HBASE-18229: create new Async Split API to embrace AM v2

Signed-off-by: Michael Stack <stack@apache.org>

hbase-client/src/main/java/org/apache/hadoop/hbase/client/Admin.java

@@ -985,6 +985,8 @@ public interface Admin extends Abortable, Closeable {
    *
    * @param regionName region to split
    * @throws IOException if a remote or network exception occurs
+   * @deprecated Since 2.0. Will be removed in 3.0. Use
+   *     {@link #splitRegionAsync(byte[], byte[])} instead.
    */
   void splitRegion(final byte[] regionName) throws IOException;
 
@@ -1004,10 +1006,21 @@ public interface Admin extends Abortable, Closeable {
    * @param regionName region to split
    * @param splitPoint the explicit position to split on
    * @throws IOException if a remote or network exception occurs
+   * @deprecated Since 2.0. Will be removed in 3.0. Use
+   *     {@link #splitRegionAsync(byte[], byte[])} instead.
    */
   void splitRegion(final byte[] regionName, final byte[] splitPoint)
     throws IOException;
 
+  /**
+   * Split an individual region. Asynchronous operation.
+   * @param regionName region to split
+   * @param splitPoint the explicit position to split on
+   * @throws IOException if a remote or network exception occurs
+   */
+  Future<Void> splitRegionAsync(byte[] regionName, byte[] splitPoint)
+    throws IOException;
+
   /**
    * Modify an existing table, more IRB friendly version.
    *

hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncHBaseAdmin.java

@@ -160,6 +160,8 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SetQuotaRe
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SetQuotaResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SnapshotRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SnapshotResponse;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SplitTableRegionRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SplitTableRegionResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.TruncateTableRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.TruncateTableResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.UnassignRegionRequest;
@@ -1102,7 +1104,7 @@ public class AsyncHBaseAdmin implements AsyncAdmin {
                       if (hri == null || hri.isSplitParent()
                           || hri.getReplicaId() != HRegionInfo.DEFAULT_REPLICA_ID)
                         continue;
-                      splitFutures.add(split(h.getServerName(), hri, Optional.empty()));
+                      splitFutures.add(split(hri, Optional.empty()));
                     }
                   }
                 }
@@ -1170,7 +1172,7 @@ public class AsyncHBaseAdmin implements AsyncAdmin {
               .toStringBinary(regionName)));
           return;
         }
-        split(serverName, regionInfo, splitPoint).whenComplete((ret, err2) -> {
+        split(regionInfo, splitPoint).whenComplete((ret, err2) -> {
           if (err2 != null) {
             future.completeExceptionally(err2);
           } else {
@@ -1181,21 +1183,36 @@ public class AsyncHBaseAdmin implements AsyncAdmin {
     return future;
   }
 
-  private CompletableFuture<Void> split(final ServerName sn, final HRegionInfo hri,
+  private CompletableFuture<Void> split(final HRegionInfo hri,
       Optional<byte[]> splitPoint) {
     if (hri.getStartKey() != null && splitPoint.isPresent()
         && Bytes.compareTo(hri.getStartKey(), splitPoint.get()) == 0) {
       return failedFuture(new IllegalArgumentException(
           "should not give a splitkey which equals to startkey!"));
     }
-    return this
+
-        .<Void> newAdminCaller()
+    CompletableFuture<Void> future = new CompletableFuture<>();
-        .action(
+    TableName tableName = hri.getTable();
-          (controller, stub) -> this.<SplitRegionRequest, SplitRegionResponse, Void> adminCall(
+    SplitTableRegionRequest request = null;
-            controller, stub,
+    try {
-            ProtobufUtil.buildSplitRegionRequest(hri.getRegionName(), splitPoint),
+      request = RequestConverter
-            (s, c, req, done) -> s.splitRegion(controller, req, done), resp -> null))
+          .buildSplitTableRegionRequest(hri, splitPoint.isPresent() ? splitPoint.get() : null,
-        .serverName(sn).call();
+              ng.getNonceGroup(), ng.newNonce());
+    } catch (DeserializationException e) {
+      future.completeExceptionally(e);
+      return future;
+    }
+
+    this.<SplitTableRegionRequest, SplitTableRegionResponse>procedureCall(request,
+        (s, c, req, done) -> s.splitRegion(c, req, done), (resp) -> resp.getProcId(),
+        new SplitTableRegionProcedureBiConsumer(this, tableName)).whenComplete((ret, err2) -> {
+      if (err2 != null) {
+        future.completeExceptionally(err2);
+      } else {
+        future.complete(ret);
+      }
+    });
+    return future;
   }
 
   @Override
@@ -2242,6 +2259,17 @@ public class AsyncHBaseAdmin implements AsyncAdmin {
     }
   }
 
+  private class SplitTableRegionProcedureBiConsumer extends  TableProcedureBiConsumer {
+
+    SplitTableRegionProcedureBiConsumer(AsyncAdmin admin, TableName tableName) {
+      super(admin, tableName);
+    }
+
+    String getOperationType() {
+      return "SPLIT_REGION";
+    }
+  }
+
   private CompletableFuture<Void> waitProcedureResult(CompletableFuture<Long> procFuture) {
     CompletableFuture<Void> future = new CompletableFuture<>();
     procFuture.whenComplete((procId, error) -> {

hbase-client/src/main/java/org/apache/hadoop/hbase/client/HBaseAdmin.java

@@ -177,6 +177,8 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SetNormali
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ShutdownRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SnapshotRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SnapshotResponse;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SplitTableRegionRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SplitTableRegionResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.StopMasterRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.TruncateTableRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.TruncateTableResponse;
@@ -1635,6 +1637,97 @@ public class HBaseAdmin implements Admin {
       return "MERGE_REGIONS";
     }
   }
+  /**
+   * Split one region. Synchronous operation.
+   * Note: It is not feasible to predict the length of split.
+   *   Therefore, this is for internal testing only.
+   * @param regionName encoded or full name of region
+   * @param splitPoint key where region splits
+   * @throws IOException
+   */
+  @VisibleForTesting
+  public void splitRegionSync(byte[] regionName, byte[] splitPoint) throws IOException {
+    splitRegionSync(regionName, splitPoint, syncWaitTimeout, TimeUnit.MILLISECONDS);
+  }
+
+
+  /**
+   * Split one region. Synchronous operation.
+   * @param regionName region to be split
+   * @param splitPoint split point
+   * @param timeout how long to wait on split
+   * @param units time units
+   * @throws IOException
+   */
+  public void splitRegionSync(byte[] regionName, byte[] splitPoint,
+    final long timeout, final TimeUnit units) throws IOException {
+    get(
+        splitRegionAsync(regionName, splitPoint),
+        timeout,
+        units);
+  }
+
+  @Override
+  public Future<Void> splitRegionAsync(byte[] regionName, byte[] splitPoint)
+      throws IOException {
+    byte[] encodedNameofRegionToSplit = HRegionInfo.isEncodedRegionName(regionName) ?
+        regionName : HRegionInfo.encodeRegionName(regionName).getBytes();
+    Pair<HRegionInfo, ServerName> pair = getRegion(regionName);
+    if (pair != null) {
+      if (pair.getFirst() != null &&
+          pair.getFirst().getReplicaId() != HRegionInfo.DEFAULT_REPLICA_ID) {
+        throw new IllegalArgumentException ("Can't invoke split on non-default regions directly");
+      }
+    } else {
+      throw new UnknownRegionException (
+          "Can't invoke merge on unknown region "
+              + Bytes.toStringBinary(encodedNameofRegionToSplit));
+    }
+
+    HRegionInfo hri = pair.getFirst();
+    return splitRegionAsync(hri, splitPoint);
+  }
+
+  Future<Void> splitRegionAsync(HRegionInfo hri, byte[] splitPoint) throws IOException {
+    TableName tableName = hri.getTable();
+    if (hri.getStartKey() != null && splitPoint != null &&
+        Bytes.compareTo(hri.getStartKey(), splitPoint) == 0) {
+      throw new IOException("should not give a splitkey which equals to startkey!");
+    }
+
+    SplitTableRegionResponse response = executeCallable(
+        new MasterCallable<SplitTableRegionResponse>(getConnection(), getRpcControllerFactory()) {
+          @Override
+          protected SplitTableRegionResponse rpcCall() throws Exception {
+            setPriority(tableName);
+            SplitTableRegionRequest request = RequestConverter
+                .buildSplitTableRegionRequest(hri, splitPoint, ng.getNonceGroup(), ng.newNonce());
+            return master.splitRegion(getRpcController(), request);
+          }
+        });
+    return new SplitTableRegionFuture(this, tableName, response);
+  }
+
+  private static class SplitTableRegionFuture extends TableFuture<Void> {
+    public SplitTableRegionFuture(final HBaseAdmin admin,
+        final TableName tableName,
+        final SplitTableRegionResponse response) {
+      super(admin, tableName,
+          (response != null && response.hasProcId()) ? response.getProcId() : null);
+    }
+
+    public SplitTableRegionFuture(
+        final HBaseAdmin admin,
+        final TableName tableName,
+        final Long procId) {
+      super(admin, tableName, procId);
+    }
+
+    @Override
+    public String getOperationType() {
+      return "SPLIT_REGION";
+    }
+  }
 
   @Override
   public void split(final TableName tableName) throws IOException {
@@ -1646,9 +1739,6 @@ public class HBaseAdmin implements Admin {
     splitRegion(regionName, null);
   }
 
-  /**
-   * {@inheritDoc}
-   */
   @Override
   public void split(final TableName tableName, final byte [] splitPoint) throws IOException {
     ZooKeeperWatcher zookeeper = null;
@@ -1662,6 +1752,9 @@ public class HBaseAdmin implements Admin {
       } else {
         pairs = MetaTableAccessor.getTableRegionsAndLocations(connection, tableName);
       }
+      if (splitPoint == null) {
+        LOG.info("SplitPoint is null, will find bestSplitPoint from Region");
+      }
       for (Pair<HRegionInfo, ServerName> pair: pairs) {
         // May not be a server for a particular row
         if (pair.getSecond() == null) continue;
@@ -1671,8 +1764,8 @@ public class HBaseAdmin implements Admin {
         // if a split point given, only split that particular region
         if (r.getReplicaId() != HRegionInfo.DEFAULT_REPLICA_ID ||
            (splitPoint != null && !r.containsRow(splitPoint))) continue;
-        // call out to region server to do split now
+        // call out to master to do split now
-        split(pair.getSecond(), pair.getFirst(), splitPoint);
+        splitRegionAsync(pair.getFirst(), splitPoint);
       }
     } finally {
       if (zookeeper != null) {
@@ -1695,23 +1788,7 @@ public class HBaseAdmin implements Admin {
     if (regionServerPair.getSecond() == null) {
       throw new NoServerForRegionException(Bytes.toStringBinary(regionName));
     }
-    split(regionServerPair.getSecond(), regionServerPair.getFirst(), splitPoint);
+    splitRegionAsync(regionServerPair.getFirst(), splitPoint);
-  }
-
-  @VisibleForTesting
-  public void split(final ServerName sn, final HRegionInfo hri,
-      byte[] splitPoint) throws IOException {
-    if (hri.getStartKey() != null && splitPoint != null &&
-         Bytes.compareTo(hri.getStartKey(), splitPoint) == 0) {
-       throw new IOException("should not give a splitkey which equals to startkey!");
-    }
-    // TODO: There is no timeout on this controller. Set one!
-    HBaseRpcController controller = rpcControllerFactory.newController();
-    controller.setPriority(hri.getTable());
-
-    // TODO: this does not do retries, it should. Set priority and timeout in controller
-    AdminService.BlockingInterface admin = this.connection.getAdmin(sn);
-    ProtobufUtil.split(controller, admin, hri, splitPoint);
   }
 
   @Override

hbase-client/src/main/java/org/apache/hadoop/hbase/shaded/protobuf/RequestConverter.java

@@ -118,6 +118,8 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.RunCleaner
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SetBalancerRunningRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SetNormalizerRunningRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SetSplitOrMergeEnabledRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SplitTableRegionRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.SplitTableRegionResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.TruncateTableRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.UnassignRegionRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.QuotaProtos.GetQuotaStatesRequest;
@@ -782,6 +784,19 @@ public final class RequestConverter {
   public static GetRegionInfoRequest
       buildGetRegionInfoRequest(final byte[] regionName,
         final boolean includeCompactionState) {
+    return buildGetRegionInfoRequest(regionName, includeCompactionState, false);
+  }
+
+  /**
+   *
+   * @param regionName the name of the region to get info
+   * @param includeCompactionState indicate if the compaction state is requested
+   * @param includeBestSplitRow indicate if the bestSplitRow  is requested
+   * @return protocol buffer GetRegionInfoRequest
+   */
+  public static GetRegionInfoRequest
+      buildGetRegionInfoRequest(final byte[] regionName,
+      final boolean includeCompactionState, final boolean includeBestSplitRow) {
     GetRegionInfoRequest.Builder builder = GetRegionInfoRequest.newBuilder();
     RegionSpecifier region = buildRegionSpecifier(
       RegionSpecifierType.REGION_NAME, regionName);
@@ -789,9 +804,13 @@ public final class RequestConverter {
     if (includeCompactionState) {
       builder.setCompactionState(includeCompactionState);
     }
+    if(includeBestSplitRow) {
+      builder.setBestSplitRow(includeBestSplitRow);
+    }
     return builder.build();
   }
 
+
   /**
    * Create a protocol buffer GetRegionLoadRequest for all regions/regions of a table.
    *
@@ -1149,6 +1168,21 @@ public final class RequestConverter {
     return builder.build();
   }
 
+  public static SplitTableRegionRequest buildSplitTableRegionRequest(
+      final HRegionInfo regionInfo,
+      final byte[] splitRow,
+      final long nonceGroup,
+      final long nonce) throws DeserializationException {
+    SplitTableRegionRequest.Builder builder = SplitTableRegionRequest.newBuilder();
+    builder.setRegionInfo(HRegionInfo.convert(regionInfo));
+    if (splitRow != null) {
+      builder.setSplitRow(UnsafeByteOperations.unsafeWrap(splitRow));
+    }
+    builder.setNonceGroup(nonceGroup);
+    builder.setNonce(nonce);
+    return builder.build();
+  }
+
   /**
    * Create a protocol buffer AssignRegionRequest
    *

hbase-protocol-shaded/src/main/java/org/apache/hadoop/hbase/shaded/protobuf/generated/AdminProtos.java

@@ -39,6 +39,15 @@ public final class AdminProtos {
      * <code>optional bool compaction_state = 2;</code>
      */
     boolean getCompactionState();
+
+    /**
+     * <code>optional bool best_split_row = 3;</code>
+     */
+    boolean hasBestSplitRow();
+    /**
+     * <code>optional bool best_split_row = 3;</code>
+     */
+    boolean getBestSplitRow();
   }
   /**
    * Protobuf type {@code hbase.pb.GetRegionInfoRequest}
@@ -53,6 +62,7 @@ public final class AdminProtos {
     }
     private GetRegionInfoRequest() {
       compactionState_ = false;
+      bestSplitRow_ = false;
     }
 
     @java.lang.Override
@@ -101,6 +111,11 @@ public final class AdminProtos {
               compactionState_ = input.readBool();
               break;
             }
+            case 24: {
+              bitField0_ |= 0x00000004;
+              bestSplitRow_ = input.readBool();
+              break;
+            }
           }
         }
       } catch (org.apache.hadoop.hbase.shaded.com.google.protobuf.InvalidProtocolBufferException e) {
@@ -162,6 +177,21 @@ public final class AdminProtos {
       return compactionState_;
     }
 
+    public static final int BEST_SPLIT_ROW_FIELD_NUMBER = 3;
+    private boolean bestSplitRow_;
+    /**
+     * <code>optional bool best_split_row = 3;</code>
+     */
+    public boolean hasBestSplitRow() {
+      return ((bitField0_ & 0x00000004) == 0x00000004);
+    }
+    /**
+     * <code>optional bool best_split_row = 3;</code>
+     */
+    public boolean getBestSplitRow() {
+      return bestSplitRow_;
+    }
+
     private byte memoizedIsInitialized = -1;
     public final boolean isInitialized() {
       byte isInitialized = memoizedIsInitialized;
@@ -188,6 +218,9 @@ public final class AdminProtos {
       if (((bitField0_ & 0x00000002) == 0x00000002)) {
         output.writeBool(2, compactionState_);
       }
+      if (((bitField0_ & 0x00000004) == 0x00000004)) {
+        output.writeBool(3, bestSplitRow_);
+      }
       unknownFields.writeTo(output);
     }
 
@@ -204,6 +237,10 @@ public final class AdminProtos {
         size += org.apache.hadoop.hbase.shaded.com.google.protobuf.CodedOutputStream
           .computeBoolSize(2, compactionState_);
       }
+      if (((bitField0_ & 0x00000004) == 0x00000004)) {
+        size += org.apache.hadoop.hbase.shaded.com.google.protobuf.CodedOutputStream
+          .computeBoolSize(3, bestSplitRow_);
+      }
       size += unknownFields.getSerializedSize();
       memoizedSize = size;
       return size;
@@ -231,6 +268,11 @@ public final class AdminProtos {
         result = result && (getCompactionState()
             == other.getCompactionState());
       }
+      result = result && (hasBestSplitRow() == other.hasBestSplitRow());
+      if (hasBestSplitRow()) {
+        result = result && (getBestSplitRow()
+            == other.getBestSplitRow());
+      }
       result = result && unknownFields.equals(other.unknownFields);
       return result;
     }
@@ -251,6 +293,11 @@ public final class AdminProtos {
         hash = (53 * hash) + org.apache.hadoop.hbase.shaded.com.google.protobuf.Internal.hashBoolean(
             getCompactionState());
       }
+      if (hasBestSplitRow()) {
+        hash = (37 * hash) + BEST_SPLIT_ROW_FIELD_NUMBER;
+        hash = (53 * hash) + org.apache.hadoop.hbase.shaded.com.google.protobuf.Internal.hashBoolean(
+            getBestSplitRow());
+      }
       hash = (29 * hash) + unknownFields.hashCode();
       memoizedHashCode = hash;
       return hash;
@@ -378,6 +425,8 @@ public final class AdminProtos {
         bitField0_ = (bitField0_ & ~0x00000001);
         compactionState_ = false;
         bitField0_ = (bitField0_ & ~0x00000002);
+        bestSplitRow_ = false;
+        bitField0_ = (bitField0_ & ~0x00000004);
         return this;
       }
 
@@ -414,6 +463,10 @@ public final class AdminProtos {
           to_bitField0_ |= 0x00000002;
         }
         result.compactionState_ = compactionState_;
+        if (((from_bitField0_ & 0x00000004) == 0x00000004)) {
+          to_bitField0_ |= 0x00000004;
+        }
+        result.bestSplitRow_ = bestSplitRow_;
         result.bitField0_ = to_bitField0_;
         onBuilt();
         return result;
@@ -462,6 +515,9 @@ public final class AdminProtos {
         if (other.hasCompactionState()) {
           setCompactionState(other.getCompactionState());
         }
+        if (other.hasBestSplitRow()) {
+          setBestSplitRow(other.getBestSplitRow());
+        }
         this.mergeUnknownFields(other.unknownFields);
         onChanged();
         return this;
@@ -645,6 +701,38 @@ public final class AdminProtos {
         onChanged();
         return this;
       }
+
+      private boolean bestSplitRow_ ;
+      /**
+       * <code>optional bool best_split_row = 3;</code>
+       */
+      public boolean hasBestSplitRow() {
+        return ((bitField0_ & 0x00000004) == 0x00000004);
+      }
+      /**
+       * <code>optional bool best_split_row = 3;</code>
+       */
+      public boolean getBestSplitRow() {
+        return bestSplitRow_;
+      }
+      /**
+       * <code>optional bool best_split_row = 3;</code>
+       */
+      public Builder setBestSplitRow(boolean value) {
+        bitField0_ |= 0x00000004;
+        bestSplitRow_ = value;
+        onChanged();
+        return this;
+      }
+      /**
+       * <code>optional bool best_split_row = 3;</code>
+       */
+      public Builder clearBestSplitRow() {
+        bitField0_ = (bitField0_ & ~0x00000004);
+        bestSplitRow_ = false;
+        onChanged();
+        return this;
+      }
       public final Builder setUnknownFields(
           final org.apache.hadoop.hbase.shaded.com.google.protobuf.UnknownFieldSet unknownFields) {
         return super.setUnknownFields(unknownFields);
@@ -762,6 +850,23 @@ public final class AdminProtos {
      * <code>optional bool mergeable = 5;</code>
      */
     boolean getMergeable();
+
+    /**
+     * <pre>
+     * Get bestSplitRow
+     * </pre>
+     *
+     * <code>optional bytes best_split_row = 6;</code>
+     */
+    boolean hasBestSplitRow();
+    /**
+     * <pre>
+     * Get bestSplitRow
+     * </pre>
+     *
+     * <code>optional bytes best_split_row = 6;</code>
+     */
+    org.apache.hadoop.hbase.shaded.com.google.protobuf.ByteString getBestSplitRow();
   }
   /**
    * Protobuf type {@code hbase.pb.GetRegionInfoResponse}
@@ -779,6 +884,7 @@ public final class AdminProtos {
       isRecovering_ = false;
       splittable_ = false;
       mergeable_ = false;
+      bestSplitRow_ = org.apache.hadoop.hbase.shaded.com.google.protobuf.ByteString.EMPTY;
     }
 
     @java.lang.Override
@@ -848,6 +954,11 @@ public final class AdminProtos {
               mergeable_ = input.readBool();
               break;
             }
+            case 50: {
+              bitField0_ |= 0x00000020;
+              bestSplitRow_ = input.readBytes();
+              break;
+            }
           }
         }
       } catch (org.apache.hadoop.hbase.shaded.com.google.protobuf.InvalidProtocolBufferException e) {
@@ -1079,6 +1190,29 @@ public final class AdminProtos {
       return mergeable_;
     }
 
+    public static final int BEST_SPLIT_ROW_FIELD_NUMBER = 6;
+    private org.apache.hadoop.hbase.shaded.com.google.protobuf.ByteString bestSplitRow_;
+    /**
+     * <pre>
+     * Get bestSplitRow
+     * </pre>
+     *
+     * <code>optional bytes best_split_row = 6;</code>
+     */
+    public boolean hasBestSplitRow() {
+      return ((bitField0_ & 0x00000020) == 0x00000020);
+    }
+    /**
+     * <pre>
+     * Get bestSplitRow
+     * </pre>
+     *
+     * <code>optional bytes best_split_row = 6;</code>
+     */
+    public org.apache.hadoop.hbase.shaded.com.google.protobuf.ByteString getBestSplitRow() {
+      return bestSplitRow_;
+    }
+
     private byte memoizedIsInitialized = -1;
     public final boolean isInitialized() {
       byte isInitialized = memoizedIsInitialized;
@@ -1114,6 +1248,9 @@ public final class AdminProtos {
       if (((bitField0_ & 0x00000010) == 0x00000010)) {
         output.writeBool(5, mergeable_);
       }
+      if (((bitField0_ & 0x00000020) == 0x00000020)) {
+        output.writeBytes(6, bestSplitRow_);
+      }
       unknownFields.writeTo(output);
     }
 
@@ -1142,6 +1279,10 @@ public final class AdminProtos {
         size += org.apache.hadoop.hbase.shaded.com.google.protobuf.CodedOutputStream
           .computeBoolSize(5, mergeable_);
       }
+      if (((bitField0_ & 0x00000020) == 0x00000020)) {
+        size += org.apache.hadoop.hbase.shaded.com.google.protobuf.CodedOutputStream
+          .computeBytesSize(6, bestSplitRow_);
+      }
       size += unknownFields.getSerializedSize();
       memoizedSize = size;
       return size;
@@ -1183,6 +1324,11 @@ public final class AdminProtos {
         result = result && (getMergeable()
             == other.getMergeable());
       }
+      result = result && (hasBestSplitRow() == other.hasBestSplitRow());
+      if (hasBestSplitRow()) {
+        result = result && getBestSplitRow()
+            .equals(other.getBestSplitRow());
+      }
       result = result && unknownFields.equals(other.unknownFields);
       return result;
     }
@@ -1217,6 +1363,10 @@ public final class AdminProtos {
         hash = (53 * hash) + org.apache.hadoop.hbase.shaded.com.google.protobuf.Internal.hashBoolean(
             getMergeable());
       }
+      if (hasBestSplitRow()) {
+        hash = (37 * hash) + BEST_SPLIT_ROW_FIELD_NUMBER;
+        hash = (53 * hash) + getBestSplitRow().hashCode();
+      }
       hash = (29 * hash) + unknownFields.hashCode();
       memoizedHashCode = hash;
       return hash;
@@ -1350,6 +1500,8 @@ public final class AdminProtos {
         bitField0_ = (bitField0_ & ~0x00000008);
         mergeable_ = false;
         bitField0_ = (bitField0_ & ~0x00000010);
+        bestSplitRow_ = org.apache.hadoop.hbase.shaded.com.google.protobuf.ByteString.EMPTY;
+        bitField0_ = (bitField0_ & ~0x00000020);
         return this;
       }
 
@@ -1398,6 +1550,10 @@ public final class AdminProtos {
           to_bitField0_ |= 0x00000010;
         }
         result.mergeable_ = mergeable_;
+        if (((from_bitField0_ & 0x00000020) == 0x00000020)) {
+          to_bitField0_ |= 0x00000020;
+        }
+        result.bestSplitRow_ = bestSplitRow_;
         result.bitField0_ = to_bitField0_;
         onBuilt();
         return result;
@@ -1455,6 +1611,9 @@ public final class AdminProtos {
         if (other.hasMergeable()) {
           setMergeable(other.getMergeable());
         }
+        if (other.hasBestSplitRow()) {
+          setBestSplitRow(other.getBestSplitRow());
+        }
         this.mergeUnknownFields(other.unknownFields);
         onChanged();
         return this;
@@ -1770,6 +1929,57 @@ public final class AdminProtos {
         onChanged();
         return this;
       }
+
+      private org.apache.hadoop.hbase.shaded.com.google.protobuf.ByteString bestSplitRow_ = org.apache.hadoop.hbase.shaded.com.google.protobuf.ByteString.EMPTY;
+      /**
+       * <pre>
+       * Get bestSplitRow
+       * </pre>
+       *
+       * <code>optional bytes best_split_row = 6;</code>
+       */
+      public boolean hasBestSplitRow() {
+        return ((bitField0_ & 0x00000020) == 0x00000020);
+      }
+      /**
+       * <pre>
+       * Get bestSplitRow
+       * </pre>
+       *
+       * <code>optional bytes best_split_row = 6;</code>
+       */
+      public org.apache.hadoop.hbase.shaded.com.google.protobuf.ByteString getBestSplitRow() {
+        return bestSplitRow_;
+      }
+      /**
+       * <pre>
+       * Get bestSplitRow
+       * </pre>
+       *
+       * <code>optional bytes best_split_row = 6;</code>
+       */
+      public Builder setBestSplitRow(org.apache.hadoop.hbase.shaded.com.google.protobuf.ByteString value) {
+        if (value == null) {
+    throw new NullPointerException();
+  }
+  bitField0_ |= 0x00000020;
+        bestSplitRow_ = value;
+        onChanged();
+        return this;
+      }
+      /**
+       * <pre>
+       * Get bestSplitRow
+       * </pre>
+       *
+       * <code>optional bytes best_split_row = 6;</code>
+       */
+      public Builder clearBestSplitRow() {
+        bitField0_ = (bitField0_ & ~0x00000020);
+        bestSplitRow_ = getDefaultInstance().getBestSplitRow();
+        onChanged();
+        return this;
+      }
       public final Builder setUnknownFields(
           final org.apache.hadoop.hbase.shaded.com.google.protobuf.UnknownFieldSet unknownFields) {
         return super.setUnknownFields(unknownFields);
@@ -30221,140 +30431,141 @@ public final class AdminProtos {
     java.lang.String[] descriptorData = {
       "\n\013Admin.proto\022\010hbase.pb\032\023ClusterStatus.p" +
       "roto\032\013HBase.proto\032\tWAL.proto\032\013Quota.prot" +
-      "o\"[\n\024GetRegionInfoRequest\022)\n\006region\030\001 \002(" +
+      "o\"s\n\024GetRegionInfoRequest\022)\n\006region\030\001 \002(" +
       "\0132\031.hbase.pb.RegionSpecifier\022\030\n\020compacti" +
-      "on_state\030\002 \001(\010\"\222\002\n\025GetRegionInfoResponse" +
+      "on_state\030\002 \001(\010\022\026\n\016best_split_row\030\003 \001(\010\"\252" +
-      "\022)\n\013region_info\030\001 \002(\0132\024.hbase.pb.RegionI" +
+      "\002\n\025GetRegionInfoResponse\022)\n\013region_info\030" +
-      "nfo\022I\n\020compaction_state\030\002 \001(\0162/.hbase.pb" +
+      "\001 \002(\0132\024.hbase.pb.RegionInfo\022I\n\020compactio" +
-      ".GetRegionInfoResponse.CompactionState\022\024" +
+      "n_state\030\002 \001(\0162/.hbase.pb.GetRegionInfoRe" +
-      "\n\014isRecovering\030\003 \001(\010\022\022\n\nsplittable\030\004 \001(\010" +
+      "sponse.CompactionState\022\024\n\014isRecovering\030\003" +
-      "\022\021\n\tmergeable\030\005 \001(\010\"F\n\017CompactionState\022\010",
+      " \001(\010\022\022\n\nsplittable\030\004 \001(\010\022\021\n\tmergeable\030\005 ",
-      "\n\004NONE\020\000\022\t\n\005MINOR\020\001\022\t\n\005MAJOR\020\002\022\023\n\017MAJOR_" +
+      "\001(\010\022\026\n\016best_split_row\030\006 \001(\014\"F\n\017Compactio" +
-      "AND_MINOR\020\003\"P\n\023GetStoreFileRequest\022)\n\006re" +
+      "nState\022\010\n\004NONE\020\000\022\t\n\005MINOR\020\001\022\t\n\005MAJOR\020\002\022\023" +
-      "gion\030\001 \002(\0132\031.hbase.pb.RegionSpecifier\022\016\n" +
+      "\n\017MAJOR_AND_MINOR\020\003\"P\n\023GetStoreFileReque" +
-      "\006family\030\002 \003(\014\"*\n\024GetStoreFileResponse\022\022\n" +
+      "st\022)\n\006region\030\001 \002(\0132\031.hbase.pb.RegionSpec" +
-      "\nstore_file\030\001 \003(\t\"\030\n\026GetOnlineRegionRequ" +
+      "ifier\022\016\n\006family\030\002 \003(\014\"*\n\024GetStoreFileRes" +
-      "est\"D\n\027GetOnlineRegionResponse\022)\n\013region" +
+      "ponse\022\022\n\nstore_file\030\001 \003(\t\"\030\n\026GetOnlineRe" +
-      "_info\030\001 \003(\0132\024.hbase.pb.RegionInfo\"\263\002\n\021Op" +
+      "gionRequest\"D\n\027GetOnlineRegionResponse\022)" +
-      "enRegionRequest\022=\n\topen_info\030\001 \003(\0132*.hba" +
+      "\n\013region_info\030\001 \003(\0132\024.hbase.pb.RegionInf" +
-      "se.pb.OpenRegionRequest.RegionOpenInfo\022\027" +
+      "o\"\263\002\n\021OpenRegionRequest\022=\n\topen_info\030\001 \003" +
-      "\n\017serverStartCode\030\002 \001(\004\022\032\n\022master_system",
+      "(\0132*.hbase.pb.OpenRegionRequest.RegionOp",
-      "_time\030\005 \001(\004\032\251\001\n\016RegionOpenInfo\022$\n\006region" +
+      "enInfo\022\027\n\017serverStartCode\030\002 \001(\004\022\032\n\022maste" +
-      "\030\001 \002(\0132\024.hbase.pb.RegionInfo\022\037\n\027version_" +
+      "r_system_time\030\005 \001(\004\032\251\001\n\016RegionOpenInfo\022$" +
-      "of_offline_node\030\002 \001(\r\022+\n\rfavored_nodes\030\003" +
+      "\n\006region\030\001 \002(\0132\024.hbase.pb.RegionInfo\022\037\n\027" +
-      " \003(\0132\024.hbase.pb.ServerName\022#\n\033openForDis" +
+      "version_of_offline_node\030\002 \001(\r\022+\n\rfavored" +
-      "tributedLogReplay\030\004 \001(\010\"\246\001\n\022OpenRegionRe" +
+      "_nodes\030\003 \003(\0132\024.hbase.pb.ServerName\022#\n\033op" +
-      "sponse\022F\n\ropening_state\030\001 \003(\0162/.hbase.pb" +
+      "enForDistributedLogReplay\030\004 \001(\010\"\246\001\n\022Open" +
-      ".OpenRegionResponse.RegionOpeningState\"H" +
+      "RegionResponse\022F\n\ropening_state\030\001 \003(\0162/." +
-      "\n\022RegionOpeningState\022\n\n\006OPENED\020\000\022\022\n\016ALRE" +
+      "hbase.pb.OpenRegionResponse.RegionOpenin" +
-      "ADY_OPENED\020\001\022\022\n\016FAILED_OPENING\020\002\"?\n\023Warm" +
+      "gState\"H\n\022RegionOpeningState\022\n\n\006OPENED\020\000" +
-      "upRegionRequest\022(\n\nregionInfo\030\001 \002(\0132\024.hb",
+      "\022\022\n\016ALREADY_OPENED\020\001\022\022\n\016FAILED_OPENING\020\002",
-      "ase.pb.RegionInfo\"\026\n\024WarmupRegionRespons" +
+      "\"?\n\023WarmupRegionRequest\022(\n\nregionInfo\030\001 " +
-      "e\"\313\001\n\022CloseRegionRequest\022)\n\006region\030\001 \002(\013" +
+      "\002(\0132\024.hbase.pb.RegionInfo\"\026\n\024WarmupRegio" +
-      "2\031.hbase.pb.RegionSpecifier\022\037\n\027version_o" +
+      "nResponse\"\313\001\n\022CloseRegionRequest\022)\n\006regi" +
-      "f_closing_node\030\002 \001(\r\022\036\n\020transition_in_ZK" +
+      "on\030\001 \002(\0132\031.hbase.pb.RegionSpecifier\022\037\n\027v" +
-      "\030\003 \001(\010:\004true\0220\n\022destination_server\030\004 \001(\013" +
+      "ersion_of_closing_node\030\002 \001(\r\022\036\n\020transiti" +
-      "2\024.hbase.pb.ServerName\022\027\n\017serverStartCod" +
+      "on_in_ZK\030\003 \001(\010:\004true\0220\n\022destination_serv" +
-      "e\030\005 \001(\004\"%\n\023CloseRegionResponse\022\016\n\006closed" +
+      "er\030\004 \001(\0132\024.hbase.pb.ServerName\022\027\n\017server" +
-      "\030\001 \002(\010\"y\n\022FlushRegionRequest\022)\n\006region\030\001" +
+      "StartCode\030\005 \001(\004\"%\n\023CloseRegionResponse\022\016" +
-      " \002(\0132\031.hbase.pb.RegionSpecifier\022\030\n\020if_ol" +
+      "\n\006closed\030\001 \002(\010\"y\n\022FlushRegionRequest\022)\n\006" +
-      "der_than_ts\030\002 \001(\004\022\036\n\026write_flush_wal_mar",
+      "region\030\001 \002(\0132\031.hbase.pb.RegionSpecifier\022",
-      "ker\030\003 \001(\010\"_\n\023FlushRegionResponse\022\027\n\017last" +
+      "\030\n\020if_older_than_ts\030\002 \001(\004\022\036\n\026write_flush" +
-      "_flush_time\030\001 \002(\004\022\017\n\007flushed\030\002 \001(\010\022\036\n\026wr" +
+      "_wal_marker\030\003 \001(\010\"_\n\023FlushRegionResponse" +
-      "ote_flush_wal_marker\030\003 \001(\010\"T\n\022SplitRegio" +
+      "\022\027\n\017last_flush_time\030\001 \002(\004\022\017\n\007flushed\030\002 \001" +
-      "nRequest\022)\n\006region\030\001 \002(\0132\031.hbase.pb.Regi" +
+      "(\010\022\036\n\026wrote_flush_wal_marker\030\003 \001(\010\"T\n\022Sp" +
-      "onSpecifier\022\023\n\013split_point\030\002 \001(\014\"\025\n\023Spli" +
+      "litRegionRequest\022)\n\006region\030\001 \002(\0132\031.hbase" +
-      "tRegionResponse\"`\n\024CompactRegionRequest\022" +
+      ".pb.RegionSpecifier\022\023\n\013split_point\030\002 \001(\014" +
-      ")\n\006region\030\001 \002(\0132\031.hbase.pb.RegionSpecifi" +
+      "\"\025\n\023SplitRegionResponse\"`\n\024CompactRegion" +
-      "er\022\r\n\005major\030\002 \001(\010\022\016\n\006family\030\003 \001(\014\"\027\n\025Com" +
+      "Request\022)\n\006region\030\001 \002(\0132\031.hbase.pb.Regio" +
-      "pactRegionResponse\"\315\001\n\031UpdateFavoredNode" +
+      "nSpecifier\022\r\n\005major\030\002 \001(\010\022\016\n\006family\030\003 \001(" +
-      "sRequest\022I\n\013update_info\030\001 \003(\01324.hbase.pb",
+      "\014\"\027\n\025CompactRegionResponse\"\315\001\n\031UpdateFav",
-      ".UpdateFavoredNodesRequest.RegionUpdateI" +
+      "oredNodesRequest\022I\n\013update_info\030\001 \003(\01324." +
-      "nfo\032e\n\020RegionUpdateInfo\022$\n\006region\030\001 \002(\0132" +
+      "hbase.pb.UpdateFavoredNodesRequest.Regio" +
-      "\024.hbase.pb.RegionInfo\022+\n\rfavored_nodes\030\002" +
+      "nUpdateInfo\032e\n\020RegionUpdateInfo\022$\n\006regio" +
-      " \003(\0132\024.hbase.pb.ServerName\".\n\032UpdateFavo" +
+      "n\030\001 \002(\0132\024.hbase.pb.RegionInfo\022+\n\rfavored" +
-      "redNodesResponse\022\020\n\010response\030\001 \001(\r\"a\n\010WA" +
+      "_nodes\030\002 \003(\0132\024.hbase.pb.ServerName\".\n\032Up" +
-      "LEntry\022\035\n\003key\030\001 \002(\0132\020.hbase.pb.WALKey\022\027\n" +
+      "dateFavoredNodesResponse\022\020\n\010response\030\001 \001" +
-      "\017key_value_bytes\030\002 \003(\014\022\035\n\025associated_cel" +
+      "(\r\"a\n\010WALEntry\022\035\n\003key\030\001 \002(\0132\020.hbase.pb.W" +
-      "l_count\030\003 \001(\005\"\242\001\n\030ReplicateWALEntryReque" +
+      "ALKey\022\027\n\017key_value_bytes\030\002 \003(\014\022\035\n\025associ" +
-      "st\022!\n\005entry\030\001 \003(\0132\022.hbase.pb.WALEntry\022\034\n" +
+      "ated_cell_count\030\003 \001(\005\"\242\001\n\030ReplicateWALEn" +
-      "\024replicationClusterId\030\002 \001(\t\022\"\n\032sourceBas",
+      "tryRequest\022!\n\005entry\030\001 \003(\0132\022.hbase.pb.WAL",
-      "eNamespaceDirPath\030\003 \001(\t\022!\n\031sourceHFileAr" +
+      "Entry\022\034\n\024replicationClusterId\030\002 \001(\t\022\"\n\032s" +
-      "chiveDirPath\030\004 \001(\t\"\033\n\031ReplicateWALEntryR" +
+      "ourceBaseNamespaceDirPath\030\003 \001(\t\022!\n\031sourc" +
-      "esponse\"\026\n\024RollWALWriterRequest\"0\n\025RollW" +
+      "eHFileArchiveDirPath\030\004 \001(\t\"\033\n\031ReplicateW" +
-      "ALWriterResponse\022\027\n\017region_to_flush\030\001 \003(" +
+      "ALEntryResponse\"\026\n\024RollWALWriterRequest\"" +
-      "\014\"#\n\021StopServerRequest\022\016\n\006reason\030\001 \002(\t\"\024" +
+      "0\n\025RollWALWriterResponse\022\027\n\017region_to_fl" +
-      "\n\022StopServerResponse\"\026\n\024GetServerInfoReq" +
+      "ush\030\001 \003(\014\"#\n\021StopServerRequest\022\016\n\006reason" +
-      "uest\"K\n\nServerInfo\022)\n\013server_name\030\001 \002(\0132" +
+      "\030\001 \002(\t\"\024\n\022StopServerResponse\"\026\n\024GetServe" +
-      "\024.hbase.pb.ServerName\022\022\n\nwebui_port\030\002 \001(" +
+      "rInfoRequest\"K\n\nServerInfo\022)\n\013server_nam" +
-      "\r\"B\n\025GetServerInfoResponse\022)\n\013server_inf" +
+      "e\030\001 \002(\0132\024.hbase.pb.ServerName\022\022\n\nwebui_p" +
-      "o\030\001 \002(\0132\024.hbase.pb.ServerInfo\"\034\n\032UpdateC",
+      "ort\030\002 \001(\r\"B\n\025GetServerInfoResponse\022)\n\013se",
-      "onfigurationRequest\"\035\n\033UpdateConfigurati" +
+      "rver_info\030\001 \002(\0132\024.hbase.pb.ServerInfo\"\034\n" +
-      "onResponse\"?\n\024GetRegionLoadRequest\022\'\n\nta" +
+      "\032UpdateConfigurationRequest\"\035\n\033UpdateCon" +
-      "ble_name\030\001 \001(\0132\023.hbase.pb.TableName\"C\n\025G" +
+      "figurationResponse\"?\n\024GetRegionLoadReque" +
-      "etRegionLoadResponse\022*\n\014region_loads\030\001 \003" +
+      "st\022\'\n\ntable_name\030\001 \001(\0132\023.hbase.pb.TableN" +
-      "(\0132\024.hbase.pb.RegionLoad\"2\n\034ClearCompact" +
+      "ame\"C\n\025GetRegionLoadResponse\022*\n\014region_l" +
-      "ionQueuesRequest\022\022\n\nqueue_name\030\001 \003(\t\"\037\n\035" +
+      "oads\030\001 \003(\0132\024.hbase.pb.RegionLoad\"2\n\034Clea" +
-      "ClearCompactionQueuesResponse\"\200\001\n\030Execut" +
+      "rCompactionQueuesRequest\022\022\n\nqueue_name\030\001" +
-      "eProceduresRequest\0220\n\013open_region\030\001 \003(\0132" +
+      " \003(\t\"\037\n\035ClearCompactionQueuesResponse\"\200\001" +
-      "\033.hbase.pb.OpenRegionRequest\0222\n\014close_re" +
+      "\n\030ExecuteProceduresRequest\0220\n\013open_regio" +
-      "gion\030\002 \003(\0132\034.hbase.pb.CloseRegionRequest",
+      "n\030\001 \003(\0132\033.hbase.pb.OpenRegionRequest\0222\n\014",
-      "\"\203\001\n\031ExecuteProceduresResponse\0221\n\013open_r" +
+      "close_region\030\002 \003(\0132\034.hbase.pb.CloseRegio" +
-      "egion\030\001 \003(\0132\034.hbase.pb.OpenRegionRespons" +
+      "nRequest\"\203\001\n\031ExecuteProceduresResponse\0221" +
-      "e\0223\n\014close_region\030\002 \003(\0132\035.hbase.pb.Close" +
+      "\n\013open_region\030\001 \003(\0132\034.hbase.pb.OpenRegio" +
-      "RegionResponse\"\244\001\n\023MergeRegionsRequest\022+" +
+      "nResponse\0223\n\014close_region\030\002 \003(\0132\035.hbase." +
-      "\n\010region_a\030\001 \002(\0132\031.hbase.pb.RegionSpecif" +
+      "pb.CloseRegionResponse\"\244\001\n\023MergeRegionsR" +
-      "ier\022+\n\010region_b\030\002 \002(\0132\031.hbase.pb.RegionS" +
+      "equest\022+\n\010region_a\030\001 \002(\0132\031.hbase.pb.Regi" +
-      "pecifier\022\027\n\010forcible\030\003 \001(\010:\005false\022\032\n\022mas" +
+      "onSpecifier\022+\n\010region_b\030\002 \002(\0132\031.hbase.pb" +
-      "ter_system_time\030\004 \001(\004\"\026\n\024MergeRegionsRes" +
+      ".RegionSpecifier\022\027\n\010forcible\030\003 \001(\010:\005fals" +
-      "ponse2\216\016\n\014AdminService\022P\n\rGetRegionInfo\022" +
+      "e\022\032\n\022master_system_time\030\004 \001(\004\"\026\n\024MergeRe" +
-      "\036.hbase.pb.GetRegionInfoRequest\032\037.hbase.",
+      "gionsResponse2\216\016\n\014AdminService\022P\n\rGetReg",
-      "pb.GetRegionInfoResponse\022M\n\014GetStoreFile" +
+      "ionInfo\022\036.hbase.pb.GetRegionInfoRequest\032" +
-      "\022\035.hbase.pb.GetStoreFileRequest\032\036.hbase." +
+      "\037.hbase.pb.GetRegionInfoResponse\022M\n\014GetS" +
-      "pb.GetStoreFileResponse\022V\n\017GetOnlineRegi" +
+      "toreFile\022\035.hbase.pb.GetStoreFileRequest\032" +
-      "on\022 .hbase.pb.GetOnlineRegionRequest\032!.h" +
+      "\036.hbase.pb.GetStoreFileResponse\022V\n\017GetOn" +
-      "base.pb.GetOnlineRegionResponse\022G\n\nOpenR" +
+      "lineRegion\022 .hbase.pb.GetOnlineRegionReq" +
-      "egion\022\033.hbase.pb.OpenRegionRequest\032\034.hba" +
+      "uest\032!.hbase.pb.GetOnlineRegionResponse\022" +
-      "se.pb.OpenRegionResponse\022M\n\014WarmupRegion" +
+      "G\n\nOpenRegion\022\033.hbase.pb.OpenRegionReque" +
-      "\022\035.hbase.pb.WarmupRegionRequest\032\036.hbase." +
+      "st\032\034.hbase.pb.OpenRegionResponse\022M\n\014Warm" +
-      "pb.WarmupRegionResponse\022J\n\013CloseRegion\022\034" +
+      "upRegion\022\035.hbase.pb.WarmupRegionRequest\032" +
-      ".hbase.pb.CloseRegionRequest\032\035.hbase.pb.",
+      "\036.hbase.pb.WarmupRegionResponse\022J\n\013Close",
-      "CloseRegionResponse\022J\n\013FlushRegion\022\034.hba" +
+      "Region\022\034.hbase.pb.CloseRegionRequest\032\035.h" +
-      "se.pb.FlushRegionRequest\032\035.hbase.pb.Flus" +
+      "base.pb.CloseRegionResponse\022J\n\013FlushRegi" +
-      "hRegionResponse\022J\n\013SplitRegion\022\034.hbase.p" +
+      "on\022\034.hbase.pb.FlushRegionRequest\032\035.hbase" +
-      "b.SplitRegionRequest\032\035.hbase.pb.SplitReg" +
+      ".pb.FlushRegionResponse\022J\n\013SplitRegion\022\034" +
-      "ionResponse\022P\n\rCompactRegion\022\036.hbase.pb." +
+      ".hbase.pb.SplitRegionRequest\032\035.hbase.pb." +
-      "CompactRegionRequest\032\037.hbase.pb.CompactR" +
+      "SplitRegionResponse\022P\n\rCompactRegion\022\036.h" +
-      "egionResponse\022\\\n\021ReplicateWALEntry\022\".hba" +
+      "base.pb.CompactRegionRequest\032\037.hbase.pb." +
-      "se.pb.ReplicateWALEntryRequest\032#.hbase.p" +
+      "CompactRegionResponse\022\\\n\021ReplicateWALEnt" +
-      "b.ReplicateWALEntryResponse\022Q\n\006Replay\022\"." +
+      "ry\022\".hbase.pb.ReplicateWALEntryRequest\032#" +
-      "hbase.pb.ReplicateWALEntryRequest\032#.hbas",
+      ".hbase.pb.ReplicateWALEntryResponse\022Q\n\006R",
-      "e.pb.ReplicateWALEntryResponse\022P\n\rRollWA" +
+      "eplay\022\".hbase.pb.ReplicateWALEntryReques" +
-      "LWriter\022\036.hbase.pb.RollWALWriterRequest\032" +
+      "t\032#.hbase.pb.ReplicateWALEntryResponse\022P" +
-      "\037.hbase.pb.RollWALWriterResponse\022P\n\rGetS" +
+      "\n\rRollWALWriter\022\036.hbase.pb.RollWALWriter" +
-      "erverInfo\022\036.hbase.pb.GetServerInfoReques" +
+      "Request\032\037.hbase.pb.RollWALWriterResponse" +
-      "t\032\037.hbase.pb.GetServerInfoResponse\022G\n\nSt" +
+      "\022P\n\rGetServerInfo\022\036.hbase.pb.GetServerIn" +
-      "opServer\022\033.hbase.pb.StopServerRequest\032\034." +
+      "foRequest\032\037.hbase.pb.GetServerInfoRespon" +
-      "hbase.pb.StopServerResponse\022_\n\022UpdateFav" +
+      "se\022G\n\nStopServer\022\033.hbase.pb.StopServerRe" +
-      "oredNodes\022#.hbase.pb.UpdateFavoredNodesR" +
+      "quest\032\034.hbase.pb.StopServerResponse\022_\n\022U" +
-      "equest\032$.hbase.pb.UpdateFavoredNodesResp" +
+      "pdateFavoredNodes\022#.hbase.pb.UpdateFavor" +
-      "onse\022b\n\023UpdateConfiguration\022$.hbase.pb.U",
+      "edNodesRequest\032$.hbase.pb.UpdateFavoredN",
-      "pdateConfigurationRequest\032%.hbase.pb.Upd" +
+      "odesResponse\022b\n\023UpdateConfiguration\022$.hb" +
-      "ateConfigurationResponse\022P\n\rGetRegionLoa" +
+      "ase.pb.UpdateConfigurationRequest\032%.hbas" +
-      "d\022\036.hbase.pb.GetRegionLoadRequest\032\037.hbas" +
+      "e.pb.UpdateConfigurationResponse\022P\n\rGetR" +
-      "e.pb.GetRegionLoadResponse\022h\n\025ClearCompa" +
+      "egionLoad\022\036.hbase.pb.GetRegionLoadReques" +
-      "ctionQueues\022&.hbase.pb.ClearCompactionQu" +
+      "t\032\037.hbase.pb.GetRegionLoadResponse\022h\n\025Cl" +
-      "euesRequest\032\'.hbase.pb.ClearCompactionQu" +
+      "earCompactionQueues\022&.hbase.pb.ClearComp" +
-      "euesResponse\022k\n\026GetSpaceQuotaSnapshots\022\'" +
+      "actionQueuesRequest\032\'.hbase.pb.ClearComp" +
-      ".hbase.pb.GetSpaceQuotaSnapshotsRequest\032" +
+      "actionQueuesResponse\022k\n\026GetSpaceQuotaSna" +
-      "(.hbase.pb.GetSpaceQuotaSnapshotsRespons" +
+      "pshots\022\'.hbase.pb.GetSpaceQuotaSnapshots" +
-      "e\022\\\n\021ExecuteProcedures\022\".hbase.pb.Execut",
+      "Request\032(.hbase.pb.GetSpaceQuotaSnapshot",
-      "eProceduresRequest\032#.hbase.pb.ExecutePro" +
+      "sResponse\022\\\n\021ExecuteProcedures\022\".hbase.p" +
-      "ceduresResponse\022M\n\014MergeRegions\022\035.hbase." +
+      "b.ExecuteProceduresRequest\032#.hbase.pb.Ex" +
-      "pb.MergeRegionsRequest\032\036.hbase.pb.MergeR" +
+      "ecuteProceduresResponse\022M\n\014MergeRegions\022" +
-      "egionsResponseBH\n1org.apache.hadoop.hbas" +
+      "\035.hbase.pb.MergeRegionsRequest\032\036.hbase.p" +
-      "e.shaded.protobuf.generatedB\013AdminProtos" +
+      "b.MergeRegionsResponseBH\n1org.apache.had" +
-      "H\001\210\001\001\240\001\001"
+      "oop.hbase.shaded.protobuf.generatedB\013Adm" +
+      "inProtosH\001\210\001\001\240\001\001"
     };
     org.apache.hadoop.hbase.shaded.com.google.protobuf.Descriptors.FileDescriptor.InternalDescriptorAssigner assigner =
         new org.apache.hadoop.hbase.shaded.com.google.protobuf.Descriptors.FileDescriptor.    InternalDescriptorAssigner() {
@@ -30377,13 +30588,13 @@ public final class AdminProtos {
     internal_static_hbase_pb_GetRegionInfoRequest_fieldAccessorTable = new
       org.apache.hadoop.hbase.shaded.com.google.protobuf.GeneratedMessageV3.FieldAccessorTable(
         internal_static_hbase_pb_GetRegionInfoRequest_descriptor,
-        new java.lang.String[] { "Region", "CompactionState", });
+        new java.lang.String[] { "Region", "CompactionState", "BestSplitRow", });
     internal_static_hbase_pb_GetRegionInfoResponse_descriptor =
       getDescriptor().getMessageTypes().get(1);
     internal_static_hbase_pb_GetRegionInfoResponse_fieldAccessorTable = new
       org.apache.hadoop.hbase.shaded.com.google.protobuf.GeneratedMessageV3.FieldAccessorTable(
         internal_static_hbase_pb_GetRegionInfoResponse_descriptor,
-        new java.lang.String[] { "RegionInfo", "CompactionState", "IsRecovering", "Splittable", "Mergeable", });
+        new java.lang.String[] { "RegionInfo", "CompactionState", "IsRecovering", "Splittable", "Mergeable", "BestSplitRow", });
     internal_static_hbase_pb_GetStoreFileRequest_descriptor =
       getDescriptor().getMessageTypes().get(2);
     internal_static_hbase_pb_GetStoreFileRequest_fieldAccessorTable = new

hbase-protocol-shaded/src/main/java/org/apache/hadoop/hbase/shaded/protobuf/generated/MasterProtos.java

@@ -11552,11 +11552,11 @@ public final class MasterProtos {
     org.apache.hadoop.hbase.shaded.protobuf.generated.HBaseProtos.RegionInfoOrBuilder getRegionInfoOrBuilder();
 
     /**
-     * <code>required bytes split_row = 2;</code>
+     * <code>optional bytes split_row = 2;</code>
      */
     boolean hasSplitRow();
     /**
-     * <code>required bytes split_row = 2;</code>
+     * <code>optional bytes split_row = 2;</code>
      */
     org.apache.hadoop.hbase.shaded.com.google.protobuf.ByteString getSplitRow();
 
@@ -11700,13 +11700,13 @@ public final class MasterProtos {
     public static final int SPLIT_ROW_FIELD_NUMBER = 2;
     private org.apache.hadoop.hbase.shaded.com.google.protobuf.ByteString splitRow_;
     /**
-     * <code>required bytes split_row = 2;</code>
+     * <code>optional bytes split_row = 2;</code>
      */
     public boolean hasSplitRow() {
       return ((bitField0_ & 0x00000002) == 0x00000002);
     }
     /**
-     * <code>required bytes split_row = 2;</code>
+     * <code>optional bytes split_row = 2;</code>
      */
     public org.apache.hadoop.hbase.shaded.com.google.protobuf.ByteString getSplitRow() {
       return splitRow_;
@@ -11752,10 +11752,6 @@ public final class MasterProtos {
         memoizedIsInitialized = 0;
         return false;
       }
-      if (!hasSplitRow()) {
-        memoizedIsInitialized = 0;
-        return false;
-      }
       if (!getRegionInfo().isInitialized()) {
         memoizedIsInitialized = 0;
         return false;
@@ -12106,9 +12102,6 @@ public final class MasterProtos {
         if (!hasRegionInfo()) {
           return false;
         }
-        if (!hasSplitRow()) {
-          return false;
-        }
         if (!getRegionInfo().isInitialized()) {
           return false;
         }
@@ -12254,19 +12247,19 @@ public final class MasterProtos {
 
       private org.apache.hadoop.hbase.shaded.com.google.protobuf.ByteString splitRow_ = org.apache.hadoop.hbase.shaded.com.google.protobuf.ByteString.EMPTY;
       /**
-       * <code>required bytes split_row = 2;</code>
+       * <code>optional bytes split_row = 2;</code>
        */
       public boolean hasSplitRow() {
         return ((bitField0_ & 0x00000002) == 0x00000002);
       }
       /**
-       * <code>required bytes split_row = 2;</code>
+       * <code>optional bytes split_row = 2;</code>
        */
       public org.apache.hadoop.hbase.shaded.com.google.protobuf.ByteString getSplitRow() {
         return splitRow_;
       }
       /**
-       * <code>required bytes split_row = 2;</code>
+       * <code>optional bytes split_row = 2;</code>
        */
       public Builder setSplitRow(org.apache.hadoop.hbase.shaded.com.google.protobuf.ByteString value) {
         if (value == null) {
@@ -12278,7 +12271,7 @@ public final class MasterProtos {
         return this;
       }
       /**
-       * <code>required bytes split_row = 2;</code>
+       * <code>optional bytes split_row = 2;</code>
        */
       public Builder clearSplitRow() {
         bitField0_ = (bitField0_ & ~0x00000002);
@@ -81243,7 +81236,7 @@ public final class MasterProtos {
       ".pb.RegionSpecifier\"\027\n\025OfflineRegionResp",
       "onse\"\201\001\n\027SplitTableRegionRequest\022)\n\013regi" +
       "on_info\030\001 \002(\0132\024.hbase.pb.RegionInfo\022\021\n\ts" +
-      "plit_row\030\002 \002(\014\022\026\n\013nonce_group\030\003 \001(\004:\0010\022\020" +
+      "plit_row\030\002 \001(\014\022\026\n\013nonce_group\030\003 \001(\004:\0010\022\020" +
       "\n\005nonce\030\004 \001(\004:\0010\"+\n\030SplitTableRegionResp" +
       "onse\022\017\n\007proc_id\030\001 \001(\004\"\177\n\022CreateTableRequ" +
       "est\022+\n\014table_schema\030\001 \002(\0132\025.hbase.pb.Tab" +

hbase-protocol-shaded/src/main/protobuf/Admin.proto

@@ -33,6 +33,7 @@ import "Quota.proto";
 message GetRegionInfoRequest {
   required RegionSpecifier region = 1;
   optional bool compaction_state = 2;
+  optional bool best_split_row = 3;
 }
 
 message GetRegionInfoResponse {
@@ -43,6 +44,8 @@ message GetRegionInfoResponse {
   optional bool splittable = 4;
   // True if region is mergeable, false otherwise.
   optional bool mergeable = 5;
+  // Get bestSplitRow
+  optional bytes best_split_row = 6;
 
   enum CompactionState {
     NONE = 0;

hbase-protocol-shaded/src/main/protobuf/Master.proto

@@ -136,7 +136,7 @@ message OfflineRegionResponse {
 
 message SplitTableRegionRequest {
   required RegionInfo region_info = 1;
-  required bytes split_row = 2;
+  optional bytes split_row = 2;
   optional uint64 nonce_group = 3 [default = 0];
   optional uint64 nonce = 4 [default = 0];
 }

hbase-server/src/main/java/org/apache/hadoop/hbase/master/MasterRpcServices.java

@@ -636,7 +636,7 @@ public class MasterRpcServices extends RSRpcServices
     try {
       long procId = master.splitRegion(
         HRegionInfo.convert(request.getRegionInfo()),
-        request.getSplitRow().toByteArray(),
+        request.hasSplitRow() ? request.getSplitRow().toByteArray() : null,
         request.getNonceGroup(),
         request.getNonce());
       return SplitTableRegionResponse.newBuilder().setProcId(procId).build();

hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/AssignmentManager.java

@@ -67,6 +67,7 @@ import org.apache.hadoop.hbase.master.assignment.RegionStates.ServerState;
 import org.apache.hadoop.hbase.master.assignment.RegionStates.ServerStateNode;
 // TODO: why are they here?
 import org.apache.hadoop.hbase.master.normalizer.NormalizationPlan.PlanType;
+import org.apache.hadoop.hbase.master.normalizer.RegionNormalizer;
 import org.apache.hadoop.hbase.master.procedure.MasterProcedureEnv;
 import org.apache.hadoop.hbase.master.procedure.MasterProcedureScheduler;
 import org.apache.hadoop.hbase.master.procedure.ProcedureSyncWait;
@@ -157,6 +158,8 @@ public class AssignmentManager implements ServerListener {
   // TODO: why is this different from the listeners (carried over from the old AM)
   private RegionStateListener regionStateListener;
 
+  private RegionNormalizer regionNormalizer;
+
   private final MetricsAssignmentManager metrics;
   private final RegionInTransitionChore ritChore;
   private final MasterServices master;
@@ -198,6 +201,9 @@ public class AssignmentManager implements ServerListener {
     int ritChoreInterval = conf.getInt(RIT_CHORE_INTERVAL_MSEC_CONF_KEY,
         DEFAULT_RIT_CHORE_INTERVAL_MSEC);
     this.ritChore = new RegionInTransitionChore(ritChoreInterval);
+
+    // Used for region related procedure.
+    setRegionNormalizer(master.getRegionNormalizer());
   }
 
   public void start() throws IOException {
@@ -301,6 +307,14 @@ public class AssignmentManager implements ServerListener {
     this.regionStateListener = listener;
   }
 
+  public void setRegionNormalizer(final RegionNormalizer normalizer) {
+    this.regionNormalizer = normalizer;
+  }
+
+  public RegionNormalizer getRegionNormalizer() {
+    return regionNormalizer;
+  }
+
   public RegionStates getRegionStates() {
     return regionStates;
   }
@@ -761,16 +775,6 @@ public class AssignmentManager implements ServerListener {
         " hriA=" + hriA + " hriB=" + hriB);
     }
 
-    try {
-      if (regionStateListener != null) {
-        regionStateListener.onRegionSplit(parent);
-      }
-    } catch (QuotaExceededException e) {
-      // TODO: does this really belong here?
-      master.getRegionNormalizer().planSkipped(parent, PlanType.SPLIT);
-      throw e;
-    }
-
     // Submit the Split procedure
     final byte[] splitKey = hriB.getStartKey();
     if (LOG.isDebugEnabled()) {

hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/MergeTableRegionsProcedure.java

@@ -49,12 +49,14 @@ import org.apache.hadoop.hbase.master.CatalogJanitor;
 import org.apache.hadoop.hbase.master.MasterCoprocessorHost;
 import org.apache.hadoop.hbase.master.MasterFileSystem;
 import org.apache.hadoop.hbase.master.RegionState;
+import org.apache.hadoop.hbase.master.normalizer.NormalizationPlan;
 import org.apache.hadoop.hbase.master.procedure.AbstractStateMachineTableProcedure;
 import org.apache.hadoop.hbase.master.procedure.MasterProcedureEnv;
 import org.apache.hadoop.hbase.master.procedure.MasterProcedureUtil;
 import org.apache.hadoop.hbase.procedure2.ProcedureSuspendedException;
 import org.apache.hadoop.hbase.procedure2.ProcedureYieldException;
 import org.apache.hadoop.hbase.procedure2.ProcedureMetrics;
+import org.apache.hadoop.hbase.quotas.QuotaExceededException;
 import org.apache.hadoop.hbase.regionserver.HRegionFileSystem;
 import org.apache.hadoop.hbase.regionserver.HStoreFile;
 import org.apache.hadoop.hbase.regionserver.StoreFileInfo;
@@ -529,7 +531,13 @@ public class MergeTableRegionsProcedure
       }
     }
     // TODO: Clean up split and merge. Currently all over the place.
+    try {
       env.getMasterServices().getMasterQuotaManager().onRegionMerged(this.mergedRegion);
+    } catch (QuotaExceededException e) {
+      env.getAssignmentManager().getRegionNormalizer().planSkipped(this.mergedRegion,
+          NormalizationPlan.PlanType.MERGE);
+      throw e;
+    }
   }
 
   /**

hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/SplitTableRegionProcedure.java

@@ -54,10 +54,12 @@ import org.apache.hadoop.hbase.master.MasterCoprocessorHost;
 import org.apache.hadoop.hbase.master.MasterFileSystem;
 import org.apache.hadoop.hbase.master.RegionState.State;
 import org.apache.hadoop.hbase.master.assignment.RegionStates.RegionStateNode;
+import org.apache.hadoop.hbase.master.normalizer.NormalizationPlan;
 import org.apache.hadoop.hbase.master.procedure.AbstractStateMachineRegionProcedure;
 import org.apache.hadoop.hbase.master.procedure.MasterProcedureEnv;
 import org.apache.hadoop.hbase.master.procedure.MasterProcedureUtil;
 import org.apache.hadoop.hbase.procedure2.ProcedureMetrics;
+import org.apache.hadoop.hbase.quotas.QuotaExceededException;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProcedureProtos;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProcedureProtos.SplitTableRegionState;
 import org.apache.hadoop.hbase.regionserver.HRegionFileSystem;
@@ -84,6 +86,7 @@ public class SplitTableRegionProcedure
   private Boolean traceEnabled = null;
   private HRegionInfo daughter_1_HRI;
   private HRegionInfo daughter_2_HRI;
+  private byte[] bestSplitRow;
 
   public SplitTableRegionProcedure() {
     // Required by the Procedure framework to create the procedure on replay
@@ -92,27 +95,70 @@ public class SplitTableRegionProcedure
   public SplitTableRegionProcedure(final MasterProcedureEnv env,
       final HRegionInfo regionToSplit, final byte[] splitRow) throws IOException {
     super(env, regionToSplit);
-
+    this.bestSplitRow = splitRow;
-    checkSplitRow(regionToSplit, splitRow);
+    checkSplittable(env, regionToSplit, bestSplitRow);
-
     final TableName table = regionToSplit.getTable();
     final long rid = getDaughterRegionIdTimestamp(regionToSplit);
-    this.daughter_1_HRI = new HRegionInfo(table, regionToSplit.getStartKey(), splitRow, false, rid);
+    this.daughter_1_HRI = new HRegionInfo(table, regionToSplit.getStartKey(), bestSplitRow, false, rid);
-    this.daughter_2_HRI = new HRegionInfo(table, splitRow, regionToSplit.getEndKey(), false, rid);
+    this.daughter_2_HRI = new HRegionInfo(table, bestSplitRow, regionToSplit.getEndKey(), false, rid);
   }
 
-  private static void checkSplitRow(final HRegionInfo regionToSplit, final byte[] splitRow)
+  /**
-      throws IOException {
+   * Check whether the region is splittable
-    if (splitRow == null || splitRow.length == 0) {
+   * @param env MasterProcedureEnv
-      throw new DoNotRetryIOException("Split row cannot be null");
+   * @param regionToSplit parent Region to be split
+   * @param splitRow if splitRow is not specified, will first try to get bestSplitRow from RS
+   * @throws IOException
+   */
+  private void checkSplittable(final MasterProcedureEnv env,
+      final HRegionInfo regionToSplit, final byte[] splitRow) throws IOException {
+    // Ask the remote RS if this region is splittable.
+    // If we get an IOE, report it along w/ the failure so can see why we are not splittable at this time.
+    if(regionToSplit.getReplicaId() != HRegionInfo.DEFAULT_REPLICA_ID) {
+      throw new IllegalArgumentException ("Can't invoke split on non-default regions directly");
+    }
+    RegionStateNode node =
+        env.getAssignmentManager().getRegionStates().getRegionNode(getParentRegion());
+    IOException splittableCheckIOE = null;
+    boolean splittable = false;
+    if (node != null) {
+      try {
+        GetRegionInfoResponse response = null;
+        if (bestSplitRow == null || bestSplitRow.length == 0) {
+          LOG.info("splitKey isn't explicitly specified, " + " will try to find a best split key from RS");
+          response =
+              Util.getRegionInfoResponse(env, node.getRegionLocation(), node.getRegionInfo(), true);
+          bestSplitRow =
+              response.hasBestSplitRow() ? response.getBestSplitRow().toByteArray() : null;
+        } else {
+          response = Util.getRegionInfoResponse(env, node.getRegionLocation(), node.getRegionInfo(), false);
+        }
+        splittable = response.hasSplittable() && response.getSplittable();
+
+        if (LOG.isDebugEnabled()) {
+          LOG.debug("Splittable=" + splittable + " " + node.toShortString());
+        }
+      } catch (IOException e) {
+        splittableCheckIOE = e;
+      }
     }
 
-    if (Bytes.equals(regionToSplit.getStartKey(), splitRow)) {
+    if (!splittable) {
+      IOException e = new IOException(regionToSplit.getShortNameToLog() + " NOT splittable");
+      if (splittableCheckIOE != null) e.initCause(splittableCheckIOE);
+      throw e;
+    }
+
+    if(bestSplitRow == null || bestSplitRow.length == 0) {
+      throw new DoNotRetryIOException("Region not splittable because bestSplitPoint = null");
+    }
+
+    if (Bytes.equals(regionToSplit.getStartKey(), bestSplitRow)) {
       throw new DoNotRetryIOException(
         "Split row is equal to startkey: " + Bytes.toStringBinary(splitRow));
     }
 
-    if (!regionToSplit.containsRow(splitRow)) {
+    if (!regionToSplit.containsRow(bestSplitRow)) {
       throw new DoNotRetryIOException(
         "Split row is not inside region key range splitKey:" + Bytes.toStringBinary(splitRow) +
         " region: " + regionToSplit);
@@ -198,6 +244,7 @@ public class SplitTableRegionProcedure
         setFailure(e);
       }
     }
+    // if split fails,  need to call ((HRegion)parent).clearSplit() when it is a force split
     return Flow.HAS_MORE_STATE;
   }
 
@@ -367,27 +414,6 @@ public class SplitTableRegionProcedure
             Arrays.toString(EXPECTED_SPLIT_STATES)));
         return false;
       }
-
-      // Ask the remote regionserver if this region is splittable. If we get an IOE, report it
-      // along w/ the failure so can see why we are not splittable at this time.
-      IOException splittableCheckIOE = null;
-      boolean splittable = false;
-      try {
-        GetRegionInfoResponse response =
-            Util.getRegionInfoResponse(env, node.getRegionLocation(), node.getRegionInfo());
-        splittable = response.hasSplittable() && response.getSplittable();
-        if (LOG.isDebugEnabled()) {
-          LOG.debug("Splittable=" + splittable + " " + this + " " + node.toShortString());
-        }
-      } catch (IOException e) {
-        splittableCheckIOE = e;
-      }
-      if (!splittable) {
-        IOException e = new IOException(parentHRI.getShortNameToLog() + " NOT splittable");
-        if (splittableCheckIOE != null) e.initCause(splittableCheckIOE);
-        setFailure(e);
-        return false;
-      }
     }
 
     // Since we have the lock and the master is coordinating the operation
@@ -414,6 +440,16 @@ public class SplitTableRegionProcedure
     if (cpHost != null) {
       cpHost.preSplitRegionAction(getTableName(), getSplitRow(), getUser());
     }
+
+    // TODO: Clean up split and merge. Currently all over the place.
+    // Notify QuotaManager and RegionNormalizer
+    try {
+      env.getMasterServices().getMasterQuotaManager().onRegionSplit(this.getParentRegion());
+    } catch (QuotaExceededException e) {
+      env.getAssignmentManager().getRegionNormalizer().planSkipped(this.getParentRegion(),
+          NormalizationPlan.PlanType.SPLIT);
+      throw e;
+    }
   }
 
   /**

hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/Util.java

@@ -44,13 +44,24 @@ class Util {
    */
   static GetRegionInfoResponse getRegionInfoResponse(final MasterProcedureEnv env,
       final ServerName regionLocation, final HRegionInfo hri)
+  throws IOException {
+    return getRegionInfoResponse(env, regionLocation, hri, false);
+  }
+
+  static GetRegionInfoResponse getRegionInfoResponse(final MasterProcedureEnv env,
+      final ServerName regionLocation, final HRegionInfo hri, boolean includeBestSplitRow)
   throws IOException {
     // TODO: There is no timeout on this controller. Set one!
     HBaseRpcController controller = env.getMasterServices().getClusterConnection().
         getRpcControllerFactory().newController();
     final AdminService.BlockingInterface admin =
         env.getMasterServices().getClusterConnection().getAdmin(regionLocation);
-    GetRegionInfoRequest request = RequestConverter.buildGetRegionInfoRequest(hri.getRegionName());
+    GetRegionInfoRequest request = null;
+    if (includeBestSplitRow) {
+      request = RequestConverter.buildGetRegionInfoRequest(hri.getRegionName(), false, true);
+    } else {
+      request = RequestConverter.buildGetRegionInfoRequest(hri.getRegionName());
+    }
     try {
       return admin.getRegionInfo(controller, request);
     } catch (ServiceException e) {

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RSRpcServices.java

@@ -1673,6 +1673,20 @@ public class RSRpcServices implements HBaseRPCErrorHandler,
       requestCount.increment();
       Region region = getRegion(request.getRegion());
       HRegionInfo info = region.getRegionInfo();
+      byte[] bestSplitRow = null;
+      if (request.hasBestSplitRow() && request.getBestSplitRow()) {
+        HRegion r = (HRegion) region;
+        region.startRegionOperation(Operation.SPLIT_REGION);
+        r.forceSplit(null);
+        bestSplitRow = r.checkSplit();
+        // when all table data are in memstore, bestSplitRow = null
+        // try to flush region first
+        if(bestSplitRow == null) {
+          r.flush(true);
+          bestSplitRow = r.checkSplit();
+        }
+        r.clearSplit();
+      }
       GetRegionInfoResponse.Builder builder = GetRegionInfoResponse.newBuilder();
       builder.setRegionInfo(HRegionInfo.convert(info));
       if (request.hasCompactionState() && request.getCompactionState()) {
@@ -1681,6 +1695,9 @@ public class RSRpcServices implements HBaseRPCErrorHandler,
       builder.setSplittable(region.isSplittable());
       builder.setMergeable(region.isMergeable());
       builder.setIsRecovering(region.isRecovering());
+      if (request.hasBestSplitRow() && request.getBestSplitRow() && bestSplitRow != null) {
+        builder.setBestSplitRow(UnsafeByteOperations.unsafeWrap(bestSplitRow));
+      }
       return builder.build();
     } catch (IOException ie) {
       throw new ServiceException(ie);

hbase-server/src/test/java/org/apache/hadoop/hbase/backup/TestIncrementalBackup.java

@@ -20,6 +20,7 @@ package org.apache.hadoop.hbase.backup;
 
 import static org.junit.Assert.assertTrue;
 
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
@@ -116,7 +117,15 @@ public class TestIncrementalBackup extends TestBackupBase {
 
     byte[] name = regions.get(0).getRegionInfo().getRegionName();
     long startSplitTime = EnvironmentEdgeManager.currentTime();
+    try {
       admin.splitRegion(name);
+    } catch (IOException e) {
+      //although split fail, this may not affect following check
+      //In old split without AM2, if region's best split key is not found,
+      //there are not exception thrown. But in current API, exception
+      //will be thrown.
+      LOG.debug("region is not splittable, because " + e);
+    }
 
     while (!admin.isTableAvailable(table1)) {
       Thread.sleep(100);

hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestAdmin1.java

@@ -903,10 +903,12 @@ public class TestAdmin1 {
     int[] rowCounts = new int[] { 6000 };
     int numVersions = HColumnDescriptor.DEFAULT_VERSIONS;
     int blockSize = 256;
-    splitTest(null, familyNames, rowCounts, numVersions, blockSize);
+    splitTest(null, familyNames, rowCounts, numVersions, blockSize, true);
 
     byte[] splitKey = Bytes.toBytes(3500);
-    splitTest(splitKey, familyNames, rowCounts, numVersions, blockSize);
+    splitTest(splitKey, familyNames, rowCounts, numVersions, blockSize, true);
+    // test regionSplitSync
+    splitTest(splitKey, familyNames, rowCounts, numVersions, blockSize, false);
   }
 
   /**
@@ -963,23 +965,23 @@ public class TestAdmin1 {
 
     // one of the column families isn't splittable
     int[] rowCounts = new int[] { 6000, 1 };
-    splitTest(null, familyNames, rowCounts, numVersions, blockSize);
+    splitTest(null, familyNames, rowCounts, numVersions, blockSize, true);
 
     rowCounts = new int[] { 1, 6000 };
-    splitTest(null, familyNames, rowCounts, numVersions, blockSize);
+    splitTest(null, familyNames, rowCounts, numVersions, blockSize, true);
 
     // one column family has much smaller data than the other
     // the split key should be based on the largest column family
     rowCounts = new int[] { 6000, 300 };
-    splitTest(null, familyNames, rowCounts, numVersions, blockSize);
+    splitTest(null, familyNames, rowCounts, numVersions, blockSize, true);
 
     rowCounts = new int[] { 300, 6000 };
-    splitTest(null, familyNames, rowCounts, numVersions, blockSize);
+    splitTest(null, familyNames, rowCounts, numVersions, blockSize, true);
 
   }
 
   void splitTest(byte[] splitPoint, byte[][] familyNames, int[] rowCounts,
-    int numVersions, int blockSize) throws Exception {
+    int numVersions, int blockSize, boolean async) throws Exception {
     TableName tableName = TableName.valueOf("testForceSplit");
     StringBuilder sb = new StringBuilder();
     // Add tail to String so can see better in logs where a test is running.
@@ -1033,12 +1035,11 @@ public class TestAdmin1 {
       scanner.next();
 
       // Split the table
+      if (async) {
         this.admin.split(tableName, splitPoint);
-
         final AtomicInteger count = new AtomicInteger(0);
         Thread t = new Thread("CheckForSplit") {
-        @Override
+          @Override public void run() {
-        public void run() {
             for (int i = 0; i < 45; i++) {
               try {
                 sleep(1000);
@@ -1066,6 +1067,10 @@ public class TestAdmin1 {
         t.setPriority(Thread.NORM_PRIORITY - 2);
         t.start();
         t.join();
+      } else {
+        // Sync split region, no need to create a thread to check
+        ((HBaseAdmin)admin).splitRegionSync(m.get(0).getRegionInfo().getRegionName(), splitPoint);
+      }
 
       // Verify row count
       rows = 1; // We counted one row above.
@@ -1166,12 +1171,23 @@ public class TestAdmin1 {
     // regions). Try splitting that region via a different split API (the difference is
     // this API goes direct to the regionserver skipping any checks in the admin). Should fail
     try {
-      TEST_UTIL.getHBaseAdmin().split(regions.get(1).getSecond(), regions.get(1).getFirst(),
+      TEST_UTIL.getHBaseAdmin().splitRegionAsync(regions.get(1).getFirst(),
           new byte[]{(byte)'1'});
     } catch (IOException ex) {
       gotException = true;
     }
     assertTrue(gotException);
+
+    gotException = false;
+    //testing Sync split operation
+    try {
+      TEST_UTIL.getHBaseAdmin().splitRegionSync(regions.get(1).getFirst().getRegionName(),
+          new byte[]{(byte)'1'});
+    } catch (IllegalArgumentException ex) {
+      gotException = true;
+    }
+    assertTrue(gotException);
+
     gotException = false;
     // Try merging a replica with another. Should fail.
     try {

hbase-server/src/test/java/org/apache/hadoop/hbase/security/access/TestTablePermissions.java

@@ -316,7 +316,16 @@ public class TestTablePermissions {
     table.put(new Put(Bytes.toBytes("row2"))
             .addColumn(TEST_FAMILY, TEST_QUALIFIER, Bytes.toBytes("v2")));
     Admin admin = UTIL.getAdmin();
+    try {
       admin.split(TEST_TABLE);
+    }
+    catch (IOException e) {
+      //although split fail, this may not affect following check
+      //In old Split API without AM2, if region's best split key is not found,
+      //there are not exception thrown. But in current API, exception
+      //will be thrown.
+      LOG.debug("region is not splittable, because " + e);
+    }
 
     // wait for split
     Thread.sleep(10000);