[PATCH] QUIC: do not arm loss detection timer if nothing was sent

[Sergey Kandaurov]

# HG changeset patch
# User Sergey Kandaurov <pluknet at nginx.com>
# Date 1643803485 -10800
#      Wed Feb 02 15:04:45 2022 +0300
# Branch quic
# Node ID 768445d1ba6e2bce9001704c52b516ad421ae776
# Parent  cd8018bc81a52ca7de2eb4e779dfd574c8a661a2
QUIC: do not arm loss detection timer if nothing was sent.

Notably, this became quite practicable after the recent fix in cd8018bc81a5.

diff --git a/src/event/quic/ngx_event_quic_output.c b/src/event/quic/ngx_event_quic_output.c
--- a/src/event/quic/ngx_event_quic_output.c
+++ b/src/event/quic/ngx_event_quic_output.c
@@ -109,7 +109,9 @@ ngx_quic_output(ngx_connection_t *c)
         ngx_add_timer(c->read, qc->tp.max_idle_timeout);
     }
 
-    ngx_quic_set_lost_timer(c);
+    if (in_flight != cg->in_flight) {
+        ngx_quic_set_lost_timer(c);
+    }
 
     return NGX_OK;
 }