[nginx] Upstream: u->request_body_blocked flag.

[Maxim Dounin]

details:   http://hg.nginx.org/nginx/rev/22f7bdbd96d3
branches:  
changeset: 7231:22f7bdbd96d3
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Sat Mar 17 23:04:22 2018 +0300
description:
Upstream: u->request_body_blocked flag.

The flag indicates whether last ngx_output_chain() returned NGX_AGAIN
or not.  If the flag is set, we arm the u->conf->send_timeout timer.
The flag complements c->write->ready test, and allows to stop sending
the request body in an output filter due to protocol-specific flow
control.

diffstat:

 src/http/ngx_http_upstream.c |  21 +++++++++++++++++++--
 src/http/ngx_http_upstream.h |   1 +
 2 files changed, 20 insertions(+), 2 deletions(-)

diffs (63 lines):

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
@@ -1616,6 +1616,7 @@ ngx_http_upstream_connect(ngx_http_reque
 
     u->request_sent = 0;
     u->request_body_sent = 0;
+    u->request_body_blocked = 0;
 
     if (rc == NGX_AGAIN) {
         ngx_add_timer(c->write, u->conf->connect_timeout);
@@ -1994,7 +1995,7 @@ ngx_http_upstream_send_request(ngx_http_
     }
 
     if (rc == NGX_AGAIN) {
-        if (!c->write->ready) {
+        if (!c->write->ready || u->request_body_blocked) {
             ngx_add_timer(c->write, u->conf->send_timeout);
 
         } else if (c->write->timer_set) {
@@ -2071,7 +2072,16 @@ ngx_http_upstream_send_request_body(ngx_
             out = NULL;
         }
 
-        return ngx_output_chain(&u->output, out);
+        rc = ngx_output_chain(&u->output, out);
+
+        if (rc == NGX_AGAIN) {
+            u->request_body_blocked = 1;
+
+        } else {
+            u->request_body_blocked = 0;
+        }
+
+        return rc;
     }
 
     if (!u->request_sent) {
@@ -2112,6 +2122,13 @@ ngx_http_upstream_send_request_body(ngx_
                 ngx_free_chain(r->pool, ln);
             }
 
+            if (rc == NGX_AGAIN) {
+                u->request_body_blocked = 1;
+
+            } else {
+                u->request_body_blocked = 0;
+            }
+
             if (rc == NGX_OK && !r->reading_body) {
                 break;
             }
diff --git a/src/http/ngx_http_upstream.h b/src/http/ngx_http_upstream.h
--- a/src/http/ngx_http_upstream.h
+++ b/src/http/ngx_http_upstream.h
@@ -391,6 +391,7 @@ struct ngx_http_upstream_s {
 
     unsigned                         request_sent:1;
     unsigned                         request_body_sent:1;
+    unsigned                         request_body_blocked:1;
     unsigned                         header_sent:1;
 };