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.kafka.streams.state.internals;
  
  import org.apache.kafka.common.utils.Bytes;
  import org.apache.kafka.streams.KeyValue;
  import org.apache.kafka.streams.kstream.Windowed;
  import org.apache.kafka.streams.kstream.internals.SessionWindow;
  import org.apache.kafka.test.KeyValueIteratorStub;
  
  import org.junit.jupiter.api.Test;
  
  import java.util.Collections;
  import java.util.Iterator;
  
  import static org.hamcrest.CoreMatchers.equalTo;
  import static org.hamcrest.MatcherAssert.assertThat;
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  public class MergedSortedCacheWrappedSessionStoreIteratorTest {
  
      private static final SegmentedCacheFunction SINGLE_SEGMENT_CACHE_FUNCTION = new SegmentedCacheFunction(null, -1) {
          @Override
          public long segmentId(final Bytes key) {
              return 0;
          }
      };
  
      private final Bytes storeKey = Bytes.wrap("a".getBytes());
      private final Bytes cacheKey = Bytes.wrap("b".getBytes());
  
      private final SessionWindow storeWindow = new SessionWindow(0, 1);
      private final Iterator<KeyValue<Windowed<Bytes>, byte[]>> storeKvs = Collections.singleton(
              KeyValue.pair(new Windowed<>(storeKey, storeWindow), storeKey.get())).iterator();
      private final SessionWindow cacheWindow = new SessionWindow(10, 20);
      private final Iterator<KeyValue<Bytes, LRUCacheEntry>> cacheKvs = Collections.singleton(
          KeyValue.pair(
              SINGLE_SEGMENT_CACHE_FUNCTION.cacheKey(SessionKeySchema.toBinary(new Windowed<>(cacheKey, cacheWindow))),
              new LRUCacheEntry(cacheKey.get())
          )).iterator();
  
      @Test
      public void shouldHaveNextFromStore() {
          final MergedSortedCacheSessionStoreIterator mergeIterator = createIterator(storeKvs, Collections.emptyIterator(), false);
          assertTrue(mergeIterator.hasNext());
      }
  
      @Test
      public void shouldHaveNextFromReverseStore() {
          final MergedSortedCacheSessionStoreIterator mergeIterator = createIterator(storeKvs, Collections.emptyIterator(), true);
          assertTrue(mergeIterator.hasNext());
      }
  
      @Test
      public void shouldGetNextFromStore() {
          final MergedSortedCacheSessionStoreIterator mergeIterator = createIterator(storeKvs, Collections.emptyIterator(), false);
          assertThat(mergeIterator.next(), equalTo(KeyValue.pair(new Windowed<>(storeKey, storeWindow), storeKey.get())));
      }
  
      @Test
      public void shouldGetNextFromReverseStore() {
          final MergedSortedCacheSessionStoreIterator mergeIterator = createIterator(storeKvs, Collections.emptyIterator(), true);
          assertThat(mergeIterator.next(), equalTo(KeyValue.pair(new Windowed<>(storeKey, storeWindow), storeKey.get())));
      }
  
      @Test
      public void shouldPeekNextKeyFromStore() {
          final MergedSortedCacheSessionStoreIterator mergeIterator = createIterator(storeKvs, Collections.emptyIterator(), false);
          assertThat(mergeIterator.peekNextKey(), equalTo(new Windowed<>(storeKey, storeWindow)));
      }
  
      @Test
      public void shouldPeekNextKeyFromReverseStore() {
          final MergedSortedCacheSessionStoreIterator mergeIterator = createIterator(storeKvs, Collections.emptyIterator(), true);
          assertThat(mergeIterator.peekNextKey(), equalTo(new Windowed<>(storeKey, storeWindow)));
      }
  
      @Test
      public void shouldHaveNextFromCache() {
          final MergedSortedCacheSessionStoreIterator mergeIterator = createIterator(Collections.emptyIterator(), cacheKvs, false);
          assertTrue(mergeIterator.hasNext());
      }
  
      @Test
      public void shouldHaveNextFromReverseCache() {
          final MergedSortedCacheSessionStoreIterator mergeIterator = createIterator(Collections.emptyIterator(), cacheKvs, true);
          assertTrue(mergeIterator.hasNext());
      }
  
      @Test
      public void shouldGetNextFromCache() {
          final MergedSortedCacheSessionStoreIterator mergeIterator = createIterator(Collections.emptyIterator(), cacheKvs, false);
          assertThat(mergeIterator.next(), equalTo(KeyValue.pair(new Windowed<>(cacheKey, cacheWindow), cacheKey.get())));
      }
  
      @Test
      public void shouldGetNextFromReverseCache() {
          final MergedSortedCacheSessionStoreIterator mergeIterator = createIterator(Collections.emptyIterator(), cacheKvs, true);
          assertThat(mergeIterator.next(), equalTo(KeyValue.pair(new Windowed<>(cacheKey, cacheWindow), cacheKey.get())));
      }
  
      @Test
      public void shouldPeekNextKeyFromCache() {
          final MergedSortedCacheSessionStoreIterator mergeIterator = createIterator(Collections.emptyIterator(), cacheKvs, false);
          assertThat(mergeIterator.peekNextKey(), equalTo(new Windowed<>(cacheKey, cacheWindow)));
      }
  
      @Test
      public void shouldPeekNextKeyFromReverseCache() {
          final MergedSortedCacheSessionStoreIterator mergeIterator = createIterator(Collections.emptyIterator(), cacheKvs, true);
          assertThat(mergeIterator.peekNextKey(), equalTo(new Windowed<>(cacheKey, cacheWindow)));
      }
  
      @Test
      public void shouldIterateBothStoreAndCache() {
          final MergedSortedCacheSessionStoreIterator iterator = createIterator(storeKvs, cacheKvs, true);
          assertThat(iterator.next(), equalTo(KeyValue.pair(new Windowed<>(storeKey, storeWindow), storeKey.get())));
          assertThat(iterator.next(), equalTo(KeyValue.pair(new Windowed<>(cacheKey, cacheWindow), cacheKey.get())));
          assertFalse(iterator.hasNext());
      }
  
      @Test
      public void shouldReverseIterateBothStoreAndCache() {
          final MergedSortedCacheSessionStoreIterator iterator = createIterator(storeKvs, cacheKvs, false);
          assertThat(iterator.next(), equalTo(KeyValue.pair(new Windowed<>(cacheKey, cacheWindow), cacheKey.get())));
          assertThat(iterator.next(), equalTo(KeyValue.pair(new Windowed<>(storeKey, storeWindow), storeKey.get())));
          assertFalse(iterator.hasNext());
      }
  
      private MergedSortedCacheSessionStoreIterator createIterator(final Iterator<KeyValue<Windowed<Bytes>, byte[]>> storeKvs,
                                                                   final Iterator<KeyValue<Bytes, LRUCacheEntry>> cacheKvs,
                                                                   final boolean forward) {
          final DelegatingPeekingKeyValueIterator<Windowed<Bytes>, byte[]> storeIterator =
              new DelegatingPeekingKeyValueIterator<>("store", new KeyValueIteratorStub<>(storeKvs));
  
          final PeekingKeyValueIterator<Bytes, LRUCacheEntry> cacheIterator =
              new DelegatingPeekingKeyValueIterator<>("cache", new KeyValueIteratorStub<>(cacheKvs));
          return new MergedSortedCacheSessionStoreIterator(cacheIterator, storeIterator, SINGLE_SEGMENT_CACHE_FUNCTION, forward);
      }
  
  }
  