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.common.serialization;
  
  import org.apache.kafka.common.header.Headers;
  import org.apache.kafka.common.utils.Utils;
  
  import java.io.Closeable;
  import java.nio.ByteBuffer;
  import java.util.Map;
  
  /**
   * An interface for converting bytes to objects.
   * A class that implements this interface is expected to have a constructor with no parameters.
   *
   * <p>This interface can be combined with {@link org.apache.kafka.common.ClusterResourceListener ClusterResourceListener}
   * to receive cluster metadata once it's available, as well as {@link org.apache.kafka.common.metrics.Monitorable Monitorable}
   * to enable the deserializer to register metrics. For the latter, the following tags are automatically added to
   * all metrics registered: {@code config} set to either {@code key.deserializer} or {@code value.deserializer},
   * and {@code class} set to the deserializer class name.
   *
   * @param <T> Type to be deserialized into.
   */
  public interface Deserializer<T> extends Closeable {
  
      /**
       * Configure this class.
       *
       * @param configs
       *        configs in key/value pairs
       * @param isKey
       *        whether the deserializer is used for the key or the value
       */
      default void configure(Map<String, ?> configs, boolean isKey) {
          // intentionally left blank
      }
  
      /**
       * Deserialize a record value from a byte array into a value or object.
       *
       * <p>It is recommended to deserialize a {@code null} byte array to a {@code null} object.
       *
       * @param topic
       *        topic associated with the data
       * @param data
       *        serialized bytes; may be {@code null}
       *
       * @return deserialized typed data; may be {@code null}
       */
      T deserialize(String topic, byte[] data);
  
      /**
       * Deserialize a record value from a byte array into a value or object.
       *
       * <p>It is recommended to deserialize a {@code null} byte array to a {@code null} object.
       *
       * <p>Note that the passed in {@link Headers} may be empty, but never {@code null}.
       * The implementation is allowed to modify the passed in headers, as a side effect of deserialization.
       * It is considered best practice to not delete or modify existing headers, but rather only add new ones.
       *
       * @param topic
       *        topic associated with the data
       * @param headers
       *        headers associated with the record
       * @param data
       *        serialized bytes; may be {@code null}
       *
       * @return deserialized typed data; may be {@code null}
       */
      default T deserialize(String topic, Headers headers, byte[] data) {
          return deserialize(topic, data);
      }
  
      /**
       * Deserialize a record value from a {@link ByteBuffer} into a value or object.
       *
       * <p>If {@code ByteBufferDeserializer} is used by an application, the application code cannot make any assumptions
       * about the returned {@link ByteBuffer} like the position, limit, capacity, etc., or if it is backed by
       * {@link ByteBuffer#hasArray() an array or not}.
       *
       * <p>Similarly, if this method is overridden, the implementation cannot make any assumptions about the
       * passed in {@link ByteBuffer} either.
       *
       * <p>It is recommended to deserialize a {@code null} {@link ByteBuffer} to a {@code null} object.
       *
       * <p>Note that the passed in {@link Headers} may be empty, but never {@code null}.
       * The implementation is allowed to modify the passed in headers, as a side effect of deserialization.
       * It is considered best practice to not delete or modify existing headers, but rather only add new ones.
       *
       * @param topic
       *        topic associated with the data
       * @param headers
       *        headers associated with the record
       * @param data
       *        serialized ByteBuffer; may be {@code null}
       *
       * @return deserialized typed data; may be {@code null}
       */
      default T deserialize(String topic, Headers headers, ByteBuffer data) {
          return deserialize(topic, headers, Utils.toNullableArray(data));
      }
  
      /**
       * Close this deserializer.
       *
       * <p>This method must be idempotent as it may be called multiple times.
       */
      @Override
      default void close() {
          // intentionally left blank
      }
  }
  