From 71d703061db945ce0271a728f8899dc7161c4625 Mon Sep 17 00:00:00 2001
From: Victor Grishchenko <victor@node301.das2.its.tudelft.nl>
Date: Tue, 9 Feb 2010 18:49:25 +0100
Subject: [PATCH] Fixes for the case of high cwnd;

Once congestion window is high, the possibility of
mistaking original ACK for retransmit ACK becomes
high; added a queue for timeouted data (data_out_tmo_)
to filter such cases. Otherwise, the min of one-way delay
is set to incorrect (low) value; it screws up everything.
---
 send_control.cpp |  1 +
 sendrecv.cpp     | 23 ++++++++++++++++-------
 swift.h          |  3 +++
 3 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/send_control.cpp b/send_control.cpp
index 216c567..609ddfc 100644
--- a/send_control.cpp
+++ b/send_control.cpp
@@ -17,6 +17,7 @@ tint Channel::MAX_SEND_INTERVAL = TINT_SEC*58;
 tint Channel::LEDBAT_TARGET = TINT_MSEC*25;
 float Channel::LEDBAT_GAIN = 1.0/LEDBAT_TARGET;
 tint Channel::LEDBAT_DELAY_BIN = TINT_SEC*30;
+tint Channel::MAX_POSSIBLE_RTT = TINT_SEC*10;
 const char* Channel::SEND_CONTROL_MODES[] = {"keepalive", "pingpong",
     "slowstart", "standard_aimd", "ledbat"};
 
diff --git a/sendrecv.cpp b/sendrecv.cpp
index a47a3f5..278fd71 100644
--- a/sendrecv.cpp
+++ b/sendrecv.cpp
@@ -352,15 +352,18 @@ bin64_t Channel::OnData (Datagram& dgram) {
 void    Channel::CleanDataOut (bin64_t ackd_pos) { // TODO: isn't it too long?
     
     int max_ack_off = 0;
-    //FIXME do LEDBAT magic somewhere here
     
     if (ackd_pos!=bin64_t::NONE) {
-        for (int i=0; i<8 && i<data_out_.size(); i++) {
+        for (int i=0; i<data_out_.size(); i++) {
             if (data_out_[i]!=tintbin() && data_out_[i].bin.within(ackd_pos)) {
-                tint rtt = NOW-data_out_[i].time;
-                rtt_avg_ = (rtt_avg_*7 + rtt) >> 3;
-                dev_avg_ = ( dev_avg_*3 + abs(rtt-rtt_avg_) ) >> 2;
-                if (peer_send_time_) {
+                if (peer_send_time_)
+                    for(tbqueue::iterator j=data_out_tmo_.begin(); j!=data_out_tmo_.end(); j++)
+                        if (j->bin==data_out_[i].bin)
+                            peer_send_time_=0; // possibly retransmit
+                if (peer_send_time_) { // well, it is sorta ACK ACK
+                    tint rtt = NOW-data_out_[i].time;
+                    rtt_avg_ = (rtt_avg_*7 + rtt) >> 3;
+                    dev_avg_ = ( dev_avg_*3 + abs(rtt-rtt_avg_) ) >> 2;
                     assert(data_out_[i].time!=TINT_NEVER);
                     tint owd = peer_send_time_ - data_out_[i].time;
                     owd_cur_bin_ = (owd_cur_bin_+1) & 3;
@@ -372,8 +375,10 @@ void    Channel::CleanDataOut (bin64_t ackd_pos) { // TODO: isn't it too long?
                     }
                     if (owd_min_bins_[owd_min_bin_]>owd)
                         owd_min_bins_[owd_min_bin_] = owd;
+                    peer_send_time_ = 0;
                 }
-                dprintf("%s #%u rtt %lli dev %lli\n",tintstr(),id_,rtt_avg_,dev_avg_);
+                dprintf("%s #%u rtt %lli dev %lli based on %s\n",
+                        tintstr(),id_,rtt_avg_,dev_avg_,data_out_[i].bin.str());
                 bin64_t pos = data_out_[i].bin;
                 ack_rcvd_recent_++;
                 data_out_[i]=tintbin();
@@ -395,6 +400,7 @@ void    Channel::CleanDataOut (bin64_t ackd_pos) { // TODO: isn't it too long?
             }
             while (max_ack_off>MAX_REORDERING) {
                 ack_not_rcvd_recent_++;
+                data_out_tmo_.push_back(data_out_.front().bin);
                 dprintf("%s #%u Rdata %s\n",tintstr(),id_,data_out_.front().bin.str());
                 data_out_.pop_front();
                 max_ack_off--;
@@ -407,6 +413,7 @@ void    Channel::CleanDataOut (bin64_t ackd_pos) { // TODO: isn't it too long?
         if (data_out_.front().bin!=bin64_t::NONE && ack_in_.is_empty(data_out_.front().bin)) {
             ack_not_rcvd_recent_++;
             data_out_cap_ = bin64_t::ALL;
+            data_out_tmo_.push_back(data_out_.front().bin);
             dprintf("%s #%u Tdata %s\n",tintstr(),id_,data_out_.front().bin.str());
         }
         data_out_.pop_front();
@@ -414,6 +421,8 @@ void    Channel::CleanDataOut (bin64_t ackd_pos) { // TODO: isn't it too long?
     while (!data_out_.empty() && data_out_.front().bin==bin64_t::NONE)
         data_out_.pop_front();
     assert(data_out_.empty() || data_out_.front().time!=TINT_NEVER);
+    while (!data_out_tmo_.empty() && data_out_tmo_.front().time<NOW-MAX_POSSIBLE_RTT)
+        data_out_tmo_.pop_front();
 
 }
 
diff --git a/swift.h b/swift.h
index cbdd734..dd74f64 100644
--- a/swift.h
+++ b/swift.h
@@ -301,6 +301,7 @@ namespace swift {
         static float LEDBAT_GAIN;
         static tint LEDBAT_DELAY_BIN;
         static bool SELF_CONN_OK;
+        static tint MAX_POSSIBLE_RTT;
         
         const std::string id_string () const;
         /** A channel is "established" if had already sent and received packets. */
@@ -340,6 +341,8 @@ namespace swift {
         bin64_t     data_in_dbl_;
         /** The history of data sent and still unacknowledged. */
         tbqueue     data_out_;
+        /** Timeouted data (potentially to be retransmitted). */
+        tbqueue     data_out_tmo_;
         bin64_t     data_out_cap_;
         /** Index in the history array. */
         binmap_t        ack_out_;
-- 
2.20.1