[PATCH] Proxy: set u->keepalive also if the whole body has already been read.

[Jan Prachař]

On Po, 2020-09-21 at 22:07 +0300, Maxim Dounin wrote:
> @@ -1915,7 +1916,7 @@
> >                  || u->headers_in.status_n == NGX_HTTP_NOT_MODIFIED
> >                  || ctx->head
> >                  || (!u->headers_in.chunked
> > -                    && u->headers_in.content_length_n == 0))
> > +                    && u->headers_in.content_length_n <= u->buffer.last-u->buffer.pos))
> >              {
> >                  u->keepalive = !u->headers_in.connection_close;
> >              }
> 
> I can't say I like the idea of connection cacheability to depend 
> on timing and buffer size factors.
> 
> Further, the "<=" comparison looks wrong: we shouldn't cache 
> connections if there are more data than expected.

Hello, I changed it in the following patch, in case you would like to use it. Now the
condition is more strict though, because previously was responsonses with Content-Lenght:
0 and non empty upstream buffer kept in connection cache.

# HG changeset patch
# User Jan Prachař  <jan.prachar at gmail.com>
# Date 1600710589 -7200
#      Mon Sep 21 19:49:49 2020 +0200
# Node ID e35b529b03781e64912e0d8a72bd0f957dc08cd2
# Parent  052ecc68d35038b1b4adde12efe6249a92055f09
set u->keepalive also if the whole body has already been read

diff -r 052ecc68d350 -r e35b529b0378 src/http/modules/ngx_http_proxy_module.c
--- a/src/http/modules/ngx_http_proxy_module.c	Wed Sep 16 18:26:25 2020 +0300
+++ b/src/http/modules/ngx_http_proxy_module.c	Mon Sep 21 19:49:49 2020 +0200
@@ -1905,7 +1905,8 @@
             }
 
             /*
-             * set u->keepalive if response has no body; this allows to keep
+             * set u->keepalive if response has no body or if the whole body
+             * has been already read to u->buffer; this allows to keep
              * connections alive in case of r->header_only or X-Accel-Redirect
              */
 
@@ -1915,7 +1916,7 @@
                 || u->headers_in.status_n == NGX_HTTP_NOT_MODIFIED
                 || ctx->head
                 || (!u->headers_in.chunked
-                    && u->headers_in.content_length_n == 0))
+                    && u->headers_in.content_length_n == u->buffer.last - u->buffer.pos))
             {
                 u->keepalive = !u->headers_in.connection_close;
             }