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.record;
  
  import org.apache.kafka.common.header.Header;
  
  import java.nio.ByteBuffer;
  
  /**
   * A log record is a tuple consisting of a unique offset in the log, a sequence number assigned by
   * the producer, a timestamp, a key and a value.
   */
  public interface Record {
  
      Header[] EMPTY_HEADERS = new Header[0];
  
      /**
       * The offset of this record in the log
       * @return the offset
       */
      long offset();
  
      /**
       * Get the sequence number assigned by the producer.
       * @return the sequence number
       */
      int sequence();
  
      /**
       * Get the size in bytes of this record.
       * @return the size of the record in bytes
       */
      int sizeInBytes();
  
      /**
       * Get the record's timestamp.
       * @return the record's timestamp
       */
      long timestamp();
  
      /**
       * Raise a {@link org.apache.kafka.common.errors.CorruptRecordException} if the record does not have a valid checksum.
       */
      void ensureValid();
  
      /**
       * Get the size in bytes of the key.
       * @return the size of the key, or -1 if there is no key
       */
      int keySize();
  
      /**
       * Check whether this record has a key
       * @return true if there is a key, false otherwise
       */
      boolean hasKey();
  
      /**
       * Get the record's key.
       * @return the key or null if there is none
       */
      ByteBuffer key();
  
      /**
       * Get the size in bytes of the value.
       * @return the size of the value, or -1 if the value is null
       */
      int valueSize();
  
      /**
       * Check whether a value is present (i.e. if the value is not null)
       * @return true if so, false otherwise
       */
      boolean hasValue();
  
      /**
       * Get the record's value
       * @return the (nullable) value
       */
      ByteBuffer value();
  
      /**
       * Check whether the record has a particular magic. For versions prior to 2, the record contains its own magic,
       * so this function can be used to check whether it matches a particular value. For version 2 and above, this
       * method returns true if the passed magic is greater than or equal to 2.
       *
       * @param magic the magic value to check
       * @return true if the record has a magic field (versions prior to 2) and the value matches
       */
      boolean hasMagic(byte magic);
  
      /**
       * For versions prior to 2, check whether the record is compressed (and therefore
       * has nested record content). For versions 2 and above, this always returns false.
       * @return true if the magic is lower than 2 and the record is compressed
       */
      boolean isCompressed();
  
      /**
       * For versions prior to 2, the record contained a timestamp type attribute. This method can be
       * used to check whether the value of that attribute matches a particular timestamp type. For versions
       * 2 and above, this will always be false.
       *
       * @param timestampType the timestamp type to compare
       * @return true if the version is lower than 2 and the timestamp type matches
       */
      boolean hasTimestampType(TimestampType timestampType);
  
      /**
       * Get the headers. For magic versions 1 and below, this always returns an empty array.
       *
       * @return the array of headers
       */
      Header[] headers();
  }
  