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.net;
  
  import java.util.Random;
  
  import org.junit.Test;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import static org.junit.Assert.*;
  
  public class PrunableArrayQueueTest
  {
      private static final Logger logger = LoggerFactory.getLogger(PrunableArrayQueueTest.class);
  
      private final PrunableArrayQueue<Integer> queue = new PrunableArrayQueue<>(8);
  
      @Test
      public void testIsEmptyWhenEmpty()
      {
          assertTrue(queue.isEmpty());
      }
  
      @Test
      public void testIsEmptyWhenNotEmpty()
      {
          queue.offer(0);
          assertFalse(queue.isEmpty());
      }
  
      @Test
      public void testEmptyPeek()
      {
          assertNull(queue.peek());
      }
  
      @Test
      public void testNonEmptyPeek()
      {
          queue.offer(0);
          assertEquals((Integer) 0, queue.peek());
      }
  
      @Test
      public void testEmptyPoll()
      {
          assertNull(queue.poll());
      }
  
      @Test
      public void testNonEmptyPoll()
      {
          queue.offer(0);
          assertEquals((Integer) 0, queue.poll());
      }
  
      @Test
      public void testTransfersInCorrectOrder()
      {
          for (int i = 0; i < 1024; i++)
              queue.offer(i);
  
          for (int i = 0; i < 1024; i++)
              assertEquals((Integer) i, queue.poll());
  
          assertTrue(queue.isEmpty());
      }
  
      @Test
      public void testTransfersInCorrectOrderWhenInterleaved()
      {
          for (int i = 0; i < 1024; i++)
          {
              queue.offer(i);
              assertEquals((Integer) i, queue.poll());
          }
  
          assertTrue(queue.isEmpty());
      }
  
      @Test
      public void testPrune()
      {
          for (int i = 0; i < 1024; i++)
              queue.offer(i);
  
          class Pruner implements PrunableArrayQueue.Pruner<Integer>
          {
              private int pruned, kept;
  
              public boolean shouldPrune(Integer val)
              {
                  return val % 2 == 0;
              }
  
              public void onPruned(Integer val)
              {
                  pruned++;
              }
  
              public void onKept(Integer val)
              {
                  kept++;
              }
          }
  
          Pruner pruner = new Pruner();
          assertEquals(512, queue.prune(pruner));
  
          assertEquals(512, pruner.kept);
          assertEquals(512, pruner.pruned);
          assertEquals(512, queue.size());
  
          for (int i = 1; i < 1024; i += 2)
              assertEquals((Integer) i, queue.poll());
          assertTrue(queue.isEmpty());
      }
  
      @Test
      public void testUnreliablePruner()
      {
          long seed = System.currentTimeMillis();
          Random rand = new Random(seed);
  
          logger.info("Testing unreliable pruner with random seed {}...", seed);
  
          int iteratons = 100;
          int startingQueueSize = 1024;
          double pruneChance = 0.1;
          double errorOnKeptChance = 0.00005;
          double errorOnPruneChance = 0.00002;
  
          for (int i = 0; i < iteratons; i++)
          {
              int failureValue = rand.nextInt(startingQueueSize);
  
              PrunableArrayQueue<Integer> testQueue = new PrunableArrayQueue<>(startingQueueSize);
  
              for (int o = 0; o < startingQueueSize; o++)
                  testQueue.offer(o);
  
              class UnreliablePruner implements PrunableArrayQueue.Pruner<Integer>
              {
                  public boolean shouldPrune(Integer value)
                  {
                      if (rand.nextDouble() < errorOnPruneChance)
                          throw new RuntimeException("Failed on pruning check for value: " + value);
  
                      return rand.nextDouble() < pruneChance;
                  }
  
                  public void onPruned(Integer value)
                  {
                      if (value == failureValue)
                          throw new RuntimeException("Failed on pruned value: " + value);
                  }
  
                  public void onKept(Integer value)
                  {
                      if (rand.nextDouble() < errorOnKeptChance)
                          throw new RuntimeException("Failed on retained value: " + value);
                  }
              }
  
              assertEquals(startingQueueSize, testQueue.size());
  
              try
              {
                  testQueue.prune(new UnreliablePruner());
              }
              catch (RuntimeException e)
              {
                  logger.info("Expected pruning failure with seed {}", seed, e);
              }
  
              for (int p = 0, postPruneSize = testQueue.size(); p < postPruneSize; p++)
              {
                  assertNotNull("Queue should contain no null elements after pruning. Seed: " + seed + ". Iteration: " + i, testQueue.poll());
              }
  
              assertEquals("Queue size should be zero after draining. Seed: " + seed + ". Iteration: " + i, 0, testQueue.size());
          }
      }
  }
  