[PATCH] Upstream: flushing of event pipe on upstream timeouts

[Maxim Dounin]

# HG changeset patch
# User Maxim Dounin <mdounin at mdounin.ru>
# Date 1787278084 -10800
#      Fri Aug 21 05:08:04 2026 +0300
# Node ID bcfb58c2512522328beeb25ad8d54d754ecc41b3
# Parent  ea83a1624c33f405172b94403003f90e378cead8
Upstream: flushing of event pipe on upstream timeouts.

Previously, on upstream read timeouts data already read from the
upstream were not flushed.  With this change, similarly to the handling
of upstream read errors (see 6672:0fa883e92895), the data that were
previously read are processed and sent to the client, minimizing the
difference from the response as returned by the upstream server.

diff --git a/src/event/ngx_event_pipe.c b/src/event/ngx_event_pipe.c
--- a/src/event/ngx_event_pipe.c
+++ b/src/event/ngx_event_pipe.c
@@ -565,6 +565,21 @@ ngx_event_pipe_write_to_downstream(ngx_e
 
         if (p->upstream_eof || p->upstream_error || p->upstream_done) {
 
+            /* the first free buf is partially filled */
+
+            if (p->upstream_error
+                && p->free_raw_bufs
+                && p->free_raw_bufs->buf->pos != p->free_raw_bufs->buf->last)
+            {
+                /* STUB */ p->free_raw_bufs->buf->num = p->num++;
+
+                if (p->input_filter(p, p->free_raw_bufs->buf) == NGX_ERROR) {
+                    return NGX_ABORT;
+                }
+
+                p->free_raw_bufs = p->free_raw_bufs->next;
+            }
+
             /* pass the p->out and p->in chains to the output filter */
 
             for (cl = p->busy; cl; cl = cl->next) {
diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -4236,6 +4236,11 @@ ngx_http_upstream_process_upstream(ngx_h
         p->upstream_error = 1;
         ngx_connection_error(c, NGX_ETIMEDOUT, "upstream timed out");
 
+        if (ngx_event_pipe(p, 1) == NGX_ABORT) {
+            ngx_http_upstream_finalize_request(r, u, NGX_ERROR);
+            return;
+        }
+
     } else {
 
         if (rev->delayed) {