RowCountEndpoint.java

package coprocessor;

import com.google.protobuf.RpcCallback;
import com.google.protobuf.RpcController;
import com.google.protobuf.Service;
import coprocessor.generated.RowCounterProtos;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.CellUtil;
import org.apache.hadoop.hbase.Coprocessor;
import org.apache.hadoop.hbase.CoprocessorEnvironment;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.coprocessor.CoprocessorException;
import org.apache.hadoop.hbase.coprocessor.CoprocessorService;
import org.apache.hadoop.hbase.coprocessor.RegionCoprocessorEnvironment;
import org.apache.hadoop.hbase.filter.Filter;
import org.apache.hadoop.hbase.filter.FirstKeyOnlyFilter;
import org.apache.hadoop.hbase.protobuf.ResponseConverter;
import org.apache.hadoop.hbase.regionserver.InternalScanner;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

// cc RowCountEndpoint Example endpoint implementation, adding a row and cell count method.
// vv RowCountEndpoint
public class RowCountEndpoint extends RowCounterProtos.RowCountService
  implements Coprocessor, CoprocessorService {

  private RegionCoprocessorEnvironment env;

  @Override
  public void start(CoprocessorEnvironment env) throws IOException {
    if (env instanceof RegionCoprocessorEnvironment) {
      this.env = (RegionCoprocessorEnvironment) env;
    } else {
      throw new CoprocessorException("Must be loaded on a table region!");
    }
  }

  @Override
  public void stop(CoprocessorEnvironment env) throws IOException {
    // nothing to do when coprocessor is shutting down
  }

  @Override
  public Service getService() {
    return this;
  }

  @Override
  public void getRowCount(RpcController controller,
    RowCounterProtos.CountRequest request,
    RpcCallback<RowCounterProtos.CountResponse> done) {
    RowCounterProtos.CountResponse response = null;
    try {
      long count = getCount(new FirstKeyOnlyFilter(), false);
      response = RowCounterProtos.CountResponse.newBuilder()
        .setCount(count).build();
    } catch (IOException ioe) {
      ResponseConverter.setControllerException(controller, ioe);
    }
    done.run(response);
  }

  @Override
  public void getCellCount(RpcController controller,
    RowCounterProtos.CountRequest request,
    RpcCallback<RowCounterProtos.CountResponse> done) {
    RowCounterProtos.CountResponse response = null;
    try {
      long count = getCount(null, true);
      response = RowCounterProtos.CountResponse.newBuilder()
        .setCount(count).build();
    } catch (IOException ioe) {
      ResponseConverter.setControllerException(controller, ioe);
    }
    done.run(response);
  }

  /**
   * Helper method to count rows or cells.
   * *
   * @param filter The optional filter instance.
   * @param countCells Hand in <code>true</code> for cell counting.
   * @return The count as per the flags.
   * @throws IOException When something fails with the scan.
   */
  private long getCount(Filter filter, boolean countCells)
  throws IOException {
    long count = 0;
    Scan scan = new Scan();
    scan.setMaxVersions(1);
    if (filter != null) {
      scan.setFilter(filter);
    }
    try (
      InternalScanner scanner = env.getRegion().getScanner(scan);
    ) {
      List<Cell> results = new ArrayList<Cell>();
      boolean hasMore = false;
      byte[] lastRow = null;
      do {
        hasMore = scanner.next(results);
        for (Cell cell : results) {
          if (!countCells) {
            if (lastRow == null || !CellUtil.matchingRow(cell, lastRow)) {
              lastRow = CellUtil.cloneRow(cell);
              count++;
            }
          } else count++;
        }
        results.clear();
      } while (hasMore);
    }
    return count;
  }
}
// ^^ RowCountEndpoint