/*
 * 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 static org.apache.hadoop.hbase.client.ConnectionUtils.noMoreResultsForReverseScan;

import java.io.IOException;
import java.util.concurrent.ExecutorService;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.ipc.RpcControllerFactory;
import org.apache.yetus.audience.InterfaceAudience;

/**
 * A reversed client scanner which support backward scanning
 */
@InterfaceAudience.Private
public class ReversedClientScanner extends ClientScanner {

  /**
   * Create a new ReversibleClientScanner for the specified table Note that the passed
   * {@link Scan}'s start row maybe changed.
   */
  public ReversedClientScanner(Configuration conf, Scan scan, TableName tableName,
    ClusterConnection connection, RpcRetryingCallerFactory rpcFactory,
    RpcControllerFactory controllerFactory, ExecutorService pool, int scanReadRpcTimeout,
    int scannerTimeout, int primaryOperationTimeout) throws IOException {
    super(conf, scan, tableName, connection, rpcFactory, controllerFactory, pool,
      scanReadRpcTimeout, scannerTimeout, primaryOperationTimeout);
  }

  @Override
  protected boolean setNewStartKey() {
    if (noMoreResultsForReverseScan(scan, currentRegion)) {
      return false;
    }
    scan.withStartRow(currentRegion.getStartKey(), false);
    return true;
  }

  @Override
  protected ReversedScannerCallable createScannerCallable() {
    return new ReversedScannerCallable(getConnection(), getTable(), scan, this.scanMetrics,
      this.rpcControllerFactory, getScanReplicaId());
  }
}
