQueue);
         // We should already have control of the monitor; ensure this is the case.
         synchronized(controller.dataAvailable) {
           controller.dataAvailable.notifyAll();
         }
         return true;
       }
       return false;
     }
 
     @Override
     public boolean keepRegionEvent(Entry entry) {
       return true;
     }
 
     void addWriterError(Throwable t) {
       thrown.add(t);
     }
 
     @Override
     public List<Path> finishWritingAndClose() throws IOException {
       try {
         if (!finishWriting(false)) {
           return null;
         }
         if (hasEditsInDisablingOrDisabledTables) {
           splits = logRecoveredEditsOutputSink.finishWritingAndClose();
         } else {
           splits = new ArrayList<Path>();
         }
         // returns an empty array in order to keep interface same as old way
         return splits;
       } finally {
         List<IOException> thrown = closeRegionServerWriters();
         if (thrown != null && !thrown.isEmpty()) {
           throw MultipleIOException.createIOException(thrown);
         }
       }
     }
 
     @Override
     int getNumOpenWriters() {
       return this.rsWriters.size() + this.logRecoveredEditsOutputSink.getNumOpenWriters();
     }
 
     private List<IOException> closeRegionServerWriters() throws IOException {
       List<IOException> result = null;
       if (!writersClosed) {
         result = Lists.newArrayList();
         try {
           for (WriterThread t : writerThreads) {
             while (t.isAlive()) {
               t.shouldStop = true;
               t.interrupt();
               try {
                 t.join(10);
               } catch (InterruptedException e) {
                 IOException iie = new InterruptedIOException();
                 iie.initCause(e);
                 throw iie;
               }
             }
           }
         } finally {
           synchronized (rsWriters) {
             for (Map.Entry<String, RegionServerWriter> entry : rsWriters.entrySet()) {
               String locationKey = entry.getKey();
               RegionServerWriter tmpW = entry.getValue();
               try {
                 tmpW.close();
               } catch (IOException ioe) {
                 LOG.error("Couldn't close writer for region server:" + locationKey, ioe);
                 result.add(ioe);
               }
             }
           }
 
           // close connections
           synchronized (this.tableNameToHConnectionMap) {
             for (Map.Entry<TableName, HConnection> entry :
                   tableNameToHConnectionMap.entrySet()) {
               TableName tableName = entry.getKey();
               HConnection hconn = entry.getValue();
               try {
                 hconn.clearRegionCache();
                 hconn.close();
               } catch (IOException ioe) {
                 result.add(ioe);
               }
             }
           }
           writersClosed = true;
         }
       }
       return result;
     }
 
     @Override
     public Map<byte[], Long> getOutputCounts() {
       TreeMap<byte[], Long> ret = new TreeMap<byte[], Long>(Bytes.BYTES_COMPARATOR);
       synchronized (rsWriters) {
         for (Map.Entry<String, RegionServerWriter> entry : rsWriters.entrySet()) {
           ret.put(Bytes.toBytes(entry.getKey()), entry.getValue().editsWritten);
         }
       }
       return ret;
     }
 
     @Override
     public int getNumberOfRecoveredRegions() {
       return this.recoveredRegions.size();
     }
 
     /**
      * Get a writer and path for a log starting at the given entry. This function is threadsafe so
      * long as multiple threads are always acting on different regions.
      * @return null if this region shouldn't output any logs
      */
     private RegionServerWriter getRegionServerWriter(String loc) throws IOException {
       RegionServerWriter ret = rsWriters.get(loc);
       if (ret != null) {
         return ret;
       }
 
       TableName tableName = getTableFromLocationStr(loc);
       if(tableName == null){
         throw new IOException("Invalid location string:" + loc + " found. Replay aborted.");
       }
 
       HConnection hconn = getConnectionByTableName(tableName);
       synchronized (rsWriters) {
         ret = rsWriters.get(loc);
         if (ret == null) {
           ret = new RegionServerWriter(conf, tableName, hconn);
           rsWriters.put(loc, ret);
         }
       }
       return ret;
     }
 
     private HConnection getConnectionByTableName(final TableName tableName) throws IOException {
       HConnection hconn = this.tableNameToHConnectionMap.get(tableName);
       if (hconn == null) {
         synchronized (this.tableNameToHConnectionMap) {
           hconn = this.tableNameToHConnectionMap.get(tableName);
           if (hconn == null) {
             hconn = HConnectionManager.getConnection(conf);
             this.tableNameToHConnectionMap.put(tableName, hconn);
           }
         }
       }
       return hconn;
     }
     private TableName getTableFromLocationStr(String loc) {
       /**
        * location key is in format <server name:port>#<table name>
        */
       String[] splits = loc.split(KEY_DELIMITER);
       if (splits.length != 2) {
         return null;
       }
       return TableName.valueOf(splits[1]);
     }
   }
 
   /**
    * Private data structure that wraps a receiving RS and collecting statistics about the data
    * written to this newly assigned RS.
    */
   private final static class RegionServerWriter extends SinkWriter {
     final WALEditsReplaySink sink;
 
     RegionServerWriter(final Configuration conf, final TableName tableName, final HConnection conn)
         throws IOException {
       this.sink = new WALEditsReplaySink(conf, tableName, conn);
     }
 
     void close() throws IOException {
     }
   }
 
   static class CorruptedLogFileException extends Exception {
     private static final long serialVersionUID = 1L;
 
     CorruptedLogFileException(String s) {
       super(s);
     }
   }
 
   /** A struct used by getMutationsFromWALEntry */
   public static class MutationReplay implements Comparable<MutationReplay> {
     public MutationReplay(MutationType type, Mutation mutation, long nonceGroup, long nonce) {
       this.type = type;
       this.mutation = mutation;
       if(this.mutation.getDurability() != Durability.SKIP_WAL) {
         // using ASYNC_WAL for relay
         this.mutation.setDurability(Durability.ASYNC_WAL);
       }
       this.nonceGroup = nonceGroup;
       this.nonce = nonce;
     }
 
     public final MutationType type;
     public final Mutation mutation;
     public final long nonceGroup;
     public final long nonce;
 
     @Override
     public int compareTo(final MutationReplay d) {
       return this.mutation.compareTo(d.mutation);
     }
 
     @Override
     public boolean equals(Object obj) {
       if(!(obj instanceof MutationReplay)) {
         return false;
       } else {
         return this.compareTo((MutationReplay)obj) == 0;
       }
     }
 
     @Override
     public int hashCode() {
       return this.mutation.hashCode();
     }
   }
 
   /**
    * This function is used to construct mutations from a WALEntry. It also
    * reconstructs WALKey &amp; WALEdit from the passed in WALEntry
    * @param entry
    * @param cells
    * @param logEntry pair of WALKey and WALEdit instance stores WALKey and WALEdit instances
    *          extracted from the passed in WALEntry.
    * @param durability
    * @return list of Pair&lt;MutationType, Mutation&gt; to be replayed
    * @throws IOException
    */
   public static List<MutationReplay> getMutationsFromWALEntry(WALEntry entry, CellScanner cells,
       Pair<WALKey, WALEdit> logEntry, Durability durability)
           throws IOException {
     if (entry == null) {
       // return an empty array
       return new ArrayList<MutationReplay>();
     }
 
     long replaySeqId = (entry.getKey().hasOrigSequenceNumber()) ?
       entry.getKey().getOrigSequenceNumber() : entry.getKey().getLogSequenceNumber();
     int count = entry.getAssociatedCellCount();
     List<MutationReplay> mutations = new ArrayList<MutationReplay>();
     Cell previousCell = null;
     Mutation m = null;
     WALKey key = null;
     WALEdit val = null;
     if (logEntry != null) val = new WALEdit();
 
     for (int i = 0; i < count; i++) {
       // Throw index out of bounds if our cell count is off
       if (!cells.advance()) {
         throw new ArrayIndexOutOfBoundsException("Expected=" + count + ", index=" + i);
       }
       Cell cell = cells.current();
       if (val != null) val.add(cell);
 
       boolean isNewRowOrType =
           previousCell == null || previousCell.getTypeByte() != cell.getTypeByte()
               || !CellUtil.matchingRow(previousCell, cell);
       if (isNewRowOrType) {
         // Create new mutation
         if (CellUtil.isDelete(cell)) {
           m = new Delete(cell.getRowArray(), cell.getRowOffset(), cell.getRowLength());
           // Deletes don't have nonces.
           mutations.add(new MutationReplay(
               MutationType.DELETE, m, HConstants.NO_NONCE, HConstants.NO_NONCE));
         } else {
           m = new Put(cell.getRowArray(), cell.getRowOffset(), cell.getRowLength());
           // Puts might come from increment or append, thus we need nonces.
           long nonceGroup = entry.getKey().hasNonceGroup()
               ? entry.getKey().getNonceGroup() : HConstants.NO_NONCE;
           long nonce = entry.getKey().hasNonce() ? entry.getKey().getNonce() : HConstants.NO_NONCE;
           mutations.add(new MutationReplay(MutationType.PUT, m, nonceGroup, nonce));
         }
       }
       if (CellUtil.isDelete(cell)) {
         ((Delete) m).addDeleteMarker(cell);
       } else {
         ((Put) m).add(cell);
       }
       m.setDurability(durability);
       previousCell = cell;
     }
 
     // reconstruct WALKey
     if (logEntry != null) {
       org.apache.hadoop.hbase.protobuf.generated.WALProtos.WALKey walKeyProto = entry.getKey();
       List<UUID> clusterIds = new ArrayList<UUID>(walKeyProto.getClusterIdsCount());
       for (HBaseProtos.UUID uuid : entry.getKey().getClusterIdsList()) {
         clusterIds.add(new UUID(uuid.getMostSigBits(), uuid.getLeastSigBits()));
       }
       // we use HLogKey here instead of WALKey directly to support legacy coprocessors.
       key = new HLogKey(walKeyProto.getEncodedRegionName().toByteArray(), TableName.valueOf(
               walKeyProto.getTableName().toByteArray()), replaySeqId, walKeyProto.getWriteTime(),
               clusterIds, walKeyProto.getNonceGroup(), walKeyProto.getNonce(), null);
       logEntry.setFirst(key);
       logEntry.setSecond(val);
     }
 
     return mutations;
   }
 }