Added "keepalive_min_timeout" directive.

The directive sets a timeout during which a keepalive connection will
not be closed by nginx for connection reuse or graceful shutdown.

The change allows clients that send multiple requests over the same
connection without delay or with a small delay between them, to avoid
receiving a TCP RST in response to one of them.  This excludes network
issues and non-graceful shutdown.  As a side-effect, it also addresses
the TCP reset problem described in RFC 9112, Section 9.6, when the last
sent HTTP response could be damaged by a followup TCP RST.  It is important
for non-idempotent requests, which cannot be retried by client.

It is not recommended to set keepalive_min_timeout to large values as
this can introduce an additional delay during graceful shutdown and may
restrict nginx from effective connection reuse.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/http/ngx_http_request.h b/src/http/ngx_http_request.h
index 65c8333f8..9407f46ae 100644
--- a/src/http/ngx_http_request.h
+++ b/src/http/ngx_http_request.h
@@ -329,6 +329,8 @@ typedef struct {
 
     ngx_chain_t                      *free;
 
+    ngx_msec_t                        keepalive_timeout;
+
     unsigned                          ssl:1;
     unsigned                          proxy_protocol:1;
 } ngx_http_connection_t;