/**
* If we receive an ACK or RST, we mark the outgoing request or response as acknowledged or
* rejected respectively and cancel its retransmission.
*/
@Override
public void receiveEmptyMessage(Exchange exchange, EmptyMessage message) {
exchange.setFailedTransmissionCount(0);
// TODO: If this is an observe relation, the current response might not
// be the one that is being acknowledged. The current response might
// already be the next NON notification.
if (message.getType() == Type.ACK) {
if (exchange.getOrigin() == Origin.LOCAL) {
exchange.getCurrentRequest().setAcknowledged(true);
} else {
exchange.getCurrentResponse().setAcknowledged(true);
}
} else if (message.getType() == Type.RST) {
if (exchange.getOrigin() == Origin.LOCAL) {
exchange.getCurrentRequest().setRejected(true);
} else {
exchange.getCurrentResponse().setRejected(true);
}
} else {
LOGGER.warning("Empty messgae was not ACK nor RST: " + message);
}
LOGGER.finer("Cancel retransmission");
exchange.setRetransmissionHandle(null);
super.receiveEmptyMessage(exchange, message);
}
/**
* Computes the back-off timer and schedules the specified retransmission task.
*
* @param exchange the exchange
* @param task the retransmission task
*/
protected void prepareRetransmission(Exchange exchange, RetransmissionTask task) {
/*
* For a new confirmable message, the initial timeout is set to a
* random number between ACK_TIMEOUT and (ACK_TIMEOUT *
* ACK_RANDOM_FACTOR)
*/
int timeout;
if (exchange.getFailedTransmissionCount() == 0) {
timeout = getRandomTimeout(ack_timeout, (int) (ack_timeout * ack_random_factor));
} else {
timeout = (int) (ack_timeout_scale * exchange.getCurrentTimeout());
}
exchange.setCurrentTimeout(timeout);
ScheduledFuture<?> f = executor.schedule(task, timeout, TimeUnit.MILLISECONDS);
exchange.setRetransmissionHandle(f);
}
/**
* When we receive a Confirmable response, we acknowledge it and it also counts as acknowledgment
* for the request. If the response is a duplicate, we stop it here and do not forward it to the
* upper layer.
*/
@Override
public void receiveResponse(Exchange exchange, Response response) {
exchange.setFailedTransmissionCount(0);
exchange.getCurrentRequest().setAcknowledged(true);
LOGGER.finest("Cancel any retransmission");
exchange.setRetransmissionHandle(null);
if (response.getType() == Type.CON && !exchange.getRequest().isCanceled()) {
LOGGER.finer("Response is confirmable, send ACK");
EmptyMessage ack = EmptyMessage.newACK(response);
sendEmptyMessage(exchange, ack);
}
if (response.isDuplicate()) {
LOGGER.fine("Response is duplicate, ignore it");
} else {
super.receiveResponse(exchange, response);
}
}