net.sf.jrtps.message.Gap Maven / Gradle / Ivy

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package net.sf.jrtps.message;

import java.util.List;

import net.sf.jrtps.transport.RTPSByteBuffer;
import net.sf.jrtps.types.EntityId;
import net.sf.jrtps.types.SequenceNumber;
import net.sf.jrtps.types.SequenceNumberSet;

/**
 * This Submessage is sent from an RTPS Writer to an RTPS Reader and indicates
 * to the RTPS Reader that a range of sequence numbers is no longer relevant.
 * The set may be a contiguous range of sequence numbers or a specific set of
 * sequence numbers.
 * 
 * 
 * see 8.3.7.4 Gap, 9.4.5.5 Gap Submessage
 * 
 * @author mcr70
 */
public class Gap extends SubMessage {
	public static final int KIND = 0x08;

	private EntityId readerId;
	private EntityId writerId;
	private SequenceNumber gapStart;
	private SequenceNumberSet gapList;

	Gap(SubMessageHeader smh, RTPSByteBuffer bb) {
		super(smh);

		this.readerId = EntityId.readEntityId(bb);
		this.writerId = EntityId.readEntityId(bb);
		this.gapStart = new SequenceNumber(bb);
		this.gapList = new SequenceNumberSet(bb);
	}

	public Gap(EntityId readerId, EntityId writerId, long gapStart, long gapEnd) {
		super(new SubMessageHeader(KIND));

		this.readerId = readerId;
		this.writerId = writerId;
		this.gapStart = new SequenceNumber(gapStart);
		this.gapList = new SequenceNumberSet(gapEnd + 1, new int[]{0x0});
	}

	/**
	 * Get the Reader Entity that is being informed of the irrelevance of a set
	 * of sequence numbers.
	 */
	public EntityId getReaderId() {
		return readerId;
	}

	/**
	 * Get the Writer Entity to which the range of sequence numbers applies.
	 */
	public EntityId getWriterId() {
		return writerId;
	}

	/**
	 * Identifies the first sequence number in the interval of irrelevant
	 * sequence numbers.
	 * 
	 * @return First irrelevant sequence number
	 */
	public long getGapStart() {
		return gapStart.getAsLong();
	}

	/**
	 * Gets the last sequence number in this Gap. 
	 * @return last sequence number
	 */
	public long getGapEnd() {
		long gapEnd = gapList.getBitmapBase() - 1;

		List sequenceNumbers = gapList.getSequenceNumbers();
		for (long sn : sequenceNumbers) {  
			// Check, that sequence numbers don't have gaps between.
			// If there is a gap in seqnums, break from the loop.
			if (sn == gapEnd + 1) {
				gapEnd = sn;
			}
			else {
				break;
			}
		}

		return gapEnd;
	}

	/**
	 * SequenceNumberSet.bitmapBase - 1 is the last sequence number of irrelevant
	 * seq nums. SequenceNumberSet.bitmaps identifies additional irrelevant
	 * sequence numbers.
	 * 
	 * @return SequenceNumberSet
	 */
	public SequenceNumberSet getGapList() {
		return gapList;
	}


	@Override
	public void writeTo(RTPSByteBuffer bb) {
		readerId.writeTo(bb);
		writerId.writeTo(bb);
		gapStart.writeTo(bb);
		gapList.writeTo(bb);
	}

	public String toString() {
		return super.toString() + " " + gapStart + ", " + gapList;
	}
}