[nginx] SPDY: push pending data while closing a stream as with k...

[Valentin Bartenev]

details:   http://hg.nginx.org/nginx/rev/2c10db908b8c
branches:  
changeset: 5923:2c10db908b8c
user:      Valentin Bartenev <vbart at nginx.com>
date:      Fri Nov 21 22:51:49 2014 +0300
description:
SPDY: push pending data while closing a stream as with keepalive.

This helps to avoid delays in sending the last chunk of data because
of bad interaction between Nagle's algorithm on nginx side and
delayed ACK on the client side.

Delays could also be caused by TCP_CORK/TCP_NOPUSH if SPDY was
working without SSL and sendfile() was used.

diffstat:

 src/http/ngx_http_spdy.c |  52 +++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 51 insertions(+), 1 deletions(-)

diffs (70 lines):

diff -r 68f64bc17fa4 -r 2c10db908b8c src/http/ngx_http_spdy.c
--- a/src/http/ngx_http_spdy.c	Thu Nov 20 20:02:21 2014 +0300
+++ b/src/http/ngx_http_spdy.c	Fri Nov 21 22:51:49 2014 +0300
@@ -3317,8 +3317,10 @@ ngx_http_spdy_close_stream_handler(ngx_e
 void
 ngx_http_spdy_close_stream(ngx_http_spdy_stream_t *stream, ngx_int_t rc)
 {
+    int                           tcp_nodelay;
     ngx_event_t                  *ev;
-    ngx_connection_t             *fc;
+    ngx_connection_t             *c, *fc;
+    ngx_http_core_loc_conf_t     *clcf;
     ngx_http_spdy_stream_t      **index, *s;
     ngx_http_spdy_srv_conf_t     *sscf;
     ngx_http_spdy_connection_t   *sc;
@@ -3344,6 +3346,54 @@ ngx_http_spdy_close_stream(ngx_http_spdy
         {
             sc->connection->error = 1;
         }
+
+    } else {
+        c = sc->connection;
+
+        if (c->tcp_nopush == NGX_TCP_NOPUSH_SET) {
+            if (ngx_tcp_push(c->fd) == -1) {
+                ngx_connection_error(c, ngx_socket_errno,
+                                     ngx_tcp_push_n " failed");
+                c->error = 1;
+                tcp_nodelay = 0;
+
+            } else {
+                c->tcp_nopush = NGX_TCP_NOPUSH_UNSET;
+                tcp_nodelay = ngx_tcp_nodelay_and_tcp_nopush ? 1 : 0;
+            }
+
+        } else {
+            tcp_nodelay = 1;
+        }
+
+        clcf = ngx_http_get_module_loc_conf(stream->request,
+                                            ngx_http_core_module);
+
+        if (tcp_nodelay
+            && clcf->tcp_nodelay
+            && c->tcp_nodelay == NGX_TCP_NODELAY_UNSET)
+        {
+            ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "tcp_nodelay");
+
+            if (setsockopt(c->fd, IPPROTO_TCP, TCP_NODELAY,
+                           (const void *) &tcp_nodelay, sizeof(int))
+                == -1)
+            {
+#if (NGX_SOLARIS)
+                /* Solaris returns EINVAL if a socket has been shut down */
+                c->log_error = NGX_ERROR_IGNORE_EINVAL;
+#endif
+
+                ngx_connection_error(c, ngx_socket_errno,
+                                     "setsockopt(TCP_NODELAY) failed");
+
+                c->log_error = NGX_ERROR_INFO;
+                c->error = 1;
+
+            } else {
+                c->tcp_nodelay = NGX_TCP_NODELAY_SET;
+            }
+        }
     }
 
     if (sc->stream == stream) {