/**
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
    *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.apache.hadoop.hbase.replication.regionserver;
  
  import java.io.IOException;
  import java.io.InterruptedIOException;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  import java.util.concurrent.Callable;
  import java.util.concurrent.ExecutionException;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Future;
  import java.util.concurrent.LinkedBlockingQueue;
  import java.util.concurrent.ThreadPoolExecutor;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicLong;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.CellScanner;
  import org.apache.hadoop.hbase.HBaseConfiguration;
  import org.apache.hadoop.hbase.HBaseIOException;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.HRegionLocation;
  import org.apache.hadoop.hbase.HTableDescriptor;
  import org.apache.hadoop.hbase.RegionLocations;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.TableNotFoundException;
  import org.apache.hadoop.hbase.TableDescriptors;
  import org.apache.hadoop.hbase.client.ConnectionFactory;
  import org.apache.hadoop.hbase.client.RegionAdminServiceCallable;
  import org.apache.hadoop.hbase.client.ClusterConnection;
  import org.apache.hadoop.hbase.client.RegionReplicaUtil;
  import org.apache.hadoop.hbase.client.RetryingCallable;
  import org.apache.hadoop.hbase.client.RpcRetryingCallerFactory;
  import org.apache.hadoop.hbase.ipc.PayloadCarryingRpcController;
  import org.apache.hadoop.hbase.ipc.RpcControllerFactory;
  import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
  import org.apache.hadoop.hbase.protobuf.ReplicationProtbufUtil;
  import org.apache.hadoop.hbase.protobuf.generated.AdminProtos;
  import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.ReplicateWALEntryResponse;
  import org.apache.hadoop.hbase.wal.WALKey;
  import org.apache.hadoop.hbase.wal.WALSplitter.PipelineController;
  import org.apache.hadoop.hbase.wal.WALSplitter.RegionEntryBuffer;
  import org.apache.hadoop.hbase.wal.WALSplitter.SinkWriter;
  import org.apache.hadoop.hbase.regionserver.wal.WALCellCodec;
  import org.apache.hadoop.hbase.wal.WAL.Entry;
  import org.apache.hadoop.hbase.wal.WALSplitter.EntryBuffers;
  import org.apache.hadoop.hbase.wal.WALSplitter.OutputSink;
  import org.apache.hadoop.hbase.replication.BaseWALEntryFilter;
  import org.apache.hadoop.hbase.replication.ChainWALEntryFilter;
  import org.apache.hadoop.hbase.replication.HBaseReplicationEndpoint;
  import org.apache.hadoop.hbase.replication.ReplicationEndpoint;
  import org.apache.hadoop.hbase.replication.WALEntryFilter;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.hbase.util.Pair;
  import org.apache.hadoop.hbase.util.Threads;
  import org.apache.hadoop.util.StringUtils;
  
  import com.google.common.cache.Cache;
  import com.google.common.cache.CacheBuilder;
  import com.google.common.collect.Lists;
  import com.google.protobuf.ServiceException;
  
  /**
   * A {@link ReplicationEndpoint} endpoint which receives the WAL edits from the
   * WAL, and sends the edits to replicas of regions.
   */
  @InterfaceAudience.Private
  public class RegionReplicaReplicationEndpoint extends HBaseReplicationEndpoint {
  
    private static final Log LOG = LogFactory.getLog(RegionReplicaReplicationEndpoint.class);
  
    // Can be configured differently than hbase.client.retries.number
    private static String CLIENT_RETRIES_NUMBER
      = "hbase.region.replica.replication.client.retries.number";
  
    private Configuration conf;
   private ClusterConnection connection;
   private TableDescriptors tableDescriptors;
 
   // Reuse WALSplitter constructs as a WAL pipe
   private PipelineController controller;
   private RegionReplicaOutputSink outputSink;
   private EntryBuffers entryBuffers;
 
   // Number of writer threads
   private int numWriterThreads;
 
   private int operationTimeout;
 
   private ExecutorService pool;
 
   /**
    * Skips the entries which has original seqId. Only entries persisted via distributed log replay
    * have their original seq Id fields set.
    */
   private class SkipReplayedEditsFilter extends BaseWALEntryFilter {
     @Override
     public Entry filter(Entry entry) {
       // if orig seq id is set, skip replaying the entry
       if (entry.getKey().getOrigLogSeqNum() > 0) {
         return null;
       }
       return entry;
     }
   }
 
   @Override
   public WALEntryFilter getWALEntryfilter() {
     WALEntryFilter superFilter = super.getWALEntryfilter();
     WALEntryFilter skipReplayedEditsFilter = getSkipReplayedEditsFilter();
 
     if (superFilter == null) {
       return skipReplayedEditsFilter;
     }
 
     if (skipReplayedEditsFilter == null) {
       return superFilter;
     }
 
     ArrayList<WALEntryFilter> filters = Lists.newArrayList();
     filters.add(superFilter);
     filters.add(skipReplayedEditsFilter);
     return new ChainWALEntryFilter(filters);
   }
 
   protected WALEntryFilter getSkipReplayedEditsFilter() {
     return new SkipReplayedEditsFilter();
   }
 
   @Override
   public void init(Context context) throws IOException {
     super.init(context);
 
     this.conf = HBaseConfiguration.create(context.getConfiguration());
     this.tableDescriptors = context.getTableDescriptors();
 
     // HRS multiplies client retries by 10 globally for meta operations, but we do not want this.
     // We are resetting it here because we want default number of retries (35) rather than 10 times
     // that which makes very long retries for disabled tables etc.
     int defaultNumRetries = conf.getInt(HConstants.HBASE_CLIENT_RETRIES_NUMBER,
       HConstants.DEFAULT_HBASE_CLIENT_RETRIES_NUMBER);
     if (defaultNumRetries > 10) {
       int mult = conf.getInt("hbase.client.serverside.retries.multiplier", 10);
       defaultNumRetries = defaultNumRetries / mult; // reset if HRS has multiplied this already
     }
 
     conf.setInt("hbase.client.serverside.retries.multiplier", 1);
     int numRetries = conf.getInt(CLIENT_RETRIES_NUMBER, defaultNumRetries);
     conf.setInt(HConstants.HBASE_CLIENT_RETRIES_NUMBER, numRetries);
 
     this.numWriterThreads = this.conf.getInt(
       "hbase.region.replica.replication.writer.threads", 3);
     controller = new PipelineController();
     entryBuffers = new EntryBuffers(controller,
       this.conf.getInt("hbase.region.replica.replication.buffersize",
           128*1024*1024));
 
     // use the regular RPC timeout for replica replication RPC's
     this.operationTimeout = conf.getInt(HConstants.HBASE_CLIENT_OPERATION_TIMEOUT,
       HConstants.DEFAULT_HBASE_CLIENT_OPERATION_TIMEOUT);
   }
 
   @Override
   protected void doStart() {
     try {
       connection = (ClusterConnection) ConnectionFactory.createConnection(this.conf);
       this.pool = getDefaultThreadPool(conf);
       outputSink = new RegionReplicaOutputSink(controller, tableDescriptors, entryBuffers,
         connection, pool, numWriterThreads, operationTimeout);
       outputSink.startWriterThreads();
       super.doStart();
     } catch (IOException ex) {
       LOG.warn("Received exception while creating connection :" + ex);
       notifyFailed(ex);
     }
   }
 
   @Override
   protected void doStop() {
     if (outputSink != null) {
       try {
         outputSink.finishWritingAndClose();
       } catch (IOException ex) {
         LOG.warn("Got exception while trying to close OutputSink");
         LOG.warn(ex);
       }
     }
     if (this.pool != null) {
       this.pool.shutdownNow();
       try {
         // wait for 10 sec
         boolean shutdown = this.pool.awaitTermination(10000, TimeUnit.MILLISECONDS);
         if (!shutdown) {
           LOG.warn("Failed to shutdown the thread pool after 10 seconds");
         }
       } catch (InterruptedException e) {
         LOG.warn("Got interrupted while waiting for the thread pool to shut down" + e);
       }
     }
     if (connection != null) {
       try {
         connection.close();
       } catch (IOException ex) {
         LOG.warn("Got exception closing connection :" + ex);
       }
     }
     super.doStop();
   }
 
   /**
    * Returns a Thread pool for the RPC's to region replicas. Similar to
    * Connection's thread pool.
    */
   private ExecutorService getDefaultThreadPool(Configuration conf) {
     int maxThreads = conf.getInt("hbase.region.replica.replication.threads.max", 256);
     int coreThreads = conf.getInt("hbase.region.replica.replication.threads.core", 16);
     if (maxThreads == 0) {
       maxThreads = Runtime.getRuntime().availableProcessors() * 8;
     }
     if (coreThreads == 0) {
       coreThreads = Runtime.getRuntime().availableProcessors() * 8;
     }
     long keepAliveTime = conf.getLong("hbase.region.replica.replication.threads.keepalivetime", 60);
     LinkedBlockingQueue<Runnable> workQueue =
         new LinkedBlockingQueue<Runnable>(maxThreads *
             conf.getInt(HConstants.HBASE_CLIENT_MAX_TOTAL_TASKS,
               HConstants.DEFAULT_HBASE_CLIENT_MAX_TOTAL_TASKS));
     ThreadPoolExecutor tpe = new ThreadPoolExecutor(
       coreThreads,
       maxThreads,
       keepAliveTime,
       TimeUnit.SECONDS,
       workQueue,
       Threads.newDaemonThreadFactory(this.getClass().getSimpleName() + "-rpc-shared-"));
     tpe.allowCoreThreadTimeOut(true);
     return tpe;
   }
 
   @Override
   public boolean replicate(ReplicateContext replicateContext) {
     /* A note on batching in RegionReplicaReplicationEndpoint (RRRE):
      *
      * RRRE relies on batching from two different mechanisms. The first is the batching from
      * ReplicationSource since RRRE is a ReplicationEndpoint driven by RS. RS reads from a single
      * WAL file filling up a buffer of heap size "replication.source.size.capacity"(64MB) or at most
      * "replication.source.nb.capacity" entries or until it sees the end of file (in live tailing).
      * Then RS passes all the buffered edits in this replicate() call context. RRRE puts the edits
      * to the WALSplitter.EntryBuffers which is a blocking buffer space of up to
      * "hbase.region.replica.replication.buffersize" (128MB) in size. This buffer splits the edits
      * based on regions.
      *
      * There are "hbase.region.replica.replication.writer.threads"(default 3) writer threads which
      * pick largest per-region buffer and send it to the SinkWriter (see RegionReplicaOutputSink).
      * The SinkWriter in this case will send the wal edits to all secondary region replicas in
      * parallel via a retrying rpc call. EntryBuffers guarantees that while a buffer is
      * being written to the sink, another buffer for the same region will not be made available to
      * writers ensuring regions edits are not replayed out of order.
      *
      * The replicate() call won't return until all the buffers are sent and ack'd by the sinks so
      * that the replication can assume all edits are persisted. We may be able to do a better
      * pipelining between the replication thread and output sinks later if it becomes a bottleneck.
      */
 
     while (this.isRunning()) {
       try {
         for (Entry entry: replicateContext.getEntries()) {
           entryBuffers.appendEntry(entry);
         }
         outputSink.flush(); // make sure everything is flushed
         ctx.getMetrics().incrLogEditsFiltered(
           outputSink.getSkippedEditsCounter().getAndSet(0));
         return true;
       } catch (InterruptedException e) {
         Thread.currentThread().interrupt();
         return false;
       } catch (IOException e) {
         LOG.warn("Received IOException while trying to replicate"
             + StringUtils.stringifyException(e));
       }
     }
 
     return false;
   }
 
   @Override
   public boolean canReplicateToSameCluster() {
     return true;
   }
 
   @Override
   protected WALEntryFilter getScopeWALEntryFilter() {
     // we do not care about scope. We replicate everything.
     return null;
   }
 
   static class RegionReplicaOutputSink extends OutputSink {
     private final RegionReplicaSinkWriter sinkWriter;
     private final TableDescriptors tableDescriptors;
     private final Cache<TableName, Boolean> memstoreReplicationEnabled;
 
     public RegionReplicaOutputSink(PipelineController controller, TableDescriptors tableDescriptors,
         EntryBuffers entryBuffers, ClusterConnection connection, ExecutorService pool,
         int numWriters, int operationTimeout) {
       super(controller, entryBuffers, numWriters);
       this.sinkWriter = new RegionReplicaSinkWriter(this, connection, pool, operationTimeout);
       this.tableDescriptors = tableDescriptors;
 
       // A cache for the table "memstore replication enabled" flag.
       // It has a default expiry of 5 sec. This means that if the table is altered
       // with a different flag value, we might miss to replicate for that amount of
       // time. But this cache avoid the slow lookup and parsing of the TableDescriptor.
       int memstoreReplicationEnabledCacheExpiryMs = connection.getConfiguration()
         .getInt("hbase.region.replica.replication.cache.memstoreReplicationEnabled.expiryMs", 5000);
       this.memstoreReplicationEnabled = CacheBuilder.newBuilder()
         .expireAfterWrite(memstoreReplicationEnabledCacheExpiryMs, TimeUnit.MILLISECONDS)
         .initialCapacity(10)
         .maximumSize(1000)
         .build();
     }
 
     @Override
     public void append(RegionEntryBuffer buffer) throws IOException {
       List<Entry> entries = buffer.getEntryBuffer();
 
       if (entries.isEmpty() || entries.get(0).getEdit().getCells().isEmpty()) {
         return;
       }
 
       // meta edits (e.g. flush) are always replicated.
       // data edits (e.g. put) are replicated if the table requires them.
       if (!requiresReplication(buffer.getTableName(), entries)) {
         return;
       }
 
       sinkWriter.append(buffer.getTableName(), buffer.getEncodedRegionName(),
         entries.get(0).getEdit().getCells().get(0).getRow(), entries);
     }
 
     @Override
     public boolean flush() throws IOException {
       // nothing much to do for now. Wait for the Writer threads to finish up
       // append()'ing the data.
       entryBuffers.waitUntilDrained();
       return super.flush();
     }
 
     @Override
     public List<Path> finishWritingAndClose() throws IOException {
       finishWriting(true);
       return null;
     }
 
     @Override
     public Map<byte[], Long> getOutputCounts() {
       return null; // only used in tests
     }
 
     @Override
     public int getNumberOfRecoveredRegions() {
       return 0;
     }
 
     AtomicLong getSkippedEditsCounter() {
       return skippedEdits;
     }
 
     /**
      * returns true if the specified entry must be replicated.
      * We should always replicate meta operations (e.g. flush)
      * and use the user HTD flag to decide whether or not replicate the memstore.
      */
     private boolean requiresReplication(final TableName tableName, final List<Entry> entries)
         throws IOException {
       // unit-tests may not the TableDescriptors, bypass the check and always replicate
       if (tableDescriptors == null) return true;
 
       Boolean requiresReplication = memstoreReplicationEnabled.getIfPresent(tableName);
       if (requiresReplication == null) {
         // check if the table requires memstore replication
         // some unit-test drop the table, so we should do a bypass check and always replicate.
         HTableDescriptor htd = tableDescriptors.get(tableName);
         requiresReplication = htd == null || htd.hasRegionMemstoreReplication();
         memstoreReplicationEnabled.put(tableName, requiresReplication);
       }
 
       // if memstore replication is not required, check the entries.
       // meta edits (e.g. flush) must be always replicated.
       if (!requiresReplication) {
         int skipEdits = 0;
         java.util.Iterator<Entry> it = entries.iterator();
         while (it.hasNext()) {
           Entry entry = it.next();
           if (entry.getEdit().isMetaEdit()) {
             requiresReplication = true;
           } else {
             it.remove();
             skipEdits++;
           }
         }
         skippedEdits.addAndGet(skipEdits);
       }
       return requiresReplication;
     }
   }
 
   static class RegionReplicaSinkWriter extends SinkWriter {
     RegionReplicaOutputSink sink;
     ClusterConnection connection;
     RpcControllerFactory rpcControllerFactory;
     RpcRetryingCallerFactory rpcRetryingCallerFactory;
     int operationTimeout;
     ExecutorService pool;
     Cache<TableName, Boolean> disabledAndDroppedTables;
 
     public RegionReplicaSinkWriter(RegionReplicaOutputSink sink, ClusterConnection connection,
         ExecutorService pool, int operationTimeout) {
       this.sink = sink;
       this.connection = connection;
       this.operationTimeout = operationTimeout;
       this.rpcRetryingCallerFactory
         = RpcRetryingCallerFactory.instantiate(connection.getConfiguration());
       this.rpcControllerFactory = RpcControllerFactory.instantiate(connection.getConfiguration());
       this.pool = pool;
 
       int nonExistentTableCacheExpiryMs = connection.getConfiguration()
         .getInt("hbase.region.replica.replication.cache.disabledAndDroppedTables.expiryMs", 5000);
       // A cache for non existing tables that have a default expiry of 5 sec. This means that if the
       // table is created again with the same name, we might miss to replicate for that amount of
       // time. But this cache prevents overloading meta requests for every edit from a deleted file.
       disabledAndDroppedTables = CacheBuilder.newBuilder()
         .expireAfterWrite(nonExistentTableCacheExpiryMs, TimeUnit.MILLISECONDS)
         .initialCapacity(10)
         .maximumSize(1000)
         .build();
     }
 
     public void append(TableName tableName, byte[] encodedRegionName, byte[] row,
         List<Entry> entries) throws IOException {
 
       if (disabledAndDroppedTables.getIfPresent(tableName) != null) {
         if (LOG.isTraceEnabled()) {
           LOG.trace("Skipping " + entries.size() + " entries because table " + tableName
             + " is cached as a disabled or dropped table");
           for (Entry entry : entries) {
             LOG.trace("Skipping : " + entry);
           }
         }
         sink.getSkippedEditsCounter().addAndGet(entries.size());
         return;
       }
 
       // If the table is disabled or dropped, we should not replay the entries, and we can skip
       // replaying them. However, we might not know whether the table is disabled until we
       // invalidate the cache and check from meta
       RegionLocations locations = null;
       boolean useCache = true;
       while (true) {
         // get the replicas of the primary region
         try {
           locations = RegionReplicaReplayCallable
               .getRegionLocations(connection, tableName, row, useCache, 0);
 
           if (locations == null) {
             throw new HBaseIOException("Cannot locate locations for "
                 + tableName + ", row:" + Bytes.toStringBinary(row));
           }
         } catch (TableNotFoundException e) {
           if (LOG.isTraceEnabled()) {
             LOG.trace("Skipping " + entries.size() + " entries because table " + tableName
               + " is dropped. Adding table to cache.");
             for (Entry entry : entries) {
               LOG.trace("Skipping : " + entry);
             }
           }
           disabledAndDroppedTables.put(tableName, Boolean.TRUE); // put to cache. Value ignored
           // skip this entry
           sink.getSkippedEditsCounter().addAndGet(entries.size());
           return;
         }
 
         // check whether we should still replay this entry. If the regions are changed, or the
         // entry is not coming from the primary region, filter it out.
         HRegionLocation primaryLocation = locations.getDefaultRegionLocation();
         if (!Bytes.equals(primaryLocation.getRegionInfo().getEncodedNameAsBytes(),
           encodedRegionName)) {
           if (useCache) {
             useCache = false;
             continue; // this will retry location lookup
           }
           if (LOG.isTraceEnabled()) {
             LOG.trace("Skipping " + entries.size() + " entries in table " + tableName
               + " because located region " + primaryLocation.getRegionInfo().getEncodedName()
               + " is different than the original region " + Bytes.toStringBinary(encodedRegionName)
               + " from WALEdit");
             for (Entry entry : entries) {
               LOG.trace("Skipping : " + entry);
             }
           }
           sink.getSkippedEditsCounter().addAndGet(entries.size());
           return;
         }
         break;
       }
 
       if (locations.size() == 1) {
         return;
       }
 
       ArrayList<Future<ReplicateWALEntryResponse>> tasks
         = new ArrayList<Future<ReplicateWALEntryResponse>>(locations.size() - 1);
 
       // All passed entries should belong to one region because it is coming from the EntryBuffers
       // split per region. But the regions might split and merge (unlike log recovery case).
       for (int replicaId = 0; replicaId < locations.size(); replicaId++) {
         HRegionLocation location = locations.getRegionLocation(replicaId);
         if (!RegionReplicaUtil.isDefaultReplica(replicaId)) {
           HRegionInfo regionInfo = location == null
               ? RegionReplicaUtil.getRegionInfoForReplica(
                 locations.getDefaultRegionLocation().getRegionInfo(), replicaId)
               : location.getRegionInfo();
           RegionReplicaReplayCallable callable = new RegionReplicaReplayCallable(connection,
             rpcControllerFactory, tableName, location, regionInfo, row, entries,
             sink.getSkippedEditsCounter());
            Future<ReplicateWALEntryResponse> task = pool.submit(
              new RetryingRpcCallable<ReplicateWALEntryResponse>(rpcRetryingCallerFactory,
                  callable, operationTimeout));
            tasks.add(task);
         }
       }
 
       boolean tasksCancelled = false;
       for (Future<ReplicateWALEntryResponse> task : tasks) {
         try {
           task.get();
         } catch (InterruptedException e) {
           throw new InterruptedIOException(e.getMessage());
         } catch (ExecutionException e) {
           Throwable cause = e.getCause();
           if (cause instanceof IOException) {
             // The table can be disabled or dropped at this time. For disabled tables, we have no
             // cheap mechanism to detect this case because meta does not contain this information.
             // HConnection.isTableDisabled() is a zk call which we cannot do for every replay RPC.
             // So instead we start the replay RPC with retries and
             // check whether the table is dropped or disabled which might cause
             // SocketTimeoutException, or RetriesExhaustedException or similar if we get IOE.
             if (cause instanceof TableNotFoundException || connection.isTableDisabled(tableName)) {
               if (LOG.isTraceEnabled()) {
                 LOG.trace("Skipping " + entries.size() + " entries in table " + tableName
                   + " because received exception for dropped or disabled table", cause);
                 for (Entry entry : entries) {
                   LOG.trace("Skipping : " + entry);
                 }
               }
               disabledAndDroppedTables.put(tableName, Boolean.TRUE); // put to cache for later.
               if (!tasksCancelled) {
                 sink.getSkippedEditsCounter().addAndGet(entries.size());
                 tasksCancelled = true; // so that we do not add to skipped counter again
               }
               continue;
             }
             // otherwise rethrow
             throw (IOException)cause;
           }
           // unexpected exception
           throw new IOException(cause);
         }
       }
     }
   }
 
   static class RetryingRpcCallable<V> implements Callable<V> {
     RpcRetryingCallerFactory factory;
     RetryingCallable<V> callable;
     int timeout;
     public RetryingRpcCallable(RpcRetryingCallerFactory factory, RetryingCallable<V> callable,
         int timeout) {
       this.factory = factory;
       this.callable = callable;
       this.timeout = timeout;
     }
     @Override
     public V call() throws Exception {
       return factory.<V>newCaller().callWithRetries(callable, timeout);
     }
   }
 
   /**
    * Calls replay on the passed edits for the given set of entries belonging to the region. It skips
    * the entry if the region boundaries have changed or the region is gone.
    */
   static class RegionReplicaReplayCallable
     extends RegionAdminServiceCallable<ReplicateWALEntryResponse> {
 
     private final List<Entry> entries;
     private final byte[] initialEncodedRegionName;
     private final AtomicLong skippedEntries;
 
     public RegionReplicaReplayCallable(ClusterConnection connection,
         RpcControllerFactory rpcControllerFactory, TableName tableName,
         HRegionLocation location, HRegionInfo regionInfo, byte[] row,List<Entry> entries,
         AtomicLong skippedEntries) {
       super(connection, rpcControllerFactory, location, tableName, row, regionInfo.getReplicaId());
       this.entries = entries;
       this.skippedEntries = skippedEntries;
       this.initialEncodedRegionName = regionInfo.getEncodedNameAsBytes();
     }
 
     @Override
     public ReplicateWALEntryResponse call(int timeout) throws IOException {
       return replayToServer(this.entries, timeout);
     }
 
     private ReplicateWALEntryResponse replayToServer(List<Entry> entries, int timeout)
         throws IOException {
       // check whether we should still replay this entry. If the regions are changed, or the
       // entry is not coming form the primary region, filter it out because we do not need it.
       // Regions can change because of (1) region split (2) region merge (3) table recreated
       boolean skip = false;
 
       if (!Bytes.equals(location.getRegionInfo().getEncodedNameAsBytes(),
         initialEncodedRegionName)) {
         skip = true;
       }
       if (!entries.isEmpty() && !skip) {
         Entry[] entriesArray = new Entry[entries.size()];
         entriesArray = entries.toArray(entriesArray);
 
         // set the region name for the target region replica
         Pair<AdminProtos.ReplicateWALEntryRequest, CellScanner> p =
             ReplicationProtbufUtil.buildReplicateWALEntryRequest(
               entriesArray, location.getRegionInfo().getEncodedNameAsBytes());
         try {
           PayloadCarryingRpcController controller = rpcControllerFactory.newController(p.getSecond());
           controller.setCallTimeout(timeout);
           controller.setPriority(tableName);
           return stub.replay(controller, p.getFirst());
         } catch (ServiceException se) {
           throw ProtobufUtil.getRemoteException(se);
         }
       }
 
       if (skip) {
         if (LOG.isTraceEnabled()) {
           LOG.trace("Skipping " + entries.size() + " entries in table " + tableName
             + " because located region " + location.getRegionInfo().getEncodedName()
             + " is different than the original region "
             + Bytes.toStringBinary(initialEncodedRegionName) + " from WALEdit");
           for (Entry entry : entries) {
             LOG.trace("Skipping : " + entry);
           }
         }
         skippedEntries.addAndGet(entries.size());
       }
       return ReplicateWALEntryResponse.newBuilder().build();
     }
   }
 }