aeron-client/src/main/java/io/aeron/ExclusivePublication.java
public long appendPadding(final int length)
    {
        checkMaxMessageLength(length);
        long newPosition = CLOSED;

        if (!isClosed)
        {
            final long limit = positionLimit.getVolatile();
            final ExclusiveTermAppender termAppender = termAppenders[activePartitionIndex];
            final long position = termBeginPosition + termOffset;

            if (position < limit)
            {
                checkPositiveLength(length);
                final int result = termAppender.appendPadding(termId, termOffset, headerWriter, length);
                newPosition = newPosition(result);
            }
            else
            {
                newPosition = backPressureStatus(position, length);
            }
        }

        return newPosition;
    }
public long appendPadding(final int length)
    {
        checkMaxMessageLength(length);
        long newPosition = CLOSED;

        if (!isClosed)
        {
            final long limit = positionLimit.getVolatile();
            final ExclusiveTermAppender termAppender = termAppenders[activePartitionIndex];
            final long position = termBeginPosition + termOffset;

            if (position < limit)
            {
                checkPositiveLength(length);
                final int result = termAppender.appendPadding(termId, termOffset, headerWriter, length);
                newPosition = newPosition(result);
            }
            else
            {
                newPosition = backPressureStatus(position, length);
            }
        }

        return newPosition;
    }
Append a padding record log of a given length to make up the log to a position.

@param length of the range to claim, in bytes..
@return The new stream position, otherwise a negative error value of {@link #NOT_CONNECTED},
{@link #BACK_PRESSURED}, {@link #ADMIN_ACTION}, {@link #CLOSED}, or {@link #MAX_POSITION_EXCEEDED}.
@throws IllegalArgumentException if the length is greater than {@link #maxMessageLength()}.