feat: 增加链路统计信息，两个链路分别显示在前端，D向A汇报D与B的信息

third_party/kcp/ikcp.c

@@ -298,6 +298,9 @@ ikcpcb *ikcp_create(IUINT32 conv, void *user)
     kcp->fastlimit = IKCP_FASTACK_LIMIT;
     kcp->nocwnd = 0;
     kcp->xmit = 0;
+    kcp->timeout_retrans_total = 0;
+    kcp->fast_retrans_total = 0;
+    kcp->duplicate_recv_total = 0;
     kcp->dead_link = IKCP_DEADLINK;
     kcp->output = NULL;
     kcp->writelog = NULL;
@@ -788,6 +791,7 @@ void ikcp_parse_data(ikcpcb *kcp, IKCPSEG *newseg)
     }
     else
     {
+        kcp->duplicate_recv_total++;
         ikcp_segment_delete(kcp, newseg);
     }
 
@@ -1192,6 +1196,7 @@ void ikcp_flush(ikcpcb *kcp)
             needsend = 1;
             segment->xmit++;
             kcp->xmit++;
+            kcp->timeout_retrans_total++;
             if (kcp->nodelay == 0)
             {
                 segment->rto += _imax_(segment->rto, (IUINT32)kcp->rx_rto);
@@ -1211,6 +1216,7 @@ void ikcp_flush(ikcpcb *kcp)
             {
                 needsend = 1;
                 segment->xmit++;
+                kcp->fast_retrans_total++;
                 segment->fastack = 0;
                 segment->resendts = current + segment->rto;
                 change++;

third_party/kcp/ikcp.h

@@ -312,6 +312,9 @@ struct IKCPCB
     IUINT32 *acklist;
     IUINT32 ackcount;
     IUINT32 ackblock;
+    IUINT64 timeout_retrans_total;
+    IUINT64 fast_retrans_total;
+    IUINT64 duplicate_recv_total;
     void *user;
     char *buffer;
     int fastresend;