/**
    * 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.client;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  
  import org.apache.hadoop.hbase.CellScannable;
  import org.apache.hadoop.hbase.CellUtil;
  import org.apache.hadoop.hbase.DoNotRetryIOException;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.HRegionLocation;
  import org.apache.hadoop.hbase.ServerName;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.ipc.PayloadCarryingRpcController;
  import org.apache.hadoop.hbase.ipc.RpcControllerFactory;
  import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
  import org.apache.hadoop.hbase.protobuf.RequestConverter;
  import org.apache.hadoop.hbase.protobuf.ResponseConverter;
  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos;
  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.MultiRequest;
  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.MutationProto;
  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.RegionAction;
  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos;
  
  import com.google.common.annotations.VisibleForTesting;
  import com.google.protobuf.ServiceException;
  
  /**
   * Callable that handles the <code>multi</code> method call going against a single
   * regionserver; i.e. A {@link RegionServerCallable} for the multi call (It is not a
   * {@link RegionServerCallable} that goes against multiple regions.
   * @param <R>
   */
  class MultiServerCallable<R> extends RegionServerCallable<MultiResponse> implements Cancellable {
    private final MultiAction<R> multiAction;
    private final boolean cellBlock;
    private final PayloadCarryingRpcController controller;
  
    MultiServerCallable(final ClusterConnection connection, final TableName tableName,
        final ServerName location, RpcControllerFactory rpcFactory, final MultiAction<R> multi) {
      super(connection, tableName, null);
      this.multiAction = multi;
      // RegionServerCallable has HRegionLocation field, but this is a multi-region request.
      // Using region info from parent HRegionLocation would be a mistake for this class; so
      // we will store the server here, and throw if someone tries to obtain location/regioninfo.
      this.location = new HRegionLocation(null, location);
      this.cellBlock = isCellBlock();
      controller = rpcFactory.newController();
    }
  
    @Override
    protected HRegionLocation getLocation() {
      throw new RuntimeException("Cannot get region location for multi-region request");
    }
  
    @Override
    public HRegionInfo getHRegionInfo() {
      throw new RuntimeException("Cannot get region info for multi-region request");
    }
  
    MultiAction<R> getMulti() {
      return this.multiAction;
    }
  
    @Override
    public MultiResponse call(int callTimeout) throws IOException {
      int countOfActions = this.multiAction.size();
      if (countOfActions <= 0) throw new DoNotRetryIOException("No Actions");
      MultiRequest.Builder multiRequestBuilder = MultiRequest.newBuilder();
      RegionAction.Builder regionActionBuilder = RegionAction.newBuilder();
      ClientProtos.Action.Builder actionBuilder = ClientProtos.Action.newBuilder();
      MutationProto.Builder mutationBuilder = MutationProto.newBuilder();
      List<CellScannable> cells = null;
      // The multi object is a list of Actions by region.  Iterate by region.
      long nonceGroup = multiAction.getNonceGroup();
      if (nonceGroup != HConstants.NO_NONCE) {
        multiRequestBuilder.setNonceGroup(nonceGroup);
      }
      for (Map.Entry<byte[], List<Action<R>>> e: this.multiAction.actions.entrySet()) {
        final byte [] regionName = e.getKey();
       final List<Action<R>> actions = e.getValue();
       regionActionBuilder.clear();
       regionActionBuilder.setRegion(RequestConverter.buildRegionSpecifier(
         HBaseProtos.RegionSpecifier.RegionSpecifierType.REGION_NAME, regionName) );
 
 
       if (this.cellBlock) {
         // Presize.  Presume at least a KV per Action.  There are likely more.
         if (cells == null) cells = new ArrayList<CellScannable>(countOfActions);
         // Send data in cellblocks. The call to buildNoDataMultiRequest will skip RowMutations.
         // They have already been handled above. Guess at count of cells
         regionActionBuilder = RequestConverter.buildNoDataRegionAction(regionName, actions, cells,
           regionActionBuilder, actionBuilder, mutationBuilder);
       } else {
         regionActionBuilder = RequestConverter.buildRegionAction(regionName, actions,
           regionActionBuilder, actionBuilder, mutationBuilder);
       }
       multiRequestBuilder.addRegionAction(regionActionBuilder.build());
     }
 
     // Controller optionally carries cell data over the proxy/service boundary and also
     // optionally ferries cell response data back out again.
     if (cells != null) controller.setCellScanner(CellUtil.createCellScanner(cells));
     controller.setPriority(getTableName());
     controller.setCallTimeout(callTimeout);
     ClientProtos.MultiResponse responseProto;
     ClientProtos.MultiRequest requestProto = multiRequestBuilder.build();
     try {
       responseProto = getStub().multi(controller, requestProto);
     } catch (ServiceException e) {
       throw ProtobufUtil.getRemoteException(e);
     }
     if (responseProto == null) return null; // Occurs on cancel
     return ResponseConverter.getResults(requestProto, responseProto, controller.cellScanner());
   }
 
   @Override
   public void cancel() {
     controller.startCancel();
   }
 
   @Override
   public boolean isCancelled() {
     return controller.isCanceled();
   }
 
   /**
    * @return True if we should send data in cellblocks.  This is an expensive call.  Cache the
    * result if you can rather than call each time.
    */
   private boolean isCellBlock() {
     // This is not exact -- the configuration could have changed on us after connection was set up
     // but it will do for now.
     HConnection connection = getConnection();
     if (!(connection instanceof ClusterConnection)) return true; // Default is to do cellblocks.
     return ((ClusterConnection) connection).hasCellBlockSupport();
   }
 
   @Override
   public void prepare(boolean reload) throws IOException {
     // Use the location we were given in the constructor rather than go look it up.
     setStub(getConnection().getClient(this.location.getServerName()));
   }
 
   @VisibleForTesting
   ServerName getServerName() {
     return location.getServerName();
   }
 }