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 com.datastax.oss.driver.internal.core.util.collection;
  
  import static com.datastax.oss.driver.Assertions.assertThat;
  import static org.mockito.Mockito.mock;
  import static org.mockito.Mockito.when;
  
  import com.datastax.oss.driver.api.core.metadata.Node;
  import java.util.Comparator;
  import java.util.Iterator;
  import java.util.Set;
  import java.util.concurrent.ConcurrentSkipListSet;
  import org.junit.Test;
  import org.junit.runner.RunWith;
  import org.mockito.Mock;
  import org.mockito.junit.MockitoJUnitRunner;
  
  @RunWith(MockitoJUnitRunner.class)
  public abstract class QueryPlanTestBase {
  
    @Mock private Node node1;
    @Mock private Node node2;
    @Mock private Node node3;
  
    @Test
    public void should_poll_elements() {
      QueryPlan queryPlan = newQueryPlan(node1, node2, node3);
      assertThat(queryPlan.poll()).isSameAs(node1);
      assertThat(queryPlan.poll()).isSameAs(node2);
      assertThat(queryPlan.poll()).isSameAs(node3);
      assertThat(queryPlan.poll()).isNull();
      assertThat(queryPlan.poll()).isNull();
    }
  
    @Test
    public void should_poll_elements_concurrently() throws InterruptedException {
      for (int runs = 0; runs < 5; runs++) {
        Node[] nodes = new Node[1000];
        for (int i = 0; i < 1000; i++) {
          nodes[i] = mock(Node.class, "node" + i);
          when(nodes[i].getOpenConnections()).thenReturn(i);
        }
        QueryPlan queryPlan = newQueryPlan(nodes);
        Set<Node> actual =
            new ConcurrentSkipListSet<>(Comparator.comparingInt(Node::getOpenConnections));
        Thread[] threads = new Thread[5];
        for (int i = 0; i < 5; i++) {
          threads[i] =
              new Thread(
                  () -> {
                    while (true) {
                      Node node = queryPlan.poll();
                      if (node == null) {
                        return;
                      }
                      actual.add(node);
                    }
                  });
        }
        for (Thread thread : threads) {
          thread.start();
        }
        for (Thread thread : threads) {
          thread.join();
        }
        assertThat(actual).hasSize(1000);
        Iterator<Node> iterator = actual.iterator();
        for (int i = 0; iterator.hasNext(); i++) {
          Node node = iterator.next();
          assertThat(node.getOpenConnections()).isEqualTo(i);
        }
      }
    }
  
    @Test
    public void should_return_size() {
      QueryPlan queryPlan = newQueryPlan(node1, node2, node3);
      assertThat(queryPlan.size()).isEqualTo(3);
      queryPlan.poll();
      assertThat(queryPlan.size()).isEqualTo(2);
      queryPlan.poll();
      assertThat(queryPlan.size()).isEqualTo(1);
      queryPlan.poll();
      assertThat(queryPlan.size()).isEqualTo(0);
      queryPlan.poll();
      assertThat(queryPlan.size()).isEqualTo(0);
    }
  
    @Test
    public void should_return_iterator() {
      QueryPlan queryPlan = newQueryPlan(node1, node2, node3);
      Iterator<Node> iterator3 = queryPlan.iterator();
      queryPlan.poll();
      Iterator<Node> iterator2 = queryPlan.iterator();
      queryPlan.poll();
      Iterator<Node> iterator1 = queryPlan.iterator();
      queryPlan.poll();
      Iterator<Node> iterator0 = queryPlan.iterator();
      queryPlan.poll();
      Iterator<Node> iterator00 = queryPlan.iterator();
  
      assertThat(iterator3).toIterable().containsExactly(node1, node2, node3);
      assertThat(iterator2).toIterable().containsExactly(node2, node3);
      assertThat(iterator1).toIterable().containsExactly(node3);
      assertThat(iterator0).toIterable().isEmpty();
      assertThat(iterator00).toIterable().isEmpty();
    }
  
    protected abstract QueryPlan newQueryPlan(Node... nodes);
  }
  