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Adjust retransmission delay based on measured RTT

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This commit is contained in:
Jeremy Lakeman 2013-08-29 15:05:32 +09:30
parent 95831a51aa
commit bf4269e98e
4 changed files with 47 additions and 11 deletions
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4
overlay_packet.h
View File

@ -31,8 +31,8 @@
struct packet_destination{
// if we've sent this packet once, what was the envelope sequence number?
int sent_sequence;
// delay the next transmission. if we don't get an ack, send it again.
time_ms_t delay_until;
// track when we last sent this packet. if we don't get an ack, send it again.
time_ms_t transmit_time;
// the actual out going stream for this packet
struct network_destination *destination;
};

49
overlay_queue.c
View File

@ -201,9 +201,10 @@ int overlay_payload_enqueue(struct overlay_frame *p)
p->resend = 1;
}
if (config.debug.verbose && config.debug.overlayframes){
int i=0;
for (i=0;i<p->destination_count;i++)
int i=0;
for (i=0;i<p->destination_count;i++){
p->destinations[i].sent_sequence=-1;
if (config.debug.verbose && config.debug.overlayframes)
DEBUGF("Sending %s on interface %s",
p->destinations[i].destination->unicast?"unicast":"broadcast",
p->destinations[i].destination->interface->name);
@ -288,8 +289,11 @@ overlay_calc_queue_time(overlay_txqueue *queue, struct overlay_frame *frame){
for(i=0;i<frame->destination_count;i++)
{
time_ms_t next_packet = limit_next_allowed(&frame->destinations[i].destination->transfer_limit);
if (next_packet < frame->destinations[i].delay_until)
next_packet = frame->destinations[i].delay_until;
if (frame->destinations[i].transmit_time){
time_ms_t delay_until = frame->destinations[i].transmit_time + frame->destinations[i].destination->resend_delay;
if (next_packet < delay_until)
next_packet = delay_until;
}
if (next_allowed_packet==0||next_packet < next_allowed_packet)
next_allowed_packet = next_packet;
}
@ -350,6 +354,15 @@ overlay_stuff_packet(struct outgoing_packet *packet, overlay_txqueue *queue, tim
if (frame->destination_count==0 && frame->destination){
link_add_destinations(frame);
int i=0;
for (i=0;i<frame->destination_count;i++){
frame->destinations[i].sent_sequence=-1;
if (config.debug.verbose && config.debug.overlayframes)
DEBUGF("Sending %s on interface %s",
frame->destinations[i].destination->unicast?"unicast":"broadcast",
frame->destinations[i].destination->interface->name);
}
// degrade packet version if required to reach the destination
if (frame->packet_version > frame->next_hop->max_packet_version)
frame->packet_version = frame->next_hop->max_packet_version;
@ -370,7 +383,8 @@ overlay_stuff_packet(struct outgoing_packet *packet, overlay_txqueue *queue, tim
continue;
}
if (frame->destinations[i].delay_until>now)
if (frame->destinations[i].transmit_time &&
frame->destinations[i].transmit_time + frame->destinations[i].destination->resend_delay > now)
continue;
if (packet->buffer){
@ -437,9 +451,13 @@ overlay_stuff_packet(struct outgoing_packet *packet, overlay_txqueue *queue, tim
frame->delay_until = now + 5;
goto skip;
}
frame->destinations[destination_index].sent_sequence = frame->destinations[destination_index].destination->sequence_number;
frame->destinations[destination_index].delay_until = now+200;
{
struct packet_destination *dest = &frame->destinations[destination_index];
dest->sent_sequence = dest->destination->sequence_number;
dest->transmit_time = now;
}
frame->transmit_count++;
if (config.debug.overlayframes){
@ -539,6 +557,19 @@ int overlay_queue_ack(struct subscriber *neighbour, struct network_destination *
char acked = (seq_delta==0 || (seq_delta <= 32 && ack_mask&(1<<(seq_delta-1))))?1:0;
if (acked){
int rtt = now - frame->destinations[j].transmit_time;
if (!destination->min_rtt || rtt < destination->min_rtt){
destination->min_rtt = rtt;
int delay = rtt * 2 + 40;
if (delay < destination->resend_delay){
destination->resend_delay = delay;
if (config.debug.linkstate)
DEBUGF("Adjusting resend delay to %d", destination->resend_delay);
}
}
if (!destination->max_rtt || rtt > destination->max_rtt)
destination->max_rtt = rtt;
if (config.debug.overlayframes)
DEBUGF("Packet %p to %s sent by seq %d, acked with seq %d",
frame, alloca_tohex_sid(neighbour->sid), frame_seq, ack_seq);

1
route_link.c
View File

@ -163,6 +163,7 @@ struct network_destination * new_destination(struct overlay_interface *interface
ret->_ref_count=1;
ret->encapsulation = encapsulation;
ret->interface = interface;
ret->resend_delay = 1000;
// DEBUGF("Create ref %p, %d - %s", ret, ret->_ref_count, ret->interface->name);
}
return ret;

4
serval.h
View File

@ -403,6 +403,10 @@ struct network_destination {
// time last packet was sent
time_ms_t last_tx;
int min_rtt;
int max_rtt;
int resend_delay;
// sequence number of last packet sent to this destination.
// Used to allow NACKs that can request retransmission of recent packets.