Hbase 协处理器（一）之RowCount代码

public class RowCountEndpoint extends ExampleProtos.RowCountService
    implements Coprocessor, CoprocessorService {
  private RegionCoprocessorEnvironment env;


  public RowCountEndpoint() {
  }

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

 
  @Override
  public void getRowCount(RpcController controller, ExampleProtos.CountRequest request,
                          RpcCallback done) {
    Scan scan = new Scan();
    scan.setFilter(new FirstKeyOnlyFilter());
    ExampleProtos.CountResponse response = null;
    InternalScanner scanner = null;
    try {
      scanner = env.getRegion().getScanner(scan);
      List results = new ArrayList();
      boolean hasMore = false;
      byte[] lastRow = null;
      long count = 0;
      do {
        hasMore = scanner.next(results);
        for (Cell kv : results) {
          byte[] currentRow = CellUtil.cloneRow(kv);
          if (lastRow == null || !Bytes.equals(lastRow, currentRow)) {
            lastRow = currentRow;
            count++;
          }
        }
        results.clear();
      } while (hasMore);


      response = ExampleProtos.CountResponse.newBuilder()
          .setCount(count).build();
    } catch (IOException ioe) {
      ResponseConverter.setControllerException(controller, ioe);
    } finally {
      if (scanner != null) {
        try {
          scanner.close();
        } catch (IOException ignored) {}
      }
    }
    done.run(response);
  }


  /**
   * Returns a count of all KeyValues in the region where this coprocessor is loaded.
   */
  @Override
  public void getKeyValueCount(RpcController controller, ExampleProtos.CountRequest request,
                               RpcCallback done) {
    ExampleProtos.CountResponse response = null;
    InternalScanner scanner = null;
    try {
      scanner = env.getRegion().getScanner(new Scan());
      List results = new ArrayList();
      boolean hasMore = false;
      long count = 0;
      do {
        hasMore = scanner.next(results);
        for (Cell kv : results) {
          count++;
        }
        results.clear();
      } while (hasMore);


      response = ExampleProtos.CountResponse.newBuilder()
          .setCount(count).build();
    } catch (IOException ioe) {
      ResponseConverter.setControllerException(controller, ioe);
    } finally {
      if (scanner != null) {
        try {
          scanner.close();
        } catch (IOException ignored) {}
      }
    }
    done.run(response);
  }

  @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
  }
}