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.kstream.internals;
  
  import org.apache.kafka.streams.processor.api.ContextualProcessor;
  import org.apache.kafka.streams.processor.api.Processor;
  import org.apache.kafka.streams.processor.api.ProcessorContext;
  import org.apache.kafka.streams.processor.api.Record;
  import org.apache.kafka.streams.processor.internals.StoreFactory;
  import org.apache.kafka.streams.state.StoreBuilder;
  import org.apache.kafka.streams.state.internals.KeyValueStoreWrapper;
  
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.Set;
  
  import static org.apache.kafka.streams.state.VersionedKeyValueStore.PUT_RETURN_CODE_NOT_PUT;
  import static org.apache.kafka.streams.state.internals.KeyValueStoreWrapper.PUT_RETURN_CODE_IS_LATEST;
  
  public class KTableKTableJoinMerger<K, V> implements KTableProcessorSupplier<K, V, K, V> {
  
      private final KTableProcessorSupplier<K, ?, K, V> parent1;
      private final KTableProcessorSupplier<K, ?, K, V> parent2;
      private final String queryableName;
      private final StoreFactory storeFactory;
      private boolean sendOldValues = false;
  
      KTableKTableJoinMerger(final KTableProcessorSupplier<K, ?, K, V> parent1,
                             final KTableProcessorSupplier<K, ?, K, V> parent2,
                             final String queryableName,
                             final StoreFactory storeFactory) {
          this.parent1 = parent1;
          this.parent2 = parent2;
          this.queryableName = queryableName;
          this.storeFactory = storeFactory;
      }
  
      public String queryableName() {
          return queryableName;
      }
  
      @Override
      public Processor<K, Change<V>, K, Change<V>> get() {
          return new KTableKTableJoinMergeProcessor();
      }
  
      @Override
      public Set<StoreBuilder<?>> stores() {
          return storeFactory == null
                  ? null
                  : Set.of(new StoreFactory.FactoryWrappingStoreBuilder<>(storeFactory));
      }
  
      @Override
      public KTableValueGetterSupplier<K, V> view() {
          // if the result KTable is materialized, use the materialized store to return getter value;
          // otherwise rely on the parent getter and apply join on-the-fly
          if (queryableName != null) {
              return new KTableMaterializedValueGetterSupplier<>(queryableName);
          } else {
              return new KTableValueGetterSupplier<K, V>() {
  
                  public KTableValueGetter<K, V> get() {
                      return parent1.view().get();
                  }
  
                  @Override
                  public String[] storeNames() {
                      final String[] storeNames1 = parent1.view().storeNames();
                      final String[] storeNames2 = parent2.view().storeNames();
                      final Set<String> stores = new HashSet<>(storeNames1.length + storeNames2.length);
                      Collections.addAll(stores, storeNames1);
                      Collections.addAll(stores, storeNames2);
                      return stores.toArray(new String[0]);
                  }
              };
          }
      }
  
      @Override
      public boolean enableSendingOldValues(final boolean forceMaterialization) {
          // Table-table joins require upstream materialization:
          parent1.enableSendingOldValues(true);
          parent2.enableSendingOldValues(true);
          sendOldValues = true;
          return true;
      }
  
      public static <K, V> KTableKTableJoinMerger<K, V> of(final KTableProcessorSupplier<K, ?, K, V> parent1,
                                                           final KTableProcessorSupplier<K, ?, K, V> parent2) {
          return of(parent1, parent2, null, null);
      }
  
      public static <K, V> KTableKTableJoinMerger<K, V> of(final KTableProcessorSupplier<K, ?, K, V> parent1,
                                                           final KTableProcessorSupplier<K, ?, K, V> parent2,
                                                           final String queryableName,
                                                           final StoreFactory stores) {
          return new KTableKTableJoinMerger<>(parent1, parent2, queryableName, stores);
      }
  
      private class KTableKTableJoinMergeProcessor extends ContextualProcessor<K, Change<V>, K, Change<V>> {
          private KeyValueStoreWrapper<K, V> store;
          private TimestampedTupleForwarder<K, V> tupleForwarder;
  
          @SuppressWarnings("unchecked")
          @Override
          public void init(final ProcessorContext<K, Change<V>> context) {
              super.init(context);
              if (queryableName != null) {
                  store = new KeyValueStoreWrapper<>(context, queryableName);
                  tupleForwarder = new TimestampedTupleForwarder<>(
                      store.store(),
                      context,
                      new TimestampedCacheFlushListener<>(context),
                      sendOldValues);
              }
          }
  
          @Override
          public void process(final Record<K, Change<V>> record) {
              if (queryableName != null) {
                  final long putReturnCode = store.put(record.key(), record.value().newValue, record.timestamp());
                  // if not put to store, do not forward downstream either
                  if (putReturnCode != PUT_RETURN_CODE_NOT_PUT) {
                      tupleForwarder.maybeForward(record.withValue(new Change<>(record.value().newValue, record.value().oldValue, putReturnCode == PUT_RETURN_CODE_IS_LATEST)));
                  }
              } else {
                  if (sendOldValues) {
                      context().forward(record);
                  } else {
                      context().forward(record.withValue(new Change<>(record.value().newValue, null, record.value().isLatest)));
                  }
              }
          }
      }
  }
  