aeron-client/src/main/java/io/aeron/logbuffer/TermAppender.java
public int appendUnfragmentedMessage(
        final HeaderWriter header,
        final DirectBuffer buffer,
        final int offset,
        final int length,
        final ReservedValueSupplier reservedValueSupplier,
        final int activeTermId)
    {
        final int frameLength = length + HEADER_LENGTH;
        final int alignedLength = align(frameLength, FRAME_ALIGNMENT);
        final UnsafeBuffer termBuffer = this.termBuffer;
        final int termLength = termBuffer.capacity();

        final long rawTail = getAndAddRawTail(alignedLength);
        final int termId = termId(rawTail);
        final long termOffset = rawTail & 0xFFFF_FFFFL;

        checkTerm(activeTermId, termId);

        long resultingOffset = termOffset + alignedLength;
        if (resultingOffset > termLength)
        {
            resultingOffset = handleEndOfLogCondition(termBuffer, termOffset, header, termLength, termId);
        }
        else
        {
            final int frameOffset = (int)termOffset;
            header.write(termBuffer, frameOffset, frameLength, termId);
            termBuffer.putBytes(frameOffset + HEADER_LENGTH, buffer, offset, length);

            if (null != reservedValueSupplier)
            {
                final long reservedValue = reservedValueSupplier.get(termBuffer, frameOffset, frameLength);
                termBuffer.putLong(frameOffset + RESERVED_VALUE_OFFSET, reservedValue, LITTLE_ENDIAN);
            }

            frameLengthOrdered(termBuffer, frameOffset, frameLength);
        }

        return (int)resultingOffset;
    }
public int appendUnfragmentedMessage(
        final HeaderWriter header,
        final DirectBuffer buffer,
        final int offset,
        final int length,
        final ReservedValueSupplier reservedValueSupplier,
        final int activeTermId)
    {
        final int frameLength = length + HEADER_LENGTH;
        final int alignedLength = align(frameLength, FRAME_ALIGNMENT);
        final UnsafeBuffer termBuffer = this.termBuffer;
        final int termLength = termBuffer.capacity();

        final long rawTail = getAndAddRawTail(alignedLength);
        final int termId = termId(rawTail);
        final long termOffset = rawTail & 0xFFFF_FFFFL;

        checkTerm(activeTermId, termId);

        long resultingOffset = termOffset + alignedLength;
        if (resultingOffset > termLength)
        {
            resultingOffset = handleEndOfLogCondition(termBuffer, termOffset, header, termLength, termId);
        }
        else
        {
            final int frameOffset = (int)termOffset;
            header.write(termBuffer, frameOffset, frameLength, termId);
            termBuffer.putBytes(frameOffset + HEADER_LENGTH, buffer, offset, length);

            if (null != reservedValueSupplier)
            {
                final long reservedValue = reservedValueSupplier.get(termBuffer, frameOffset, frameLength);
                termBuffer.putLong(frameOffset + RESERVED_VALUE_OFFSET, reservedValue, LITTLE_ENDIAN);
            }

            frameLengthOrdered(termBuffer, frameOffset, frameLength);
        }

        return (int)resultingOffset;
    }
Append an unfragmented message to the the term buffer.

@param header                for writing the default header.
@param buffer                containing the message.
@param offset                at which the message begins.
@param length                of the message in the source buffer.
@param reservedValueSupplier {@link ReservedValueSupplier} for the frame.
@param activeTermId          used for flow control.
@return the resulting offset of the term after the append on success otherwise {@link #FAILED}