content: /*
   * 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.cassandra.service.reads.range;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import com.google.common.collect.Iterators;
  import org.junit.BeforeClass;
  import org.junit.Test;
  
  import org.apache.cassandra.SchemaLoader;
  import org.apache.cassandra.Util;
  import org.apache.cassandra.db.ColumnFamilyStore;
  import org.apache.cassandra.db.ConsistencyLevel;
  import org.apache.cassandra.db.Keyspace;
  import org.apache.cassandra.db.PartitionPosition;
  import org.apache.cassandra.db.PartitionRangeReadCommand;
  import org.apache.cassandra.db.RowUpdateBuilder;
  import org.apache.cassandra.dht.AbstractBounds;
  import org.apache.cassandra.dht.Range;
  import org.apache.cassandra.dht.Token;
  import org.apache.cassandra.exceptions.ConfigurationException;
  import org.apache.cassandra.locator.ReplicaPlan;
  import org.apache.cassandra.locator.ReplicaPlans;
  import org.apache.cassandra.schema.KeyspaceParams;
  import org.apache.cassandra.schema.TableId;
  import org.apache.cassandra.service.reads.ReadCoordinator;
  import org.apache.cassandra.transport.Dispatcher;
  import org.apache.cassandra.utils.CloseableIterator;
  
  import static org.junit.Assert.assertEquals;
  
  public class RangeCommandIteratorTest
  {
      private static final String KEYSPACE1 = "RangeCommandIteratorTest";
      private static final String CF_STANDARD1 = "Standard1";
      private static final TableId TABLE_ID = TableId.generate();
  
      @BeforeClass
      public static void defineSchema() throws ConfigurationException
      {
          SchemaLoader.prepareServer();
          SchemaLoader.createKeyspace(KEYSPACE1,
                                      KeyspaceParams.simple(1),
                                      SchemaLoader.standardCFMD(KEYSPACE1, CF_STANDARD1));
      }
  
      @Test
      public void testRangeCountWithRangeMerge()
      {
          List<Token> tokens = setTokens(100, 200, 300, 400);
          int vnodeCount = 0;
  
          Keyspace keyspace = Keyspace.open(KEYSPACE1);
          List<ReplicaPlan.ForRangeRead> ranges = new ArrayList<>();
          for (int i = 0; i + 1 < tokens.size(); i++)
          {
              Range<PartitionPosition> range = Range.makeRowRange(tokens.get(i), tokens.get(i + 1));
              ranges.add(ReplicaPlans.forRangeRead(keyspace, TABLE_ID, null, ConsistencyLevel.ONE, range, 1));
              vnodeCount++;
          }
  
          ReplicaPlanMerger merge = new ReplicaPlanMerger(ranges.iterator(), keyspace, TABLE_ID, ConsistencyLevel.ONE);
          ReplicaPlan.ForRangeRead mergedRange = Iterators.getOnlyElement(merge);
          // all ranges are merged as test has only one node.
          assertEquals(vnodeCount, mergedRange.vnodeCount());
      }
  
      @Test
      public void testRangeQueried()
      {
          List<Token> tokens = setTokens(100, 200, 300, 400);
          int vnodeCount = tokens.size() + 1; // n tokens divide token ring into n+1 ranges
  
          Keyspace keyspace = Keyspace.open(KEYSPACE1);
          ColumnFamilyStore cfs = keyspace.getColumnFamilyStore(CF_STANDARD1);
          cfs.clearUnsafe();
  
          int rows = 100;
          for (int i = 0; i < rows; ++i)
          {
              RowUpdateBuilder builder = new RowUpdateBuilder(cfs.metadata(), 10, String.valueOf(i));
              builder.clustering("c");
              builder.add("val", String.valueOf(i));
              builder.build().applyUnsafe();
          }
          Util.flush(cfs);
  
          PartitionRangeReadCommand command = (PartitionRangeReadCommand) Util.cmd(cfs).build();
          AbstractBounds<PartitionPosition> keyRange = command.dataRange().keyRange();
  
          // without range merger, there will be 2 batches requested: 1st batch with 1 range and 2nd batch with remaining ranges
          CloseableIterator<ReplicaPlan.ForRangeRead> replicaPlans = replicaPlanIterator(keyRange, keyspace, false);
          RangeCommandIterator data = new RangeCommandIterator(replicaPlans, command, ReadCoordinator.DEFAULT, 1, 1000, vnodeCount, Dispatcher.RequestTime.forImmediateExecution());
          verifyRangeCommandIterator(data, rows, 2, vnodeCount);
  
          // without range merger and initial cf=5, there will be 1 batches requested: 5 vnode ranges for 1st batch
          replicaPlans = replicaPlanIterator(keyRange, keyspace, false);
          data = new RangeCommandIterator(replicaPlans, command, ReadCoordinator.DEFAULT, vnodeCount, 1000, vnodeCount, Dispatcher.RequestTime.forImmediateExecution());
          verifyRangeCommandIterator(data, rows, 1, vnodeCount);
  
          // without range merger and max cf=1, there will be 5 batches requested: 1 vnode range per batch
          replicaPlans = replicaPlanIterator(keyRange, keyspace, false);
          data = new RangeCommandIterator(replicaPlans, command, ReadCoordinator.DEFAULT, 1, 1, vnodeCount, Dispatcher.RequestTime.forImmediateExecution());
          verifyRangeCommandIterator(data, rows, vnodeCount, vnodeCount);
  
          // with range merger, there will be only 1 batch requested, as all ranges share the same replica - localhost
          replicaPlans = replicaPlanIterator(keyRange, keyspace, true);
          data = new RangeCommandIterator(replicaPlans, command, ReadCoordinator.DEFAULT, 1, 1000, vnodeCount, Dispatcher.RequestTime.forImmediateExecution());
          verifyRangeCommandIterator(data, rows, 1, vnodeCount);
  
          // with range merger and max cf=1, there will be only 1 batch requested, as all ranges share the same replica - localhost
          replicaPlans = replicaPlanIterator(keyRange, keyspace, true);
          data = new RangeCommandIterator(replicaPlans, command, ReadCoordinator.DEFAULT, 1, 1, vnodeCount, Dispatcher.RequestTime.forImmediateExecution());
          verifyRangeCommandIterator(data, rows, 1, vnodeCount);
      }
  
      @Test
      public void testComputeConcurrencyFactor()
      {
          int maxConcurrentRangeRequest = 32;
  
          // no live row returned, fetch all remaining ranges but hit the max instead
          int cf = RangeCommandIterator.computeConcurrencyFactor(100, 30, maxConcurrentRangeRequest, 500, 0);
          assertEquals(maxConcurrentRangeRequest, cf); // because 100 - 30 = 70 > maxConccurrentRangeRequest
  
          // no live row returned, fetch all remaining ranges
          cf = RangeCommandIterator.computeConcurrencyFactor(100, 80, maxConcurrentRangeRequest, 500, 0);
          assertEquals(20, cf); // because 100-80 = 20 < maxConccurrentRangeRequest
  
          // returned half rows, fetch rangesQueried again but hit the max instead
          cf = RangeCommandIterator.computeConcurrencyFactor(100, 60, maxConcurrentRangeRequest, 480, 240);
          assertEquals(maxConcurrentRangeRequest, cf); // because 60 > maxConccurrentRangeRequest
  
          // returned half rows, fetch rangesQueried again
          cf = RangeCommandIterator.computeConcurrencyFactor(100, 30, maxConcurrentRangeRequest, 480, 240);
          assertEquals(30, cf); // because 30 < maxConccurrentRangeRequest
  
          // returned most of rows, 1 more range to fetch
          cf = RangeCommandIterator.computeConcurrencyFactor(100, 1, maxConcurrentRangeRequest, 480, 479);
          assertEquals(1, cf); // because 1 < maxConccurrentRangeRequest
      }
  
      private static List<Token> setTokens(int... values)
      {
          return new TokenUpdater().withKeys(values).update().getTokens();
      }
  
      private static CloseableIterator<ReplicaPlan.ForRangeRead> replicaPlanIterator(AbstractBounds<PartitionPosition> keyRange,
                                                                                     Keyspace keyspace,
                                                                                     boolean withRangeMerger)
      {
          CloseableIterator<ReplicaPlan.ForRangeRead> replicaPlans = new ReplicaPlanIterator(keyRange, null, keyspace, null, ConsistencyLevel.ONE);
          if (withRangeMerger)
              replicaPlans = new ReplicaPlanMerger(replicaPlans, keyspace, null, ConsistencyLevel.ONE);
  
          return  replicaPlans;
      }
  
      private static void verifyRangeCommandIterator(RangeCommandIterator data, int rows, int batches, int vnodeCount)
      {
          int num = Util.size(data);
          assertEquals(rows, num);
          assertEquals(batches, data.batchesRequested());
          assertEquals(vnodeCount, data.rangesQueried());
      }
  }
  