aeron-client/src/main/java/io/aeron/Publication.java
public long position()
    {
        if (isClosed)
        {
            return CLOSED;
        }

        final long rawTail = rawTailVolatile(logMetaDataBuffer);
        final int termOffset = termOffset(rawTail, termBufferLength);

        return computePosition(termId(rawTail), termOffset, positionBitsToShift, initialTermId);
    }
public long position()
    {
        if (isClosed)
        {
            return CLOSED;
        }

        final long rawTail = rawTailVolatile(logMetaDataBuffer);
        final int termOffset = termOffset(rawTail, termBufferLength);

        return computePosition(termId(rawTail), termOffset, positionBitsToShift, initialTermId);
    }
Get the current position to which the publication has advanced for this stream.

@return the current position to which the publication has advanced for this stream or {@link #CLOSED}.