[PATCH 5 of 5] QUIC: ignore blocked status in congestion event handlers

[Roman Arutyunyan]

# HG changeset patch
# User Roman Arutyunyan <arut at nginx.com>
# Date 1690874694 -14400
#      Tue Aug 01 11:24:54 2023 +0400
# Node ID 80df0852e7ed58631025398694da6dd4dab42611
# Parent  cd0ef56b0f1afaa54d7d2756dad2182628445e04
QUIC: ignore blocked status in congestion event handlers.

Sometimes, while congestion window allows to send more bytes, the next frame
still cannot be sent since it's too big.  When this happens, push event is not
triggered from congestion ack/loss event handlers which may delay packet send.

Now the blocked status is ignored and push event is always posted when
congestion window grows bigger.

diff --git a/src/event/quic/ngx_event_quic_ack.c b/src/event/quic/ngx_event_quic_ack.c
--- a/src/event/quic/ngx_event_quic_ack.c
+++ b/src/event/quic/ngx_event_quic_ack.c
@@ -307,7 +307,6 @@ ngx_quic_handle_ack_frame_range(ngx_conn
 void
 ngx_quic_congestion_ack(ngx_connection_t *c, ngx_quic_frame_t *f)
 {
-    ngx_uint_t              blocked;
     ngx_msec_t              timer;
     ngx_quic_congestion_t  *cg;
     ngx_quic_connection_t  *qc;
@@ -319,8 +318,6 @@ ngx_quic_congestion_ack(ngx_connection_t
     qc = ngx_quic_get_connection(c);
     cg = &qc->congestion;
 
-    blocked = (cg->in_flight >= cg->window) ? 1 : 0;
-
     cg->in_flight -= f->plen;
 
     timer = f->last - cg->recovery_start;
@@ -358,7 +355,7 @@ ngx_quic_congestion_ack(ngx_connection_t
 
 done:
 
-    if (blocked && cg->in_flight < cg->window) {
+    if (cg->in_flight < cg->window) {
         ngx_post_event(&qc->push, &ngx_posted_events);
     }
 }
@@ -648,7 +645,6 @@ ngx_quic_resend_frames(ngx_connection_t 
 static void
 ngx_quic_congestion_lost(ngx_connection_t *c, ngx_quic_frame_t *f)
 {
-    ngx_uint_t              blocked;
     ngx_msec_t              timer;
     ngx_quic_congestion_t  *cg;
     ngx_quic_connection_t  *qc;
@@ -660,8 +656,6 @@ ngx_quic_congestion_lost(ngx_connection_
     qc = ngx_quic_get_connection(c);
     cg = &qc->congestion;
 
-    blocked = (cg->in_flight >= cg->window) ? 1 : 0;
-
     cg->in_flight -= f->plen;
     f->plen = 0;
 
@@ -690,7 +684,7 @@ ngx_quic_congestion_lost(ngx_connection_
 
 done:
 
-    if (blocked && cg->in_flight < cg->window) {
+    if (cg->in_flight < cg->window) {
         ngx_post_event(&qc->push, &ngx_posted_events);
     }
 }