/**
    * 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.junit.Assert.assertEquals;
  import static org.junit.Assert.assertTrue;
  
  import com.google.protobuf.ServiceException;
  
  import java.io.IOException;
  
  import org.apache.hadoop.hbase.HBaseTestingUtility;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.client.ConnectionManager.HConnectionImplementation;
  import org.apache.hadoop.hbase.ipc.HBaseRpcController;
  import org.apache.hadoop.hbase.ipc.HBaseRpcControllerImpl;
  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.ScanRequest;
  import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.ScanResponse;
  import org.apache.hadoop.hbase.testclassification.MediumTests;
  import org.apache.hadoop.hbase.testclassification.RegionServerTests;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.junit.AfterClass;
  import org.junit.BeforeClass;
  import org.junit.Test;
  import org.junit.experimental.categories.Category;
  
  /**
   * Testcase to make sure that we do not close scanners if ScanRequest.numberOfRows is zero. See
   * HBASE-18042 for more details.
   */
  @Category({ RegionServerTests.class, MediumTests.class })
  public class TestScanWithoutFetchingData {
  
    private static final HBaseTestingUtility UTIL = new HBaseTestingUtility();
  
    private static final TableName TABLE_NAME = TableName.valueOf("test");
  
    private static final byte[] CF = Bytes.toBytes("cf");
  
    private static final byte[] CQ = Bytes.toBytes("cq");
  
    private static final int COUNT = 10;
  
    private static HRegionInfo HRI;
  
    private static ClientProtos.ClientService.BlockingInterface STUB;
  
    @BeforeClass
    public static void setUp() throws Exception {
      UTIL.startMiniCluster(1);
      try (Table table = UTIL.createTable(TABLE_NAME, CF)) {
        for (int i = 0; i < COUNT; i++) {
          table.put(new Put(Bytes.toBytes(i)).addColumn(CF, CQ, Bytes.toBytes(i)));
        }
      }
      HRI = UTIL.getHBaseAdmin().getTableRegions(TABLE_NAME).get(0);
      STUB = ((HConnectionImplementation) UTIL.getConnection())
          .getClient(UTIL.getHBaseCluster().getRegionServer(0).getServerName());
    }
  
    @AfterClass
    public static void tearDown() throws Exception {
      UTIL.shutdownMiniCluster();
    }
  
    private void assertResult(int row, Result result) {
      assertEquals(row, Bytes.toInt(result.getRow()));
      assertEquals(row, Bytes.toInt(result.getValue(CF, CQ)));
    }
  
    @Test
    public void test() throws ServiceException, IOException {
      Scan scan = new Scan();
      ScanRequest req = RequestConverter.buildScanRequest(HRI.getRegionName(), scan, 0, false);
      HBaseRpcController hrc = new HBaseRpcControllerImpl();
      ScanResponse resp = STUB.scan(hrc, req);
      assertTrue(resp.getMoreResults());
      assertTrue(resp.getMoreResultsInRegion());
      assertEquals(0, ResponseConverter.getResults(hrc.cellScanner(), resp).length);
      long scannerId = resp.getScannerId();
     int nextCallSeq = 0;
     // test normal next
     for (int i = 0; i < COUNT / 2; i++) {
       req = RequestConverter.buildScanRequest(scannerId, 1, false, nextCallSeq++, false, false, -1);
       hrc.reset();
       resp = STUB.scan(hrc, req);
       assertTrue(resp.getMoreResults());
       assertTrue(resp.getMoreResultsInRegion());
       Result[] results = ResponseConverter.getResults(hrc.cellScanner(), resp);
       assertEquals(1, results.length);
       assertResult(i, results[0]);
     }
     // test zero next
     req = RequestConverter.buildScanRequest(scannerId, 0, false, nextCallSeq++, false, false, -1);
     hrc.reset();
     resp = STUB.scan(hrc, req);
     assertTrue(resp.getMoreResults());
     assertTrue(resp.getMoreResultsInRegion());
     assertEquals(0, ResponseConverter.getResults(hrc.cellScanner(), resp).length);
     for (int i = COUNT / 2; i < COUNT; i++) {
       req = RequestConverter.buildScanRequest(scannerId, 1, false, nextCallSeq++, false, false, -1);
       hrc.reset();
       resp = STUB.scan(hrc, req);
       assertTrue(resp.getMoreResults());
       assertEquals(i != COUNT - 1, resp.getMoreResultsInRegion());
       Result[] results = ResponseConverter.getResults(hrc.cellScanner(), resp);
       assertEquals(1, results.length);
       assertResult(i, results[0]);
     }
     // close
     req = RequestConverter.buildScanRequest(scannerId, 0, true, false);
     resp = STUB.scan(null, req);
   }
 }