content: /*
   * Copyright 2014-2025 Real Logic Limited.
   *
   * Licensed 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
   *
   * https://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 io.aeron;
  
  import org.agrona.DirectBuffer;
  
  /**
   * Supplies the reserved value field for a data frame header. The returned value will be set in the header as
   * {@link java.nio.ByteOrder#LITTLE_ENDIAN} format.
   * <p>
   * This will be called as the last action of encoding a data frame right before the length is set. All other fields
   * in the header plus the body of the frame will have been written at the point of supply.
   * <p>
   * The reserved value can be used for carrying out of band data with message fragments such a checksums or timestamps.
   */
  @FunctionalInterface
  public interface ReservedValueSupplier
  {
      /**
       * Callback to provide the reserved value to be encoded with each message fragment as the last action
       * before the length field is set which commits the fragment for sending to the media.
       *
       * @param termBuffer  containing the encoding message fragment.
       * @param termOffset  at which the header of the frame begins.
       * @param frameLength Total length of the frame including header.
       * @return the value to be used for storing in the reserved value field.
       */
      long get(DirectBuffer termBuffer, int termOffset, int frameLength);
  }
  