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.serialization.Serializer;
  import org.apache.kafka.common.utils.Bytes;
  import org.apache.kafka.streams.KeyValue;
  import org.apache.kafka.streams.processor.StateStore;
  import org.apache.kafka.streams.processor.StateStoreContext;
  import org.apache.kafka.streams.processor.internals.InternalProcessorContext;
  import org.apache.kafka.streams.state.KeyValueIterator;
  import org.apache.kafka.streams.state.KeyValueStore;
  
  import java.util.List;
  
  import static org.apache.kafka.streams.processor.internals.ProcessorContextUtils.asInternalProcessorContext;
  
  public class ChangeLoggingKeyValueBytesStore
          extends WrappedStateStore<KeyValueStore<Bytes, byte[]>, byte[], byte[]>
          implements KeyValueStore<Bytes, byte[]> {
  
      InternalProcessorContext<?, ?> internalContext;
  
      ChangeLoggingKeyValueBytesStore(final KeyValueStore<Bytes, byte[]> inner) {
          super(inner);
      }
  
      @Override
      public void init(final StateStoreContext stateStoreContext,
                       final StateStore root) {
          internalContext = asInternalProcessorContext(stateStoreContext);
          super.init(stateStoreContext, root);
          maybeSetEvictionListener();
      }
  
      private void maybeSetEvictionListener() {
          // if the inner store is an LRU cache, add the eviction listener to log removed record
          if (wrapped() instanceof MemoryLRUCache) {
              ((MemoryLRUCache) wrapped()).setWhenEldestRemoved((key, value) -> {
                  // pass null to indicate removal
                  log(key, null, internalContext.recordContext().timestamp());
              });
          }
      }
  
      @Override
      public long approximateNumEntries() {
          return wrapped().approximateNumEntries();
      }
  
      @Override
      public void put(final Bytes key,
                      final byte[] value) {
          wrapped().put(key, value);
          log(key, value, internalContext.recordContext().timestamp());
      }
  
      @Override
      public byte[] putIfAbsent(final Bytes key,
                                final byte[] value) {
          final byte[] previous = wrapped().putIfAbsent(key, value);
          if (previous == null) {
              // then it was absent
              log(key, value, internalContext.recordContext().timestamp());
          }
          return previous;
      }
  
      @Override
      public void putAll(final List<KeyValue<Bytes, byte[]>> entries) {
          wrapped().putAll(entries);
          for (final KeyValue<Bytes, byte[]> entry : entries) {
              log(entry.key, entry.value, internalContext.recordContext().timestamp());
          }
      }
  
      @Override
      public <PS extends Serializer<P>, P> KeyValueIterator<Bytes, byte[]> prefixScan(final P prefix,
                                                                                      final PS prefixKeySerializer) {
          return wrapped().prefixScan(prefix, prefixKeySerializer);
      }
  
      @Override
      public byte[] delete(final Bytes key) {
          final byte[] oldValue = wrapped().delete(key);
          log(key, null, internalContext.recordContext().timestamp());
          return oldValue;
      }
  
      @Override
      public byte[] get(final Bytes key) {
          return wrapped().get(key);
      }
  
      @Override
      public KeyValueIterator<Bytes, byte[]> range(final Bytes from,
                                                   final Bytes to) {
          return wrapped().range(from, to);
      }
  
      @Override
      public KeyValueIterator<Bytes, byte[]> reverseRange(final Bytes from,
                                                          final Bytes to) {
          return wrapped().reverseRange(from, to);
      }
  
      @Override
      public KeyValueIterator<Bytes, byte[]> all() {
          return wrapped().all();
      }
  
      @Override
      public KeyValueIterator<Bytes, byte[]> reverseAll() {
          return wrapped().reverseAll();
      }
  
      void log(final Bytes key, final byte[] value, final long timestamp) {
          internalContext.logChange(name(), key, value, timestamp, wrapped().getPosition());
      }
  }
  