HBASE-18107: [AMv2] Remove DispatchMergingRegionsRequest & DispatchMergingRegions

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

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

@@ -1341,13 +1341,6 @@ class ConnectionImplementation implements ClusterConnection, Closeable {
         return stub.mergeTableRegions(controller, request);
       }
 
-      @Override
-      public MasterProtos.DispatchMergingRegionsResponse dispatchMergingRegions(
-          RpcController controller, MasterProtos.DispatchMergingRegionsRequest request)
-          throws ServiceException {
-        return stub.dispatchMergingRegions(controller, request);
-      }
-
       @Override
       public MasterProtos.AssignRegionResponse assignRegion(RpcController controller,
           MasterProtos.AssignRegionRequest request) throws ServiceException {

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

@@ -505,10 +505,4 @@ public class ShortCircuitMasterConnection implements MasterKeepAliveConnection {
       throws ServiceException {
     return stub.splitRegion(controller, request);
   }
-
-  @Override
-  public DispatchMergingRegionsResponse dispatchMergingRegions(RpcController controller,
-      DispatchMergingRegionsRequest request) throws ServiceException {
-    return stub.dispatchMergingRegions(controller, request);
-  }
 }

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

@@ -95,7 +95,6 @@ import org.apache.hadoop.hbase.io.TimeRange;
 import org.apache.hadoop.hbase.master.RegionState;
 import org.apache.hadoop.hbase.procedure2.LockInfo;
 import org.apache.hadoop.hbase.protobuf.ProtobufMagic;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.MergeRegionsRequest;
 import org.apache.hadoop.hbase.quotas.QuotaScope;
 import org.apache.hadoop.hbase.quotas.QuotaType;
 import org.apache.hadoop.hbase.quotas.SpaceViolationPolicy;
@@ -2024,46 +2023,6 @@ public final class ProtobufUtil {
     }
   }
 
-  /**
-   * A helper to merge regions using admin protocol. Send request to
-   * regionserver.
-   * @param admin
-   * @param region_a
-   * @param region_b
-   * @param forcible true if do a compulsory merge, otherwise we will only merge
-   *          two adjacent regions
-   * @param user effective user
-   * @throws IOException
-   */
-  public static void mergeRegions(final RpcController controller,
-      final AdminService.BlockingInterface admin,
-      final HRegionInfo region_a, final HRegionInfo region_b,
-      final boolean forcible, final User user) throws IOException {
-    final MergeRegionsRequest request = ProtobufUtil.buildMergeRegionsRequest(
-        region_a.getRegionName(), region_b.getRegionName(),forcible);
-    if (user != null) {
-      try {
-        user.runAs(new PrivilegedExceptionAction<Void>() {
-          @Override
-          public Void run() throws Exception {
-            admin.mergeRegions(controller, request);
-            return null;
-          }
-        });
-      } catch (InterruptedException ie) {
-        InterruptedIOException iioe = new InterruptedIOException();
-        iioe.initCause(ie);
-        throw iioe;
-      }
-    } else {
-      try {
-        admin.mergeRegions(controller, request);
-      } catch (ServiceException se) {
-        throw ProtobufUtil.getRemoteException(se);
-      }
-    }
-  }
-
 // End helpers for Admin
 
   /*
@@ -3393,28 +3352,6 @@ public final class ProtobufUtil {
     return builder.build();
   }
 
-   /**
-    * Create a MergeRegionsRequest for the given regions
-    * @param regionA name of region a
-    * @param regionB name of region b
-    * @param forcible true if it is a compulsory merge
-    * @return a MergeRegionsRequest
-    */
-   public static MergeRegionsRequest buildMergeRegionsRequest(
-       final byte[] regionA, final byte[] regionB, final boolean forcible) {
-     MergeRegionsRequest.Builder builder = MergeRegionsRequest.newBuilder();
-     RegionSpecifier regionASpecifier = RequestConverter.buildRegionSpecifier(
-         RegionSpecifierType.REGION_NAME, regionA);
-     RegionSpecifier regionBSpecifier = RequestConverter.buildRegionSpecifier(
-         RegionSpecifierType.REGION_NAME, regionB);
-     builder.setRegionA(regionASpecifier);
-     builder.setRegionB(regionBSpecifier);
-     builder.setForcible(forcible);
-     // send the master's wall clock time as well, so that the RS can refer to it
-     builder.setMasterSystemTime(EnvironmentEdgeManager.currentTime());
-     return builder.build();
-   }
-
   /**
    * Get a ServerName from the passed in data bytes.
    * @param data Data with a serialize server name in it; can handle the old style

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

@@ -273,22 +273,6 @@ message ExecuteProceduresResponse {
   repeated CloseRegionResponse close_region = 2;
 }
 
-/**
- * Merges the specified regions.
- * <p>
- * This method currently closes the regions and then merges them
- */
-message MergeRegionsRequest {
-  required RegionSpecifier region_a = 1;
-  required RegionSpecifier region_b = 2;
-  optional bool forcible = 3 [default = false];
-  // wall clock time from master
-  optional uint64 master_system_time = 4;
-}
-
-message MergeRegionsResponse {
-}
-
 service AdminService {
   rpc GetRegionInfo(GetRegionInfoRequest)
     returns(GetRegionInfoResponse);
@@ -350,7 +334,4 @@ service AdminService {
 
   rpc ExecuteProcedures(ExecuteProceduresRequest)
     returns(ExecuteProceduresResponse);
-
-  rpc MergeRegions(MergeRegionsRequest)
-    returns(MergeRegionsResponse);
 }

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

@@ -81,20 +81,6 @@ message MoveRegionRequest {
 message MoveRegionResponse {
 }
 
- /**
- * Dispatch merging the specified regions.
- */
-message DispatchMergingRegionsRequest {
-  required RegionSpecifier region_a = 1;
-  required RegionSpecifier region_b = 2;
-  optional bool forcible = 3 [default = false];
-  optional uint64 nonce_group = 4 [default = 0];
-  optional uint64 nonce = 5 [default = 0];
-}
-
-message DispatchMergingRegionsResponse {
-  optional uint64 proc_id = 1;
-}
 
 /**
  * Merging the specified regions in a table.
@@ -667,10 +653,6 @@ service MasterService {
   rpc ModifyColumn(ModifyColumnRequest)
     returns(ModifyColumnResponse);
 
- /** Master dispatch merging the regions */
-  rpc DispatchMergingRegions(DispatchMergingRegionsRequest)
-    returns(DispatchMergingRegionsResponse);
-
   /** Move the region region to the destination server. */
   rpc MoveRegion(MoveRegionRequest)
     returns(MoveRegionResponse);

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

@@ -115,7 +115,6 @@ import org.apache.hadoop.hbase.master.procedure.CreateTableProcedure;
 import org.apache.hadoop.hbase.master.procedure.DeleteColumnFamilyProcedure;
 import org.apache.hadoop.hbase.master.procedure.DeleteTableProcedure;
 import org.apache.hadoop.hbase.master.procedure.DisableTableProcedure;
-import org.apache.hadoop.hbase.master.procedure.DispatchMergingRegionsProcedure;
 import org.apache.hadoop.hbase.master.procedure.EnableTableProcedure;
 import org.apache.hadoop.hbase.master.procedure.MasterProcedureConstants;
 import org.apache.hadoop.hbase.master.procedure.MasterProcedureEnv;
@@ -1530,59 +1529,6 @@ public class HMaster extends HRegionServer implements MasterServices {
     this.catalogJanitorChore.setEnabled(b);
   }
 
-  @Override
-  public long dispatchMergingRegions(
-      final HRegionInfo regionInfoA,
-      final HRegionInfo regionInfoB,
-      final boolean forcible,
-      final long nonceGroup,
-      final long nonce) throws IOException {
-    checkInitialized();
-
-    TableName tableName = regionInfoA.getTable();
-    if (tableName == null || regionInfoB.getTable() == null) {
-      throw new UnknownRegionException ("Can't merge regions without table associated");
-    }
-
-    if (!tableName.equals(regionInfoB.getTable())) {
-      throw new IOException ("Cannot merge regions from two different tables");
-    }
-
-    if (regionInfoA.compareTo(regionInfoB) == 0) {
-      throw new MergeRegionException(
-        "Cannot merge a region to itself " + regionInfoA + ", " + regionInfoB);
-    }
-
-    final HRegionInfo [] regionsToMerge = new HRegionInfo[2];
-    regionsToMerge [0] = regionInfoA;
-    regionsToMerge [1] = regionInfoB;
-
-    return MasterProcedureUtil.submitProcedure(
-        new MasterProcedureUtil.NonceProcedureRunnable(this, nonceGroup, nonce) {
-      @Override
-      protected void run() throws IOException {
-        MasterCoprocessorHost mcph = getMaster().getMasterCoprocessorHost();
-        if (mcph != null) {
-          mcph.preDispatchMerge(regionInfoA, regionInfoB);
-        }
-
-        LOG.info(getClientIdAuditPrefix() + " Dispatch merge regions " +
-          regionsToMerge[0].getEncodedName() + " and " + regionsToMerge[1].getEncodedName());
-
-        submitProcedure(new DispatchMergingRegionsProcedure(
-            procedureExecutor.getEnvironment(), tableName, regionsToMerge, forcible));
-        if (mcph != null) {
-          mcph.postDispatchMerge(regionInfoA, regionInfoB);
-        }
-      }
-
-      @Override
-      protected String getDescription() {
-        return "DispatchMergingRegionsProcedure";
-      }
-    });
-  }
-
   @Override
   public long mergeRegions(
       final HRegionInfo[] regionsToMerge,

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

@@ -810,28 +810,6 @@ public class MasterCoprocessorHost
     });
   }
 
-  public void preDispatchMerge(final HRegionInfo regionInfoA, final HRegionInfo regionInfoB)
-  throws IOException {
-    execOperation(coprocessors.isEmpty() ? null : new CoprocessorOperation() {
-      @Override
-      public void call(MasterObserver oserver, ObserverContext<MasterCoprocessorEnvironment> ctx)
-          throws IOException {
-        oserver.preDispatchMerge(ctx, regionInfoA, regionInfoB);
-      }
-    });
-  }
-
-  public void postDispatchMerge(final HRegionInfo regionInfoA, final HRegionInfo regionInfoB)
-  throws IOException {
-    execOperation(coprocessors.isEmpty() ? null : new CoprocessorOperation() {
-      @Override
-      public void call(MasterObserver oserver, ObserverContext<MasterCoprocessorEnvironment> ctx)
-          throws IOException {
-        oserver.postDispatchMerge(ctx, regionInfoA, regionInfoB);
-      }
-    });
-  }
-
   public void preMergeRegions(final HRegionInfo[] regionsToMerge)
       throws IOException {
     execOperation(coprocessors.isEmpty() ? null : new CoprocessorOperation() {

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

@@ -2009,34 +2009,4 @@ public class MasterRpcServices extends RSRpcServices
       throw new ServiceException(e);
     }
   }
-
-  @Override
-  public DispatchMergingRegionsResponse dispatchMergingRegions(RpcController controller,
-      DispatchMergingRegionsRequest request) throws ServiceException {
-    final byte[] encodedNameOfRegionA = request.getRegionA().getValue().toByteArray();
-    final byte[] encodedNameOfRegionB = request.getRegionB().getValue().toByteArray();
-    if (request.getRegionA().getType() != RegionSpecifierType.ENCODED_REGION_NAME ||
-        request.getRegionB().getType() != RegionSpecifierType.ENCODED_REGION_NAME) {
-      LOG.warn("mergeRegions specifier type: expected: " + RegionSpecifierType.ENCODED_REGION_NAME +
-          " actual: region_a=" +
-          request.getRegionA().getType() + ", region_b=" +
-          request.getRegionB().getType());
-    }
-    RegionStates regionStates = master.getAssignmentManager().getRegionStates();
-    RegionState regionStateA = regionStates.getRegionState(Bytes.toString(encodedNameOfRegionA));
-    RegionState regionStateB = regionStates.getRegionState(Bytes.toString(encodedNameOfRegionB));
-    if (regionStateA == null || regionStateB == null) {
-      throw new ServiceException(new UnknownRegionException(
-        Bytes.toStringBinary(regionStateA == null? encodedNameOfRegionA: encodedNameOfRegionB)));
-    }
-    final HRegionInfo regionInfoA = regionStateA.getRegion();
-    final HRegionInfo regionInfoB = regionStateB.getRegion();
-    try {
-      long procId = master.dispatchMergingRegions(regionInfoA, regionInfoB, request.getForcible(),
-          request.getNonceGroup(), request.getNonce());
-      return DispatchMergingRegionsResponse.newBuilder().setProcId(procId).build();
-    } catch (IOException ioe) {
-      throw new ServiceException(ioe);
-    }
-  }
 }

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

@@ -281,23 +281,6 @@ public interface MasterServices extends Server {
       final long nonce)
       throws IOException;
 
-  /**
-   * Merge two regions. The real implementation is on the regionserver, master
-   * just move the regions together and send MERGE RPC to regionserver
-   * @param region_a region to merge
-   * @param region_b region to merge
-   * @param forcible true if do a compulsory merge, otherwise we will only merge
-   *          two adjacent regions
-   * @return procedure Id
-   * @throws IOException
-   */
-  long dispatchMergingRegions(
-    final HRegionInfo region_a,
-    final HRegionInfo region_b,
-    final boolean forcible,
-    final long nonceGroup,
-    final long nonce) throws IOException;
-
   /**
    * Merge regions in a table.
    * @param regionsToMerge daughter regions to merge

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

@@ -622,37 +622,6 @@ public class ServerManager {
     }
   }
 
-  /**
-   * Sends an MERGE REGIONS RPC to the specified server to merge the specified
-   * regions.
-   * <p>
-   * A region server could reject the close request because it either does not
-   * have the specified region.
-   * @param server server to merge regions
-   * @param region_a region to merge
-   * @param region_b region to merge
-   * @param forcible true if do a compulsory merge, otherwise we will only merge
-   *          two adjacent regions
-   * @throws IOException
-   */
-  public void sendRegionsMerge(ServerName server, HRegionInfo region_a,
-      HRegionInfo region_b, boolean forcible, final User user) throws IOException {
-    if (server == null)
-      throw new NullPointerException("Passed server is null");
-    if (region_a == null || region_b == null)
-      throw new NullPointerException("Passed region is null");
-    AdminService.BlockingInterface admin = getRsAdmin(server);
-    if (admin == null) {
-      throw new IOException("Attempting to send MERGE REGIONS RPC to server "
-          + server.toString() + " for region "
-          + region_a.getRegionNameAsString() + ","
-          + region_b.getRegionNameAsString()
-          + " failed because no RPC connection found to this server");
-    }
-    HBaseRpcController controller = newRpcController();
-    ProtobufUtil.mergeRegions(controller, admin, region_a, region_b, forcible, user);
-  }
-
   @VisibleForTesting
   public void moveFromOnlineToDeadServers(final ServerName sn) {
     synchronized (onlineServers) {

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

@@ -1,584 +0,0 @@
-/**
- * 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.master.procedure;
-
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.InterruptedIOException;
-import java.io.OutputStream;
-import java.util.Map;
-import java.util.concurrent.atomic.AtomicBoolean;
-
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
-import org.apache.hadoop.hbase.HRegionInfo;
-import org.apache.hadoop.hbase.RegionLoad;
-import org.apache.hadoop.hbase.ServerLoad;
-import org.apache.hadoop.hbase.ServerName;
-import org.apache.hadoop.hbase.TableName;
-import org.apache.hadoop.hbase.UnknownRegionException;
-import org.apache.hadoop.hbase.classification.InterfaceAudience;
-import org.apache.hadoop.hbase.exceptions.MergeRegionException;
-import org.apache.hadoop.hbase.exceptions.RegionOpeningException;
-import org.apache.hadoop.hbase.master.assignment.AssignmentManager;
-import org.apache.hadoop.hbase.master.assignment.RegionStates;
-import org.apache.hadoop.hbase.master.CatalogJanitor;
-import org.apache.hadoop.hbase.master.RegionPlan;
-import org.apache.hadoop.hbase.master.RegionState;
-import org.apache.hadoop.hbase.master.ServerManager;
-import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProcedureProtos;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProcedureProtos.DispatchMergingRegionsState;
-import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
-
-/**
- * The procedure to Merge a region in a table.
- */
-@InterfaceAudience.Private
-public class DispatchMergingRegionsProcedure
-    extends AbstractStateMachineTableProcedure<DispatchMergingRegionsState> {
-  private static final Log LOG = LogFactory.getLog(DispatchMergingRegionsProcedure.class);
-
-  private final AtomicBoolean aborted = new AtomicBoolean(false);
-  private Boolean traceEnabled;
-  private AssignmentManager assignmentManager;
-  private int timeout;
-  private ServerName regionLocation;
-  private String regionsToMergeListFullName;
-  private String regionsToMergeListEncodedName;
-
-  private TableName tableName;
-  private HRegionInfo [] regionsToMerge;
-  private boolean forcible;
-
-  public DispatchMergingRegionsProcedure() {
-    this.traceEnabled = isTraceEnabled();
-    this.assignmentManager = null;
-    this.timeout = -1;
-    this.regionLocation = null;
-    this.regionsToMergeListFullName = null;
-    this.regionsToMergeListEncodedName = null;
-  }
-
-  public DispatchMergingRegionsProcedure(
-      final MasterProcedureEnv env,
-      final TableName tableName,
-      final HRegionInfo [] regionsToMerge,
-      final boolean forcible) {
-    super(env);
-    this.traceEnabled = isTraceEnabled();
-    this.assignmentManager = getAssignmentManager(env);
-    this.tableName = tableName;
-    // For now, we only merge 2 regions.  It could be extended to more than 2 regions in
-    // the future.
-    assert(regionsToMerge.length == 2);
-    this.regionsToMerge = regionsToMerge;
-    this.forcible = forcible;
-
-    this.timeout = -1;
-    this.regionsToMergeListFullName = getRegionsToMergeListFullNameString();
-    this.regionsToMergeListEncodedName = getRegionsToMergeListEncodedNameString();
-  }
-
-  @Override
-  protected Flow executeFromState(
-      final MasterProcedureEnv env,
-      final DispatchMergingRegionsState state) throws InterruptedException {
-    if (isTraceEnabled()) {
-      LOG.trace(this + " execute state=" + state);
-    }
-
-    try {
-      switch (state) {
-      case DISPATCH_MERGING_REGIONS_PREPARE:
-        prepareMergeRegion(env);
-        setNextState(DispatchMergingRegionsState.DISPATCH_MERGING_REGIONS_PRE_OPERATION);
-        break;
-      case DISPATCH_MERGING_REGIONS_PRE_OPERATION:
-        //Unused for now - reserve to add preMerge coprocessor in the future
-        setNextState(DispatchMergingRegionsState.DISPATCH_MERGING_REGIONS_MOVE_REGION_TO_SAME_RS);
-        break;
-      case DISPATCH_MERGING_REGIONS_MOVE_REGION_TO_SAME_RS:
-        if (MoveRegionsToSameRS(env)) {
-          setNextState(DispatchMergingRegionsState.DISPATCH_MERGING_REGIONS_DO_MERGE_IN_RS);
-        } else {
-          LOG.info("Cancel merging regions " + getRegionsToMergeListFullNameString()
-            + ", because can't move them to the same RS");
-          setNextState(DispatchMergingRegionsState.DISPATCH_MERGING_REGIONS_POST_OPERATION);
-        }
-        break;
-      case DISPATCH_MERGING_REGIONS_DO_MERGE_IN_RS:
-        doMergeInRS(env);
-        setNextState(DispatchMergingRegionsState.DISPATCH_MERGING_REGIONS_POST_OPERATION);
-        break;
-      case DISPATCH_MERGING_REGIONS_POST_OPERATION:
-        //Unused for now - reserve to add postCompletedMerge coprocessor in the future
-        return Flow.NO_MORE_STATE;
-      default:
-        throw new UnsupportedOperationException(this + " unhandled state=" + state);
-      }
-    } catch (IOException e) {
-      LOG.warn("Error trying to merge regions " + getRegionsToMergeListFullNameString() +
-        " in the table " + tableName + " (in state=" + state + ")", e);
-
-      setFailure("master-merge-regions", e);
-    }
-    return Flow.HAS_MORE_STATE;
-  }
-
-  @Override
-  protected void rollbackState(
-      final MasterProcedureEnv env,
-      final DispatchMergingRegionsState state) throws IOException, InterruptedException {
-    if (isTraceEnabled()) {
-      LOG.trace(this + " rollback state=" + state);
-    }
-
-    try {
-      switch (state) {
-      case DISPATCH_MERGING_REGIONS_POST_OPERATION:
-      case DISPATCH_MERGING_REGIONS_DO_MERGE_IN_RS:
-        String msg = this + " We are in the " + state + " state."
-            + " It is complicated to rollback the merge operation that region server is working on."
-            + " Rollback is not supported and we should let the merge operation to complete";
-        LOG.warn(msg);
-        // PONR
-        throw new UnsupportedOperationException(this + " unhandled state=" + state);
-      case DISPATCH_MERGING_REGIONS_MOVE_REGION_TO_SAME_RS:
-        break; // nothing to rollback
-      case DISPATCH_MERGING_REGIONS_PRE_OPERATION:
-        break; // nothing to rollback
-      case DISPATCH_MERGING_REGIONS_PREPARE:
-        break; // nothing to rollback
-      default:
-        throw new UnsupportedOperationException(this + " unhandled state=" + state);
-      }
-    } catch (Exception e) {
-      // This will be retried. Unless there is a bug in the code,
-      // this should be just a "temporary error" (e.g. network down)
-      LOG.warn("Failed rollback attempt step " + state + " for merging the regions "
-          + getRegionsToMergeListFullNameString() + " in table " + tableName, e);
-      throw e;
-    }
-  }
-
-  @Override
-  protected DispatchMergingRegionsState getState(final int stateId) {
-    return DispatchMergingRegionsState.valueOf(stateId);
-  }
-
-  @Override
-  protected int getStateId(final DispatchMergingRegionsState state) {
-    return state.getNumber();
-  }
-
-  @Override
-  protected DispatchMergingRegionsState getInitialState() {
-    return DispatchMergingRegionsState.DISPATCH_MERGING_REGIONS_PREPARE;
-  }
-
-  /*
-   * Check whether we are in the state that can be rollback
-   */
-  @Override
-  protected boolean isRollbackSupported(final DispatchMergingRegionsState state) {
-    switch (state) {
-    case DISPATCH_MERGING_REGIONS_POST_OPERATION:
-    case DISPATCH_MERGING_REGIONS_DO_MERGE_IN_RS:
-        // It is not safe to rollback if we reach to these states.
-        return false;
-      default:
-        break;
-    }
-    return true;
-  }
-
-  @Override
-  public void serializeStateData(final OutputStream stream) throws IOException {
-    super.serializeStateData(stream);
-
-    MasterProcedureProtos.DispatchMergingRegionsStateData.Builder dispatchMergingRegionsMsg =
-        MasterProcedureProtos.DispatchMergingRegionsStateData.newBuilder()
-        .setUserInfo(MasterProcedureUtil.toProtoUserInfo(getUser()))
-        .setTableName(ProtobufUtil.toProtoTableName(tableName))
-        .setForcible(forcible);
-    for (HRegionInfo hri: regionsToMerge) {
-      dispatchMergingRegionsMsg.addRegionInfo(HRegionInfo.convert(hri));
-    }
-    dispatchMergingRegionsMsg.build().writeDelimitedTo(stream);
-  }
-
-  @Override
-  public void deserializeStateData(final InputStream stream) throws IOException {
-    super.deserializeStateData(stream);
-
-    MasterProcedureProtos.DispatchMergingRegionsStateData dispatchMergingRegionsMsg =
-        MasterProcedureProtos.DispatchMergingRegionsStateData.parseDelimitedFrom(stream);
-    setUser(MasterProcedureUtil.toUserInfo(dispatchMergingRegionsMsg.getUserInfo()));
-    tableName = ProtobufUtil.toTableName(dispatchMergingRegionsMsg.getTableName());
-
-    assert(dispatchMergingRegionsMsg.getRegionInfoCount() == 2);
-    regionsToMerge = new HRegionInfo[dispatchMergingRegionsMsg.getRegionInfoCount()];
-    for (int i = 0; i < regionsToMerge.length; i++) {
-      regionsToMerge[i] = HRegionInfo.convert(dispatchMergingRegionsMsg.getRegionInfo(i));
-    }
-  }
-
-  @Override
-  public void toStringClassDetails(StringBuilder sb) {
-    sb.append(getClass().getSimpleName());
-    sb.append(" (table=");
-    sb.append(tableName);
-    sb.append(" regions=");
-    sb.append(getRegionsToMergeListFullNameString());
-    sb.append(" forcible=");
-    sb.append(forcible);
-    sb.append(")");
-  }
-
-  @Override
-  protected LockState acquireLock(final MasterProcedureEnv env) {
-    if (!getTableName().isSystemTable() && env.waitInitialized(this)) {
-      return LockState.LOCK_EVENT_WAIT;
-    }
-    if (env.getProcedureScheduler().waitRegions(this, getTableName(), regionsToMerge)) {
-      return LockState.LOCK_EVENT_WAIT;
-    }
-    return LockState.LOCK_ACQUIRED;
-  }
-
-  @Override
-  protected void releaseLock(final MasterProcedureEnv env) {
-    env.getProcedureScheduler().wakeRegions(this, getTableName(), regionsToMerge[0], regionsToMerge[1]);
-  }
-
-  @Override
-  public TableName getTableName() {
-    return tableName;
-  }
-
-  @Override
-  public TableOperationType getTableOperationType() {
-    return TableOperationType.REGION_MERGE;
-  }
-
-  /**
-   * Prepare merge and do some check
-   * @param env MasterProcedureEnv
-   * @throws IOException
-   */
-  private void prepareMergeRegion(final MasterProcedureEnv env) throws IOException {
-    // Note: the following logic assumes that we only have 2 regions to merge.  In the future,
-    // if we want to extend to more than 2 regions, the code needs to modify a little bit.
-    //
-    CatalogJanitor catalogJanitor = env.getMasterServices().getCatalogJanitor();
-    boolean regionAHasMergeQualifier = !catalogJanitor.cleanMergeQualifier(regionsToMerge[0]);
-    if (regionAHasMergeQualifier
-        || !catalogJanitor.cleanMergeQualifier(regionsToMerge[1])) {
-      String msg = "Skip merging regions " + regionsToMerge[0].getRegionNameAsString()
-          + ", " + regionsToMerge[1].getRegionNameAsString() + ", because region "
-          + (regionAHasMergeQualifier ? regionsToMerge[0].getEncodedName() : regionsToMerge[1]
-              .getEncodedName()) + " has merge qualifier";
-      LOG.info(msg);
-      throw new MergeRegionException(msg);
-    }
-
-      RegionStates regionStates = getAssignmentManager(env).getRegionStates();
-      RegionState regionStateA = regionStates.getRegionState(regionsToMerge[0].getEncodedName());
-      RegionState regionStateB = regionStates.getRegionState(regionsToMerge[1].getEncodedName());
-      if (regionStateA == null || regionStateB == null) {
-        throw new UnknownRegionException(
-          regionStateA == null ?
-              regionsToMerge[0].getEncodedName() : regionsToMerge[1].getEncodedName());
-      }
-
-      if (!regionStateA.isOpened() || !regionStateB.isOpened()) {
-        throw new MergeRegionException(
-          "Unable to merge regions not online " + regionStateA + ", " + regionStateB);
-      }
-
-      if (regionsToMerge[0].getReplicaId() != HRegionInfo.DEFAULT_REPLICA_ID ||
-          regionsToMerge[1].getReplicaId() != HRegionInfo.DEFAULT_REPLICA_ID) {
-        throw new MergeRegionException("Can't merge non-default replicas");
-      }
-
-      if (!forcible && !HRegionInfo.areAdjacent(regionsToMerge[0], regionsToMerge[1])) {
-        throw new MergeRegionException(
-          "Unable to merge not adjacent regions "
-            + regionsToMerge[0].getRegionNameAsString() + ", "
-            + regionsToMerge[1].getRegionNameAsString()
-            + " where forcible = " + forcible);
-      }
-  }
-
-  /**
-   * Move all regions to the same region server
-   * @param env MasterProcedureEnv
-   * @return whether target regions hosted by the same RS
-   * @throws IOException
-   */
-  private boolean MoveRegionsToSameRS(final MasterProcedureEnv env) throws IOException {
-    // Make sure regions are on the same regionserver before send merge
-    // regions request to region server.
-    //
-    boolean onSameRS = isRegionsOnTheSameServer(env);
-    if (!onSameRS) {
-      // Note: the following logic assumes that we only have 2 regions to merge.  In the future,
-      // if we want to extend to more than 2 regions, the code needs to modify a little bit.
-      //
-      RegionStates regionStates = getAssignmentManager(env).getRegionStates();
-      ServerName regionLocation2 = regionStates.getRegionServerOfRegion(regionsToMerge[1]);
-
-      RegionLoad loadOfRegionA = getRegionLoad(env, regionLocation, regionsToMerge[0]);
-      RegionLoad loadOfRegionB = getRegionLoad(env, regionLocation2, regionsToMerge[1]);
-      if (loadOfRegionA != null && loadOfRegionB != null
-          && loadOfRegionA.getRequestsCount() < loadOfRegionB.getRequestsCount()) {
-        // switch regionsToMerge[0] and regionsToMerge[1]
-        HRegionInfo tmpRegion = this.regionsToMerge[0];
-        this.regionsToMerge[0] = this.regionsToMerge[1];
-        this.regionsToMerge[1] = tmpRegion;
-        ServerName tmpLocation = regionLocation;
-        regionLocation = regionLocation2;
-        regionLocation2 = tmpLocation;
-      }
-
-      long startTime = EnvironmentEdgeManager.currentTime();
-
-      RegionPlan regionPlan = new RegionPlan(regionsToMerge[1], regionLocation2, regionLocation);
-      LOG.info("Moving regions to same server for merge: " + regionPlan.toString());
-      getAssignmentManager(env).moveAsync(regionPlan);
-      do {
-        try {
-          Thread.sleep(20);
-          // Make sure check RIT first, then get region location, otherwise
-          // we would make a wrong result if region is online between getting
-          // region location and checking RIT
-          boolean isRIT = regionStates.isRegionInTransition(regionsToMerge[1]);
-          regionLocation2 = regionStates.getRegionServerOfRegion(regionsToMerge[1]);
-          onSameRS = regionLocation.equals(regionLocation2);
-          if (onSameRS || !isRIT) {
-            // Regions are on the same RS, or regionsToMerge[1] is not in
-            // RegionInTransition any more
-            break;
-          }
-        } catch (InterruptedException e) {
-          InterruptedIOException iioe = new InterruptedIOException();
-          iioe.initCause(e);
-          throw iioe;
-        }
-      } while ((EnvironmentEdgeManager.currentTime() - startTime) <= getTimeout(env));
-    }
-    return onSameRS;
-  }
-
-  /**
-   * Do the real merge operation in the region server that hosts regions
-   * @param env MasterProcedureEnv
-   * @throws IOException
-   */
-  private void doMergeInRS(final MasterProcedureEnv env) throws IOException {
-    long duration = 0;
-    long startTime = EnvironmentEdgeManager.currentTime();
-    do {
-      try {
-        if (getServerName(env) == null) {
-          // The merge probably already happen. Check
-          RegionState regionState = getAssignmentManager(env).getRegionStates().getRegionState(
-            regionsToMerge[0].getEncodedName());
-          if (regionState.isMerging() || regionState.isMerged()) {
-            LOG.info("Merge regions " +  getRegionsToMergeListEncodedNameString() +
-              " is in progress or completed.  No need to send a new request.");
-          } else {
-            LOG.warn("Cannot sending merge to hosting server of the regions " +
-              getRegionsToMergeListEncodedNameString() + " as the server is unknown");
-          }
-          return;
-        }
-        // TODO: the following RPC call is not idempotent.  Multiple calls (eg. after master
-        // failover, re-execute this step) could result in some exception thrown that does not
-        // paint the correct picture.  This behavior is on-par with old releases.  Improvement
-        // could happen in the future.
-        env.getMasterServices().getServerManager().sendRegionsMerge(
-          getServerName(env),
-          regionsToMerge[0],
-          regionsToMerge[1],
-          forcible,
-          getUser());
-        LOG.info("Sent merge to server " + getServerName(env) + " for region " +
-            getRegionsToMergeListEncodedNameString() + ", forcible=" + forcible);
-        return;
-      } catch (RegionOpeningException roe) {
-        // Do a retry since region should be online on RS immediately
-        LOG.warn("Failed mergering regions in " + getServerName(env) + ", retrying...", roe);
-      } catch (Exception ie) {
-        LOG.warn("Failed sending merge to " + getServerName(env) + " for regions " +
-            getRegionsToMergeListEncodedNameString() + ", forcible=" + forcible, ie);
-        return;
-      }
-    } while ((duration = EnvironmentEdgeManager.currentTime() - startTime) <= getTimeout(env));
-
-    // If we reaches here, it means that we get timed out.
-    String msg = "Failed sending merge to " + getServerName(env) + " after " + duration + "ms";
-    LOG.warn(msg);
-    throw new IOException(msg);
-  }
-
-  private RegionLoad getRegionLoad(
-      final MasterProcedureEnv env,
-      final ServerName sn,
-      final HRegionInfo hri) {
-    ServerManager serverManager =  env.getMasterServices().getServerManager();
-    ServerLoad load = serverManager.getLoad(sn);
-    if (load != null) {
-      Map<byte[], RegionLoad> regionsLoad = load.getRegionsLoad();
-      if (regionsLoad != null) {
-        return regionsLoad.get(hri.getRegionName());
-      }
-    }
-    return null;
-  }
-
-  /**
-   * The procedure could be restarted from a different machine. If the variable is null, we need to
-   * retrieve it.
-   * @param env MasterProcedureEnv
-   * @return whether target regions hosted by the same RS
-   */
-  private boolean isRegionsOnTheSameServer(final MasterProcedureEnv env) throws IOException{
-    Boolean onSameRS = true;
-    int i = 0;
-    RegionStates regionStates = getAssignmentManager(env).getRegionStates();
-    regionLocation = regionStates.getRegionServerOfRegion(regionsToMerge[i]);
-    if (regionLocation != null) {
-      for(i = 1; i < regionsToMerge.length; i++) {
-        ServerName regionLocation2 = regionStates.getRegionServerOfRegion(regionsToMerge[i]);
-        if (regionLocation2 != null) {
-          if (onSameRS) {
-            onSameRS = regionLocation.equals(regionLocation2);
-          }
-        } else {
-          // At least one region is not online, merge will fail, no need to continue.
-          break;
-        }
-      }
-      if (i == regionsToMerge.length) {
-        // Finish checking all regions, return the result;
-        return onSameRS;
-      }
-    }
-
-    // If reaching here, at least one region is not online.
-    String msg = "Skip merging regions " + getRegionsToMergeListFullNameString() +
-        ", because region " + regionsToMerge[i].getEncodedName() + " is not online now.";
-    LOG.warn(msg);
-    throw new IOException(msg);
-  }
-
-  /**
-   * The procedure could be restarted from a different machine. If the variable is null, we need to
-   * retrieve it.
-   * @param env MasterProcedureEnv
-   * @return assignmentManager
-   */
-  private AssignmentManager getAssignmentManager(final MasterProcedureEnv env) {
-    if (assignmentManager == null) {
-      assignmentManager = env.getMasterServices().getAssignmentManager();
-    }
-    return assignmentManager;
-  }
-
-  /**
-   * The procedure could be restarted from a different machine. If the variable is null, we need to
-   * retrieve it.
-   * @param env MasterProcedureEnv
-   * @return timeout value
-   */
-  private int getTimeout(final MasterProcedureEnv env) {
-    if (timeout == -1) {
-      timeout = env.getMasterConfiguration().getInt(
-        "hbase.master.regionmerge.timeout", regionsToMerge.length * 60 * 1000);
-    }
-    return timeout;
-  }
-
-  /**
-   * The procedure could be restarted from a different machine. If the variable is null, we need to
-   * retrieve it.
-   * @param env MasterProcedureEnv
-   * @return serverName
-   */
-  private ServerName getServerName(final MasterProcedureEnv env) {
-    if (regionLocation == null) {
-      regionLocation =
-          getAssignmentManager(env).getRegionStates().getRegionServerOfRegion(regionsToMerge[0]);
-    }
-    return regionLocation;
-  }
-
-  /**
-   * The procedure could be restarted from a different machine. If the variable is null, we need to
-   * retrieve it.
-   * @param fullName whether return only encoded name
-   * @return region names in a list
-   */
-  private String getRegionsToMergeListFullNameString() {
-    if (regionsToMergeListFullName == null) {
-      StringBuilder sb = new StringBuilder("[");
-      int i = 0;
-      while(i < regionsToMerge.length - 1) {
-        sb.append(regionsToMerge[i].getRegionNameAsString() + ", ");
-        i++;
-      }
-      sb.append(regionsToMerge[i].getRegionNameAsString() + " ]");
-      regionsToMergeListFullName = sb.toString();
-    }
-    return regionsToMergeListFullName;
-  }
-
-  /**
-   * The procedure could be restarted from a different machine. If the variable is null, we need to
-   * retrieve it.
-   * @return encoded region names
-   */
-  private String getRegionsToMergeListEncodedNameString() {
-    if (regionsToMergeListEncodedName == null) {
-      StringBuilder sb = new StringBuilder("[");
-      int i = 0;
-      while(i < regionsToMerge.length - 1) {
-        sb.append(regionsToMerge[i].getEncodedName() + ", ");
-        i++;
-      }
-      sb.append(regionsToMerge[i].getEncodedName() + " ]");
-      regionsToMergeListEncodedName = sb.toString();
-    }
-    return regionsToMergeListEncodedName;
-  }
-
-  /**
-   * The procedure could be restarted from a different machine. If the variable is null, we need to
-   * retrieve it.
-   * @return traceEnabled
-   */
-  private Boolean isTraceEnabled() {
-    if (traceEnabled == null) {
-      traceEnabled = LOG.isTraceEnabled();
-    }
-    return traceEnabled;
-  }
-}

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

@@ -208,20 +208,6 @@ public class CompactSplit implements CompactionRequestor, PropagatingConfigurati
     return queueLists.toString();
   }
 
-  public synchronized void requestRegionsMerge(final Region a,
-      final Region b, final boolean forcible, long masterSystemTime, User user) {
-    try {
-      mergePool.execute(new RegionMergeRequest(a, b, this.server, forcible, masterSystemTime,user));
-      if (LOG.isDebugEnabled()) {
-        LOG.debug("Region merge requested for " + a + "," + b + ", forcible="
-            + forcible + ".  " + this);
-      }
-    } catch (RejectedExecutionException ree) {
-      LOG.warn("Could not execute merge for " + a + "," + b + ", forcible="
-          + forcible, ree);
-    }
-  }
-
   public synchronized boolean requestSplit(final Region r) {
     // don't split regions that are blocking
     if (shouldSplitRegion() && ((HRegion)r).getCompactPriority() >= Store.PRIORITY_USER) {

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

@@ -84,7 +84,6 @@ import org.apache.hadoop.hbase.client.Scan;
 import org.apache.hadoop.hbase.client.VersionInfoUtil;
 import org.apache.hadoop.hbase.conf.ConfigurationObserver;
 import org.apache.hadoop.hbase.exceptions.FailedSanityCheckException;
-import org.apache.hadoop.hbase.exceptions.MergeRegionException;
 import org.apache.hadoop.hbase.exceptions.OutOfOrderScannerNextException;
 import org.apache.hadoop.hbase.exceptions.ScannerResetException;
 import org.apache.hadoop.hbase.filter.ByteArrayComparable;
@@ -150,8 +149,6 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.GetServerIn
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.GetServerInfoResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.GetStoreFileRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.GetStoreFileResponse;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.MergeRegionsRequest;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.MergeRegionsResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.OpenRegionRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.OpenRegionRequest.RegionOpenInfo;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.OpenRegionResponse;
@@ -3490,45 +3487,4 @@ public class RSRpcServices implements HBaseRPCErrorHandler,
      }
      return builder.build();
   }
-
-  /**
-   * Merge regions on the region server.
-   *
-   * @param controller the RPC controller
-   * @param request the request
-   * @return merge regions response
-   * @throws ServiceException
-   */
-  @Override
-  @QosPriority(priority = HConstants.ADMIN_QOS)
-  // UNUSED AS OF AMv2 PURGE!
-  public MergeRegionsResponse mergeRegions(final RpcController controller,
-      final MergeRegionsRequest request) throws ServiceException {
-    try {
-      checkOpen();
-      requestCount.increment();
-      Region regionA = getRegion(request.getRegionA());
-      Region regionB = getRegion(request.getRegionB());
-      boolean forcible = request.getForcible();
-      long masterSystemTime = request.hasMasterSystemTime() ? request.getMasterSystemTime() : -1;
-      regionA.startRegionOperation(Operation.MERGE_REGION);
-      regionB.startRegionOperation(Operation.MERGE_REGION);
-      if (regionA.getRegionInfo().getReplicaId() != HRegionInfo.DEFAULT_REPLICA_ID ||
-          regionB.getRegionInfo().getReplicaId() != HRegionInfo.DEFAULT_REPLICA_ID) {
-        throw new ServiceException(new MergeRegionException("Can't merge non-default replicas"));
-      }
-      LOG.info("Receiving merging request for  " + regionA + ", " + regionB
-          + ",forcible=" + forcible);
-      regionA.flush(true);
-      regionB.flush(true);
-      regionServer.compactSplitThread.requestRegionsMerge(regionA, regionB, forcible,
-          masterSystemTime, RpcServer.getRequestUser());
-      return MergeRegionsResponse.newBuilder().build();
-    } catch (DroppedSnapshotException ex) {
-      regionServer.abort("Replay of WAL required. Forcing server shutdown", ex);
-      throw new ServiceException(ex);
-    } catch (IOException ie) {
-      throw new ServiceException(ie);
-    }
-  }
 }

hbase-server/src/test/java/org/apache/hadoop/hbase/master/MockNoopMasterServices.java

@@ -451,12 +451,6 @@ public class MockNoopMasterServices implements MasterServices, Server {
   public void checkIfShouldMoveSystemRegionAsync() {
   }
 
-  @Override
-  public long dispatchMergingRegions(HRegionInfo region_a, HRegionInfo region_b, boolean forcible, long nonceGroup,
-      long nonce) throws IOException {
-    return 0;
-  }
-
   @Override
   public ProcedureEvent getInitializedEvent() {
     // TODO Auto-generated method stub

hbase-server/src/test/java/org/apache/hadoop/hbase/master/MockRegionServer.java

@@ -69,8 +69,6 @@ import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.GetServerIn
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.GetServerInfoResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.GetStoreFileRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.GetStoreFileResponse;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.MergeRegionsRequest;
-import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.MergeRegionsResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.OpenRegionRequest;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.OpenRegionResponse;
 import org.apache.hadoop.hbase.shaded.protobuf.generated.AdminProtos.ReplicateWALEntryRequest;
@@ -733,11 +731,4 @@ ClientProtos.ClientService.BlockingInterface, RegionServerServices {
       throws ServiceException {
     return null;
   }
-
-  @Override
-  public MergeRegionsResponse mergeRegions(RpcController controller, MergeRegionsRequest request)
-      throws ServiceException {
-    // TODO Auto-generated method stub
-    return null;
-  }
 }

hbase-server/src/test/java/org/apache/hadoop/hbase/replication/regionserver/TestReplicator.java

@@ -403,13 +403,6 @@ public class TestReplicator extends TestReplicationBase {
       throws ServiceException {
         return null;
       }
-
-      @Override
-      public MergeRegionsResponse mergeRegions(RpcController controller,
-                                               MergeRegionsRequest request)
-      throws ServiceException {
-        return null;
-      }
     }
 
     public class FailureInjectingReplicatorForTest extends ReplicatorForTest {