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.test;
  
  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.state.KeyValueIterator;
  import org.apache.kafka.streams.state.KeyValueStore;
  import org.apache.kafka.streams.state.internals.CacheFlushListener;
  import org.apache.kafka.streams.state.internals.DelegatingPeekingKeyValueIterator;
  import org.apache.kafka.streams.state.internals.WrappedStateStore;
  
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Map.Entry;
  import java.util.NavigableMap;
  import java.util.TreeMap;
  
  /**
   * This class is a generic version of the in-memory key-value store that is useful for testing when you
   *  need a basic KeyValueStore for arbitrary types and don't have/want to write a serde
   */
  public class GenericInMemoryKeyValueStore<K extends Comparable, V>
      extends WrappedStateStore<StateStore, K, V>
      implements KeyValueStore<K, V> {
  
      private final String name;
      private final NavigableMap<K, V> map;
      private volatile boolean open = false;
  
      public GenericInMemoryKeyValueStore(final String name) {
          // it's not really a `WrappedStateStore` so we pass `null`
          // however, we need to implement `WrappedStateStore` to make the store usable
          super(null);
          this.name = name;
  
          this.map = new TreeMap<>();
      }
  
      @Override
      public String name() {
          return this.name;
      }
  
      @Override
      public void init(final StateStoreContext stateStoreContext, final StateStore root) {
          if (root != null) {
              stateStoreContext.register(root, null);
          }
  
          this.open = true;
      }
  
      @Override
      public boolean setFlushListener(final CacheFlushListener<K, V> listener,
                                      final boolean sendOldValues) {
          return false;
      }
  
      @Override
      public boolean persistent() {
          return false;
      }
  
      @Override
      public boolean isOpen() {
          return this.open;
      }
  
      @Override
      public synchronized V get(final K key) {
          return this.map.get(key);
      }
  
      @Override
      public synchronized void put(final K key,
          final V value) {
          if (value == null) {
              this.map.remove(key);
          } else {
              this.map.put(key, value);
          }
      }
  
      @Override
      public synchronized V putIfAbsent(final K key,
          final V value) {
          final V originalValue = get(key);
          if (originalValue == null) {
              put(key, value);
          }
          return originalValue;
      }
  
      @Override
      public synchronized void putAll(final List<KeyValue<K, V>> entries) {
          for (final KeyValue<K, V> entry : entries) {
              put(entry.key, entry.value);
          }
      }
  
      @Override
      public synchronized V delete(final K key) {
          return this.map.remove(key);
      }
  
      @Override
      public synchronized KeyValueIterator<K, V> range(final K from,
          final K to) {
          return new DelegatingPeekingKeyValueIterator<>(
              name,
              new GenericInMemoryKeyValueIterator<>(this.map.subMap(from, true, to, true).entrySet().iterator()));
      }
  
      @Override
      public synchronized KeyValueIterator<K, V> all() {
          final TreeMap<K, V> copy = new TreeMap<>(this.map);
          return new DelegatingPeekingKeyValueIterator<>(name, new GenericInMemoryKeyValueIterator<>(copy.entrySet().iterator()));
      }
  
      @Override
      public long approximateNumEntries() {
          return this.map.size();
      }
  
      @Override
      public void flush() {
          // do-nothing since it is in-memory
      }
  
      @Override
      public void close() {
          this.map.clear();
          this.open = false;
      }
  
      private static class GenericInMemoryKeyValueIterator<K, V> implements KeyValueIterator<K, V> {
          private final Iterator<Entry<K, V>> iter;
  
          private GenericInMemoryKeyValueIterator(final Iterator<Map.Entry<K, V>> iter) {
              this.iter = iter;
          }
  
          @Override
          public boolean hasNext() {
              return iter.hasNext();
          }
  
          @Override
          public KeyValue<K, V> next() {
              final Map.Entry<K, V> entry = iter.next();
              return new KeyValue<>(entry.getKey(), entry.getValue());
          }
  
          @Override
          public void close() {
              // do nothing
          }
  
          @Override
          public K peekNextKey() {
              throw new UnsupportedOperationException("peekNextKey() not supported in " + getClass().getName());
          }
      }
  }