[PATCH 04 of 12] Upstream: simplified ngx_http_upstream_process_header()

[Maxim Dounin]

# HG changeset patch
# User Maxim Dounin <mdounin at mdounin.ru>
# Date 1754683248 -10800
#      Fri Aug 08 23:00:48 2025 +0300
# Node ID 367106bfe31eddfa021fab9403fcefdc8243bf72
# Parent  533246d275487cfbc51111e7ee05d0c014dd7d78
Upstream: simplified ngx_http_upstream_process_header().

This restores the simple loop structure which was somewhat screwed up
in 9237:41db21d1ca7c, and also removes some commented out artifacts of
the past.

Note that checking c->read->ready before the first c->recv() is not
required, since ngx_http_upstream_process_header() is an event handler
and it cannot be called multiple times in a loop.

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
@@ -2469,25 +2469,11 @@ ngx_http_upstream_process_header(ngx_htt
 
     for ( ;; ) {
 
-        if (c->read->ready) {
-            n = c->recv(c, u->buffer.last, u->buffer.end - u->buffer.last);
-
-        } else {
-            n = NGX_AGAIN;
-        }
+        n = c->recv(c, u->buffer.last, u->buffer.end - u->buffer.last);
 
         if (n == NGX_AGAIN) {
-#if 0
-            ngx_add_timer(rev, u->read_timeout);
-#endif
-
-            if (ngx_handle_read_event(c->read, 0) != NGX_OK) {
-                ngx_http_upstream_finalize_request(r, u,
-                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
-                return;
-            }
-
-            return;
+            rc = NGX_AGAIN;
+            break;
         }
 
         if (n == 0) {
@@ -2501,15 +2487,8 @@ ngx_http_upstream_process_header(ngx_htt
         }
 
         u->state->bytes_received += n;
-
         u->buffer.last += n;
 
-#if 0
-        u->valid_header_in = 0;
-
-        u->peer.cached = 0;
-#endif
-
         rc = u->process_header(r);
 
         if (rc == NGX_AGAIN) {
@@ -2523,12 +2502,26 @@ ngx_http_upstream_process_header(ngx_htt
                 return;
             }
 
+            if (!c->read->ready) {
+                break;
+            }
+
             continue;
         }
 
         break;
     }
 
+    if (rc == NGX_AGAIN) {
+        if (ngx_handle_read_event(c->read, 0) != NGX_OK) {
+            ngx_http_upstream_finalize_request(r, u,
+                                               NGX_HTTP_INTERNAL_SERVER_ERROR);
+            return;
+        }
+
+        return;
+    }
+
     if (rc == NGX_HTTP_UPSTREAM_INVALID_HEADER) {
         ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_INVALID_HEADER);
         return;