io.aeron.ReservedValueSupplier Maven / Gradle / Ivy
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/*
* Copyright 2014-2020 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.
*
* 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.
*
* 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);
}