/**
    *
    * 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 org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.HRegionLocation;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.TableNotEnabledException;
  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.ClientService;
  import org.apache.hadoop.hbase.util.Bytes;
  
  /**
   * Implementations call a RegionServer and implement {@link #call(int)}.
   * Passed to a {@link RpcRetryingCaller} so we retry on fail.
   * TODO: this class is actually tied to one region, because most of the paths make use of
   *       the regioninfo part of location when building requests. The only reason it works for
   *       multi-region requests (e.g. batch) is that they happen to not use the region parts.
   *       This could be done cleaner (e.g. having a generic parameter and 2 derived classes,
   *       RegionCallable and actual RegionServerCallable with ServerName.
   * @param <T> the class that the ServerCallable handles
   */
  @InterfaceAudience.Private
  public abstract class RegionServerCallable<T> implements RetryingCallable<T> {
    // Public because used outside of this package over in ipc.
    private static final Log LOG = LogFactory.getLog(RegionServerCallable.class);
    protected final Connection connection;
    protected final TableName tableName;
    protected final byte[] row;
    protected HRegionLocation location;
    private ClientService.BlockingInterface stub;
  
    /**
     * @param connection Connection to use.
     * @param tableName Table name to which <code>row</code> belongs.
     * @param row The row we want in <code>tableName</code>.
     */
    public RegionServerCallable(Connection connection, TableName tableName, byte [] row) {
      this.connection = connection;
      this.tableName = tableName;
      this.row = row;
    }
  
    /**
     * Prepare for connection to the server hosting region with row from tablename.  Does lookup
     * to find region location and hosting server.
     * @param reload Set to true to re-check the table state
     * @throws IOException e
     */
    @Override
    public void prepare(final boolean reload) throws IOException {
      // check table state if this is a retry
      if (reload &&
          !tableName.equals(TableName.META_TABLE_NAME) &&
          getConnection().isTableDisabled(tableName)) {
        throw new TableNotEnabledException(tableName.getNameAsString() + " is disabled.");
      }
      try (RegionLocator regionLocator = connection.getRegionLocator(tableName)) {
        this.location = regionLocator.getRegionLocation(row);
      }
      if (this.location == null) {
        throw new IOException("Failed to find location, tableName=" + tableName +
          ", row=" + Bytes.toString(row) + ", reload=" + reload);
      }
      setStub(getConnection().getClient(this.location.getServerName()));
    }
  
    /**
     * @return {@link HConnection} instance used by this Callable.
     */
    HConnection getConnection() {
      return (HConnection) this.connection;
    }
  
    protected ClientService.BlockingInterface getStub() {
      return this.stub;
    }
  
   void setStub(final ClientService.BlockingInterface stub) {
     this.stub = stub;
   }
 
   protected HRegionLocation getLocation() {
     return this.location;
   }
 
   protected void setLocation(final HRegionLocation location) {
     this.location = location;
   }
 
   public TableName getTableName() {
     return this.tableName;
   }
 
   public byte [] getRow() {
     return this.row;
   }
 
   @Override
   public void throwable(Throwable t, boolean retrying) {
     if (location != null) {
       getConnection().updateCachedLocations(tableName, location.getRegionInfo().getRegionName(),
           row, t, location.getServerName());
     }
   }
 
   @Override
   public String getExceptionMessageAdditionalDetail() {
     return "row '" + Bytes.toString(row) + "' on table '" + tableName + "' at " + location;
   }
 
   @Override
   public long sleep(long pause, int tries) {
     return ConnectionUtils.getPauseTime(pause, tries);
   }
 
   /**
    * @return the HRegionInfo for the current region
    */
   public HRegionInfo getHRegionInfo() {
     if (this.location == null) {
       return null;
     }
     return this.location.getRegionInfo();
   }
 }