[nginx] SPDY: always push pending data.

[Valentin Bartenev]

details:   http://hg.nginx.org/nginx/rev/c81d79a7befd
branches:  
changeset: 6059:c81d79a7befd
user:      Valentin Bartenev <vbart at nginx.com>
date:      Mon Mar 23 21:04:13 2015 +0300
description:
SPDY: always push pending data.

This helps to avoid suboptimal behavior when a client waits for a control
frame or more data to increase window size, but the frames have been delayed
in the socket buffer.

The delays can be caused by bad interaction between Nagle's algorithm on
nginx side and delayed ACK on the client side or by TCP_CORK/TCP_NOPUSH
if SPDY was working without SSL and sendfile() was used.

The pushing code is now very similar to ngx_http_set_keepalive().

diffstat:

 src/http/ngx_http_spdy.c |  91 +++++++++++++++++++++--------------------------
 1 files changed, 40 insertions(+), 51 deletions(-)

diffs (123 lines):

diff -r 7ba52c995325 -r c81d79a7befd src/http/ngx_http_spdy.c
--- a/src/http/ngx_http_spdy.c	Mon Mar 23 20:47:46 2015 +0300
+++ b/src/http/ngx_http_spdy.c	Mon Mar 23 21:04:13 2015 +0300
@@ -662,6 +662,7 @@ ngx_http_spdy_write_handler(ngx_event_t 
 ngx_int_t
 ngx_http_spdy_send_output_queue(ngx_http_spdy_connection_t *sc)
 {
+    int                         tcp_nodelay;
     ngx_chain_t                *cl;
     ngx_event_t                *wev;
     ngx_connection_t           *c;
@@ -710,6 +711,44 @@ ngx_http_spdy_send_output_queue(ngx_http
         goto error;
     }
 
+    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");
+            goto error;
+        }
+
+        c->tcp_nopush = NGX_TCP_NOPUSH_UNSET;
+        tcp_nodelay = ngx_tcp_nodelay_and_tcp_nopush ? 1 : 0;
+
+    } else {
+        tcp_nodelay = 1;
+    }
+
+    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;
+            goto error;
+        }
+
+        c->tcp_nodelay = NGX_TCP_NODELAY_SET;
+    }
+
     if (cl) {
         ngx_add_timer(wev, clcf->send_timeout);
 
@@ -3321,10 +3360,8 @@ 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             *c, *fc;
-    ngx_http_core_loc_conf_t     *clcf;
+    ngx_connection_t             *fc;
     ngx_http_spdy_stream_t      **index, *s;
     ngx_http_spdy_srv_conf_t     *sscf;
     ngx_http_spdy_connection_t   *sc;
@@ -3350,54 +3387,6 @@ 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) {