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;
  
  import org.apache.kafka.streams.KeyValue;
  import org.apache.kafka.streams.errors.InvalidStateStoreException;
  import org.apache.kafka.streams.processor.StateStore;
  
  import java.util.List;
  
  /**
   * A key-value store that supports put/get/delete and range queries.
   *
   * @param <K> The key type
   * @param <V> The value type
   */
  public interface KeyValueStore<K, V> extends StateStore, ReadOnlyKeyValueStore<K, V> {
  
      /**
       * Update the value associated with this key.
       *
       * @param key   The key to associate the value to
       * @param value The value to update, it can be {@code null};
       *              if the serialized bytes are also {@code null} it is interpreted as deletes
       * @throws NullPointerException If {@code null} is used for key.
       * @throws InvalidStateStoreException if the store is not initialized
       */
      void put(K key, V value);
  
      /**
       * Update the value associated with this key, unless a value is already associated with the key.
       *
       * @param key   The key to associate the value to
       * @param value The value to update, it can be {@code null};
       *              if the serialized bytes are also {@code null} it is interpreted as deletes
       * @return The old value or {@code null} if there is no such key.
       * @throws NullPointerException If {@code null} is used for key.
       * @throws InvalidStateStoreException if the store is not initialized
       */
      V putIfAbsent(K key, V value);
  
      /**
       * Update all the given key/value pairs.
       *
       * @param entries A list of entries to put into the store;
       *                if the serialized bytes are also {@code null} it is interpreted as deletes
       * @throws NullPointerException If {@code null} is used for key.
       * @throws InvalidStateStoreException if the store is not initialized
       */
      void putAll(List<KeyValue<K, V>> entries);
  
      /**
       * Delete the value from the store (if there is one).
       *
       * @param key The key
       * @return The old value or {@code null} if there is no such key.
       * @throws NullPointerException If {@code null} is used for key.
       * @throws InvalidStateStoreException if the store is not initialized
       */
      V delete(K key);
  }