823e9cf358df7d6131b8db4ddd6cb9ade4e7baf5,src/org/jgroups/protocols/UNICAST.java,UNICAST,handleDataReceived,#Address#number#number#boolean#Message#,487

Before Change


            undelivered_msgs.incrementAndGet();

        if(win.smallerThanNextToRemove(seqno))
            sendAck(msg.getSrc(), seqno);

        // message is passed up if OOB. Later, when remove() is called, we discard it. This affects ordering !
        // http://jira.jboss.com/jira/browse/JGRP-377

After Change


            }
        }

        if(send_request_for_first_seqno != null) {
            sendRequestForFirstSeqno(send_request_for_first_seqno);
            return;
        }

        byte result=win.add2(seqno, msg); // win is guaranteed to be non-null if we get here
        boolean added=result > 0;
        num_msgs_received++;
        num_bytes_received+=msg.getLength();

        if(added && !msg.isFlagSet(Message.OOB))
            undelivered_msgs.incrementAndGet();

        // Cannot be replaced with if(!added), see https://jira.jboss.org/jira/browse/JGRP-1043 comment 15/Sep/09 06:57 AM

        // We *have* to do send the ACK, to cover the following scenario:
        // - A sends #3 to B
        // - B removes #3 and sends ACK(3) to A. B's next_to_remove is now 4
        // - B's ACK(3) to A is dropped by the network
        // - A keeps retransmitting #3 to B, until it gets an ACK(3)
        // -B will never ACK #3 if the 2 lines below are commented ==> endless retransmission of A's #3 !
        if(result == -1) { // only ack if seqno was < next_to_remove !
            sendAck(msg.getSrc(), seqno);
        }

        // message is passed up if OOB. Later, when remove() is called, we discard it. This affects ordering !